Enel’s Fusina hydrogen-fed power generation
plant
M. Balestri*, G. Benelli*, F. Donatini*, F. Arlati ** , G.Conti**
* Enel GEM/AT Ricerca, Via A.Pisano 120 56100 Pisa, (Italy)
** ENEL GEM/SRI, Milano, (Italy)
Abstract -- The project foresees the erection of a 12 MWe
hydrogen-fed gas turbine cycle able to couple high efficiency
fuel utilization with low nitrogen-oxide emissions. The
project will be put into practice at Enel’s coal-fired Fusina
power plant.
The aim of a first demonstrative phase is to verify the
correct operation of the gas turbine with pure hydrogen as
fuel and to acquire know-how of hydrogen combustion,
safety aspects and control technologies in gas cycles. In a
second phase of the program, the goal will be to optimize the
combustion technology, paying particular attention to NOx
emissions.
At this stage the final design of the plant has been
completed, the public and statutory permission for
construction has been obtained and the gas turbine has been
chosen and ordered. This paper will present the final design
of the plant as well as the on-going development program
for the design and testing of the low NOx hydrogen-fed
combustion chamber.
There is in fact a wide social acceptability in the public
opinion for hydrogen economy for the following main
reasons:
•
When used, hydrogen generates water as the main
by-product and not CO2, which is generally
considered the cause of the greenhouse effect
•
It’s generally considered a “zero emissions” clean
fuel if used with fuel cells
•
Its typical use will be transport and stationary
generation in urban centres to ecologically generate
electric power and heat on a small scale
•
In energy conversion, hydrogen, unlike electricity,
can be considered “intermediate in time” because it
“stores” the energy spent generating it and can, in
turn, be stored; in essence, it functions like a battery
and could be a strategic asset for the energy market
for storing the excess energy produced overnight in
base coal or nuclear power plants or energy
produced by renewable sources that is discontinuous
in time
•
Hydrogen, like electricity, can be considered
“intermediate in space” because it carries energy
anywhere, for use in a distributed way
•
It is generally also considered “intermediate in
process”, encouraging the diversification of energy
fonts because it can be produced by both fossil and
renewable sources through several different
processes and even by many small-size units
distributed across the territory
For these reasons, hydrogen is almost unanimously
considered the strategic clean energy carrier of the future
that will coexist with electric energy and natural gas;
more and more research is focusing on technologies
enabling its use in every possible field, and the main
industrialized countries (USA, Japan, EU and Canada)
have financed large research and development programs
to sustain the start of the hydrogen economy.
The main problem is how to economically produce the
necessary hydrogen for distributed uses without
increasing environmental pollution and CO2 emissions.
Possible future means of production are through:
1) chemical processes (reforming or coal gasification
or others) starting from fossil fuels in large
advanced centralized plants with CO2 sequestration
2) advanced electrolysis processes, but only if the
necessary electricity is produced in a clean way
(zero emission plants if possible) and limiting CO2
emissions (e.g. with renewable sources, nuclear
source, fossil sources with CO2 sequestration)
Index Terms — Hydrogen, hydrogen cycle, hydrogen
turbine, power generation
I. NOMENCLATURE
GE:
General Electric Nuovo Pignone (FI)
CREAR: Centro Ricerca Energie Alternative e
Rinnovabili (University of Florence)
CPR:
Consorzio Pisa Ricerche
DIMSET: Dipartimento di Macchine Sistemi Energetici
e Trasporti (University of Genova)
DIM:
Dipartimento di Ingegneria Meccanica
(University of Padova)
DIMS:
Dipartimento di Ingegneria Meccanica e
Strutturale
Laboratorio
di
Ingegneria
(University of Trento)
IRC-CNR: Istituto di Ricerche sulla Combustione del
CNR (Napoli)
CFD:
Computational Fluid Dynamics
HRSG:
Heat Recovery Steam Generator
LHV:
Low Heat Value
II. INTRODUCTION
In industrialized countries, many people think that the
future of energy lies in a hydrogen economy since it
offers a better quality of life for those living in large cities
and could be a force towards achieving sustainable
growth.
The use of hydrogen fuel cells in the future for transport
and distributed generation is generally accepted to be a
way of decreasing pollution inside city centres and
positive for the people who live there.
1-4244-0632-3/07/$20.00 ©2007 IEEE.
