PHYS 1110
Lecture 15
Professor Stephen Thornton
October 23, 2012
Reading Quiz
Which of the following statements is most true?
A) The sun is about 5-6 million years old.
B) Most of our energy on Earth comes from the
hydrologic cycle.
C) Power towers refer to an ancient Greek device
that was used to deliver large boulders.
D) Fresnel was a vice presidential candidate in
the 1948 election.
E) The sun will shine for about another 5 billion
years and is primarily responsible for life on
Earth.
Reading Quiz
Which of the following statements is most true?
A) The sun is about 5-6 million years old.
B) Most of our energy on Earth comes from the
hydrologic cycle.
C) Power towers refer to an ancient Greek device
that was used to deliver large boulders.
D) Fresnel was a vice presidential candidate in
the 1948 election.
E) The sun will shine for about another 5
billion years and is primarily responsible
for life on Earth.
Homework is due today.
Quiz next Tuesday, October 30 on
Ch. 5 Thermodynamics
Ch. 6 Fossil Fuels
Ch. 7 Hydropower only
Let’s go through the list of disadvantages
and advantages of hydropower. Which ones
do you disagree with? Divide up room.
Take a few minutes to go over these on your
computer. You can talk among yourselves.
There are more than 850,000 dams globally. Of the
80,000 dams in the United States, only 3% produce
hydroelectricity. Most of these (81%) are earthen
dams, both large and small, but many of them
could be converted to hydropower dams,
particularly as the price of electricity increases.
During periods of the 20th century, hydropower
provided almost 50% of the electricity in the
United States. During the middle part of the 20th
century, dams were constructed at a rapid rate, but
the rate slowed considerably after 1980. It takes a
considerable amount of land and a strong river for
a dam replacement.
Worst dam failures in history.
Banqiao Dam, China, 1975; killed
175,000 during Typhoon Nina (26,000
flooding and 145,000 epidemics and
famine. 62 dams failed.
Johnstown flood, 1889. Earthen dam
broke and killed 2200.
Quiz
You own a 5000 acre parcel in the mountains of
western Albemarle county. Which would you
rather build on your property to generate
income?
A)
B)
C)
D)
E)
A 250 acre pumped storage facility.
An overshoot water wheel on a creek.
A pay parking lot for hikers.
A 1500 acre lake behind a 50 m high dam.
A coal burning plant.
Quiz
You own a 5000 acre parcel in the mountains of
western Albemarle county. Which would you
rather build on your property to generate income?
A)
B)
C)
D)
E)
A 250 acre pumped storage facility.
An overshoot water wheel on a creek.
A pay parking lot for hikers.
A 1500 acre lake behind a 50 m high dam.
A coal burning plant.
Solar Energy
Burning a metric
ton (1000 kg) of
coal provides
~4x1010 J.
The time for
sunlight on Earth to
provide this energy
is ~3x10-7 s.
Solar PV. Existing world
capacity, 1996-2010.
Germany had 45%; Europe
75%.
Divide up into groups and discuss
•Passive solar heating and lighting for
buildings.
•Solar water heaters
•Solar thermal collectors – heat and cool
The USDOE estimates that about 1/3 of
household energy is used to heat water.
Probably closer to 20%.
Table 7-2 Specific Heats of Thermal Masses
Material Density Specific Heat Energy Density
(kg/m3)
(kJ/kg 0C)
(kJ/m3 0C)
Brick
2400
1
2400
Concrete 2400
0.96
2300
Dry earth 1250
1.26
1580
Dry sand 1600
0.80
1280
Stone
2500
0.84
2100
Oak wood
700
2
1400
Water
1000
4.2
4200
Trombe wall
Glass X windows in 20-unit senior
housing in Switzerland.
Figure 7-20 Sunlight falls on a solar
collector panel that absorbs the radiant
energy and heats water in the pipes.
Figure 7-21 A rooftop of an apartment building in
China with many solar water heaters. The water storage
is the cylinder perched on top of the solar panel.
Figure 7-23 A simple thermosiphon solar water
heater with a backup. The backup is often omitted.
Figure 7-24
Passive water
heaters rely on the
fact that hot fluids
rise and cold water
sinks. The hot
water is taken off
the top of the
insulated tank for
use.
Figure 7-25 The solar
batch system is
passive, and the
potable water is heated
directly. They are
simple and low in cost.
Figure 7-26 An
open-loop direct
solar water heating
system, often used
in tropical
climates. Active
system using a
water pump.
Everything but
collector can be in
attic or house.
Figure 7-27 A pressurized glycol system
that is an active, closed-loop system that
can be used in cold climates.
Figure 7-28 A closed-loop
drainback system utilizes distilled
water and is an active system
requiring a water pump.
