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ELECTRICITY IN
2020
Wind – Natural Gas – Solar – Hydro
A powerful switch:
Balancing the needs of the
economy and the environment as we
feed the world’s hunger for electricity
A special publication in cooperation with the Siemens Energy Sector
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Approach with clarity
Act with vision
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C O MMENTARY
CONTE N T S
Wolfgang Hess,
editor-in-chief
3 Commentary
4 Electricity
Electric power is growing in
importance and helps to save energy
wolfgang.hess@konradin.de
10 “Germany needs a good dozen
combined cycle power plants”
Interview with Siemens Energy CEO
Michael Suess
The fatal earthquake that struck Japan on March 11, 2011, followed by the
devastating tsunami and the resulting failure of the Fukushima nuclear power
plant, was an event that dramatically underlined the limits to modern society’s
technological powers, by demonstrating that even a power plant built to the
highest standards of nuclear safety is not immune to the risk of catastrophic
failure.
After the earthquake in Japan, political and public opinion in Germany
quickly swung around to a consensus that nuclear power was on its way out.
Federal Chancellor Angela Merkel called for a fundamental change in the
country’s energy policy, which from now on should give greater emphasis to
renewable energy sources, power plants with reduced CO2 emissions, and energysaving technologies, capable of meeting Germany’s electricity needs without
placing an excessive burden on the environment or unnecessarily depleting
natural resources.
Since then, new voices have joined the debate, calling into question Germany’s
envisaged schedule and the choice of the right approach. In January 2012, a
group of 30 energy scientists warned that the government’s plans were doomed
to failure. An increasing number of ordinary citizens have lost confidence in
green energy solutions and returned to an attitude of “not in my backyard”. This
regressive trend is counterproductive. If the country is to meet its ambitious
goals and ring in a new energy era, steps must be taken to smooth the way
forward and establish fixed milestones. After all, Germany has already signed
a commitment to cover at least 35 percent of its energy requirements from renewable sources such as solar and wind energy by the year 2020; and to increase
this share to 80 percent by 2050. So it is high time to conclude the necessary
agreements that will accelerate technological developments, simplify approval
procedures, and define financial incentives.
This special supplement, compiled in collaboration with Siemens AG, shows
examples of power generation technologies and their present capabilities, and
indicates where the greatest progress has been made in recent years. The
Siemens viewpoint is an interesting one because the company’s Energy Sector
sells its products to customers in many different regions of our globalized
economy, and therefore has to adopt an approach that extends well beyond
its domestic market – to the benefit of its employees at home in Germany.
For the bild der wissenschaft editorial team, our collaboration with Siemens
has opened doors that normally remain closed to journalists. Ralf Butscher,
for instance, who headed the project to publish this special supplement, had
the privilege of visiting the prototype of a gigantic 6-megawatt wind farm in
north-western Denmark. I myself had the chance to look around the Ulrich
Hartmann power plant in Irsching, only a few days after the validation of its
world record for efficiency.
14 A new lease of life
Modernizing gas turbines to meet
future energy challenges
16 Winged giants
More and more energy is being harvested
by gigantic offshore wind farms
24 The whirlwind
Henrik Stiesdal takes the wind industry
by storm with his novel ideas
28 Transform without tears
Fraunhofer president Hans-Joerg Bullinger
on Germany’s energy transformation
30 No need to worry about energy shortages!
We still have plenty of resources
35 Arteries for green power
HVDC transmission links form the
backbone of tomorrow’s electricity grid
Cover design: Peter Kotzur; Photos: ullstein bild/Chromorange/C. Ohde; ccvision.de
W. Scheible for bdw
Energy transformation: The way and the means
38 World record – and what next?
The world’s most efficient gas-fired power
plant is operating in Irsching, Bavaria
“Electricity 2020”:
global perspectives
for a sustainable
future in which
electricity is 100
percent renewable
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E L E C T R I C I T Y G E N E R AT I O N
It may already be an essential part of our lives,
but electricity’s true time is yet to come. It is turning into the
most important source of energy the world over – and putting
huge energy savings within our grasp.
BY TIM SCHROEDER
THE FUTURE is electric, and there are
many good reasons for this. Instead of
using crude oil, cars can in future be powered by electricity – ideally generated
by wind farms or photovoltaic plants.
Electric drives are much more efficient
than internal-combustion engines, which
saves lots of energy. They also avoid
emissions on the spot. Experts predict
electricity demand to be almost 70 percent higher by 2030. The world’s power
plant fleet will also experience astonishing growth, with installed capacity
set to expand from today’s 5,000 gigawatts (GW) to anywhere up to 10,500
GW, according to various estimates.
This growth is equivalent to up to
8,000 new large power stations; taken
together with some 2,000 GW of expected decommissioning over the next
20 years, it means around 7,000 GW of
new plant capacity will need to be built
– or more than today’s entire global
installed capacity.
Given the quantities of carbon dioxide
that humans are already releasing into
the atmosphere, this is a truly alarming
prospect. Currently, most electricity is
generated in power stations that burn
coal, gas or oil – except in certain countries that rely primarily on nuclear power.
So there are two questions that must
be answered for the future: how can
we meet the demand for electricity? And, more importantly,
4
how can we minimize emissions of the
greenhouse gas carbon dioxide (CO2)?
There is no easy answer, since the solutions are as varied as each country’s
requirements. In Europe, demand for
electricity is high, but efficient technologies have kept growth down in recent
years. The picture in the Far East couldn’t
be more different. In India, many regions
are not even connected to the power
grid and blackouts are an everyday
occurrence in many areas. Here, the
primary goal is to roll out a comprehensive and reliable supply of power –
something Europeans take for granted.
Meanwhile, China will continue to build
power stations to meet rising demand in
its flourishing industrial centers. So it is
no surprise that one in three of the new
power stations set to come on stream
by 2030 will be built either in China or
in India.
In Europe, green energy is very much
in vogue. In the USA, on the other
hand, customers just want
their electricity to be as
cheap as possible. While the details of
electricity’s future vary wildly from
country to country, what needs to be
done overall is pretty clear. The Intergovernmental Panel on Climate Change
(IPCC) has judged that the world’s climate should be allowed to warm up by
no more than two degrees Celsius above
pre-industrial levels if humans are to be
spared the worst outcomes of the greenhouse effect. “According to analyses
carried out by the International Energy
Agency (IEA), the cuts in greenhouse-gas
emissions this target entails will above
all have to come from energy efficiency
measures and an expansion of renewables,” says Manfred Fischedick, Vice
President of the Wuppertal Institute for
Climate, Environment and Energy.
50 percent of the necessary CO2 reduction could be achieved through energy
efficiency and 20 percent through
green energy. The IEA thinks
the remaining CO2 emissions
could be avoided by
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Technology developed by Siemens engineers makes it possible to capture over 90
percent of the CO2 produced in coal-fired
power stations that would otherwise harm
the atmosphere.
far less CO2 into the atmosphere. The
carbon dioxide can in turn be employed
in the oil & gas industry. A study the experts in Erlangen are currently conducting on behalf of the US energy supplier
Summit Texas Clean Energy provides a
picture of how this could work in practice. The plan is to set up a urea plant
based on coal gasification together with
an associated 400 megawatt gas-fired
power plant. The CO2 released by the
chemical process would be stored in oil
fields, with the happy side effect of increasing their oil output. It also makes
sense to capture carbon dioxide in steel
works and cement works, which are
among the biggest energy consumers.
“In terms of CCS, all it takes is
a bit of joined-up thinking.
There are plenty ways
Westend61/F1 online
Nicolas Vortmeyer, an expert in fossil
power generation for Siemens Energy in
Erlangen. The carbon dioxide can then
for instance be pumped into depleted
natural-gas fields deep underground
and stored there. This process is known
as Carbon Capture and Storage (CCS).
Vortmeyer is aware that large sections
of Germany’s population oppose both
major new power stations and the storage
of carbon dioxide underground. But the
technology is being welcomed with open
arms in other countries – including China
and the USA.
For Vortmeyer, the carbon dioxide is
much more than an unwelcome byproduct. “It is essentially a high-quality
chemical product.”If a power station is
built next to a chemical plant, the chemical plant can benefit from coal gasification to produce high-quality chemicals and at the same time provide the
power station with low-carbon fuel
gas. Burning this gas releases
Siemens
capturing the carbon dioxide produced
in power stations and by using nuclear
power. Regardless of developments in
Germany, the IEA is expecting nuclear
power to be a major source of electricity
for many years in some countries such
as South Korea. Coal, the world’s biggest source of CO2, will continue to be
the primary fuel for power generation
in China and India, since it is cheap and
available in large quantities. According
to current calculations, more than a
third of the world’s electricity will still
be generated using coal in 2030.
“There is only one way for this electricity to be generated in a largely climateneutral way: by fitting coal-fired power
stations with equipment to filter the exhaust gases and remove the CO2,” says
Positive trend: Electricity is
growing in significance all
around the world. This makes it
even more important to produce
it in climate-friendly ways.
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E L E C T R I C I T Y G E N E R AT I O N
A huge building site in the belly of the mega-dam:
Chinese workers install the stator for a hydroelectric
plant beneath the Three Gorges Dam. Its six hydroelectric turbines have a total capacity of 4.2 gigawatts.
Over the next 10 years, demand for electricity will develop in very different ways from one country to another. Forecasts suggest
that energy consumption will stagnate in Germany and most other European countries, while consumption is predicted to rocket
in newly industrialized countries such as China and India. Experts expect electricity consumption to approximately double in China
by 2020 and to increase threefold in India over the same period. Both countries are primarily relying on coal to keep pace with
rising demand, though renewable energy sources are also playing an increasingly important role.
6
bdw graphics; sources: bdew, Statistisches Bundesamt, prb, India Ministry of Power, China Daily
GROWTH AND STAGNATION
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A bird’s-eye view of the Kranzberg
hydroelectric plant, close to the town of
Freising in Bavaria: Small hydro plants
have proven to be a practical and intelligent source of energy.
Picture Press; Siemens
to make use of carbon dioxide,” says
Vortmeyer before adding that the technology is definitely affordable. In a comparison with other electricity generating
technologies that cause CO2 emissions,
coal power stations plus CCS are in a
good position. It costs little more than
electricity generated by onshore wind
turbines and can be a lot cheaper than
power from offshore wind.
GREENHOUSE GAS CAPTURED BY SALTS
The engineers in Vortmeyer’s team have
developed their own CO2 capturing
process in which the greenhouse gas
sticks to what are known as aminoacid salts. CO2 is normally captured by
spraying an ammonium solution into
the flue gas. But ammonium is poisonous
and reacts quickly with oxygen. The
new salt used by Siemens is both more
robust and non-toxic. Since 2009 an
amino-acid salt test facility has been in
operation at the Staudinger coal-fired
power station in Grosskrotzenburg, in Germany’s Hesse region. Now the Norwegian
This scenario developed by the International Energy Agency (IEA) shows how
available global power plant capacity might evolve in the future. Many existing
plants with capacities greater than 5,000 gigawatts will reach the end of their
service life and be decommissioned over the course of the next 25 years. They
will largely be replaced by plants that produce electricity from renewable energy
sources such as wind, solar and hydro, though natural gas and coal will continue
to play an important role. According to the IEA’s estimates, total installed capacity
will reach some 9000 gigawatts by 2035.
government is working with companies
such as energy giant Statoil to see whether the facility is suitable for use on an
industrial scale. Norway is looking to
store the captured CO2 in depleted oil and
gas fields.
In global terms, coal is nowhere near
losing its preeminence in electricity generation. So for a climate-friendly future
we must above all look to new, efficient
technologies that can be applied to
electricity consumption. Harald Bradke,
Head of the Competence Center Energy
Technology and Energy Systems at the
Fraunhofer Institute for Systems and
Innovation Research ISI in Karlsruhe,
thinks the greatest potential for more
efficient use of electricity lies in industry. In Germany, industry accounts
for 40 percent of total electricity consumption. Of this share, no less than 70
percent is used to drive electric motors
and the equipment they power, such as
compressors, pumps and ventilators.
The problem is that energy efficiency is
usually low down on managers’ priority
bdw graphics; source: IEA; E. Carin/Photos.com
THE FUTURE IS GREEN
lists; their focus is on productivity, revenue growth and product quality. “When
buying machinery, many companies look
first and foremost at price,” says Bradke.
“But energy costs generally make up 80
percent of machinery’s lifetime costs, so
you can save a whole lot of money by
using efficient technology.”
Piping systems consume vast amounts
of electricity. The flow of liquid within
pipelines is controlled via flow control
valves, and it is here that the energy
from the pumps that push the liquid
through the pipelines is lost. A simple
solution is at hand: employ speed control that matches the pump’s output to
the current demand – with no need for
flow control valves. Bradke realizes that
there is still much to be done to convince
people of the merits of this approach,
which is why Fraunhofer ISI together
with partners launched the “30 pilot
networks” project a number of years
ago. Each network is made up of 10 to
15 companies whose members not only
receive professional energy efficiency
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Siemens
E L E C T R I C I T Y G E N E R AT I O N
advice individually but also share their
experiences directly. On average, this
brings down companies’ annual energy
consumption by two to three percent.
“It might not sound like much, but if
all German energy users did likewise,
no further action would be needed for
Germany to meet its share of the twodegree target for global warming,” says
Bradke. The initiative is set to be expanded to comprise 300 to 600 networks over
the next few years, and a delegation of
energy experts who visited from China
recently is also keen to take up the model.
Current estimates suggest that renewables’ share of global electricity supply
in 2030 could reach 13 percent. Today’s
figure is 4 percent. Germany and the EU
are aiming even higher, with an EU target for electricity from renewables of 20
percent by 2020 – and as much as 80 percent by 2050. But supplies of wind and
therefore of electricity are variable; as
the proportion of green electricity rises,
these supply swings become more severe, causing instability in the power grid.
One solution would be to set up a smart
grid linking wind energy, solar power
and biogas plants with consumers such
as electric cars and matching them all together. This would mean e-vehicles could
charge their batteries whenever power
was most plentiful in the grid.
Manfred Fischedick is convinced that
additional large energy storage facilities
will also be needed in future to soak
up electricity when too much is being
generated and then release it back to the
grid when the winds slacken. “The idea
of using this electricity to produce hydrogen is an old one, but still relevant,”
says Fischedick. Alternatives are thin on
the ground: it’s no simple matter to dot the
countryside with the large reservoirs
needed for pumped-storage hydroelectric
plants; and sufficiently large and affordable batteries are also a long way off.
HYDROGEN FOR THE GAS GRID
The hydrogen could be fed into the
existing network of natural-gas pipelines
and burned on demand in gas-fired power
stations. Blending standard natural gas
with some 5 to 10 percent hydrogen would
present no problems. “Of course, converting electricity into hydrogen and
back again gives rise to energy losses,”
says Manfred Fischedick, but that is
better than simply turning off wind turbines when demand is low.