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x innovative combustion systems
x CO2 capture and sequestration
x hydrogen
Starting from these general motivations, ENEL, being
one of the main European electric energy and gas
operators and having a long-term strategic view, has
decided to take an active part in hydrogen research and is
working on a program dealing with both hydrogen
production and utilisation, thus contributing towards
starting the transition to the new hydrogen economy, and
it intends to lead this transition in Italy using its Research
Department.
Since ENEL’s core business is the production of electric
energy, ENEL Research has given priority to the use of
hydrogen for medium size power generation, but it also
deals with hydrogen production through coal gasification,
hydrogen storage, fuel cells and hydrogen-natural gas
mixture for transport.
When ENEL started to work on a hydrogen-fed power
generation plant in 2005, there were also short-term
economic incentives for the company to begin. At that
time, by considering hydrogen to be a renewable source
of energy, Italian regulations made incentives available
for hydrogen power generation by providing utilities with
a form of Green Certificate. This fact would in practice
have allowed the energy producer to almost triple its
hydrogen-made electricity sale proceeds compared to
profits made from fossil fuels, but this advantage has
been recently cancelled and at the moment, without any
economic help, hydrogen generation power plants are still
not economically profitable. In spite of this not
insignificant change in economic circumstances, Enel has
decided to go on with its hydrogen project, demonstrating
its real long-term strategic interest in this new energy
carrier.
The medium-period goals of the Enel hydrogen project
are:
x
To acquire direct know-how of hydrogen
emission
control
combustion
and
NOx
technologies in gas cycles (technological
feasibility, efficiency, long-term reliability,
availability)
x
To start acquiring know-how about all other
aspects concerning hydrogen as a possible energy
carrier in the future, used either pure or mixed
with methane (safety, landing, transport, storage,
etc.)
x
Already having coal logistic infrastructures in its
power plants, to evaluate the opportunity in the
medium term to extract hydrogen from coal in an
ecological and economical way with a
simultaneous production of electric energy
through IGCC systems in innovatively designed
thermal power plants with CO2 separation
x
To evaluate opportunities in the long term to use
innovative hydrogen cycles with high efficiency
and zero emissions
This will probably be the long term future for energy, but
it is very difficult to arrive at this hypothetical scenario
directly mid term due to the large number of technical
and economic difficulties and barriers. In order to get
there, an intermediate period will be necessary in which
all processes and technologies aimed at increasing
production and use of hydrogen and the diffusion of its
transfer network must be accepted, encouraged and
economically sustained to start up this new economy,
which is also a long way from the real start up point.
As far as power generation is concerned, fuel cells seem
to be the best choice, as they couple the highest
conversion efficiencies with no pollutant emissions, but
their massive use can only be expected in the medium to
long-term future and they will probably only be used for
distributed and small scale power generation. On the
contrary, the future technological frontier for large scale
power generation appears to be coal gasification
integrated with advanced combined cycles including CO2
separation and hydrogen production; both the FuturGen
project in the USA (275 MW of equivalent power) and
the RWE project in Germany are moving in this
direction.
III. THE STRATEGIC MOTIVATIONS OF ENEL ABOUT
HYDROGEN
All energy dealers recognise the great importance of
renewable resources for the future and Enel intends to be
a leading energy company that strongly cares about
environmental problems with its 2007-2011 programme
for “Research, Innovation and Renewable Resources”.
In December 2006 Enel launched a large investment
project that shows its real commitment towards research,
technological innovation and development of renewable
resources.
Enel’s mission statement is “Not changing the world”,
which emphasises its strategic vision to reinforce its
attention towards protecting the environment.
The size of the investment shows that this is a concrete
commitment, which has few paragons throughout the
world.
For this reason, Enel will be developing a large
investment programme over the next five years (20072011) for over four billion euros. The majority of this
(3.3 billion euros) will be destined to developing
renewable sources, building new plants to provide a total
of about 1700 MW, to which about 800 million euros are
to be added for investments in highly innovative new
projects.
This plan will avoid the production of over four million
tones of CO2 emissions a year.
To reach this scope, Enel is committed in three main
areas:
x renewable sources
x energy efficiency and distributed generation
x “zero emissions” and hydrogen frontier
ENEL’s investments planned in this third area are for
about 330 million euros assigned to research activities
and demonstrative innovative plants in the following
fields:
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IV.
HYDROGEN PARK
populated areas with electricity and heat with very low
additional side effects to the environment.
