Solar Energy
The earth receives a huge amount of energy in the form
of solar radiation.
On average, it is 1,700 kWh per square meter per year
(= 194 W/m2)
The total amount received on the planet’s surface is
equal to approximately 10,000 times the global energy
consumption.
Prof. R. Shanthini
Jan 21, 2012
Solar Energy
Solar Thermal (Solar T) or Concentrated Solar Power (CSP):
is a technology by which sunlight is
focused by mirrors or reflective
lenses to heat a fluid in a collector at
high temperature.
Solar Photovoltaics (Solar PVs):
are arrays of cells containing a
semiconductor material that
converts solar radiation into direct
current (DC) electricity.
Prof. R. Shanthini
Jan 21, 2012
Mark Z. Jacobson, Energy & Environtal Science., 2009, 2, 148-173
Solar Thermal
Solar heating capacity was 145 GW-thermal in 2008.
Prof. R. Shanthini
Jan 21, 2012
Solar Thermal
Active solar
water heater
Prof. R. Shanthini
Jan 21, 2012
Passive solar
water heater
Solar Thermal
Solar heater heats up water without
involving electricity generation.
Solar
heater on
roof
Prof. R. Shanthini
Jan 21, 2012
CSP for electricity generation - parabolic trough
Prof. R. Shanthini
Jan 21, 2012
http://www.greenrhinoenergy.com/solar/technologies/cst_technologies.php
CSP for electricity generation - parabolic trough
A solar parabolic trough is constructed as a long parabolic
mirror (usually coated silver or polished aluminum) with a
Dewar tube running its length at the focal point.
Sunlight is reflected by the mirror and
concentrated on the Dewar tube.
The fluid (eg. Oil) running
through the Dewar tube is
therefore heated up.
The trough is usually aligned on
a north-south axis, and rotated
to track the sun as it moves
across the sky each day.
Prof. R. Shanthini
Jan 21, 2012
Source: http://en.wikipedia.org/wiki/Parabolic_trough
CSP for electricity generation - parabolic trough
Solar energy trapped
by solar troughs
heats the thermal oil.
Oil circulating in a
closed loop heats
high volumes of
water to generate
steam at high
temperatures (up to
400oC).
Steam turbine
generates electricity
(at about 30%
conversion efficiency).
Prof. R. Shanthini
Jan 21, 2012
Solar Troughs
Steam Turbine
Thermal oil is
circulated in a
closed loop
Electric
Generator
Steam
Generator
Condenser
Cooling Tower
Source: http://www.solarpanelsplus.com/parabolic-trough-collectors/
CSP for electricity generation - parabolic trough
Solar Energy Generating Systems (SEGS)
consists of nine solar power plants (built between
1984 and 1990) in California's Mojave Desert, where
insolation is among the best available in the US.
- 354 MW installed capacity
- power 232,500 homes
- have a total of 936,384 mirrors
- cover more than 1,600 acres (6.5 km2)
- lined up, the parabolic mirrors would
extend over 370 km.
- 3000 broken mirrors (mostly by wind)
per year are replaced
Prof. R. Shanthini
Jan 21, 2012
Source:
http://en.wikipedia.org/wiki/Solar_Energy_Generating_Systems
CSP for electricity generation - solar tower
Prof. R. Shanthini
Jan 21, 2012 http://www.abengoasolar.com/corp/web/en/technologies/concentrated_solar_power/power_tower/index.html
CSP for electricity generation - solar tower
Prof. R. Shanthini
Jan 21, 2012
Solarfor
CSP
Thermal
electricity
/ Concentrated
generation -Solar
solar tower
Power
- There is a central tower receiver surrounded by a filed of
mirrors (called heliostats)
- The mirrors (tracking the angle of the sun) concentrate the
solar radiation onto a central heat absorber situated in the
tower.
- The temperature of the fluid in the absorber on the tower
can reach up to 500 to 1000oC.
- The fluid is used to heat water and run the steam turbine
that produces electricity.