Producing eco-friendly hydrogen for
modern gas-fired power plants is a solution that should be taken seriously, because
gas-fired power plants are now entering
into a golden age. Gas is cleaner to burn
than coal. What’s more, gas-fired power
stations have the flexibility to meet variations in demand and swings in the
supply of wind and solar energy. Not so
coal-fired power stations, which are best,
left to run flat out once they have been
started up, since the technology involved
is cumbersome. The latest forecasts give
gas a 24 percent share of global electricity generation in 2030. Clearly, burning gas to generate electricity also
releases carbon dioxide, so adding hydrogen would be a way to reduce these CO2
emissions.
Volkmar Pflug is also certain that hydrogen has a role to play as a storage medium
Washing machine
for exhaust
gases: E.ON and
Siemens are using
a pilot facility at
the Staudinger
coal-fired power
station to test the
capturing of carbon
dioxide. The picture
shows a technician
testing components
in the laboratory.
8
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bdw table graphics; source: Siemens
Different countries and regions face different challenges when it comes to securing
future electricity supplies. Some countries such as India, China and nations in the
Middle East are facing sharp increases in electricity demand. Other countries are
primarily concerned with improving the efficiency of power plants and energyconsuming systems and reducing atmospheric pollution by limiting climatedamaging emissions from electricity generating plants. Following the nuclear meltdowns in three reactors at its Fukushima plant, Japan needs to rapidly find ways of
switching from nuclear power to other energy sources.
for electricity. “We’ve developed an electrolyzer for splitting water (in the process known as electrolysis) which allows
us to generate large quantities of hydrogen,” says Pflug, an energy expert at
Siemens Energy. Today’s gas grid already
provides the infrastructure necessary for
getting hydrogen to consumers.
A green electric future will only come
about if effort goes into some other areas
too – in terms of both consumption and
generation. And each country has its
own ideas about how to proceed. Denmark is looking to meet 100 percent of
its electricity demand from renewable
sources by 2050, predominantly through
wind power. Poland, on the other hand,
has lots of coal and wants to use it. Here,
CCS would be a more climate-friendly
option. And France continues to favor
nuclear power. But on one point there
is agreement: all European nations want
to further expand renewables. Many experts are of the opinion that renewables
could make up at least 20 to 30 percent
of electricity generation in the next 10 to
20 years.
As the success of Germany’s renewable energy law shows, national promotion policies can achieve much. But in
other instances it is up to industrial companies to take the lead. The quantities of
energy that they stand to save are considerable. This is no less true in the oil
& gas industry, since the production and
refining of these fuels is in itself very
energy-intensive. A fair few of the relevant facilities are decades old and were
built in times when the topics of energy
efficiency and climate change were on
nobody’s agenda.
It is estimated that some 200 to 250
GW of power is required around the
world for the production and transportation of crude oil and natural gas
alone. By way of comparison, Germany’s
entire installed power generation capacity adds up to around 170 GW. What’s
more, up to 20 percent of the oil and
gas produced is itself consumed in the
process of production and transportation, as well as in downstream processing in refineries and the petrochemicals industry. “Modern technology
could halve this figure,” says Hendrik
Jogschies, an oil & gas expert working
for Siemens in Duisburg, for instance by
replacing pumps and compressors that
are powered by gas turbines with electrically driven ones; electric motors are
simply much more efficient.
Compressors and turbines in many oil
& gas facilities spend much of the time
operating at partial load, just in case
one of the machines breaks down. For
safety’s sake they all run simultaneously, since it takes a while after they are
started up for them to get up to speed.
On the other hand, a replacement electric motor takes no time at all to start up,
and in the event of an outage it can reach
full load in a very short time. This means
that electricity is not merely consumed;
it also helps to save energy. As Manfred
Fischedick from the Wuppertal Institute
says, “The priority now is to make the
right decisions and install the most
modern and efficient technology without
delay.”
■
P. Langrock
EIGHT REGIONS – EIGHT DIFFERENT APPROACHES
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INTERVIEW
“Germany needs
a good dozen combined
cycle power plants”
For Michael Suess, Member of the Managing Board of Siemens AG, some elements
of the feed-in tariff under the German Renewable Energy Act are in some parts
clearly misdirected. Nevertheless, he describes Germany with view to a modern
power generation system as a powerful example for other industrial countries.
INTERVIEW BY RALF BUTSCHER AND WOLFGANG HESS
Siemens Energy (2)
Siemens recently received the German
Industry Innovation Award for its world
record breaking power plant in Irsching.
Congratulations, Dr. Suess!
Michael Suess: I thought it was great that
the Fossil Power Generation Division
managed to apply for it, because the
pressure of day-to-day business often
means such things can’t be done. It is
recognition of our sustainable corporate management. After all, a full ten
years have passed since the Siemens
Managing Board decided to embark
on a new generation of gas turbines,
a development which had to prove its
worth within the company two or three
times. Launching a new gas turbine
poses a considerable risk. Some manufacturers have wasted hundreds of millions of euros by developing products
with the wrong specifications.
What have you learned from those kinds
of failed ventures?
We have minimized the risk by using all
available modern development tools –
even to the extent of being able to take
a virtual tour of the machine. It was
fantastic that we were able to realize the
validation process for the new power
plant together with the present plant
10
operator E.ON. That gave us a far better
understanding of the optimization than
just a development in the test environment. The result: Our very first newgeneration product has even achieved
an efficiency level of 60.75 percent,
certified by the Technical Control Board,
and more than 61 percent in testing. The
plant has now been running smoothly
for several thousand hours. That’s a
unique achievement and it demonstrates that Germany still has the ability
to launch highly innovative technological products on the market.
Did you ever have any doubts about
whether the project would succeed?
To be honest, I didn’t. But of course
we had a ‘Plan B’ up our sleeves! One
of the most heavily debated points
when we started was whether the gas
turbine should be steam or air cooled.
Steam cooling would have actually
nudged the efficiency level even higher,
but in the end we chose air cooling
because it allows the plant to be used
more flexibly. And that fits exactly to
the needs of the market.
What prospects do you see for combined cycle power plants which use a
combination of gas and steam turbine
technology?
Combined cycle power plants already
form the backbone of the electricity
supply in many regions of the world.
If we intend to take the issue of CO2
emissions seriously, we will need to
replace a lot of existing coal-fired power
plants with gas-fired power plants.
So are coal-fired power stations on the
way out?
We certainly need to phase out old
coal-fired plants, but that’s not easy
in regions with a massively growing
energy demand such as India, China,
Southeast Asia and Eastern Europe.
They can hardly afford to shut down
fully functional coal power stations
there, even if the plants have a poor
efficiency and are big polluters. Gasfired power plants do, however, offer
an exciting opportunity. If we replaced
the existing power plants with stateof-the-art coal and gas-fired plants,
then we could cut CO2 emissions from
power plants by a third. And if we
were to replace the world’s entire fleet
of power plants with the most modern
natural gas-fired combined cycle power
plants, then we could reduce CO2
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emissions even further, by around two
thirds. Obviously that is a somewhat
abstract analysis which is far removed
from the current situation, but it shows
how much potential this technology has.
Are we at least heading in the right
direction here in Germany?
We need to change tack quite considerably. Our enthusiasm for promoting
renewables has created an unchecked
system of feed-in tariffs for photovoltaic
installations. A few years ago that was
a sensible way of giving the photovoltaic industry a helping hand. But
now it has led to a situation where six
out of every seven gigawatts of photovoltaic capacity installed each year in
Germany use technology from China
– a technology that is six or seven
years old. And we will be continuing
to promote this obsolete technology for
another 20 years under the German Renewable Energy Act without mandating
any increases in efficiency. In contrast
to this, coal and gas-fired power plants
in Germany have to be modernized and
upgraded after 10 years at the latest to
meet cost efficiency expectations.
So you are quite critical of the guaranteed feed-in tariff?
I’m critical of it because by introducing
it we have eliminated any incentive to
invest in state-of-the-art technology. I’m
very glad that politicians are now starting
to react by reducing the subsidies for
solar panels significantly. We have to
balance the boom in fluctuating renewables with guaranteed conventional
generation capacity; otherwise we will
run into problems. But the market
opportunities for modern combined
cycle power plants are severely
limited in Germany at the
moment.
Every winter we hear about bottlenecks
in the gas supply from Russia. Doesn’t
it worry you that our modern gas-fired
power plants might end up sitting idle if
Russia turns off the gas?
There is plenty of gas available, and we
have huge gas reserves in Germany!
The problem occurs when suppliers
or wholesale gas buyers fail to scale
their contracts properly in order to be
Even with record-breaking
efficiencies…?
For electricity utilities in
Germany, combined cycle
power plants are power producers which are only switched
on during peak load periods, so
they are only used for around
1000 or 1500 hours a year. That
means their capacity utilization
is too low to warrant the
investment.
MICHAEL SUESS
has been a Member of the Managing
Board of Siemens AG and CEO of
Siemens Energy since 2011. After
studying mechanical engineering at
Munich Technical University, he began
work as a production engineer at BMW
in 1989 while pursuing his doctorate
at the Institute of Ergonomics and
Process Management at the University
of Kassel, which he completed in
1995. Suess worked at MTU from 2001
to 2006. In October 2006, he moved
to Siemens as a Member of the Group
Executive Management of the Power
Generation Group. Suess, who was
born in 1963, describes Siemens as
“the world’s leading energy company”.
At least 80,000 of Siemens’ 360,000
employees work in the energy sector,
one third of them in Germany.
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INTERVIEW
able to obtain gas at the pre-negotiated
prices also when demand rockets. The
real challenge in Germany is to replace
nuclear power stations with modern
gas-fired power plants and wind power.
From a technical perspective, we can
install combined cycle power plants
at exactly the same locations as our
existing nuclear power stations, because
those sites offer rivers for cooling, transformers, power lines and everything
else you need to feed power outputs in
excess of 1000 MW into the grid.
How many combined cycle power plants
would you say Germany needs in conjunction with renewable electricity sources in
order to provide secure foundations for
industry?
Approximately the same number as
the nuclear power plants that had been
in use so far, about a good dozen. But
that would only work if the combined
cycle power plants could be operated
for at least 3000 hours a year.
So what do you think should be done?
We need to move away from the
regulation of the electricity market
back towards the process of deregulation that we successfully embarked
on in 1998. Our current approaches
are forcing us towards a completely
regulated energy market. Moreover,
this regulated energy market actually
contains an unsocial component, because house owners who install solar
panels on their roof receive generous
subsidies under the feed-in legislation:
That turns the energy market into the
plaything of profit-oriented investors,
which never should have happened.
…Speculation has always been an
integral part of the business practices in
this country!
The energy market is the lifeblood of
modern industrialized societies. In fact,
you can only build up a modern industrialized society if you have access to
three key factors: People with the right
know-how, capital and energy. None
of these three critical factors should
become the plaything of speculators:
Not people, not capital, and not the
energy market.
12
So you consider the Renewable Energy
Act to have been a wrong turn?
The Renewable Energy Act is, in
essence, the right approach, and it
has made a valuable contribution by
triggering positive developments and
encouraging the use of wind power and
solar energy. But now it has become
outdated, and it is being abused by
financial investors. Germany already
has some 25 gigawatts of installed
photovoltaic capacity. If we are really
serious about cutting CO2 emissions
then we should be focusing on installing solar panels on Greek islands
or in southern Italy, for example.
Furthermore, one should push for the
replacement of low-efficiency coal-fired
power plants by modern technology.
That would make far more sense than
investing in wind farms in places like
the Swabian Jura or fitting more solar
panels to houses in the Ruhr region,
which is not exactly sun-drenched!
People in Germany seem to be stuck in
a provincial or regional stance on this
issue instead of thinking on a European
or global level.
You are unhappy with how Germany
subsidizes the photovoltaic sector, but
at the same time Siemens is a global
player in electricity generation from
wind power. Surely you also benefit from
legislation modeled on the Renewable
Energy Act in that field?
The installation of wind turbines is
an industrial business, not a subsidydriven financial investment that
photovoltaic has become in Germany.
By continuing to industrialize the construction of wind turbines we can cut
costs and, in the medium term, bring
the generation costs down to a level
which can compete with conventional
sources of electricity. This cost reduction
is important: An offshore wind farm of
comparable capacity costs five times as
much as a combined cycle power plant.
The fact that offshore wind turbines
do not have any fuel costs and have
lower operating costs means that any
reduction in the cost of their construction will result in a significantly more
favorable overall assessment. That is
an exciting challenge. And no other
manufacturer is meeting that challenge
as successfully as Siemens – that’s why
we are the world’s number one in offshore wind farms and are successfully
earning money in this business.
What is Siemens’ current market share?
We lead the way in the offshore sector
and are a long way ahead of our
competitors. Our market share in this
sector will probably level out at about
50 percent in the future.
If wind turbine manufacturers are no
longer earning any money, how can
things continue?
The gold rush mentality that prevailed
between 2008 and 2010 has evaporated.
Over the next two or three years we can
expect to witness a range of turbulent
developments and some companies will
throw in the towel. Nevertheless, the
world will never achieve a sustainable
renewable energy supply without wind
power, quite simply because wind
offers such tremendous generating
capacity in many regions of the world.
What is Siemens doing to reduce the
cost of building offshore wind farms?
Up to 70 percent of the costs are
attributable to the foundations, towers,
connection and installation rather
than to the turbine itself. That’s why
it’s important to build bigger turbines.
Compared to one of today’s threemegawatt standard wind turbines, a
six-megawatt wind turbine would eliminate the need for one additional support
structure, while a 12-megawatt wind
turbine would save us having to build
three additional support structures! If,
on top of that, we succeed in making
the turbines lighter – which we have
managed to do with our gearless, directdrive wind turbines – then we can
reduce the weight of the overall system
by 200 tons. That simplifies the design
of the support structure, which makes
further cost savings possible. We are a
long way ahead of our competitors in
these aspects. The prospects are also
looking good for turbine blades. At the
moment we are developing a new blade
design almost every year, each time
producing a solution that makes better
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and better use of the available wind
energy. Siemens is better placed than
traditional wind turbine providers: We
develop and produce wind turbines
that work with gearboxes as well as
without a gearbox and we can connect
the turbines to the grid ourselves. All
of that adds value and is coupled with
a breathtaking pace of innovation!
How do you think electricity consumption will develop from here, both in
Germany and worldwide?
Siemens takes the view that we will
hardly see any more growth in Germany
at all, and consumption will remain
roughly at today’s level of 600 terawatthours a year. In contrast, global
electricity consumption will probably
increase by more than two thirds, rising
from 22,000 terawatt-hours to 37,000
terawatt-hours by 2030. That would
mean we would need to add power
plant capacity of approximately 7000
gigawatts, which is equivalent to the
output of 10,000 conventional large
power plants. To illustrate what that
means, all the world’s power plants
currently connected to the grid have a
total installed capacity of 5000 gigawatts.
‚‚
to become an industrialized society with
a sustainable energy supply. For me,
this is an ambitious and very positive
perspective. And this process of transformation is being driven by a broad
social consensus that extends across
all the political parties.
Is there really a consensus?