As the project feasibility study progressed in Marghera,
practical difficulties were found in using the cogeneration heat for other civil or industrial uses so Enel
decided to adapt it to increase the efficiency of its coal
fired generation power plant at Fusina.
An interesting opportunity for a real demonstration of
hydrogen-fed power generation technology presented
itself in Veneto about 3 years ago.
The petrochemical plants of the Marghera industrial area
near Venice produce a significant amount of hydrogen at
acceptable costs as a by-product from other existing
processes and most of this hydrogen is only used to
produce process heat. This can be easily replaced by
natural gas, and so hydrogen could be made available to
be used in a more innovative and efficient way in order to
start up new frontier technological applications.
In this industrial context, with the aim of promoting the
development and application of hydrogen technologies in
the transport and stationary generation sectors, a new
consortium, named Hydrogen Park, was founded in 2003
at this site in Venice, joining the forces of both private
companies (Sapio, Berengo, SAE Impianti, Unindustria
Venezia, EVC Italia, etc.) and public companies (Vega,
Venezia Tecnologie). ENEL, with its interest in hydrogen
technology applications and with two important coal fired
power plants on this site (Fusina and Marghera), saw the
possibility of playing a concrete role in this field and
decided to enter the consortium at the beginning of 2004.
A new associated company was constituted in April 2005
from the transformation of the Hydrogen Park
consortium, keeping the same name and aim, and under
Enel control (51% stake).
This associated company has the potential to really drive
the expansion of the largest experimental park in Italy to
create a full-scale hydrogen-based economy in the
following years by performing both research and
experimental activities and new applied technologies,
providing opportunities for the entire site.
In this context, ENEL is working on a large scale
program for the development and testing of advanced
hydrogen technologies.
As a first step of the program, ENEL decided to build a
medium-size hydrogen-fed demonstration plant for the
production of electric energy on the site of Enel Fusina
coal-fired power plant. It will be the first in the world in
terms of size and innovative technologies employed.
The Fusina hydrogen-fed generation power plant is
envisaged in the future to be a full scale experimental
research station, further new innovative components can
also be tested for use in hydrogen technology. All these
research activities will be carried out through a close
collaboration of the Enel Research Department with
Hydrogen Park.
VI.
THE PLANNED HYDROGEN DEMONSTRATION POWER
PLANT
The above mentioned hydrogen demonstration power
plant will consist of a 12 MWe hydrogen-fed gas turbine
cycle, closely integrated with the existing Fusina coal
power plant units and able to couple high efficiency fuel
utilisation with low nitrogen-oxide emissions.
Some critical aspects in the project have appeared since it
started:
x the hydrogen supply guaranteed by producers
x the development of critical innovative
components
x the engineering phase of the different innovative
aspects together with the gas turbine maker
towards reaching the stage of erecting and
commissioning an industrial demonstrative plant
x the economic aspects for long term operation in
the absence of public support.
VII.
THE FUEL
The presence at the Marghera/Fusina site of such a
complex industrial area with several chemical plants
producing hydrogen as a by-product, combined with the
presence of large generation power plants has provided
an important technical and economical opportunity that
has driven the installation of innovative hydrogen-fed
plants.
The hydrogen required to feed the new turbine will be
supplied by the chemical plants operating close to the
power production site.
The short distance between the Enel Fusina coal power
plant and the hydrogen producers means the hydrogen
can be carried by simply crossing a channel using an
existing industrial bridge; the relative positions of the
facilities are shown in Figure 1. The purple line shows the
boundary of the Enel coal power plant. The yellow line is
the hydrogen pipeline. Possible close hydrogen producers
are indicated in red.
V. BASIC PROCESS WITH CO-GENERATION
The initial idea of the project 1 was to design an
independent hydrogen-fed gas turbine-based cogenerative cycle, in which steam injection in the gas
turbine would be adopted to couple high process
efficiencies with very low nitrous oxide emissions. This
kind of plant would have been able to provide densely
1
References n° 9 and 10
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10 t/h to be achieved for each test cell with minimal
pressure losses.
Fig. 2 shows a panoramic image of ENEL’s existing
facilities at Sesta, which are specifically dedicated to
testing different kinds of gas turbine combustion
chambers.2
Fig. 1.
A view of the area
At the moment, Enel has already placed a contract to
obtain hydrogen from Polimeri Europa and business
negotiations are underway with other producers to
increase the amount of hydrogen available for the project.
