HỌC TỐT TIẾNG ANH 11 THEO CHƯƠNG TRÌNH GLOBAL SUCCESS ĐÁP ÁN CHI TIẾT - CẢ NĂ...
Solar Thermal Energy: Harnessing the Sun's Rays to Generate Electricity
1.
2. Solar thermal energy
(STE) is a form of
energy and a
technology for
harnessing solar energy
to generate
thermal energy or
electrical energy for use
in industry, and in the
residential and
commercial sectors.
What is it?
4. Electricity is genearted from solar thermal
energy
Solar thermal
power plants use
the sun's rays to heat a
fluid to high
temperatures. The fluid is
then circulated through
pipes so that it can
transfer its heat to water
and produce steam. The
steam is converted into
mechanical energy in a
turbine, which powers a
generator to
produce electricity.
5. SOLAR THERMAL ENERGY STORAGE
Thermal energy storage (TES) TES are high-pressure liquid storage tanks used
along with a solar thermal system to allow plants to bank several hours of
potential electricity.
1.Two-tank direct system: solar
thermal energy is stored right in
the same heat-transfer fluid that
collected it.
2.Two-tank indirect system:
functions basically the same as the
direct system except it works with
different types of heat-transfer
fluids
3.Single-tank
thermocline system:
stores thermal energy as
a solid, usually silica
sand.
6. Types of solar thermal power
plants
A. Parabolic trough
B .Solar Dish
C .Solar Power tower
A
B
C
7. PARABOLIC TROUGH
A parabolic trough is a
type of SOLAR THERMAL
COLLECTOR that is
straight in one dimension
and curved as
a parabola in the other
two, lined with a polished
metal mirror. The energy
of sunlight which enters
the mirror parallel to its
plane of symmetry is
focused along the focal
line, where objects are
positioned that are
intended to be heated.
8. PARABOLIC TROUGH EFFICIANCY
It is used to predict the
performance of a given
parabolic trough and
compare competing
technologies. NREL
tests show the Sky
Trough's
thermal efficiency at
350 °C (662 °F) to be
over 73%, meaning that
nearly three quarters of
the solar radiation
striking
the trough surface is
converted into thermal
energy.
9. Parabolic Trough Design
A parabolic trough is made
of a number of solar
collector modules (SCM)
fixed together to move as
one solar collector
assembly (SCA). A SCM
could have a length up to
15 metres (49 ft) or more.
About a dozen or more of
SCM make each SCA up
to 200 metres (660 ft)
length. Each SCA is an
independently tracking
parabolic trough.
10. SOLAR DISH
A solar thermal
DISHcollector collects heat by abs
orbing sunlight. A collector is a
device for capturing solar radiation.
Solar radiation is energy in the form
of electromagnetic radiation from
the infrared(long) to
the ultraviolet (short) wavelengths.
The quantity of solar energy
striking the Earth's surface (solar
constant) averages about 1,000
watts per square meter under clear
skies, depending upon weather
conditions, location and orientation.
11. SOLAR DISH MECHANISM
Solar Dish engine
systems use mirrored
dishes (about 10 times
larger than a backyard
satellite dish) to focus and
concentrate sunlight onto a
receiver. As shown in Figure
5, the receiver is mounted at
the focal point of the dish. To
capture the maximum
amount of solar energy, the
dish assembly tracks the sun
across the sky. The receiver
is integrated into a high-
efficiency "external"
combustion engine.
12. Contd.
The engine has thin tubes
containing hydrogen or helium gas
that run along the outside of the
engine's four piston cylinders and
open into the cylinders. As
concentrated sunlight falls on the
receiver, it heats the gas in the
tubes to very high temperatures,
which causes hot gas to expand
inside the cylinders. The expanding
gas drives the pistons. The pistons
turn a crankshaft, which drives an
electric generator. The receiver,
engine, and generator comprise a
single, integrated assembly
mounted at the focus of the
mirrored dish.
13. SOLAR POWER TOWER
The solar power tower, also
known as 'central tower'
power plants or 'heliostat'
power plants or power
towers, is a type
of solar furnace using
a tower to receive the
focused sunlight. It uses an
array of flat, movable mirrors
(called heliostats) to focus
the sun's rays upon a
collector tower (the target).
14. SOLAR POWER TOWER MECHANISM
The technology uses
many large, sun-tracking
mirrors commonly referred
to as heliostats to focus
sunlight on a receiver at the
top of a tower. A heat
transfer fluid heated in the
receiver is used to generate
steam, which, in turn, is
used in a conventional
turbine-generator to
produce electricity.
15. ADVANTAGES of SOLAR THERMAL ENERGY
No Fuel Cost – Solar Thermal Energy does
not require any fuel like most other sources of
renewable energy. This is a huge advantage
over other fossil fuels whose costs are
increasing at a drastic rate every year.