Prof. R. Shanthini
Jan 21, 2012
http://www.greenrhinoenergy.com/solar/technologies/cst_technologies.php
Solarfor
CSP
Thermal
electricity
/ Concentrated
generation -Solar
solar tower
Power
Solucar PS10 (in Spain) is a commercial solar thermal power
tower-based plant
Prof. R. Shanthini
Jan 21, 2012
http://en.wikipedia.org/wiki/Solar_power_tower
CSP for electricity generation - solar tower
Facts on Solucar PS10:
- Solar tower is 115 m high, 40-story tower where
a solar receiver and a steam turbine are located
- 624 movable mirrors (called heliostats) with 120
m2 surface area each
- four years to build
- cost 35 million Euros
- 11 MW installed capacity
Prof. R. Shanthini
Jan 21, 2012
http://en.wikipedia.org/wiki/PS10_solar_power_tower
Solarfor
CSP
Thermal
electricity
/ Concentrated
generation -Solar
solar tower
Power
If heat received could also be stored in a thermal storage
media, the parabolic-trough and central tower CSP plants can
reduce the effects of solar intermittency by producing
electricity at night.
Storage media used are:
- pressurized steam
- concrete
- molten sodium nitrate
- molten potassium nitrate
- purified graphite
Prof. R. Shanthini
Jan 21, 2012
http://www.greenrhinoenergy.com/solar/technologies/cst_technologies.php
CSP for electricity generation - Dish-Stirling system
Prof. R. Shanthini
Jan 21, 2012
Mark Z. Jacobson, Energy & Environtal Science., 2009, 2, 148-173
CSP for electricity generation - Dish-Stirling system
- A parabolic dish-shaped (e.g., satellite dish) reflector rotates
to track the sun.
- The reflector concentrates sun radiation onto a receiver.
- At the receiver, energy is transferred to hydrogen in a closed
loop.
- Heated hydrogen (up to 650oC) expands against a piston or
turbine producing mechanical power.
- This power is used to run a generator to produce electricity
in kilowatts range.
- The power conversion unit is air cooled, so water cooling is
not needed.
- Up to 20% efficiency is possible, but costly
Prof. R. Shanthini
Jan 21, 2012
http://www.volker-quaschning.de/articles/fundamentals2/index.php
Solar PVs
PV cell turns sunlight directly into DC electricity.
Total of installed PV was more than 16 GW in 2008.
Solar irradiance
PV module
Inverter
Charge controller
Battery
AC loads
DC loads
Stand Alone System
Prof. R. Shanthini
Jan 21, 2012
Solar PVs
When photons (sunlight) hits the semiconductor, an electron
springs up and is attracted to the n-type semiconductor.
This causes more negative electrons in the n-type
semiconductor and more positive electrons in the p-type.
Thus a flow of electricity is generated in a process known as
the “photovoltaic effect.
Commercially available
solar cells achieve solar
energy to electricity
conversion efficiencies
of approximately 15%.
Prof. R. Shanthini
Jan 21, 2012
http://global.kyocera.com/solarexpo/solar_power/mechanism.html
Solar Energy
How much electricity can
we get from solar roof?
Roof area (assumed)
= 10 m2 (all covered with PV cells)
Solar radiation on earth
= 2 – 6 kWh/m2/day
(from http://www.nrel.gov/docs/fy03osti/34645.pdf)
Conversion efficiency
= 20% (max in the market)
Electricity obtainable
= 0.2 x (2 – 6) x 10 kWh/day
= 4 – 12 kWh/day
= 166 – 500 W
= 3 to 8 bulbs of 60 W strength
Prof. R. Shanthini
Jan 21, 2012
Solar Energy
Photovoltaic
Power for
Rural Homes
In Sri Lanka
Prof. R. Shanthini
Jan 21, 2012
Solar Energy
7W CFL, 12V Electronics, 10Wp Panel
7Ah MF Battery Backup: 3 to 4 hours
Solar Panel Warrantee: 10 years
Lantern Warrantee: 1 year
Solar lantern
About Rs 2500/=
Prof. R. Shanthini
Jan 21, 2012
Solar PVs
Photovoltaic 'tree'