VIII. UPGRADING SESTA STATION FOR COMBUSTION
Fig. 2. The gas turbine combustor test facilities at Sesta
EXPERIMENTAL TESTS
Enel’s researchers have already gained direct experience
of hydrogen combustion with previous tests at Sesta and
Livorno as references show 3 and they will work in close
collaboration with the gas turbine maker.
Particular attention shall also be paid to safety aspects
due to the presence of the large amount of hydrogen.
The development of innovative components such as
hydrogen-fed gas turbine combustors will make heavy
demands on full-scale hydrogen combustion tests.
The chosen solution has therefore been to upgrade the
capabilities of Enel’s Sesta experimental station in
Tuscany, which has been utilized for many years for fullscale combustion tests by all the main gas turbine makers
throughout the world (Siemens, GE, Ansaldo, MHI).
Enel was able to perform syngas and pure hydrogen tests
here in the past, but the best performances obtained were
not sufficient for the new needs of full scale plants.
The necessary new investments have just been made and
the Sesta feed system upgrading was completed in
February 2007, making it now available for use both for
Enel’s hydrogen project and, in the future, for other
customers’ tests.
The Sesta facility is now able to perform the necessary
full scale tests, firing both pure hydrogen and gas
mixtures up to 0.36 kg/s at 20 bara thanks to the following
upgradings:
x Hydrogen storage capacity: has been increased from
2 to 4 bottle track bunkers, reaching a total storage of
18000 Nm3 (4500 Nm3 at 200 bar for each bottle
track)
x Hydrogen mass flow: a new 4" feed line in AISI 304L
ANSI 600 has been installed, increasing the total
hydrogen mass flow up to 0.360 kg/s at 20 bara
x Natural gas storage: a new bottle track bunker has
already been installed and monitored, increasing the
total number of available bottle tracks from 4 to 5.
x Steam mass flow and pressure: the steam feed plant
has been upgraded and a new 4" feed line in AISI 316
ANSI 1500 has been installed from the boiler to each
test cell (1&2), permitting a total steam mass flow of
IX.
THE ENEL RESEARCH AND DEVELOPMENT PROGRAM
FOR A PURE HYDROGEN-FED GAS TURBINE
The whole programme foresees a close connection
between investment and research activities.
The joint outstanding research activity will be only
partially sustained by funds from the Italian Ministry of
the Environmental (MATT) and Veneto Region. The
amount available for the “zero-emission cycle
development with hydrogen combustion” research project
is a maximum of 2 980 000 euros at 50 % to be divided
between the Enel Research Department and the other
research partners involved (GE, CREAR, CPR, DIMSET,
DIMS, DIM , IRC). This funded research project startedup in June 2006 and it has an expected duration of three
years.
Mathematical computer simulations and atmospheric tests
will be carried out by the Enel Research Department in
Pisa and Livorno respectively. The most promising
burner solutions will also be tested under pressure with
pure hydrogen in full scale burner tests planned at the
ENEL Sesta experimental station (Siena) starting from
next summer.
The research activities will be divided into the following
tasks:
x conceptual development
2
3
Reference n° 7
References n° 3, 4, 6 and 8
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x
Marghera petrochemical plants. The gas turbine chosen
was GE 10 by GE Oil & Gas N. Pignone, originally
designed to run on natural gas. This gas turbine is quite
simple and has only one vertical combustion chamber.
The original gas turbine to be modified is shown in Fig.
3.
preliminary activity concerning advanced
diagnostic
instruments
for
monitoring
components during the tests (such as a new
innovative flame vision system able to see in
the ultraviolet and visible fields and guarantee
on-line flame vision)
x mathematical computer simulations (to be
performed by CREAR)
x
fluid dynamic atmospheric tests (planned in
Enel’s
laboratories in Livorno) and CFD
analysis (to be performed by Enel and CPR 4)
x
hot tests at Enel’s laboratories in Sesta for
promising combustor chamber prototype
geometries
x integration studies of the new hydrogen
combustion system in the existing gas turbine
(mainly performed by the gas turbine maker GE
and also by DIMSET5 and DIM 6 )
x long term experimental tests and continuous
operation of the hydrogen-fed power generation
plant at Fusina (charged at Enel)
x development of a second phase version of the
combustion system
x preliminary studies for new technology low NOx
hydrogen combustion system (prevalently
performed by Enel and also by DIMS 7, IRC 8
and GE )
The first step of the program is to modify the existing
original natural gas burner and the combustion chamber
in order to run the original machine with pure hydrogen
with only minor modifications, limiting the NOx
emissions to 200 ppmv , which is the contractual value for
the GE order. In any case, ENEL researchers are still
confident of reaching below 100 ppmv with only minor
modifications.