Figure 7-29 A solar
heating system can
heat both in ground
and above ground
pools.
Figure 7-30 A typical installation of a
solar heating system for a swimming
pool.
Figure 7-31 A simple system to
both heat water and the house.
Figure 7-32 A simple flat plate to heat
a room while the sun is shining.
Figure 7-33
A forced air
solar space
heating
system.
Quiz
Which of the following statements is most
true?
A) Most states in the US average 8 to 9 sunny
hours a day.
B) The average household in the US uses about
20% of its energy to heat water.
C) The average household in the US uses about
10% of its energy to heat water.
D) Both A) and B) are true.
E) Both A) and C) are true.
Quiz
Which of the following statements is most
true?
A) Most states in the US average 8 to 9 sunny
hours a day.
B) The average household in the US uses about
20% of its energy to heat water.
C) The average household in the US uses about
10% of its energy to heat water.
D) Both A) and B) are true.
E) Both A) and C) are true.
Solar Thermal Concentrating Systems
The CSP global market had 1.2 GW of
generating electrical power by 2011 with
about 600 MW in Spain and 500 MW in the
United States. The market has been
exploding since 2007 with something like a
doubling of capacity each year. Parabolic
trough plants dominate the market. In 2011
an astounding 17 GW of capacity was under
development globally with the United States
having about 8 GW, Spain having 4.5 GW,
and China having 2.5 GW.
Concentrated Solar Power (CSP)
•
•
•
•
Parabolic trough
Power tower
Dish Stirling
Fresnel reflectors
Divide up into groups, discuss, and
make report.
Figure 7-35. A schematic of the parabolic
trough design is shown on the left and a
photo of a parabolic trough mirror
reflectors.
Figure 7-36 A schematic of a
parabolic trough solar power plant.
Figure 7-37 The Gemasolar power tower plant
in Andalucia, Spain has 2600 mirrors reflected
light onto a receiver at the top of a 140 m high
tower to heat molten salt.
Figure 7-38 The PS10 (in
foreground) and PS20 power tower
sites near Seville, Spain.
Figure 7-39 A schematic diagram of a power
tower solar power plant. Several hundreds of
mirrored heliostats heat molten salt that
eventually produces steam to produce power.
Figure 7-40 The
SunCatcher parabolic
Dish Sterling unit.
Sunlight is focused
onto a small area
where heat is
concentrated and
transmitted to a
Stirling engine to
produce electricity
Figure 7-41 A photo of the receiver and Stirling
engine for the SunCatcher dish Stirling system.
This entire system is mounted so that the sunlight
reflected off the mirrors is collected by the receiver.
Although there are no utility-scale dish Sterling systems
operating, there has been experience with operating units
like the SunCatcher for more than 10 years. The first
commercial system consists of 60 units producing 1.5
MW. It is called the Maricopa Solar Project and is
located west of Phoenix, Arizona. The plant began
producing grid electricity in 2010. Each SunCatcher
dish Sterling unit produces 25 kW. This plant is
considered a test unit to learn how the system, especially
the Sterling engine, works long term.
The Plataforma Solar de Ameria, PSA, is a Spanish research laboratory dedicated
to industrial applications of CSP. PSA has developed three generations of
prototypes since 1992, the DISTAL I, DISTAL II, and EUROdish. The
EUROdish project is a Spanish-German collaboration to test pre-commercial
units. It (see Figure 7-43) is a 10 kW system and several prototypes have been in
successful operation throughout several European countries and India?? for more
than 15 years. There are no commercial plants operating using the EUROdish.
Figure 7-44 The linear Fresnel
reflector (LFR) system. The mirrors
rotate to focus light on the receiver.
A demonstration plant at the Plataforma Solar de Almeria
(PSA) facility in Spain site (see Figure 7-45) opened in 2007
and uses a small mirror above the receiver tube to focus
reflected light on the receiver, which has water passing
through it that is heated to 450 0C and high pressure. The
mirrors are quite narrow but are much less sensitive to wind
than parabolic troughs or the dish Sterling system.
Right: the absorber of
the sunlight indicating
the steam tubes
surrounded by
insulation and reflective
walls on the side to
increase the collection
of reflected sunlight.
Left: example of linear
tracking reflectors that
reflect sunlight on either
of two linear absorber
reflectors in the CLFR
system.
Figure 7-47 Photo of the Kimberlina Solar
Thermal Power Plant in Bakersfield, California.
This is a 3 line CLFR plant producing 25 MW of
thermal power and 5 MW of electrical power.
Figure 7-48 The CFLR systems have the advantage
that the receivers are fixed in space. Only the mirrors
move on one axis. The system is relatively simple
structurally, which allows the space under the arrays to
be used for other purposes like parking cars.