Electricity prices are increasingly rapidly in
most parts of the world much faster than
general inflation. Price shocks due to high fuel
costs are a big risk with fossil fuel energy
these days.
Predictable, 24/7 Power -Solar Thermal
Energy can generate power 24 hours a day.
This is made possible as solar thermal
power plants store the energy in the form of
molten salts etc. Other forms of Renewable
Energy like Solar PV and Wind Energy are
intermittent in nature. The electricity supply
is much more uniform and reliable.
16. No Pollution and Global Warming
Effects – Solar Thermal Energy does
not cause pollution which is one of the
biggest advantages. Note there are
costs associated with the equipment
used to build and transport Solar
Thermal Energy Equipment.
Using Existing Industrial Base –
Solar Thermal Energy uses
equipment like solar thermal mirrors
and turbines which is made in large
scale at low cost by the existing
Industrial Base and requires no major
changes in equipment and materials
unlike new technologies such as
CIGs Panels.
Contd.
17. DISADVANTAGES of SOLAR THERMAL ENERGY
High Costs – Solar Thermal Energy costs at least
Euro 3.5/watt and has not declined too much in the
last 3-4 years. However these costs are too
high as Solar PV already costs Euro 2.5/watt and
even on a conservative basis will have its costs
reduced by 5% in the next 10 years making it
attain half the cost of Solar Thermal Technology by
2020.
Water Issue – Solar Thermal Plants
use lots of Water which is Major
Problem in Desert Areas. Using non-
water cooling raises the cost of CSP
projects too much. While using Sea
Water has been proposed it remains to
be seen if it possible to implement this
solution as this would imply building
Plants very near the Coastline.
18. Ecological and Cultural Issues – The
Usage of Massive Arrays of Mirrors is
noted to heavily impact the
Desert Wildlife endangering the
endangered species. California has
already seen a massive fight on this
issue with Project Developers curtailing
the size of their Plants and spending
money to move the wildlife.
Contd.
Limited Locations and Size Limitations – Solar
Thermal Energy can only be built in places which
have the high amount of solar radiation. They can
be built in deserts mostly and require a large land
area. This means its not possible to build them in
populated areas. Solar Thermal Energy also can
only be built in large sizes which are at least 50
MW in size to be economical. This contrasts to
Solar PV which is sold in sizes as low as 5 Watts.
19. LOAD by DEMAND
This load curve diagram shows that
much of the electricity demand is in
fact for continuous 24/7 supply
(base-load), while some is for a
lesser amount of predictable supply
for about three quarters of the day,
and less still for variable peak
demand up to half of the time; Some
of the overnight demand is for
domestic hot water systems on
cheap tariff. With overnight charging
of electric vehicles it is easy to see
how the base-load proportion would
grow, increasing the scope for
nuclear and other plants which
produce it. Source: Vencorp
20. ROADMAP to 2050
The roadmap emphasises
that solar thermal cooling
technology can fully or
partially replace
conventional electrically
powered air conditioners in
buildings. As well as this,
there are several industry
sectors requiring significant
energy demand for low-
and medium-temperature
heat in such processes as
washing, drying agricultural
products, pasteurisation
and cooking.
21. Contribution of SOLAR THERMAL ENERGY
Solar Thermal power has grown at a
similarly impressive rate
22. SOLAR THERMAL ENERGY IN INDIA
India is densely populated
and has high
solar insolation, an ideal
combination for
using solar thermal
power in India. One of the
first applications of solar
power has been for water
pumping, to begin
replacing India's four to
five million diesel
powered water pumps,
each consuming about
3.5 kilowatts, and off-grid
lighting.Graph show solar
thermal resources in india.
23. SOLAR THERMAL CAPACITY in INDIA
According to GOVT. record 3743.97 MW solar power in
india till Mar-2015
24. FURTHER DEVLOPMENT-THERMAL
CHIMNEYS
Thermal chimneys are passive solar
ventilation systems, which means they are
non-mechanical.
Typically made of a black, hollow thermal
mass with an opening at the top for hot air
to exhaust.
Inlet openings are smaller than
exhaust outlets and are placed at low
to medium height in a room.
When hot air rises, it escapes through the
exterior exhaust outlet, either to the outside
or into an open stairwell or atria.
• Turbines similar to those used in
hydroelectric power plants convert the air
flow into mechanical energy.
25. CONCLUSION
In the face of global warming, rising fuel costs and an ever-growing
demand for energy, energy needs are expected to increase by nearly the
equivalent of 335 million barrels of oil per day, mostly for electricity. By
concentrating solar energy with reflective materials and converting it into
electricity, modern solar thermal power plants, if adopted today as an
indispensable part of energy generation, may be capable of sourcing
electricity to more than 100 million people in the next 20 years.In caes of
economical point of view , intitial costs are very high, but for
UNDEVLOPED and DEVLOPING countries it creates a avenue to
EMPLOYBILITY. All from one big renewable resource: THE SUN.