The second step is to develop a new burner that will
allow the hydrogen gas turbine to run with NOx emission
values under 50 ppmv
In the medium term, the goal of the project is to arrive at
a highly efficient hydrogen turbine with even lower NOx
emission values (near zero emissions).
In a long-term strategic view, this zero emission
hydrogen burner could become a prototype of burners to
be used by makers for future large hydrogen turbines.
Fig. 3. The natural gas turbine GE10 to be modified 9
XI. PLANT CYCLE DESCRIPTION
The complete plant design foresees two different
pipelines that carry the hydrogen to the plant; one is unpurified hydrogen at 27 barg and the other is pure
hydrogen at 5 barg. It is necessary to raise the pressure of
the pure hydrogen before mixing it with the other to
obtain a final mixture entering the combustion chamber
with 97.5 % purity (percentage by volume).
The hydrogen cycle will be closely integrated with the
existing coal fired power station.
A simplified scheme of the process is shown in Fig. 4.
H2
Electric output
11.44 M W e net from H2
Comp.
Air 15°C
Gen.
GasTurb.
Steam
Steam 340 °C 31 bar
H2O
Exhaust
H2O 140 °C
M ostly N2 e O2
H2O 53 °C
X. THE
Unit 4
320 M W e
w ith coal
41 °C
HYDROGEN–FED GAS TURBINE
H2O 33 °C
Increase of
gross thermal
cycle efficiency
from 45.25%
to 45.85%
in unit 4
41 °C
The size of the gas turbine (about 12 MWe) was chosen
according to the availability of hydrogen from the
Condensate recovery
Fig. 4. General scheme 10
The exhaust flue gas coming from the turbine exit is sent
to a heat recovery steam generator (HRSG) to produce
steam. Part of this steam is re-used in the gas turbine
combustion chamber with the aim of both minimizing the
NOx formation and increasing the efficiency of the cycle.
4
CPR will be involved in CFD simulations of the diffusion
combustion chamber using Fluent, a commercial modeling program
5
DIMSET will be mainly involved in heat exchange studies
concerning both the gas turbine blades (in the presence of high
temperature fluids with high steam concentrations) and the heat
recovery steam generator (where steam condensation is expected)
6
DIM will be mainly involved in computer simulations of the
combustion chamber thermoacustics
7
DIMS will be involved in studies of innovative new materials in
the field of transpiration and effusion
8
IRC will be involved in studies of catalytic combustion systems
using pure hydrogen or hydrogen-natural gas mixture; new recently
developed materials will be studied.
9
Source: GE commercial brochure
The 320 MW unit gross thermal cycle efficiency values reported
in the scheme are defined as the ratio between the electrical power
produced (measured at the output terminals of the main generator) and
the thermal power adsorbed by the fluid in the boiler
10
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The residual steam is sent to the coal fired power station,
thus contributing to an increase in the thermal efficiency
of the plant. In the second part of the HRSG, the
condensate from the power station is heated-up before
being re-sent to the plant. A considerable amount of heat
is recovered from the wet gas thanks to the condensation
of most of the water present, which will be re-injected
after treatment into the cycle of the nearby 320 MW coal
fired power plant. Thanks to this integration, the
hydrogen cycle will be able to produce up to 16 MW of
electric power (about 12 MWe produced by the gasturbine and about 4 MWe as extra power produced by the
existing power station burning the same amount of coal)
with a total gross thermal efficiency of about 43 %.
More details of the base full load case with air
temperature at 15°C are presented in Fig. 5. 11
some (14 %) is re-injected at 140°C after the third low
pressure pre-heater and the remainder (5 %) is
transformed into steam at 340 °C and mixed with the
steam coming from the medium pressure turbine. There is
also a residual amount (2 %) of water that enters the
combustion chamber of the hydrogen-fed gas turbine
which has to be re-integrated.
34 ata 538°C
170 ata 538°C
7,03 ata
Boiler
BP
BP
Cond.