People in Germany have always been
enthusiastic about industrial production, and technical professions are as
respected as ever. Even politicians are
essentially in agreement on the goals
– though there is certainly far less of
a consensus on what measures we
should take. Cooperation between key
stakeholders is working and produces
quick results when it comes to major
challenges. Just think back to the
study published by the Massachusetts
Institute of Technology (MIT) in 1993
saying that the German car industry
was unproductive and in a terrible
state. And just look at the car industry now! I can see the energy sector
heading in a similar positive direction,
and I think that other countries will
subsequently follow our lead. Japan is
already looking to Germany to discover
how to move forward without nuclear
power. The problem is that we sometimes muddle up hopes with facts, react
over-emotionally and end up punching
holes in otherwise solid arguments.
It’s difficult to predict whether we will
really achieve the goal of producing 35
percent of our electricity from renewable
sources exactly by 2020. But even if it
takes us a little longer than anticipated,
Germany will soon have a balanced
electricity generation portfolio that
includes gas, wind, solar, hydro and
coal. And the world can use that as a
model. One critical point is to ensure
that the technologies that Germany
sells to the world also have to be used
here in Germany. If record-breaking
combined cycle power plants were no
longer wanted in Germany, then other
countries would stop and think twice
before buying them – and, ultimately,
that would result in the CO2 problem
getting even worse.
■
How would you rate Germany’s efforts to
move towards a cleaner, more sustainable
energy economy?
Calculated on the basis of its size and
output, Germany is the world’s leading
industrial nation. And it has decided to
follow an entirely new path: It intends
Japan is already looking to
Germany to discover how to move
forward without nuclear power.
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EFFICIENCY
A new lease of life
New gas turbines are more efficient than old ones. But with a complete overhaul, even the
oldest equipment can be upgraded to meet the latest standards, significantly extending its
operating life.
Power plant rejuvenation:
The gas turbines of the
990-megawatt Tapada do
Outeiro plant in Portugal
were modernized after 13
years in service.
Siemens (2)
BY BERND MUELLER
MORE POWER – Only ten years ago, this
wish ranked high on the plant operators’
list when they set out to modernize their
old gas turbines. Manufacturers can fulfill this wish by fitting new blades and
combustion chambers. This can easily
boost performance by up to six percent
and improve efficiency by at least one
percentage point, which correspondingly lowers fuel costs and raises profit
margins.
But times are changing, and today’s
gas turbines are required to operate with
greater flexibility in order to cope with
the increasing integration of alternative
power sources in the grid and the widely
fluctuating input of energy from the sun
and the wind. Instead of being started up
in the morning and shut down at night,
14
today’s turbines have to cope with several start-stop cycles each day. And they
are frequently required to operate in a
low-power regime. For example in bright
sunny weather, when the output of the
many photovoltaic installations connected to the grid is at its maximum, the
performance of the gas turbines has to
be throttled down to 50 percent of their
rated capacity, or even 38 percent in the
case of more modern plants.
All modern gas turbines manufactured by Siemens have this turndown
capability, enabling them to reduce their
output to a small percentage of their
rated capacity and start up again with
the minimum of delay. But even older
models are capable of responding more
flexibly to such load fluctuations if they
have been modernized accordingly. One
possible solution is to modify the technical parameters of the variable inlet
guide vanes on the compressor, with
corresponding modifications to the control system. With a wider setting range
for the first row of guide vanes, the air
mass flow rate can be reduced further,
so that the combustion process runs at
a lower output but nonetheless delivers
good efficiency.
SPRINKLER SYSTEM FOR COMPRESSORS
Even if part-load operation has become
more important to gas-turbine operators, they are equally interested in ways
of further increasing peak performance.
They need this to discharge additional power into the grid at short notice,
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“Availability is of utmost importance to
us,” says Carlos Carqueja, the plant’s
technical director. The three 330-megawatt gas-turbine units had accumulated
100,000 operating hours at an availability of 98 percent. During the overhaul,
Siemens replaced all of the burners and
compressor blades. The gas turbines are
now fit for another 100,000 operating
hours and 3,000 starts, and the maintenance agreement has been renewed for
a further twelve years.
Each year, Siemens modernizes between 20 and 30 old gas turbines. The
cost to the operator ranges from a few
thousand to several million euros – depending on whether this “simply” involves replacing hardware components
in the gas turbine – such as compressor
and turbine blade assemblies or parts of
the combustion chamber – or whether
it is also necessary to upgrade the control system to optimize plant operation.
In either case, it is still cheaper than
buying a new gas turbine and, more
importantly, the plant is back online
much sooner. With a modernized or
overhauled turbine, the customer can
be earning money again within a matter
of weeks, instead of having to wait up
to two years – the time it takes on average from tendering to commissioning of a new gas turbine. “In the
long-term, a Lifetime Extension
definitely saves costs,” says
Dirk Kampe, an expert in
this subject at Siemens
Energy.
Lifetime Extension and other
performance
SIEMENS_2012_Innen1-23.indd 15
60 %
55 %
50 %
45 %
40 %
35 %
The efficiency of new gas power
plants has increased by 50
percent since 1960. Combined
cycle (gas and steam turbine)
power plants are particularly
efficient, with today‘s designs
notching up efficiencies of
more than 60 percent.
Bituminous coal-fired power
plants are slightly less efficient, yet even they have seen
a steady increase in energy
yield over recent decades.
30 %
25 %
20 %
15 %
10 %
5%
2015
2010
2000
1990
1980
1970
1960
1950
1940
1930
1920
0%
1910
compensating for sudden dips in supply when the wind drops or a bank of
clouds obscures the sun. The solution
is a technique known as wet compression, which can also be retrofitted to
older-generation gas turbines. It could
be compared to a sprinkler system,
which sprays fine droplets of water into
the compressor inlet in order to increase
the relative humidity of the air to 100
percent. The evaporating water cools
the air flow at the compressor inlet,
increasing the mass flow through the
compressor. As a result, more fuel is
converted into energy in the combustion chamber, enabling a gas turbine
with a rated output of 290 megawatts
to temporarily boost its output by an
additional 35 megawatts. Another solution frequently chosen by Siemens
customers is to equip their gas turbines
with 3D-optimized blades, which the
company developed from 2000 onward
and can be retrofitted to older gas turbines on request. This measure alone
can increase conversion efficiency by up
to 1.3 percentage points, significantly
reducing fuel consumption and carbondioxide emissions.
No less than 1,500 Siemens gas turbines are currently in operation around
the world, many of them for over ten
years. With regular maintenance, they
can be expected to remain in service
for 40 years. As a rule, operators generally envisage an overhaul after 10 to 15
years, when age-related maintenance
costs, according to experience, are
likely to increase. An overhauled gas
turbine is almost as good as new and
capable of providing reliable service for
several more decades.
The operator of the Tapada do Outeiro
power plant in Portugal opted for a
Lifetime Extension, as Siemens calls
its rejuvenation plan for gas turbines,
after approximately 13 years in service.
1900
Images: bdw; Content: Siemens, E.ON
Small changes
with a big impact:
Even the slightest
design modifications can improve
gas turbine efficiency.
enhancement programs are a worthwhile investment for the gas turbine
manufacturers too. Customer relationships based on long-term contracts are
of benefit to all concerned: the customers gain from lower prices and longer
availability of spare parts, and Siemens
benefits from more reliable planning.
The manufacturer is also able to offer
maintenance contracts that guarantee
certain operating characteristics. If, for
example, the gas turbine is designed
with more flexibility in mind, in order
to deal with the higher proportion of
solar and wind energy being fed into
the grid, the maintenance contract can
guarantee a greater number of start-stop
cycles or improved part-load operation,
as well as a defined output capacity and
efficiency.
What’s more, there is no limit to the
number of times one and the same gas
turbine can be modernized. Dirk Kampe:
“It is perfectly feasible to carry out a
second Lifetime Extension to
rejuvenate a previously
modernized plant.” ■
31.07.12 10:32
WIND POWER
Dynamic growth: The use of wind power
has picked up huge momentum worldwide. Giant blades such as those on this
six-megawatt turbine will be spinning
above offshore waters
in the future.
BY RALF BUTSCHER
16
Sea coast, to test the prototype of a new
wind turbine – the SWT-6.0-120. The
name indicates a power rating of 6 megawatts and a rotor diameter of 120 meters,
a category of turbine which is currently
the pinnacle of technology for converting
wind into electricity.
The test site in this rural idyll illustrates how researchers and engineers are
preparing for the future of energy supply.
These huge rotating blades are ultimately
destined for offshore wind power plants,
out on the open sea where the conditions are excellent for harvesting wind
energy. Offshore winds blow more consistently and, on average, more strongly
than on land, which means they can
be used to generate considerably more
electricity each year from the power of
the wind. Wind turbines in near-offshore
areas are capable of supplying some 40
to 50 percent more electricity than turbines in good land-based coastal areas.
THE BOOM BEGAN 10 YEARS AGO
The wind energy boom got underway in
Germany around a decade ago. Fuelled
by the German Renewable Energy Act,
which guaranteed a high minimum feedin tariff for renewable electricity sources
when it came into force in April 2000,
the number of wind turbines skyrocketed, especially in windy areas such as
north and east Germany and on highland peaks. Germany gradually took on
a pioneering role in generating energy
through wind power, and in 2002 it
overtook hydroelectric power to become
P. Langrock for bdw (3)
WITH A FAINT RATTLING SOUND, the elevator makes its way up the steel shaft
inside the giant tower and comes to a
gentle halt. Climb a few more meters up
a ladder and through a hatchway, and
you find yourself in a large room which
looks like a carefully tidied workshop.
Yet a glance out the window is enough to
remind you that you are actually inside
the nacelle of a huge wind turbine,
some 90 meters above the ground. This
enormous tower is just one of the many winged giants that loom over the
grassland and drainage ditches directly
behind the dike in Høvsøre, a small municipality in the north-west of Denmark.
Since May 2011, engineers from Siemens Wind Power have been working
here, within sight of the Danish North
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Winged
Giants
In the future, more and more electricity will be produced by offshore wind power
plants. This will call for wind turbines that are particularly robust and efficient.
Trial run in the
factory yard:
Testing out turbines at Siemens
Wind Power in the
Danish town of
Brande.
Room with a
view: On top of
the nacelle of
a six-megawatt
prototype, some
90 meters above
the ground.
the most important renewable energy
source in Germany’s energy supply
network. Today, some six percent of
the country’s electricity is generated by
wind power. Between 1999 and 2011,
the total installed capacity of Germany’s
wind turbines climbed from five to 30
gigawatts – and the German Wind Energy Association predicts that this latter
figure will double again by 2020.
This growth in the wind turbine sector
will increasingly take place at sea. By
2030, the German federal government
plans to have offshore wind farms in the
North and Baltic seas supplying up to 25
gigawatts of power, and the Hamburgbased Federal Maritime and Hydrographic Agency has already set aside large
areas out at sea for this purpose. More
than two dozen planning applications
for offshore wind power plants – a total
of some 8 gigawatts of installed capacity
– have already been approved, and several wind power plants are under construction. In April 2010, the first German
offshore wind power plant came online
some 45 kilometers off the North Sea
island of Borkum. Known as ‘alpha ventus’, it is primarily intended as a test
facility. The first commercial offshore
wind power plant went into operation
in the Baltic Sea in May 2012. The 21
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wind turbines supplied by Siemens for
the ‘EnBW Baltic 1’ wind farm generate
up to 185 gigawatt-hours of electricity
a year, enough to supply some 50,000
households.
Denmark took to the seas considerably
earlier than Germany. Bonus Energy, a
company that has been part of Siemens
since 2004, built the world’s first offshore wind power plant, ‘Vindeby’, in
A service technician checks
external equipment on a giant
wind turbine at a test site on
Denmark’s North Sea coast.
Danish waters in 1991. Since then, however, it is the UK that has become the
world’s leading market for offshore wind
development thanks to the frequent lowpressure fronts that offer such good wind
production off its coasts. It already has
more than a dozen offshore wind power plant hooked up to its national grid,
including ‘Walney’, the world’s biggest
offshore wind farm, which was put into
operation in the Irish Sea in February
2012. The farm consists of 102 Siemensmade turbines capable of producing up
to 370 megawatts of power.
British plans for developing offshore
wind power are significantly more ambitious than those of their German counterparts. Some wind farms off the UK’s
P. Langrock für bdw (2)
WIND POWER
Landing site for maintenance personnel:
A spacious platform on top of the nacelle
allows service technicians to be lowered
onto the wind turbine from a helicopter.
This makes it easier to access offshore
wind farms far out at sea.
18
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coast will be built on a truly extraordinary scale. One example is the ‘London
Array’ – already under construction in
the outer reaches of the Thames estuary
– which will have an installed capacity
of one gigawatt (1000 megawatts) when
the final stage is completed. The initial
stage of 175 wind turbines is scheduled
to come on line by the end of 2012.
A wind farm with an energy output
of up to 4.2 gigawatts is already being
planned for the Irish Sea, while an even
bigger wind farm of 9 gigawatts has
been given the go-ahead on the Dogger
Bank in the North Sea. The next round
of offshore projects, Round 3, has seen
approval granted for an additional 32
gigawatts of new capacity. The aim is
to cover a quarter of the UK’s total electricity needs using offshore wind power
by 2020. In Germany, progress has been
markedly slower.
One important caveat is that harnessing wind power is far more challenging
out at sea than on land. Swells and salt
water gnaw away at the towers unless
specific steps have been taken to protect
them. Constructing the wind turbines
and anchoring them to the ocean floor
require extraordinary technical and logistical skills, especially if the foundations are more than 100 kilometers away
from the coast and are submerged in 40
meters of water – the situation facing
most of the offshore wind farms being
planned in Germany. Maintaining the
turbines is a costly and sometimes dangerous process, with wind and waves
making access difficult. Storms and
heavy rain often make it impossible for
the service engineers to reach the turbines at all.
DEMAND FOR NEW CONCEPTS
Researchers and developers – for example
the team led by Henrik Stiesdal, Chief
Technology Officer (CTO) of Siemens
Wind Power, in the Danish town of Brande
(see p.24. “The whirlwind”) – are therefore seeking new concepts and feats of
engineering to create wind turbines that
are highly robust and reliable and easy
to install. Above all, they are aiming to
boost performance based on the fundamental precept that the more power a
wind turbine can produce, the greater its
efficiency – in other words, the greater
its ability to pull energy out of the wind.
Maximizing energy output is a crucial
consideration, especially when building
offshore wind power plants.
However, greater capacity inevitably
means larger dimensions, and the current flagships of the wind turbine sector
are already enormous. The six-megawatt
giant off Høvsøre, for example, features
a tower more than 90 meters high which
is equipped with three blades covering
a diameter of some 120 meters. The tips
of these extraordinarily long blades can
reach speeds of up to 300 kilometers an
hour in strong winds. By mid of 2012,
the six-megawatt class will include a
second machine featuring a new rotor
with a diameter of 154 meters.