Prof. R. Shanthini
Jan 21, 2012
Solar PVs
US$87 million
sheep are now grazing
under and around the
57,912 photovoltaic
modules
Prof. R. Shanthini
Jan 21, 2012
The Pocking Solar Park is a
10 MWp PV solar power plant.
- started in August 2005
- completed in March 2006
Solar PVs
World's largest PV Power Stations
- Huanghe Hydropower Golmud Solar Park (China, 200 MW)
- Perovo Solar Park (Ukraine, 100 MW),
- Sarnia PV Power Plant (Canada, 97 MW)
- Montalto di Castro PV Power Station (Italy, 84.2 MW)
- Senftenberg Solarpark (Germany, 82 MW)
- Finsterwalde Solar Park (Germany, 80.7 MW)
- Okhotnykovo Solar Park (Ukraine, 80 MW)
(completed in 2010 and 2011)
Prof. R. Shanthini
Jan 21, 2012
Solar PVs
Large PV Power Stations
in planning / under construction
- Ordos Solar Project (China, 2000 MW)
- Barmer, Bikaner, Jaisalmer and Jodhpur Solar Projects
(India, 1000 MW each)
- Calico Solar Energy Project (USA, 563 MW)
- Topaz Solar Farm (USA, 550 MW)
- and more….
Prof. R. Shanthini
Jan 21, 2012
Solar PVs
Inorganic Solar Cells
2nd Generation
Thin-film
Bulk
3rd Generation
Materials
Germanium
Silicon
CIS
CIGS
Silicon
Amorphous
Silicon
Mono-crystalline
CdTe
Poly-crystalline
Ribbon
Prof. R. Shanthini
Jan 21, 2012
GaAs
Light
absorbing dyes
Nonocrystalline
Silicon
Solar PVs
Inorganic Solar Cells
2nd Generation
Thin-film
Bulk
CdTe (cadmium
telluride) is easier
Germanium
Siliconto
deposit and more
suitable for largeMono-crystalline
scale
production.
3rd Generation
Materials
CIS
CIGS
Silicon
Amorphous
Silicon
CdTe
China’s 2000 MW PV
Poly-crystalline
plant
will use this
GaAs
technology.
Ribbon
Light
Prof. R. Shanthini
Cd
however toxic. absorbing dyes
Jan
21,is
2012
Nonocrystalline
Silicon
Solar PVs
Inorganic Solar Cells
2nd Generation
Thin-film
Bulk
3rd Generation
GaAs (gallium arsenide) is Materials
highly toxic and
Germanium
Silicon
CIS
carcinogenic.
When ground into very fine
CIGS
particles
(wafer-polishing
Mono-crystalline
processes), the high
CdTe
surface
area enables more
Poly-crystalline
GaAs
reaction with water
releasing
some arsine
Ribbon
Light
Prof. R. Shanthini
and/or
dissolved arsenic.absorbing dyes
Jan 21, 2012
Silicon
Amorphous
Silicon
Nonocrystalline
Silicon
Solar PVs
Inorganic Solar Cells
2nd Generation
Thin-film
Bulk
Processing silica (SiO2)
produce silicon is aSilicon
very high
3rdtoGeneration
energy process, and itMaterials
takes over two years for a
conventionalSilicon
solar cell to generate as much energy as was
Germanium
CISit contains.
used to make the silicon
Amorphous
Silicon
CIGS
Silicon
is produced by reacting carbon (charcoal) and silica
Mono-crystalline
CdTe
at a temperature around
1700 deg C.
Poly-crystalline
Nonocrystalline
GaAs
And, 1.5 tonnes of CO2 is emitted for each tonne ofSilicon
silicon
Ribbon (about 98% pure)
Light produced.