BP
1
P
H2 97,51 %v
CH4 1,738 %v
N2
0,628 %v
CO
0,124 %v
0,36 kg/s
36,85 MWt
101.823 kJ/kg
11.893 Nm3/h
0,1095 kg/Nm3
PM 2,455
20 bar 70°C
4,57 kg/s
CC
GT
Steam
30,2 bar
240°C
1,22 kg/s
15°C
46,18 kg/s
60% relative umidity
101,3 kPa
inlet pressure losses 100mmH2O
N2 77,30 %v
O2 20,74 %v
H2O 1,01 %v
Ar
0,92 %v
CO2 0,03 %v
AP
1
BP
3
AP
3
AP
2
P
Steam/fuel mass ratio = 3,37
Steam/air mass ratio = 2,64 %
CO
Air
DEG
BP
2
cvt
Thermal efficiency
31,06 %
Heat rate at ISO condition 11.590 kJ/kWh
H2
16 bar
417 °C
AP
MP
N2 70,98 %v
O2 14,61 %v
H2O 13,37 %v
Ar
0,85 %v
CO2 0,19 %v
1,09 kg/s
GE
Steam
11,445 MWe
47,76 kg/s
PM 27,39
340°C 31 bar
H2O
25,0 bar
140°C
12,01 kg/s
H2O
27,5 bar
53°C
66,51 kg/s
17,8 kg/s
5,79 kg/s
0,10 kg/s
4,8 bar
Exhaust
losses
250
mmH2O
45,76 kg/s
228°C
N2
O2
H2O
Ar
CO2
PM 28,85
150°C
H2O
0,13 kg/s
472°C
442°C
248°C
210°C
85°C
H2O
Steam
12,0 kg/ s
140°C
25 bar
4,6 kg/ s
340°C
31 bar
Fig. 6. The existing 320 MWe unit 4 in Fusina Enel power plant
41°C
75,80 %v
15,60 %v
7,50 %v
0,90 %v
0,20 %v
In this case, there is an increase in Unit 4 gross thermal
cycle efficiency 13 from 45.25 % to 45.85 %.
On the contrary, calculations have demonstrated that if
the coal feed remains the same, it is possible to obtain
about 4 MWe of extra power.
The complete plant design foresees similar connections to
coal-fed unit 2. The hydrogen turbine will be able to run
connected alternatively with either unit 4 or unit 2.
PM 28,03
35 bar
150°C
5,89 kg/s
H2O
66,5 kg/ s
53°C
27,5 bar
Exhaust
1,57 kg/s
32,5 bar
238°C
H2O
84,3 kg/ s
30 bar
33°C
41°C
33 °C
5,75 kg/s
H2O
84,31 kg/s
30 bar
1,99 kg/s 41 °C
Auxiliary power: 482 kW
Condensate
recovery
Fig. 5. Detailed scheme
Referring to our old preliminary scheme12 that foresaw
operation with injected steam-to-air ratios of around 10 %
in weight, the amount of steam that can be injected in the
combustion chamber is limited by the characteristics of
the existing GE10 turbine and by real problems that still
have to be solved (flame stability, surge margin,
mechanical resistance and heat transfer issues). An
acceptable steam-to-air ratio value is below 3 % and this
limits the efficiency of the thermodynamic cycle.
XIII. PREDICTED PERFORMANCE
The following Table I and Table II show the predicted
base performance of the plant.
The efficiencies refer to the fuel LHV (Low Heat Value).
TABLE I
GE 10 NOMINAL PERFORMANCE WITH H2 AS FUEL
Electric power in H2 gas turbine
11.44 MWe
XII. INTEGRATION OF THE HYDROGEN GAS TURBINE
CYCLE WITH THE COAL FIRED UNIT
The connections between the new 12 MWe hydrogen-fed
plant and the existing 320 MWe coal-fed plant are shown
in Fig. 6.
The detailed balance shown refers to a case in which the
amount of electric power generated by the existing unit 4
remains the same and the coal consumption decreases
thanks to the introduced heat. Part of the condensate from
the power station condenser (more than 300 t/h) is
heated-up. Most of this water (70 %) is re-injected at
53°C to the plant before the first low pressure pre-heater,
11
At the moment the amount of hydrogen already guaranteed by
contract is only 5 000 Nm3/h, not enough to run the gas turbine at full
load; if this amount doesn’t increase it might be necessary to run the gas
turbine at a lower load or with a hydrogen-natural gas mixture
12
References n° 9 e n° 10
Thermal efficiency just in the H2 gas turbine
31.1 %
Thermal efficiency with integration with Unit 4 14
42,9 %
Heat use index with integration with Unit 4
97.8 %
13
As defined before in the note
The thermal efficiency with integration with unit 4 is defined as
the ratio between the electrical power (produced in the hydrogen plant
plus the 320 MW plant extra power) and the hydrogen thermal power
burning the same amount of coal
14
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TABLE II
EXISTING COAL-FIRED UNIT 4 PERFORMANCE WHEN INTEGRATED WITH
H2 GAS TURBINE
Reduction in thermal input
from coal
Case 1
Running at the same
electric load
(about 320 MWe)
Case 2
Burning the same amount
of coal
XIV.