Over the last 30 years, there has been a tremendous increase in both the installed
capacity and size of wind turbines. In the future, offshore wind farms could feature
wind turbines with 200-meter rotor diameters that are capable of generating 20 megawatts of power.
bdw graphics; sources: German Wind Energy Association (BWE), German Wind Energy Institute (DEWI),
German Renewable Energies Agency; image: Photos.com
TREMENDOUS GROWTH
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WIND POWER
In the past, Siemens has primarily
used turbines from the 2.3 and 3.6-megawatt categories for offshore wind farms,
but, in the future, the plan is to use powerhouses such as the six-megawatt colossus to capture energy from offshore
wind. Prototype testing at the Danish
test site on the North Sea coast is going
well, and the new wind turbines have
also demonstrated their efficiency in an
accelerated life testing program carried
out at the Siemens Wind Power site in
Brande. These tests apply a dynamic
load to individual components such
as the blades in order to simulate the
forces they will be exposed to during 20
years of operation. By the end of 2013,
Siemens hopes to have installed a preseries version of the six-megawatt wind
turbine at various sites in Denmark,
Germany, Great Britain and the Netherlands. Series production is scheduled to
begin in 2014. The giant machines will
be assembled at a port site and then
transported by ship to their offshore
destination.
In the future, wind farm operators
will be able to choose between different
variants of this Herculean construction
of steel and concrete. The largest version
will have a rotor diameter of 154 meters,
making it bigger than any wind turbine
ever built before. Yet despite their enormous size, these wind turbines are astonishingly lightweight. The combination
of the tower head and rotor blades of
the Høvsøre prototype weighs in at just
350 tons. The nacelle weighs 200 tons
– only marginally more than the weight
of a nacelle in a wind turbine offering
half as much energy output.
focusing on to take the technology to
the next level. The ingenious Dane often
refers to the cubic law of wind power in
this context: Doubling the rotor size of
a wind turbine quadruples the energy
yield – and results in an eightfold increase in weight. “Our job is to overcome
that law,” says Stiesdal. The six-megawatt wind turbine marks the first occasion that Siemens developers have succeeded in breaking this rule – primarily
thanks to the use of ‘direct drive’ technology. Instead of using complex, heavy
gearboxes to convert the rotation of the
blades into faster revolutions to drive an
SAME WEIGHT, GREATER CAPACITY
Significantly more power with a minimal
increase in weight: That’s the solution
Siemens Wind Power CTO Stiesdal is
Wind strength varies across Europe, but it blows especially
hard over the North Sea and off the coast of Scotland. The
wind power densities are mean values and do not take topography into account.
20
bdw map graphics; sources: Risø DTU
WIND IS CAPRICIOUS
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A door at the base of the steel tower
provides access to an elevator which
can take service technicians up to the
nacelle in a matter of minutes.
take up so much room, so it feels very
different to the oppressively cramped
interior of the nacelles used in older
wind turbines. On the rare occasions
that maintenance or repairs are required, the service technicians can use
this extra space to work and sleep in. The
turbine also features a platform on top
of the nacelle which provides helicopter access for maintenance personnel,
thereby avoiding long and arduous boat
journeys and the risky climb from the
boat to the base of the tower.
The direct drive concept paves the
way for even bigger and more powerful
wind turbines. In fact, Siemens engineers
are already working on wind turbines
that will be capable of producing up to
10 megawatts of electricity. “We expect
them to be commercially viable sometime
after 2015,” says Stiesdal. Experts even
consider 20-megawatt wind turbines
to be feasible. As part of the European
project UpWind, researchers from various companies, universities and public
institutions from all over Europe developed the technological basis for very
large wind turbines of the future. These
could have a rotor diameter of 200 meters
or more.
However, sheer size is not the only
consideration. Developers also have a
whole series of technical innovations
up their sleeves which are designed
to increase the energy output of wind
turbines. For example, the blades on
more recent models are equipped with
a device known as a ‘winglet’, a kind
of mini-spoiler which is positioned on
the wing tips to avoid the problem of
tip vortices.
A similar purpose is served by small
slits in the blades and saw-shaped
grooves on the edges of the blades. “In
2013, we also plan to test initial prototypes of wind turbines with scimitar
blades,” says Stiesdal. Modeled on the
oriental weapon of the same name,
these blades are aerodynamically optimized to exhibit the least possible air
resistance when they rotate.
In the future, new materials will help
to reduce weight and enhance turbine
efficiency. For example, lightweight yet
extremely durable carbon fiber composites will replace the fiberglass mats
A majestic sight: A giant wind
turbine towers over fields
and grassland in north-west
Denmark on the North Sea
coast.
that are typically used to produce rotor
blades, while aluminum and plastic
will replace the steel in the nacelles. At
the same time, extensive automation
of turbine operation and maintenance
could help reduce costs. All new wind
turbines produced by Siemens over the
last ten years come with a Condition
Monitoring System which monitors the
functions and status of the turbine and
sounds the alarm as soon as there is any
risk of something going wrong. In the
future, an interactive controller should
make it possible to control the wind turbine systems from land.
PLUNGING ELECTRICITY COSTS
Ultimately, all these developments are
aimed at reducing the cost of generating energy from wind power to a level
comparable to conventional gas and
coal-fired power plants. Currently, one
kilowatt-hour of electricity from a coalfired or nuclear power station costs
between four and five eurocents on the
European Energy Exchange. Michael
Weinhold, Chief Technology Officer at
Siemens Energy in Erlangen, reckons that
P. Langrock for bdw (3)
electrical generator – the method employed in most current wind turbines –
the Siemens direct drive technology uses
a magnet generator to generate electrical
power directly from the mechanical rotation of the blades. This gearless solution
reduces the number of moving parts in
a turbine by almost 50 percent, resulting
in considerable weight savings and lower
construction costs.
One handy knock-on effect of gearless
wind turbines is that they require less
frequent maintenance thanks to the
smaller number of wear parts – just one
example of a trend towards making wind
turbine technology simpler.
The machine room of the SWT-6.0
is considerably more spacious without
the bulky gearbox that would normally
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WIND POWER
bdw map graphics; sources: EWEA
WIND POWER HEADS OFFSHORE
The countries that border the North Sea and the Baltic Sea have big plans to generate electricity in offshore wind farms. The first offshore
wind farm went into operation off the south-east coast of Denmark in 1991. Today, Germany and Great Britain are leading the way in
the development of offshore wind turbines. Sweden, Spain, Norway and France are also planning numerous wind farms out at sea.
electricity generated by wind turbines at
good land-based sites could be available
at approximately the same price in just
a few years time. In the case of offshore
wind farms, it could take slightly longer
to achieve a price level that can compete
with electricity from conventional power
22
plants. Yet Weinhold is confident that by
2020 even offshore wind power should
be capable of producing electricity at a
competitive cost.
In the meantime – largely thanks to
government subsidies – the use of wind
power is expanding in leaps and bounds,
not only in Europe, but also in Asia and
North America. Over the last few years,
China has become the world’s biggest
market for wind power, representing almost a quarter of total global installed
capacity in 2010 with its more than 42
gigawatts of wind turbine installations.
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Siemens
20 turbines, 40 megawatts of installed capacity: When
the Middelgrunden wind farm went into operation off the
coast of Copenhagen in the year 2000, it was the largest
offshore wind farm in the world. More recent projects are
on a far bigger scale.
The USA is the second biggest market,
with Germany in third place. In 2010,
almost every second gigawatt of new
capacity was installed in Chinese wind
farms.
Currently, most new wind turbines
are still being built on land, but offshore
wind farms are also gradually picking up
momentum in many parts of the world,
including China. Current plans envisage
the installation of wind turbines with a
total capacity of 30 gigawatts in China’s
coastal waters by 2020.
In contrast, Germany’s wind farms in
the North and Baltic Seas are progressing slower than hoped. This is partly
due to the cost, which is higher than in
countries such as Denmark and Great
Britain because the offshore locations
are further from the coast. A further
obstacle is the sluggish pace at which
transmission lines are being installed
to bring the electricity to land and
transport it to the main centers of consumption (see p. 35, “Arteries for green
power”).
Offshore wind farms can only be connected to the grid by installing current
collectors at sea and laying cables, some
of which may be several hundred kilometers long. Wind turbine manufacturers such as Siemens are braving harsh
environments to carry out pioneering
work in this field. They plan to install
high-tech wind turbines far out at sea –
in some cases more than 100 kilometers
from the coast – which are designed to
generate power for decades under the
most severe weather conditions.
■
FLOATING TURBINES
Many parts of the world have long coastlines with lots of wind, but
are still not suitable for building offshore wind power plants. In many
such areas, the sea floor drops off so steeply that the water gets too
deep just a few kilometers out – for example, off Norway, Japan, and
the West Coast of the USA. One solution is floating wind turbines,
whose towers are not set firmly on the sea floor in the usual way, but
anchored to it by long steel cables. One technical concept for such
floating systems has been developed by the Norwegian oil and gas
conglomerate Statoil, working jointly with Siemens.
A first full scale prototype of the “Hywind” has been undergoing
a trial run since the fall of 2009, about 20 kilometers offshore from
the coast near the southern Norwegian city of Stavanger. The unit
comprises a tower that rises 65 meters to the hub, supporting a
Siemens wind turbine with a capacity of 2.3 megawatts. As a counterweight to the gondola, the tower, and the three rotor blades, a steel
cylinder filles with ballast of water and extends almost 100 meters
below the water’s surface. Three steel mooring lines hold the turbine
firmly in place in 200 meters of water. To keep the system stable in the
swell, the engineers included a stabilizer system: sensors measure
the water movement and an electronic control calibrates the floating
turbine so that it always remains stable even in high seas. “Stabilizing
the unit is the biggest technical challenge in Hywind,” says Kristin
Aamondt, a Project Manager at Statoil Wind Energy in Stavanger.
The trial run of more than two years was almost trouble-free, and
quite promising. The turbine ran almost without downtime, and
supplied significantly more electricity than the Statoil experts had
expected. In 2011, Hywind produced over 10 GW hours of electricity
energy, or the equivalent to power over 600 Norwegian homes.
Statoil is assessing locations for developing a small pilot park of 3-5
turbines which would test the next phase of the concept, .equipped
with higher-power turbines. “From depths of about 30 meters on out,
it’s most likely going to be cheaper to build a floating turbine than
one standing on the sea floor,” Aamondt says. Floating wind turbines
are technically feasible out to depths of about 700 meters – which
will make it possible to tap vast additional potential from the power
of the wind over the sea.
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PROFILE
Henrik Stiesdal
The whirlwind
He built his first large-scale wind
turbine on his parents’ farm when
he was just 19 years old. Today, he
is a wind power visionary and an
award-winning inventor who produces a steady stream of technical
innovations.
Ideas need to be put
into practice: Henrik
Stiesdal’s invigorating
inventiveness has already given substance
to many of those ideas.
24
HENRIK STIESDAL IS PASSIONATE about
the wind. One glance at the Chief
Technology Officer (CTO) of Siemens
Wind Power on this cloudy morning is
enough to tell you that. He is holding a
meeting with his team and a colleague
from the marketing department in his
glass-walled office in the Danish town
of Brande. A lively discussion is underway about a wind energy exhibition
at the German Museum of Technology
in Berlin. Siemens – one of the special
exhibition’s sponsors – has been offered
the chance to present its perspective on
the uses of wind power to the museum’s
visitors.
Stiesdal’s enthusiasm is palpable as
he briskly outlines his idea on the blackboard, accompanied by animated gestures and rousing explanations that say
it all. The man chosen by Siemens as
‘Inventor of the Year’ in 2008 and ‘Top
Innovator’ in 2010 is brimming over with
bright ideas. The Brande-based CTO
is adamant that the museum visitors
should be offered more than just a few
colorful posters and dry explanations,
insisting that they should be given the
opportunity to gain a real insight into
the topic of the exhibition. This calls for
an exhibit that is in motion, tangible, capable of vividly showing how a modern
P. Langrock for bdw (4)
BY RALF BUTSCHER
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wind turbine works and revealing the
technical tricks experts use to make
wind turbines so remarkable.
The spirited Dane ploughs on into
the details of how that could work, occasionally injecting spontaneous new
thoughts. He argues that the company
must surely have some components in
storage somewhere or other that could
be used to build the exhibit, and, if not,
then it will just have to be built from
scratch; and maybe they could take this
opportunity to come up with an information leaflet for school classes too!
The people listening are clearly enthusiastic and quickly convinced that he is
on the right track. They leave the office
and get straight down to work.
When Henrik Stiesdal has a brainwave, he likes to see it put into practice
right away. Postponing things that he
considers to be important is as intolerable to him as having exhausting,
fruitless discussions about side issues
or allowing innovative projects to be
derailed by pedantic skeptics. What on
earth should stand in the way of putting
a good idea into practice to try it out?
This passion for research has motivated the 55-year-old throughout his entire
life – and has helped him achieve some
impressive results. His first success
came in late 1976 at the age of 19 when
he painstakingly constructed the first
of his hand-made wind turbines. The
ambitious Dane had just completed his
university entrance examinations. “It was
around the time of the big oil crisis,”
Stiesdal recalls. The multinational oil
companies in the Arab countries had
cut back the supply of oil, causing the
price of black gold to rocket. Stiesdal’s
parents, who ran a farm close to Brande,
were hit hard by the resulting spike in
prices. “The oil crisis made it almost impossible to even buy fuel for the stove,”
says Stiesdal, recalling how his parents’
farm was plunged into difficulties.
The crisis prompted a surge in efforts
to find alternative sources of energy.
Stiesdal himself was spurred on by a
competition organized by Tvind – an
alternative Danish educational organization – under the motto “Let’s build
the biggest wind turbine in the world!”
Stiesdal poured his heart and soul into
the project. “The task of building a
wind turbine had just the right degree of
difficulty about it,” he says. “It was far
from easy – but it was possible.” His first
wind turbine consisted of two blades
made of laminated wood which he had
mounted on a piece of water pipe. “You
could hold the wind turbine in your
hand to keep it steady. It was a fantastic
experience!” His second wind generator
was mounted on a trailer and could be
turned into the wind for test purposes.
Eventually he built a large wind turbine
which was designed to produce electricity for his parents’ farm.
“Back then there were hardly any
manuals or other sources of information on how to build a wind turbine,”
Stiesdal explains. But that didn’t stop
him from putting his plan into action.
He gleaned the basic information he
needed on mechanical and electrical
engineering from reference books, but
otherwise he relied on his technical instincts and his inexhaustible supply of
off-beat ideas.
The young handyman made the ninemeter-long blades of his wind turbine
out of wood and picked up the machine
parts he needed from a scrap yard at
a knockdown price. A few weeks later,
the farm was in proud possession of a
Starting small:
The first wind turbines from Brande
were very modest
in size. Nowadays
the facility produces systems on
a giant scale.
12-meter-high wind turbine which, on
good days, was capable of producing 15
kilowatts of power. It was only in 1991,
after almost 15 years in operation, that
the turbine finally succumbed to the ravages of the Danish climate.