Prof. R. Shanthini
absorbing dyes
Jan 21, 2012
Solar PVs
Inorganic Solar Cells
Bulk
2nd Generation
Thin-film
Germanium is an “un-substitutable” industrial
mineral.
3rd Generation
75% of germanium
is used in opticalSilicon
fibre
Materials
systems, infrared
optics, solar electrical
and otherCIS
speciality glass uses.
Germanium applications,
Silicon
Amorphous
Germanium gives these glasses their desired
Silicon
CIGS
optical
properties.
Mono-crystalline
CdTe
Germanium use will likely
increase with solarelectric power becomes widely available
and as
Poly-crystalline
Nonocrystalline
GaAs
optic cables continue to replace traditional
Silicon
Ribboncopper wire.
Light
Prof. R. Shanthini
absorbing dyes
Jan 21, 2012
Solar PVs
Calculation of United States’ Sustainable Limiting
Rate of Germanium Consumption:
Step 1: Virgin material supply limit
The reserve base for germanium in 1999
=
500 Mg
So the virgin material supply limit over the next 50 years
= 500 Mg / 50 years
= 10 Mg/yr
Prof. R. Shanthini
Jan 21, 2012
Source: Graedel, T.E. and Klee, R.J., 2002.
Getting serious about sustainability, Env. Sci. & Tech. 36(4): 523-9
Solar PVs
Calculation of United States’ Sustainable Limiting
Rate of Germanium Consumption:
Step 2: Allocation of virgin material
Average U.S. population over the next 50 years
=
340 million
Equal allocation of germanium among the average U.S.
population gives
(10 Mg/yr) / 340 million
= 29 mg / (person.yr)
Prof. R. Shanthini
Jan 21, 2012
Source: Graedel, T.E. and Klee, R.J., 2002.
Getting serious about sustainability, Env. Sci. & Tech. 36(4): 523-9
Solar PVs
Calculation of United States’ Sustainable Limiting
Rate of Germanium Consumption:
Step 3: Regional “re-captureable” resource base
Worldwide germanium production from recycled material
≈ 25% of the total germanium consumed
Equal allocation of virgin germanium among the average U.S.
population therefore becomes 1.25*29 mg / (person.yr)
= 36 mg / (person.yr)
The sustainable limiting rate of germanium
consumption in U.S. is thus 36 mg / (person.yr)
Prof. R. Shanthini
Jan 21, 2012
Source: Graedel, T.E. and Klee, R.J., 2002.
Getting serious about sustainability, Env. Sci. & Tech. 36(4): 523-9
Solar PVs
Calculation of United States’ Sustainable Limiting
Rate of Germanium Consumption:
Step 4: Current consumption rate vs. sustainable limiting
rate
Germanium consumption in U.S. in 1999 = 28 Mg
Population in U.S. in 1999 = 275 million
So, germanium consumption rate in U.S. in 1999
= 28 Mg / 275 million = 102 mg / (person.yr)
which is about 2.8 times the sustainable limiting rate
of germanium consumption in U.S.
Prof. R. Shanthini
Jan 21, 2012
Source: Graedel, T.E. and Klee, R.J., 2002.
Getting serious about sustainability, Env. Sci. & Tech. 36(4): 523-9
Solar Energy
- Solar power systems generate no air pollution during
operation.
- Environmental, health, and safety issues involve how
they are manufactured, installed, and ultimately
disposed of.
- Energy is required to manufacture and install solar
components, and any fossil fuels used for this purpose
will generate emissions.
- Thus, an important question is how much fossil energy
input is required for solar systems.
Prof. R. Shanthini
Jan 21, 2012
http://www.ucsusa.org/clean_energy/technology_and_impacts/impacts/environmental-impacts-of.html
Solar Energy
- Materials used in some solar systems can create
health and safety hazards for workers and anyone else
coming into contact with them.
- Manufacturing of PV cells often requires hazardous
materials such as arsenic and cadmium.