The technical goals of this research project are in order of
time:
• Hydrogen combustion technology development
together with the gas turbine maker, arriving at
an adaptation of the existing gas turbine to run
with both pure hydrogen and hydrogen-natural
gas mixtures
• Optimization of the integration between the
existing power plant and the H2 cycle to utilize
the available exhaust heat as much as possible
• Second-phase optimization of a combustion
technology, paying particular attention to
emissions and efficiency
• To test the cycle with long period tests.
10.11
MWt
Reduction in coal
consumption
1.43 t/h
Reduction in CO2 emissions
3.43 t/h
Increase in thermal cycle
efficiency
0.6 %
Increase in electric load
4.37
MWe
XVI.
TIMING OF THE PROJECT
During the second half of 2006, all ready component
orders were stopped by Enel, while they were waiting for
the definitive signing of the hydrogen supply contracts.
This problem has now been overcome. The entire plant
investment and research program was definitively
approved by the ENEL managing director in December
2006.
The current situation is as follows:
x basic plant design was completed in December
2005
x the gas turbine was chosen and design order was
sent to GE in December 2005
x public and statutory consent for plant
construction was obtained in June 2006
x hydrogen supply contract with Polimeri Europa
was signed in February 2007
x basic design of pipelines for carrying hydrogen
to the Enel plant has been defined
A summarised schedule of the project is shown in Fig. 8
FINAL DESIGN OF THE HYDROGEN PLANT
An overview of the future hydrogen plant in the existing
Fusina power station is shown in Fig. 7. The 3D
representation shows the relative positions of the main
components.
The presence of three chimneys (bypass chimney,
intermediate chimney and dry flue gas chimney) is
motivated by the need for operation flexibility, research
reasons and to have the possibility of running without any
integration with the existing coal power plant.
2007
Q1
Q2
2008
Q3
Q4
Q1
Q2
2009
Q3
Q4
Q1
Q2
Q3
Q4
Placing H2 supply contracts
Test hydrogen burner design and supplying
Hydrogen burner development tests
Detailed design
Placing contracts and procurement
Gas turbine supplying (GE)
First synchronised
GVR supplying
Gas turbine assembling on site
Fig. 7. Main components of the plant
Nominal load
Construction (Civil works and assembling)
Preliminary Set-up (Natural Gas as fuel)
XV.
Final Set-up (Hydrogen as fuel)
THE TECHNOLOGICAL INNOVATION
Commercial operation and long-term tests
The main innovative aspects of the thermal cycle process
can be synthesized in the following points:
• Pure hydrogen as base fuel 15
• Tests with hydrogen-natural gas mixtures with
different rates of hydrogen
• A great deal of steam injected in the combustion
chamber together with the hydrogen to reduce
emissions and increase efficiency
• A new burner configuration
• Significant heat recovery from the gas turbine
exhaust to increase efficiency, including
condensation of the steam present in the exhaust
IPC
Notice to proceed to GE
First firing
TU
Fig.8. Timescale
ENEL hopes to have the first firing with hydrogen as fuel
by the end of May 2009.
XVII. CONCLUSIONS
At Fusina (Venice), Enel will be able to run its hydrogenfed gas turbine with very low emissions and high
efficiency. This concrete result will be obtained thanks to
the company’s strategic vision aimed at industrial
innovation and applied research in order to reduce
pollutant emissions from its plants and achieve
sustainable growth.
15
Worldwide there are as yet no gas turbines tested in a continuous
operation with pure H2 as fuel
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This demonstration project will be an important step in
the development of the hydrogen economy.
In the Venice area, furthermore, it may be possible to
create the largest hydrogen district in Italy, and ENEL is
fully involved in trying to reach this goal.
[6]
[7]
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[4] HJ. Tomczak, G. Benelli, L. Carrai, D. Cecchini:
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