AN EMOTIONAL MOMENT
For Stiesdal, the completion of his first
wind turbine was a “very emotional
moment”. “The first time the wind set
the blades in motion, I felt as though the
machine had come to life,” he recalls.
“I had this great feeling of having built
something that served a real practical
purpose.” Buoyed by the success of his
engineering skills, he felt an intimate
relationship with the power of the wind
which would never leave him. Not long
after, he and a friend worked together on
the farm to come up with a new and improved version of his hand-made wind
generator. In 1979, they licensed their
design to the company Vestas in Aarhus,
which used their plans as a blueprint for
producing a commercial system.
Stiesdal spent seven years working
for Vestas, and his innovative designs
played a major role in the company’s
success. Alongside this fledgling career,
he began studying medicine – a sidestep
from engineering which proved to be
a short-lived episode in the life of this
passionate inventor. “I loved the scientific
side of it, studying anatomy, physics, and
the brain. But three years later, when
the time came to actually get down to
work in a hospital, I quickly realized
that it wasn’t where I wanted to be,”
Stiesdal says, explaining how his love
of engineering caused him to switch his
studies to physics and biology.
Despite all the hard work he put into
studying the ‘hard’ sciences, he never
lost sight of his main goal, which was
to improve the technology used to harness wind power and make it broadly
acceptable as a serious competitor to
coal, oil and nuclear energy. He parted
ways from Vestas in 1986 when he realized that his aims did not coincide with
those of the management at the time.
In 1987, he started working for Bonus
Wind Energy, where he discovered a
“unique combination of sound, conservative business practices and a fantastic
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PROFILE
Visible success:
Numerous wind
turbines waiting
to be shipped
from the Siemens
facility in the
Danish town of
Brande.
pioneering spirit”. He was promoted to
managing director within his first year
and became part of a small management team responsible for guiding the
company’s fortunes. When Bonus was
incorporated in the Siemens Group in
2004, the Danish wind energy pioneer
played a major part in the negotiations.
This pioneering spirit lives on in
Brande to this day, especially in one
particular laboratory situated behind
one of the large production halls. The
lab contains electron microscopes and
a range of other ultra-modern devices
that members of Stiesdal’s team use to
investigate the ageing of materials for
wind turbines. Visitors are only invited
into this research laboratory in exceptional cases – an indication of how crucial it
is to maintain a technological advantage
over the competition in the wind energy
industry, and how determined Stiesdal
is to retain this competitive edge.
The enthusiasm for innovation that
motivates the wind power expert and
his team is also on display two floors beneath his office, where the ‘Black Bird’
waits in readiness for its next flight. The
eagle-sized flying machine, which was
developed and built by Brande employees, is packed full of electronics and
equipped with a powerful camera. These
generate maps that are accurate to the
nearest meter and serve as the basis for
forecasting wind yield. The artificial bird
can be sent out to fly over a designated
area on a pre-programmed route to capture numerous razor-sharp images. A
software program compiles the crystalclear pictures into a three-dimensional
representation of the area which makes
26
every tree and elevation visible. This detailed rendering can then be transferred
into what is known as a computerized
fluid dynamics (CFD) model. By studying the layout of the land, it is possible to
determine how the wind will blow across
the area. This provides valuable assistance in choosing the best site to erect a
wind turbine. In 2011, the artificial bird
with the eagle eye was used for the first
time to help plan a new wind farm.
TWO PILLARS OF SUCCESS
Siemens Wind Power – a business unit
of Siemens Energy formed in 2004 following the acquisition of Bonus Wind
Energy – has established itself as one
of the leading suppliers of onshore and
offshore wind power solutions and currently has orders worth nearly 11 billion
euros. Stiesdal argues that its success
is based on two key pillars: Innovation
and quality. To illustrate this point, he
points to two elongated objects next to
his desk: They are cut-up pieces of wind
turbine blades, one made by Siemens
and the other by a competitor.
“The standard approach is to make
blades from two components by sticking
them together – but we make our blades
from a single piece.” To manufacture this
‘integral blade’, epoxy resin is injected
into a pre-formed die under a vacuum.
The die contains fiberglass mats which
combine with the resin to produce a
highly robust blade. Its hollow interior
is formed into the right shape using a
kind of inflatable balloon.
Stiesdal first came up with the idea for
this innovative manufacturing technique
back in the 1990s. Currently, Siemens
is the only manufacturer that uses this
technique to produce its blades, some
of which are made in a factory in Aalborg.
“The blades we produce there are the
world’s biggest fiberglass components
to be made from a single mold,” Stiesdal
says enthusiastically. That makes the
giant wind turbine blades particularly
robust and durable – and the manufacturing process itself is clean and environmentally friendly: “Visitors often
comment on the fact that our production facility in Aalborg is the only glass
fiber plant that doesn’t smell of glue!
The only thing you notice is the smell of
the balsa wood that we use in the blades”.
Interestingly enough, the adhesive-free
manufacturing process actually makes
the blades cheaper to produce than
conventional versions, rather than more
expensive. Well aware of the ups and
downs of the development process, Stiesdal is doubly proud to have achieved two
goals in one stroke by reducing costs and
improving quality at the same time.
Alongside innovations, the other key
issue that inspires the energetic Dane is
quality. “Quality is our greatest asset,”
he says, explaining how the drive for
quality has been rapidly assimilated by
staff at Siemens Wind Power as one of
their key guiding principles.
Stiesdal focuses on creating wind
turbines that last longer and operate
smoothly and reliably. To illustrate just
how long his team has been achieving
that goal, he likes to share an anecdote
from the period when the Siemens Group
was negotiating the acquisition of Bonus
Wind Energy. As usual in a business
deal of that nature, the Siemens experts
asked to see a list of the complaints filed
by Bonus customers. “But we simply
didn’t have a list of customer complaints,” says Stiesdal – not because of
slack bookkeeping, but simply because
it was standard practice in Brande to
accept claims before they were even put
down in writing. “It took a long time for
our puzzled counterparts from Munich
to actually get their heads around the
fact that we weren’t joking!”
Even the hundreds of wind turbines
in California which the Danish company
acquired from other manufacturers in
the 1980s and subsequently equipped
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with technology from Brande are still
mostly running without a hitch. “Siemens’
quality standards are just as rigorous as
the ones we applied at Bonus,” says
Stiesdal emphatically. “That’s why the
merger of the two companies worked so
well right from the start.”
He is quick to point out, however,
that sitting back and basking in the excellent reputation their products enjoy
is not an option if they want to maintain their leading position in the wind
energy market. The idea of resting on
his laurels would anyway go against
the very nature of this restless inventor,
who can already lay claim to some 200
patents, and who develops many of his
ideas on the daily train journeys between
his home in Odense and his office in
Brande 120 kilometers away.
One thing Stiesdal is convinced of
is that the technological development
of wind turbines will be making great
strides in the future. “One of the hottest
topics at the moment is the use of new
materials for blades and other components,” he says, noting that many wind
turbines will be offshore in the future,
in some cases dozens of kilometers
away from the coast. The main thing that
counts out at sea is size, because the infrastructure costs of larger wind turbines
do not increase at the same rate as their
energy yield. To ensure that the winged
giants remain manageable despite their
huge dimensions, engineers are seeking
to build them from even lighter materials.
“Carbon fiber composites will play a
major role in the construction of offshore
wind power plants in the future,” Stiesdal
suggests, shrewdly aware of the advantages of this technology even though it is
significantly more expensive than fiberglass. But the wind energy experts from
Brande are also focusing on improved
steels and new design concepts for the
wind turbines themselves. “We already
have a lot of promising ideas in the pipeline,” Stiesdal says – something that comes
as no surprise to anyone who has had
the pleasure of meeting this tenacious and
ingenious innovator.
■
Looking ahead: The Siemens
CTO intends to use new
materials and engineering
concepts to make wind
power fit for the future.
His goal is to make wind
power economical enough to
compete with electricity from
conventional power plants.
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VIEWPOINT
Transform without tears
PUBLIC MEDIA often propagate the opinion
that Germany’s plan to switch to renewable energy sources for its electricity supply
are doomed to failure, simply because of
the high costs involved. At first glance,
a comparison of power generation costs
seems to bear this out. In 2010, the cost
of one kilowatt-hour amounted to 1.5 to
2.5 cents for a fully amortized nuclear
power plant, 7 cents for new wind turbines and new coal-fired power stations,
and between 20 and 30 cents for photovoltaic installations. But a closer look at the
long-term trends reveals that fossil fuels
will become increasingly expensive as
supplies begin to run out, whereas renewables will steadily become cheaper. The
gap between the two is narrowing, and
one day the difference will be reversed.
The price end users pay for electricity
depends on a number of different factors.
The present tariff rates are 24 cents per
kilowatt-hour for private households, 12
cents for industrial users, and 7 cents for
power-intensive heavy industry. To prove
that the price increases of recent years
were not caused by the growing proportion of renewables in the energy mix, the
following fact should be considered: The
prices charged to households and indusHans-Joerg Bullinger has been the
President of the Fraunhofer-Gesellschaft
since 2002. The organization currently
employs more than 20,000 people and
has an annual research budget of 1.8
billion euros.
28
trial electricity users have been rising at
a steady rate of around four percent per
year for over a decade. The apportionment payments under the Renewable
Energy Act (EEG) have only gained significance in the last few years, and yet they
have not caused retail electricity tariffs
to rise any faster.
So electricity prices are not rising as a
result of the expansion of renewables.
On the contrary, renewables have actually
helped to bring down electricity prices on
the power trading market. This effect was
documented in a study by the Fraunhofer
Institute for Systems and Innovation Research ISI, according to which the system
of feed-in tariffs established by the Renewable Energy Act (EEG) led to a reduction in electricity trading prices of over
0.5 cents per kilowatt-hour in 2010. If you
multiply this figure by the total annual
electricity consumption in Germany, the
theoretical savings amount to approximately 2.8 billion euros. This is the merit
order effect of the dispatch system under
which demand is met in the first instance
by the power sources with the lowest fuel
costs. The more expensive power plants
are only used at times of peak demand,
with a corresponding effect on average
electricity trading prices. The increasing
volume of electricity being fed into the
grid from renewable energy sources
has reduced the demand for peak-load
generating capacity, resulting in lower
trading prices.
According to the ISI study, the main
beneficiaries are likely to be power-intensive companies, because almost half
of all industrial power consumption in
Germany is entirely or partially exempt
from EEG apportionment payments.
And it is indeed true that energy
costs in the power-intensive sectors of industry have fallen over
the past few years.
T. Klink for bdw
The cost of generating electricity from renewables is by no means as high as many people
fear, declares Professor Hans-Joerg Bullinger in the viewpoint he contributes here.
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‚‚
Altogether, over the period 2010 to 2050, it is estimated
that savings of half a trillion euros could be achieved by
using renewable sources to generate electricity.
For these various reasons, the issue
needs to be judged in its wider context,
with all its ramifications. After all, the
transformation of our energy system is
one of the most important challenges of
the 21st century.
In 2010, the Renewable Energy Research Association FVEE published its
vision of Germany’s energy system in
2050 based on improved energy efficiency and 100-percent reliance on renewable energy sources. Several Fraunhofer
Institutes contributed to this research
project, which included determining
whether the costs of implementing the
envisaged transformation would be acceptable.
The researchers concluded that it
would indeed be possible to establish a
reliable, cost-efficient and robust energy supply system in Germany based
on renewable energy sources by 2050.
Over the long term, the cost of this sustainable energy system – if designed for
optimum efficiency – would be lower
than that for conventional alternatives.
This solution might cost more initially,
but these expenses would be more than
balanced out in the long term by a reduction in costs for conventional fossil
fuels. It is impossible to predict with
certainty what additional investments
will be necessary to modify the grid to
meet future requirements over the coming 40 years, but current estimates assume an annual increase in electricity
costs of around 10 to 15 percent.
ADVANTAGES OF A MIXED-SOURCE GRID
Future sustainable power generation
strategies will require a balanced mix of
wind farms, photovoltaic installations
and biomass plants. Nonetheless, the
FVEE’s vision by no means aims to
create an isolated national power infrastructure. It sees Germany as one
element in a pan-European grid, which
would enable the energy storage capacity of each country to be minimized. According to calculations by the Fraunhofer Institute for Wind Energy and Energy
System Technology IWES, in order to
make the final transition from a system
that derives 90 percent of its energy
from renewable sources to zero reliance
on fossil fuels, it will be necessary to
cover around 10 percent of the country’s
electricity requirements using long-term
storage facilities. One of the possible options is to store excess production from
renewables in the form of methane gas,
which can be stored in existing natural
gas storage facilities before being converted back into electricity.
The increased demand for electricity
can be met by constructing more offshore
wind farms and increasing the number of
photovoltaic installations, and if needed
by importing more electricity from neighboring countries. Up to 2020, measures
to increase the capacity of the national
grid will be sufficient to meet demand. It
is only later that it might become necessary to import electricity from renewable sources elsewhere. This gives policymakers time to set up an integrated European power network.
The expansion of renewable energy
will initially involve additional costs both
for the generation of electricity and heat
and in the transportation sector. But these
additional costs can be expected to reach
their peak relatively soon, in 2015, at an
estimated 17 billion euros. This represents
no more than eight percent of Germany’s
total energy bill, which amounts to 212
billion euros per year based on the monetary value of the country’s final energy
consumption. Such calculations disprove
the argument that renewables will cause
the cost of the German energy system to
increase dramatically.
Renewable energy sources could
reach parity with fossil fuels in the decade between 2020 and 2030 if costs
continue to fall as a result of efficiency
improvements and mass production. In
a recent study on the development of
solar and wind power generation costs,
the Fraunhofer Institute for Solar Energy Systems ISE reckoned that the cost
of producing electricity with photovoltaic (PV) installations could drop from
30 cents at present to 14 cents by 2020,
and from 24 to 9.5 cents in the case of
freestanding PV systems.
The power generation costs for the current renewables mix will peak at around
13 cents per kilowatt-hour in 2015, then
gradually but continuously decrease: to
7.6 cents in 2030 and to 6.3 cents by 2050.
Each year the associated cost savings will
increase, rising to a massive 61 billion
euros per year by 2050. Altogether, over
the period 2010 to 2050, it is estimated
that savings of half a trillion euros could
be achieved by using renewable sources
to generate electricity.
HEADING FOR 25 PERCENT SOLAR
The FVEE’s 2050 energy concept envisages a renewable power generating capacity of around 764 terawatt-hours (one
terawatt is one billion kilowatts), which is
enough to cover 100 percent of Germany’s
gross power consumption. The highest
share, 38 percent, is to be provided by
offshore wind farms. Photovoltaics will
meet 15 percent of the country’s electricity needs, and land-based wind turbines
will contribute around 12 percent. Even
imported power will be generated to a
large extent in photovoltaic and solar
thermal power plants, making it possible
to reach the target of 25 percent solar
power in the German electricity grid.