- Even relatively inert silicon, a major material used in
solar cells, can be hazardous to workers if it is breathed
in as dust.
- There is an additional-probably very small-danger that
hazardous fumes released from PV modules attached
to burning homes or buildings could injure fire fighters.
Prof. R. Shanthini
Jan 21, 2012
http://www.ucsusa.org/clean_energy/technology_and_impacts/impacts/environmental-impacts-of.html
Solar Energy
- Large amount of land is required for utility-scale solar
power plants (approximately one square kilometer for
every 20-60 MW generated).
- Disruption of what might have been pristine property
- Intensive construction activities and having large
parabolic solar panels or mirrors taking up acres of land
could displace migration routes and habitat of wildlife,
flora and fauna.
- New solar installation sites are graded and sprayed
with weed control chemicals.
- Humans will be present on a more regular basis
driving to the site in vehicles and disposing of trash, etc.
Prof. R. Shanthini
Jan 21, 2012
http://www.ucsusa.org/clean_energy/technology_and_impacts/impacts/environmental-impacts-of.html
Solar Energy
- Solar-thermal plants (like most conventional power
plants) also require cooling water, which may be costly or
scarce in desert areas.
- Large central power plants are not the only option for
generating energy from sunlight.
- Because sunlight is dispersed, small-scale, dispersed
applications are a better match to the resource.
- They can take advantage of unused space on the roofs
of homes and buildings and in urban and industrial lots.
- And, in solar building designs, the structure itself acts as
the collector, so there is no need for any additional space
at all.
Prof. R. Shanthini
Jan 21, 2012
http://www.ucsusa.org/clean_energy/technology_and_impacts/impacts/environmental-impacts-of.html
Solar Energy
CIS Tower, Manchester,
England is 118 m skyscraper
with a weatherproof cladding
(replacing the mosaic tiles)
around the tower made up of
PV cells (alive & dummy cells).
It generates 21 kW electricity
(enough to power 61 average
3-bed houses) and feeds part
of it to the national grid.
£5.5 million
Prof. R. Shanthini
Jan 21, 2012
Solar Energy
Photovoltaic
Power for
Rural Homes
In Sri Lanka
Prof. R. Shanthini
Jan 21, 2012
Solar Power
Technological status
“niche” markets
Average growth
10.6% per year
Total share of global
energy mix
0.06% of electricity in 2008
0.54% of electricity in 2035 (potential)
Prof. R. Shanthini
Jan 21, 2012
Source: International Energy Outlook 2011
Total solar electricity generation projection:
200
Electricity generation
(Terawatt-hours)
Average growth is 10.6% per year
150
100
50
0
2008
2015
2020
2025
2030
2035
Year
Prof. R. Shanthini
Jan 21, 2012
Source: International Energy Outlook 2011
World electricity generation projection:
100%
Electricity generation
90%
80%
70%
Rest
Solar
60%
50%
40%
30%
20%
10%
0%
2008
2015
2020
2025
2030
2035
Year
Prof. R. Shanthini
Jan 21, 2012
Source: International Energy Outlook 2011
Comparison of Technologies:
Technology
Available
energy
(PWh/yr)
Technical
potential
energy
(PWh/yr)
Current
installed
power
(GW)
Current
electricity
generation
(TWh/yr)
16.5
< 16.5
778
2840
Solar PV
14900
<3000
8.7
11.4
CSP
9250 –
11800
1.05 – 7.8
0.354
0.4
Hydroelectric
Prof. R. Shanthini
Jan 21, 2012
RE technology options:
- Hydroelectric
- Solar Photovoltaics (Solar PVs)
- Solar Thermal (Solar T),
also known as Concentrated Solar Power (CSP)
- Wind
- Geothermal
- Marine (Wave and Tidal)
- Biofuels (Biomass, Bioethanol and Biodiesel)
Prof. R. Shanthini
Jan 21, 2012
Anything else?