The actual development of the differential costs of renewable electricity will
nonetheless depend on a number of unknown factors, the most significant being
the future rate of increase in the price of
fossil fuels. But it is already clear that,
in the long term, the savings that can be
achieved through the use of renewables
far outweigh the cost of the additional investments required to reach the breakeven
point. In other words: Germany’s plan to
transform its energy system by aiming for
a target of 100 percent renewables is not
only feasible but also makes economic
sense. And that’s without factoring in
the costs that would otherwise have to
be paid for damage to the environment
and human health, measures to combat
climate change, special security measures, and site rehabilitation.
■
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NEW RESOURCES
No need to worry
about energy shortages!
Alongside solar and wind power, other entirely new sources of
renewable energy will play a role in transforming our electricity
supply. But fossil fuels are nevertheless not a thing of the past.
Harvesting energy from sunlight:
The Les Mées solar farm consists
of a vast array of solar modules,
spread out across a high plateau
in the south of France.
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Siemens
BY KLAUS JACOB
“MAY IS THE IDEAL month for photovoltaics,” says Michael Weinhold. The late
spring season is blessed with abundant
sunshine, but temperatures are normally
relatively cool. These are the conditions
that solar installations like most, and the
solar harvest is correspondingly high.
The Siemens Energy CTO is a keen observer of developments in the electricity
market. He says 2011 was “the best year
for photovoltaics ever”. An unusually
high number of hours of sunshine set
the meters spinning and pushed up the
yield of existing installations by 10 percent and sometimes considerably more.
At the same time, wind turbines fed
even more power into the grid than the
vast network of solar cells.
The rest of the world is watching
with great interest as Germany shuts
down its nuclear plants and steps up
investments in renewable energy sources in a bid to further reduce its greenhouse gas emissions. The country is
setting the example for other nations
who, sooner or later, will be forced to
revise their energy policies. The statistics on greenhouse gas emissions amply
illustrate this point. Global emissions
of carbon dioxide from fossil fuels rose
by 5.9 percent between 2009 and 2010.
Since 1990, the base year for the Kyoto
protocol, these emissions have increased
by 49 percent. The measures being taken
in Germany could be likened to a huge
open-air research project enabling scientists to study the consequences of replacing uranium, petroleum and coal with
alternative energy sources such as the
wind and the sun. This ambitious plan
also involves a complete overhaul of
the existing energy infrastructure. The
present system is dominated by centralized power plants, which are situated
in the vicinity of the major population
centers and distribute electricity over a
network of high-, medium-, and lowvoltage power lines to the end user. In
future, there will be more and more decentralized power generation facilities.
But even these plants will not be located
in the consumption, but rather at sites
offering the most favorable conditions
for harvesting solar and wind energy.
This is why the output of numerous
productive wind turbines never reaches
the grid –because there are not enough
transmission lines to transport electricity from the wind-swept northern coast
to regions further south. The challenge
of building an integrated power distribution network is compounded by the
fact that the majority of solar cells are
connected to the low-voltage network,
while cogeneration plants mainly deliver power to the low-to-medium-voltage
distribution network, and wind turbines
are connected to the medium-to-highvoltage sector of the grid.
Ironically, the booming demand for
photovoltaic (PV) installations has added to the problem. Until recently, their
role in the power supply system was
rarely taken seriously. The requirement
that power generation facilities connected to the low-voltage distribution
network should be automatically shut
off when the network frequency rises
above 50.2 hertz, a situation that can
arise temporarily in the event of major brownouts, is a legacy of this early
period. Today this requirement, which
was originally meant to protect the grid,
is a headache for utilities. Weinhold
describes it as “the currently biggest risk
to the stability of Germany’s electricity
supply”. Because in the meantime nearly a million PV systems are feeding
power into the grid – and the majority
of this vast and rapidly expanding fleet
of distributed generators are connected
to the low-voltage network.
MORE AND MORE SOLAR CELLS
Averaged over the country as a whole,
these systems “only” meet 3.2 percent
of Germany’s electricity needs (2010: 1.9
percent), but in regions with a high density of PV installations, such as Bavaria,
and when nuclear power is no longer
available, they can occasionally represent
50 percent of the generating capacity at
peak hours. The sudden disconnection of
a large part of this great armada would
lead to serious problems. What’s more,
according to initial estimates by the Federal Network Agency, around 7.5 gigawatts
of new PV capacity was added in 2011,
which is more than in 2010 (7.4 gigawatts,
spread over 249,000 individual systems).
New regulations prescribing a gradual
reduction in in-feed are now applicable
to new PV systems installed since the
beginning of 2012. The majority of existing photovoltaic systems with an output
of over 10 kilowatts must be retrofitted.
Rooftop systems on private homes usually have a much lower output, and are
exempt from the retrofitting requirement.
Even if the eyes of the world are focused on Germany, the country will not
be able to play a pioneering role in every
form of renewable power. For alongside
the sun and the wind, there are other
sources of renewable energy to which
Germany only has limited access. This
applies particularly to the oceans, where
wave and tidal energy holds significant
potential. Engineers and inventors have
been seeking ways of exploiting this natural resource for decades. The first technology to make a commercial breakthrough
will probably be the underwater turbine.
It’s an obvious idea when you think
about it: Powerful underwater currents
can be harnessed to produce energy in
much the same way as a stiff breeze on
land. All you need to do is place a rotor in
their path. And because water is around
800 times denser than air, a relatively
small “waterwheel” with a diameter of
20 meters is often sufficient.
The British Isles have the ideal geography for harvesting energy from the
sea. The tidal range can be as high as 12
meters, creating strong tidal currents in
many estuaries and bays. But similarly
favorable conditions can also be found in
other countries, including France, Canada, China, India, Russia, Chile, and the
United States. Kai Oliver Koelmel, Head
of Hydro & Ocean Power at Siemens
estimates the global potential at somewhere between 100 and 300 gigawatts
– or roughly half the output of all the nuclear reactors in the world. Nonetheless,
it will take a few more years before wave
and tidal power technologies will be able
to compete with solar and wind energy.
The world’s first underwater turbine
went into operation in the Bristol Channel off the coast of Devon in 2003 – a
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Siemens; Marine Current Turbines
Rotors to harness the tidal stream:
The change in water level between
ebb and flood tides creates enough
energy to drive large turbines.
The world’s first commercial tidal
stream power station (left) was built
in the Irish Sea in 2008.
picture-alliance/empics
Riehle/laif
The rapidly
growing volume of
traffic on China’s
roads (here:
in front of the
Olympic Stadium
in Beijing) clearly
illustrates the
country’s exploding demand for
energy.
32
Huge reserves:
Large quantities
of petroleum are
extracted from the
oil sands near Fort
McMurray in the
Canadian province
of Alberta by the
operators of gigantic plants like
this one.
modest prototype with a rated output of
300 kilowatts. Five years later, the Bristolbased UK company Marine Current
Turbines (MCT) constructed the world’s
first and so far largest tidal stream power
station, delivering an output of 1.2 megawatts, off the coast of Northern Ireland.
Within the next two years, the company plans to build two tidal farms off the
coasts of Scotland and Wales, consisting
of four and five generators respectively,
with an output of 8 and 10 megawatts.
They will cost around six million euros
per megawatt of installed capacity.
Siemens acquired 100% in MCT in
February 2012 – a further sign that the
technology is ripe for commercial deployment. Siemens expert Koelmel estimates
that by 2020 wave and tidal power plants
with a total output of 1 to 2 gigawatts
could be installed throughout the world.
He anticipates that the price of electricity generated by these plants will have
dropped to the same level as today’s offshore wind farms by then.
NO FUTURE WITHOUT FOSSIL FUELS
The future belongs to water, wind, and
solar, but it won’t be possible to completely do without oil, gas and coal.
Conventional power plants are needed
to bridge the gap on windless or cloudy
days. And the vehicles we drive will
still need gasoline and diesel for many
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NEW RESOURCES
bdw: map; source: U.S. Energy Information Administration
TREASURE TROVE OF SHALE
Natural gas is typically extracted from underground geological reservoirs – but in
the future a major part of this prized energy source could come from shale rock. In
many areas of the world, vast quantities of natural gas are locked in shale formations.
Extracting this shale gas is more complicated and expensive than extracting natural
gas from conventional sources, but increasing energy prices mean that it is a lucrative
business. The USA is currently leading the way in retrieving this treasure trove from
underground rocks.
years to come. But the biggest reason is
the huge pent-up demand in developing
and newly industrializing countries. The
International Energy Agency (IEA) in
Paris estimates that global demand for
oil will rise from the present 89.2 million
barrels per day to 99 million barrels per
day by 2035. Whereas oil consumption
in the OECD countries is on the decline,
demand in China is exploding due to
the massive increase in car ownership.
Natural gas consumption is climbing at
an even faster rate than oil. The IEA’s
experts have calculated that demand will
increase by 44 percent between now and
2035, which represents an average annual growth rate of 1.4 percent.
It seems that the known deposits are
more than adequate to meet this demand. Energy experts are more worried
about the climate than about keeping
up the supply. Bernd Wacker at Siemens is convinced that “we won’t have
any problem with reserves for the next
200 years”. While it is true that most of
the easier-to-access sites will be depleted within the foreseeable future, the
exploration companies are increasingly
turning their attention to other, more
unconventional deposits. New technologies and rising fuel prices have made
such ventures a lucrative affair.
Deposits once considered unviable
are now being exploited – and resources become reserves. Take subsea oil for
example: 20 years ago it was thought impossible to drill for oil beyond shallow
coastal waters. Now there are offshore
oil wells extending to a depth of 3000
meters below the ocean waves. Approximately one third of all oil extracted today
is brought to the surface by offshore platforms, and one tenth of this is deep-sea
oil – tendency rising.
It takes a huge engineering effort to
build structures capable of drilling for oil
at such tremendous depths. In this world
of permanent darkness, with temperatures barely above freezing point, the
sea water exerts 300 times atmospheric
pressure the surface oneequipment that
resides in water depths of 3000m. It is
impossible for divers to work there –
the furthest they can go is 200 meters.
Instead the oil companies have to use
robots, or remote operating vehicles
(ROVs), to do the necessary work in this
hostile environment. There is a whole
army of such remote-controlled vehicles
deployed in offshore oil fields, but their
manipulation is anything but easy. It is
almost like maneuvering a robotic vehicle on the moon. Despite the difficulties, the oil companies have been able
to build an entire subsea infrastructure
with giant pumps, compressors, separators, and innumerable pipelines leading
to the various oil wells. Siemens is developing new technology to enhance
the performance of these underwater
infrastructures, including the local integration of major power distribution and
control components.
Until now, a separate cable was used
to deliver power from the topside facility
to each main electrical consumer on the
seabed. The disadvantage of this solution
is that submarine cables are expensive,
and the topside structures often lack
space to install the necessary auxiliary
equipment. This includes transformers
to regulate the voltage, switchgear to distribute power to the various consumers,
and electric motor controllers or adjustable speed drives. All in all, the whole
system weighs several hundred tons – not
surprising when you bear in mind that
the power requirements of an oil field are
equivalent to the output of an averagesized commercial power plant.
Siemens is developing a solution,
called the “Subsea Power Grid”, which
can be immersed in the ocean. It is designed to exacting reliability standards
of oil and gas operators, on the principle
of zero defects, with the aim of ensuring
maintenance-free operation even under
extreme conditions. The Subsea Power
Grid is scheduled to be deployed for the
first time toward the end of 2014. The
ultimate aim is to increase the profitability of deep-sea oil and gas operations by
improving recovery and allowing access
to previously unrecoverable reserves.
Huge unexploted oil and gas reserves
are not only to be found in the oceans.
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NEW RESOURCES
Siemens
Box of tricks on the seabed:
The Subsea Power Grid is an
innovative control unit that
coordinates the automated
systems used in deep-sea oil
and gas drilling operations.
There are also plenty of resources on dry
land that have hardly been touched,
because until now their exploitation
would have been too expensive. These
include the oil sands that only Canada
has begun to exploit on a large scale.
The high price of petroleum has now
made such operations a potentially
lucrative proposition. In the years to
come, these unconventional oil deposits
will make an important contribution to
Diagram: bdw; source: BGR
STILL PLENTY OF OIL
The world still has large oil resources.
Experts define oil reserves as deposits
that are claimed to be recoverable under current economic constraints.
34
tomorrow’s diversified energy supply
When companies in the United States
started to extract natural gas from unconventional gas deposits on an industrial
scale in 2006, they sent tremors around
the world. Production increased so sharply
that gas prices collapsed, and demand
was further depressed by the economic
crisis of 2008/2009. The “gas fever” has
since spread far beyond the United States,
because such deposits can be found all
over the world. Unconventional gas reserves have meanwhile been discovered in
Europe, too. Poland was the first country
to issue exploration permits, and expects
to launch the first extraction projects in
two or three years’ time.
FINE-GRAINED HOST ROCK
The various types of unconventional
gas are differentiated by the rocks that
host them: “tight gas” (trapped in impermeable rock), “shale gas” (in shale
formations), and “coalbed methane” (in
underground coal seams). The feature
they have in common, which sets them
apart from conventional resources, is the
fine-grained structure of the host rock.
Conventional deposits are relatively easy
to extract, because the gas has collected
in an underground cavity created by a
fold in the surrounding impermeable
rock. When the drill breaks through the
confining layer of rock, the gas shoots
out at a pressure of up to 1000 bar – and
keeps on flowing out of adjacent fissures
even when the pressure sinks.
This technology doesn’t work if the
gas is trapped in tiny pores distributed
throughout a dense rock formation. In
this case, a vertical borehole has to be
drilled down to the gas-bearing stratum, and then horizontally in several
directions. The more holes are drilled,
the better. But these narrow holes are
not enough on their own to set the gas
flowing. A mixture of water, sand and
chemicals (referred to as fracking fluid)
is therefore injected into the borehole
at a pressure of 200 or 300 bar. The
pressure creates fractures in the target
formation, and the sand grains in the
fracking fluid prevents them from closing up again immediately. Now the gas
can finally escape upward. Thousands
of wells of this type have already been
sunk into shale formations in the United
States. Shale gas extraction has become
economically viable because drilling
costs have sunk dramatically over the
past ten years.
A different future might be reserved
for gas in Germany. Here it’s not a question of exploiting natural gas deposits
but of making use of the existing infrastructure in a different way. Germany
not only has an extensive network of gas
pipelines but also large underground
storage facilities. And that’s precisely
what the energy experts are desperately looking for – albeit as a means of
storing electricity. Energy storage will
be indispensable when the country
switches over to 100% renewables, because the electricity has to keep flowing
even when there’s no wind or the sun
is obscured by clouds. The capacity of
the pumped storage power plants currently used as a buffer system for electrical energy is far from sufficient. And
the ingenious idea of using the batteries
of parked electric vehicles as temporary grid storage cannot solve the problem on its own. But if the gas storage
and distribution network were used
as a buffer, it could supply energy for
months. The electricity merely has to be
converted into gas beforehand.
Looking further into the future, there
could be an even simpler solution.
Michael Weinhold talks of a massive
transcontinental power grid, or super
grid, stretching across numerous time
zones and climatic regions and linking
together offshore wind farms, solar
power plants and hydroelectric plants.
This would significantly reduce the need
for energy storage facilities. For when it
is night or winter in one place, the sun
is shining somewhere else; when the air
is still in one place, the wind is blowing
somewhere else; and when demand is
high in one place, consumption is low
somewhere else. It’s a vision that gives a
whole new meaning to globalization. ■
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ELECTRICITY TRANSMISSION
High-powered
excitement: The
world’s most powerful high-voltage
direct-current transmission system
entered service in
2011 in China. It has
a capacity of 5,000
megawatts.
Arteries for
power
As the use of hydroelectric, wind and solar power expands,
new transmission lines must be built. The best way to transport
this electrical energy is in the form of direct current.
MAJORCA IS SETTING TRENDS – not only
for sun-seeking tourists but also for power
supply. Since the fall of 2011, a good
portion of this holiday island’s electricity
has come from the Spanish mainland
– via a 244 kilometer long cable that
runs from Valencia through the Mediterranean to Majorca and brings up to
400 megawatts (MW) of power to the
Balearic isle.
Once it arrives there, the electricity
is first “prepared” before being fed into
the local distribution network. This step
is necessary since the electrical energy
flows along the cable from Spain in the
form of direct current. Experts refer
to this as high-voltage, direct current
transmission, or HVDC for short. But
electricity on Majorca – as everywhere
else in the world – is distributed using
a grid that carries alternating
current. This is why a
so-called converter
station is needed
to transform the
power from direct
Long link: A 200 kilometer long direct current cable connects the BorWin2 offshore
wind park to the power grid. It passes beneath the island of Norderney, Germany.
to alternating current. “Building a new
gas-fired power station would have taken less investment, and would have
met Majorca’s growing demand just
as well,” says Karlheinz Springer, CEO
of the Power Transmission division at
Siemens Energy in Erlangen, “but the
operating costs of the HVDC connection
are lower – and both local residents and
holidaymakers benefit from the fact that
importing power from the mainland
keeps local emissions down.”
A reasonably high share of the electricity – some 35 percent – comes from
renewable sources, chiefly wind, hydro
and solar. This was one reason Red
Eléctrica de España, which operates
Spain’s national grid, opted to build the
undersea cable – contributing to the
transformation of Europe’s energy supply
industry in the process.
“This transformation is also forcing
us to redesign our electricity grids,”
Siemens; TenneT TSO
BY RALF BUTSCHER
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ELECTRICITY TRANSMISSION
The existing capacity of HVDC links
around the world adds up to some 100
GW. “We’re expecting global tenders for
around 250 GW of new HVDC transmission capacity to be held by the end of
this decade alone,” says Michael Suess,
CEO of Siemens Energy.
TenneT TSO
TUNNELLING THROUGH THE PYRENEES
Some regions are already seeing this expansion happen. For instance, a 65 kilometer long HVDC cable is being built
between Spain and France that cuts
right through the Pyrenees and is par tially housed in tunnels. From the end
of 2013 the link will be able to transport
up to 2 GW of electricity between the
two countries – which makes it a major
The undersea cables that engineers are laying in the North Sea and the
stepping stone toward a trans-European
Baltic Sea are as thick as a leg. These cables will bring electricity from the
supply network. This network will in
major wind parks that lie far out to sea onto dry land. Special ships carry
future include HVDC links across the
giant rolls of cable and the specialized equipment needed to lay it.
Mediterranean: construction work is
already underway on a cable between
A few such power lines have already Sicily and Calabria, and in the coming
says Springer. The example of Germany,
years this will be complemented by
been built or are under construction.
where the intended switch to renewables
links between Tunisia and Sicily and
One example is the 260 kilometer long
is expected to be both comprehensive
between Algeria and southern Italy.
and rapid, because it is being actively driv- HVDC link between the Netherlands
These power lines will connect with
and England, which entered into service
en by the federal government’s energy
in April 2011. It has a maximum capa - a “Mediterranean ring” of HVDC cables
policies, makes this particularly clear.
All the solar modules on roofs across the city of 1 gigawatt (GW), and is used
stretching along the coast of North Africa
land are a symbol for this energy trans- solely for electricity trading. One of the from Cairo to Gibraltar and back to Egypt
formation, as are the powerful wind tur- attractions of this is the hour’s time dif- along the northern shores of the Medi ference between the UK and continental terranean. In future, the ring will serve
bines that sprout from the countryside
Europe: this means peaks in electricity
like giant winged stalks of asparagus.
to collect and transport the electricity
demand occur an hour apart.
It is above all those turbines that
generated in huge solar power stations.
are making it necessary to upgrade
Germany’s power grids. The prospect of
LOWER RESISTANCE
generating electricity from wind is at its
most compelling in the blustery north of
the country. Power consumption, on the
When it comes to transporting electricity, electrical engineers differentiate between two
other hand, is highest in the south and
kinds of current: direct current, where electrical charge always flows in one direction;
west – regions which are home to many
and alternating current, where the direction of flow (or polarity) switches at a fixed
energy-intensive industrial sites. So
rate – usually a frequency of 50 hertz, which is to say 50 times a second. Three-phase
the wind energy has to travel from north
power is a special kind of alternating-current power that can be used to transport a
particularly high volume of energy. The advantage of direct-current transmission at high
to south. The problem is, as things stand,
voltage (HVDC transmission) is that it results in a lower level of electrical losses. Since
the German transmission grid is unthe power does not need to constantly switch polarity, direct current flows with lower
able to cope with this flow, as it is not
resistance. This is what makes HVDC links particularly suited to transporting energy over
designed to move large volumes of ener
long distances. In addition, they allow electricity to be switched directly from one spegy over long distances. That’s why there
cific point to another, which is something that is not possible with alternating current.
is an urgent need for new grid capacity.
A general rule is that the higher the voltage, the more efficient the transmission. DirectAnd Karlheinz Springer is convinced
current power lines’ drawback is their higher construction costs. But once lines reach
that HVDC transmission technology will
a certain length, these higher costs are compensated for by the reduced losses. A rule
play a central role in this thanks to its
of thumb has it that upwards of around 800 kilometers, HVDC overhead lines are more
low electrical losses, which make a very
economical than three-phase power transmission. In the case of underground cables,
big difference in long-distance power
direct current wins out around distances as short as 80 kilometers.
transmission.
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RAPID EXPANSION OF DIRECT CURRENT TRANSMISSION
Map: bdw; source: Siemens
The North Sea, too, is set to see new
power lines soon – and these will similarly feature HVDC transmission technology. The aim is to send excess power from German or British wind farms
to Norway or Sweden on windy days,
allowing hydroelectric power generation
there to be reduced. It would also be
possible to store the electricity temporarily in pumped-storage hydro plants.
One such interconnector has been in
operation since 2008, covering the 580
kilometers between Eemshaven in the
Netherlands and Feda in Norway.
All the projects built or planned in
Europe are minnows compared to the
mammoth direct-current connections
that Siemens engineers are building in
China. The Chinese are relying heavily
on hydroelectricity as they expand their
supply network, and they are currently
building enormous power stations, for
instance in the water-rich province of
Yunnan. This sparsely populated province in the south of the country has
little energy demand of its own, so overhead cables – some of them thousands
of kilometers long – bring the hydroelectricity to the heavily populated and
economically powerful coastal province
of Guangdong. Since 2009, power has
been flowing here along the world’s first
HVDC link to operate at the very high
voltage of 800,000 volts.
China is making systematic use of
HVDC transmission technology and
plans to build additional connections.
A brand new 800,000 volt line is about
to begin carrying 7.6 GW of electricity.
And there is a chance that the first ever
1.1 million volt line will enter service
before the end of 2012 – with a capacity
of 10 GW. “These kinds of enormous
but remote sources of renewable energy
only become viable with HVDC transmission technology,” says Springer in
relation to the colossal hydroelectric
potential of Siberia and Mongolia.
In Europe, HVDC transmission is set
to push the use of renewable sources of
energy. A study by the German energy
agency dena reckons that up to 3,600
kilometers of power lines need to be added to Germany’s transmission grid. But
this expansion is happening at a snail’s
pace, not least because of resistance
High-voltage, direct current (HVDC) electric power transmission systems are particularly
suitable for transmitting bulk quantities of electrical power over long distances. Some
HVDC links already exist in Europe, most of them running through undersea transmission cables. A number of additional lines are under construction or at the planning stage.
to the construction of overhead power
lines. This is where HVDC transmission
can come into play: Michael Suess, CEO
of Siemens’ Energy sector, is certain that
in the end many lines will be put underground.
WIND PARKS’ UMBILICAL CORD
HVDC technology is the ideal choice
to transport the electricity that will be
generated in the wind parks Germany
and the United Kingdom are looking to
build out at sea. The first of these offshore wind parks have already begun to
deliver power, and there is already one
HVDC transmission line leading from
German wind-park projects further out
in the North Sea back to land – cutting
right through the sea and across East
Frisia to a connection point south of
Emden, where the electricity is fed into
the grid. In the coming years, further
offshore wind parks are set to sprout in
the North Sea and the Baltic Sea – as
are HVDC links, which will connect the
parks with the land. The longest such
link, known as SylWin, will stretch all
the way from the island of Sylt to Brunsbuettel, close to Hamburg. Of a total
length of 250 kilometers, 200 kilometers
of this link will lie beneath the sea.
Siemens will be building the connections for numerous wind parks to
collect the power from individual wind
turbines before bringing it onshore.
“The challenges presented by construction projects such as these, which must
contend with the harsh conditions out
at sea, are simply enormous,” says
Karlheinz Springer. To overcome them,
Siemens has put together a team of experts in Hamburg which even includes
two sea captains - a first in the colorful
history of the technology giant.
■
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COMBINED CYCLE POWER PLANTS
World record –
±
The star of the new
power plant in Irsching
(top right) is without
doubt the newly designed gas turbine
(left). It is a masterpiece of international
turbine technology.
and what next?
Not long ago, a power plant in Irsching, Bavaria, set a new world record in efficiency by
converting 60.75 percent of the energy contained in natural gas into electricity. In February,
Siemens received the German Industry Innovation Award for this phenomenal achievement.
But Germany’s power generators are slow to place orders.
BY WOLFGANG HESS
MAY 11, 2011. This was an unforgettable
day for Willibald Fischer, who describes
it as “the absolute highlight of my whole
working life up to now”. The head of
the Siemens gas turbine program with
the cryptic title SGT5-8000H is referring
to the world record set that day, and
38
validated by Technical Control Board
(TUEV Sued) observers, in a power
plant, located in the village of Irsching at
the river Danube. That day, the Irsching
4 plant converted 60.75 percent of the
primary energy content of natural gas
into electricity - the plant’s own power
needs already considered. No other thermal power plant before it has even got
close to the 60-percent mark, let alone
surpassed it.
A little over two months later, Siemens
handed over the plant to its operator,
E.ON. The energy utility, too, is delighted
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Irsching, can reduce fuel costs by around
65 to 70 million euros over the operating
life of the plant. But even then, the total
fuel costs over the lifecycle of this type of
power plant still amount to somewhere
in the region of 2.5 to 3 billion euros, calculated on the basis of current gas prices.
The cost of the plant itself, which has a
total capacity of 561 megawatts, is specifically lower: Balling quotes a figure of 320
to 370 million euros for Central Europe.
THE ULRICH HARTMANN
POWER PLANT IN BRIEF
Since its inauguration by its operator E.ON in September 2011, the
Irsching 4 combined gas-and-steam power plant, which was built
by Siemens, has been known as the Ulrich Hartmann power plant
after the former chairman of the E.ON supervisory board, who had
worked for E.ON and its predecessor companies for 39 years.
Total net power output: 561 megawatts (MW)
of which gas turbine
375 MW
of which steam turbine
186 MW
Efficiency of plant in continuous operation
(conversion of natural-gas primary energy into electricity, net of
power required for its own operation): 60.4 percent
Carbon dioxide emissions per kilowatt-hour: approx. 330 grams
(lignite-fired power plant: almost 1 kilogram)
Siemens (2)
Startup time from idle to full capacity: 2 hours in a warm start,
30 minutes in a hot start. Development time for the SGT5-8000H
gas turbine: 7 years
Time to construct prototype: 22 months
with the performance of the new plant.
Lothar Balling, Head of Gas Turbine Power
Plant Solutions at Siemens, is proud to
note that: “The plant is running perfectly.
Almost every morning, depending on
demand, the operator starts it up in less
than 30 minutes if required and shuts it
down and takes it offline late in the evening – with highest reliability.” And yet
it is precisely this load cycling that often
creates headaches for turbine manufacturers, as Balling knows all too well after
working in the gas turbine business since
1990: “It is the first time that a plant of
this complexity, requiring the interoperation of a newly designed gas turbine and
a steam turbine, has run so consistently
smoothly so soon after its commercial
launch.” International competitors in the
market for gas-and-steam combined cycle
power plants, such as General Electric
and Alstom, were by far overtaken by
this Siemens technology, which excels
both in terms of efficiency and in its
flexibility in daily operation.
An increase in efficiency of around 1.5
percentage points compared with the previous model, as is the case of the plant in
HEAT-RESISTANT TO OVER 1,500 DEGREES
Engineers have been studying the possibility of combining gas and steam turbines
in a single plant as a means of increasing
the yield of electricity from fossil fuels
since the 1970s. The two types of turbine
operate in different temperature ranges.
Advances in gas turbine technology have
been hugely boosted by work on jet engines for the aircraft industry. In the 1980s,
the maximum inlet temperature, that a
gas turbine could support, was 900 degrees Celsius. This limit had been pushed
up to 1,100 degrees Celsius by the early
1990s thanks to the introduction of air
cooling for components in the hottest regions of the combustion chamber and in
the turbine inlet system. Nowadays gas
turbines can even support inlet temperatures exceeding 1,500 degrees Celsius.
Steam turbines, on the other hand, operate at much lower temperatures but at
significantly higher pressure levels. The
steam turbines employed in combined
cycle processes in the early 1990s were
capable of withstanding steam temperatures of up to 500 degrees Celsius at
a pressure of 80 bar. Today, they are designed to support steam temperatures of
up to 600 degrees Celsius at the inlet
and pressure levels of 170 bar.
Manufacturers who design plants in
which the two systems are linked, and
the exhaust heat from the gas turbine is
used to produce steam for the generation
of additional electricity by a steam turbine, are the environmental champions
among fossil-fueled power plant builders. For this ingenious technology is capable of converting the energy contained
in natural gas into electricity much more
efficiently and environmentally friendly
than any other type of fossil-fueled power
plant. Per unit of generated electricity,
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COMBINED CYCLE POWER PLANTS
ä
the new plant in Irsching emits only half
as much carbon dioxide as the most modern coal-fired power plants, and only a
third of the amount released on average
by the coal-fired power plants currently
operating in Europe.
Siemens constructed its first combined
cycle power plant in Thailand at the end
of the 1970s. It achieved an efficiency
of around 43 percent. In the thirty years
since then, the manufacturer has improved the efficiency of its CCPPs by more
than 12 percentage points, which corresponds to an increase of the fuel utilization
of more than 25 percent. And the chase
for records still goes on: According to a
recent presentation, Siemens has set itself
the goal of reaching an efficiency of more
than 61.5 percent with its CCPPs by 2015.
The foundations for this dynamic progress were laid well in advance through
the concerted efforts of materials scientists, flow modeling and turbine design engineers, CAD experts, plant design specialists, and business managers. The starting
gun was fired in March 2001 when Siemens
top executives gave the go-ahead for the
SGT-8000H development project, aiming
to build a CCPP capable of delivering an
efficiency of over 60 percent and at the
same time offering a maximum of operating flexibility and environmental compatibility – all within the space of ten years.
HALF A BILLION EUROS
The first gas turbine to emerge from this
development program was delivered by
the Siemens turbine manufacturing plant
in Berlin in April 2007. Eight months later,
it was up and running for the first time in
Irsching. Another 30 months of intensive
tests were necessary before the plant finally
went online – which only goes to show that
the development of new, resource-saving,
high-capacity power plants takes time – and
costs money: “We invested half a billion euros in the development and testing of this
prototype plant,” reports Lothar Balling.
The engineers pulled out all the stops
in their efforts to beat the previous world
record for efficiency. “We had to come up
with an all-round optimization strategy in
order to increase the performance of our
SGT5-4000F turbine generation – which
we had launched in 1996 and which
was already able to deliver a combinedcycle efficiency of 56 percent – and push
it all the way up to the current level,”
says Balling, who spent ten years working around the development, from its
inception through to commercialization.
The gas turbine is decisive for reaching
Siemens (4)
A series of sophisticated measures have been employed to make turbine blades heat-resistant,
enhance their performance, and contribute to the improved efficiency of gas turbines. The combination of a metal adhesive film and a ceramic thermal insulation coating (left) dramatically increases
the service life of the blades (center: EM image of the ceramic powder). Blade performance is
further improved by cooling holes (right), through which air is forced when the plant is in operation.
The four blade rows of the SGT5-8000H gas
turbine: Each of the 280 blades delivers
an average of 1.5 megawatts at full load. A
single turbine of this model operating in
combination with a steam turbine would
be capable of supplying all households in
the city of Berlin with electricity.
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B. Mueller
the target of 60.75 percent efficiency, contributing with two thirds to the plant’s
record-breaking performance. The fourstage turbine generates a total output of
750 megawatts, a good half of which –
380 megawatts to be exact – is utilized
by the system that compresses the air
entering the gas turbine to the necessary pressure of 19 bars. This compression
process alone heats up the air to over
400 degrees Celsius. But this is nothing
compared with the temperature that
reigns inside the combustion chamber
when the plant is fired up. The 16 burners transform the incoming natural gas
fuel into a hot gas with a temperature of
over 1,500 degrees Celsius. This creates
the extremely powerful air flow that acts
on the approximately 280 turbine blades
arranged in four successive rings around
a central shaft. Each turbine blade delivers
an electrical output of roughly 1.5 megawatts. In this way, thermal energy is converted into rotational energy that sets the
turbine blades in motion, which in turn
drive both the compressor and the rotor
of the generator. Superimposed magnetic
fields in the generator create an electrical
voltage (as in a bicycle dynamo), thus
producing electricity.
The compressor of the 8000H gas
turbine consists of 13 stages, each with
one ring of blades and one ring of guide
vanes, which suck in 800 kilograms of
air per second – around 660 cubic meters
– when operating at full load. It is this
volume flow rate, along with the firing
temperature, that determines a gas turbine’s power output.
The 1,500 degrees Celsius in the combustion chamber causes steel to glow
bright red, while the rotating components
of the blade-and-vane assemblies are subjected to a centrifugal force almost 10,000
times stronger than Earth’s gravity. To
enable the blades to keep working efficiently for many years under these grueling
conditions, the engineers have thought
up various clever cooling solutions. A
labyrinth of tiny channels runs through
the interior of the cast blades, allowing
cold air to be blown through them to carry away some of the heat. This cooling
system is complemented by lines of tiny
holes drilled into the outer surface of the
turbine blades. The relatively cool air that
emerges through these openings spreads
out evenly over the outer surface of the
blade, creating a protective film of air
that prevents the blade from coming into
direct contact with the surrounding hot
air. For additional protection, these hightech blades are also enveloped in a microscopically thin ceramic coating. This
ceramic material is so finely distributed
over the structure of the blades that it
does not compromise their extreme heat
resistance – the original advantage. The
coating material was specially designed
to avoid the traditional drawback of ceramics, namely their brittleness.
As if this wasn’t enough, the blades
are no longer made of steel but of a nickelbased alloy, which offers much greater
heat resistance. And in the rings of blades
in the turbine stages most exposed to
physical and chemical loads, each blade
is cast in a directionally solidified, singlecrystal alloy. They therefore have no
grain boundaries in the direction of the
centrifugal force – a feature that increases
their strain resistance and reduces their
susceptibility to intergranular corrosion.
THE REMAINING TRUMP CARD
Balling emphasizes that the Irsching
plant’s record-breaking efficiency is due
principally to these and other gas turbine
enhancements. Beside optimizing the compressor and the turbine, and improving
A look back to the construction
phase: The generator is gently
moved into position and set
down on its base. Since this
photo was taken, the “giant
dynamo” has clocked up
thousands of operating hours,
driven by the gas turbine at
its front end and the steam
turbine at its rear.
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COMBINED CYCLE POWER PLANTS
the air cooling system – Siemens diverts
air from the compressor and thus, unlike
its competitors, does not need external
air coolers or steam from complex heat
exchangers – the company pulls out another trump card. Thanks to an inspired
modification, Siemens has found a better
way of dealing with thermal expansion.
The problem is that the turbine housing
and the turbine blades expand at different rates when the plant is fired up. In
the past, power plant manufacturers have
been obliged to leave a safety gap between
the blade assemblies and the housing, to
accommodate the effects of thermal expansion. But in certain operating regimes,
this gap allows a significant quantity of
hot air to flow through the turbine unimpeded, without acting directly on any
of the blades. This in turn reduces the
plant’s efficiency. “We use a smart hydraulic actuator that automatically adjusts
the gap to the minimum clearance required in any specific operating scenario. At
present, Siemens is the only company capable of doing this,” says Balling proudly.
What more could there be to add?
• World-record efficiency of over 60 percent
• German Industry Innovation Award for
the SGT5-8000H gas turbine on February
11, 2012
42
COMBINED CYCLE PRINCIPLE
The combined cycle power plant in Irsching sucks up to 660 cubic meters of air into
the system each second to operate the gas turbine (1). The air is compressed to 19.2
bar (2), fed to the combustors and burned with natural gas. This produces exhaust
gases at a temperature of around 1500 degrees which are subsequently routed to
the gas turbine (3). The next stage is the heat recovery steam generator (4), which
generates steam at 600 degrees Celsius to drive the steam turbine (7). Both turbines
transfer their kinetic energy to the same generator (5). A clutch (12) enables independent operation of the steam and gas turbine during the initial phase.
Illustration: bdw; source: Siemens
Siemens
The gas turbine was
packed in a special
transport container
for its journey by
barge and truck
from Berlin, where
it was designed and
built, to its operating site in Irsching
near Ingolstadt.
Bridges along the
route had to be
reinforced to bear
the weight of the
440-ton turbine.
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FURTHER READING
• A plant that can be brought up to its full
capacity within only 30 minutes
• Carbon dioxide emissions reduced by
around 4.2 million tons per year compared with the average coal-fired power
plant in Europe (based on an output of
1,000 megawatts, an efficiency of 36 percent, and 8,000 operating hours per year):
That surely has to be the market winner!
“It could become a market winner,”
says Lothar Balling, measuring his words.
“But so far we have sold two power plants
of this type in Germany: Irsching and
Duesseldorf. On the other hand, utility companies in the USA have already
purchased six of these turbines, and
South Korea has ordered several plants
in which 7 units are to be installed.”
Even Greenpeace has recognized the
necessity of building new gas-fired power plants, and recommended that this
route should be intensively pursued in
its roadmap for Germany’s sustainable
energy future, published in 2011. For the
situation is as follows:
• In 2011, eight of Germany’s 17 nuclear reactors were closed down in one
fell swoop, and the final date for phasing out the remaining nine was brought
forward to 2022.
• Much of the population opposes the
idea of building new coal-fired power
plants. In its above-mentioned roadmap,
Greenpeace demanded that the larger
coal-fired plants should be removed
from the grid by 2030 at the latest, as
the next stage after closing down all the
nuclear reactors.
• Renewable energy sources such as
solar and wind power plants are shooting up like mushrooms, but the drawback is that their productivity depends
on the capricious moods of Mother
Nature.
• Until an efficient solution has been
found to the problem of storing excess
electricity generated by solar installations and wind farms, there is a need for
“back up plants” capable of stepping in
at short notice to avoid the risk of widescale blackouts when the wind is calm
or the sky is overcast.
So why are German utilities so hesitant to invest in new gas-turbine technology? Balling points to the current costbenefit structure as the reason why the
investment conditions are not considered attractive at the moment. The wholesale price of a kilowatt-hour (kWh) of
electricity generated by a lignite-fired or
nuclear power plant lies in the region of
less than 5 cents. It is virtually impossible for a more technologically advanced
CCPP to compete with these prices,
as the cost of the fuel required to produce a kilowatt-hour of electricity already amounts to around 4 cents. On top
of this, the operator has to pay at least
1.2 cents per kWh for the necessary
carbon trading credits. This leaves only
a fraction of a cent per kWh to cover
all other overheads. “What we need is a
margin of at least 1 or 1.5 cents per kWh,”
says Lothar Balling.
The calculation gives better results if
it is possible to recover waste process
heat for use in district heating or industrial applications, enabling fuel efficiency
to be increased to over 80 percent, as
is actually the case in the Duesseldorf
plant. But very few power plants in
Germany are installed in locations that
enable such solutions to be applied on
a large scale.
NO DEMAND IN GERMANY
To sum up: Germany has a manufacturer
that offers the most efficient and flexible
fossil-fueled power plant in the world.
But the German electricity market has
been slow to take up this offer because
operators cannot earn sufficient money
with this technology under the present
conditions. “The greater the amount of
electricity generated by wind farms,
which are subsidized through the Renewable Energy Act, the fewer the number
of operating hours of combined cycle
power plants, and yet the more flexible these units need to be,” says Balling.
Hence his plea for a market model to
create a regulatory framework enabling
and supporting the commercial viability of reserve capacity to be provided
by means of rapidly deployable power
plants s, as is already the case in the
United States and the UK for example.
“After all, these gas-fired power plants
are the guarantee of a stable electricity
supply, as they can step in at once to fill
the gap left when power from wind and
sun is on the wane,” argues Balling. ■
Siemens Energy home page:
www.siemens.com/energy
International Energy Agency (IEA):
www.iea.org
Fraunhofer Energy Alliance:
www.energie.fraunhofer.de
Wuppertal Institute for Climate,
Environment and Energy:
www.wupperinst.org
German Association of Energy and
Water Industries (BDEW):
www.bdew.de
German Renewable Energies Agency
Information Portal:
www.unendlich-viel-energie.de
dena Grid Study II:
http://www.dena.de/fileadmin/
user_upload/Publikationen/
Erneuerbare/Dokumente/
Summary_dena_Grid_Study_II.pdf
German Wind Energy Association (BWE):
www.wind-energie.de
World Wind Energy Association:
www.wwindea.org
Offshore wind energy – by the German
Maritime and Hydrographic Agency (BSH):
www.bsh.de/de/Meeresnutzung/
Wirtschaft/Windparks/index.jsp
Information on Siemens Smart Grid:
www.siemens.com/smartgrid
EDITORIAL NOTES
ELECTRICITY 2020
A special issue of bild der wissenschaft
produced in cooperation with the Siemens
Energy Sector
DATE OF PUBLICATION – ENGLISH ISSUE:
August 2012
PUBLISHER: Katja Kohlhammer
PRODUCED BY: Konradin Medien GmbH
Ernst-Mey-Strasse 8
D–70771 Leinfelden-Echterdingen
PUBLISHING DIRECTOR: Karen Heidl
EDITOR-IN-CHIEF: Wolfgang Hess
PROJECT MANAGER: Ralf Butscher
GRAPHIC DESIGN: Peter Kotzur
AUTHORS: Hans-Joerg Bullinger, Ralf Butscher,
Wolfgang Hess, Klaus Jacob, Bernd Mueller,
Tim Schroeder
ENGLISH TRANSLATION:
Burton, Van Iersel & Whitney GmbH, Munich
PICTURE EDITOR: Ruth Rehbock
SIEMENS EDITOR: Alfons Benzinger
DISTRIBUTION: Kosta Poulios
PRINTED BY: Konradin Druck GmbH
Kohlhammerstrasse 1–15
D–70771 Leinfelden-Echterdingen
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1866
Discovery of the dynamo-electric
principle, enabling electricity to be
generated cost-effectively on an
industrial scale
1885
Berlin: The first public power station
in Germany
1892
Erding: First municipal three-phase
AC power station, enabling plants to
be built at a greater distance from the
end users
1927
Siemens acquires Thyssen’s steam
turbine factory and starts to manufacture its own turbines
1939
Preliminary development work on gas
turbines
1979
Construction of the world’s most powerful gas turbine, with an output of 116
megawatts
1991
The first unit of the Ambarli (Turkey)
combined gas-and-steam power plant
sets the world record for the efficiency of a thermal power plant at 52.5
percent
2000
The largest steam turbo set for
conventional power stations (with an
output of 900 megawatts) goes into
operation at the Boxberg brown-coalfired power plant in Saxony
2008
Order received for the world’s longest
and highest-capacity HVDC transmission line from the Xiangjiaba hydroelectric power plant in South-West
China to Shanghai (completed in 2011)
SIEMENS_2012_Innen24-48.indd 44
Advances in
power technology
2009
China: First station built for the world’s
first 800-kV high-voltage DC transmission line with a transmission capacity
of 5000 megawatts and covering a
distance of more than 1,400 kilometers
2011
Irsching (Bavaria): A combined gasand-steam power plant achieves the
record-breaking efficiency of 60.75
percent (net) and outstanding performance in terms of operating flexibility
London: Construction starts on the
world’s largest offshore wind park
(the London Array) with an output of
1 gigawatt. Siemens supplies the wind
turbines and grid connections
Mallorca:244 kilometers of submarine
cable are laid on the Mediterranean
seabed, providing an HVDC transmission link between the island and the
Spanish mainland capable of supplying
3.5 million tourists per year with electricity from sustainable sources
2012
The combined cycle power plant in
Irsching wins the German Industry
Innovation Award for its world-record
efficiency
Siemens is awarded a contract to provide HVDC technology for a submarine
cable link with the unprecedented
voltage rating of 600 kilovolts and
one-third-reduced transmission losses.
The transmission line with a capacity
of 2200 megawatts is scheduled to
go into operation in 2015, linking the
national power grids of Scotland and
England.
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