1. Prof. R. Shanthini Jan 21, 2012 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/m 2 ) The total amount received on the planet’s surface is equal to approximately 10,000 times the global energy consumption.

2. Prof. R. Shanthini Jan 21, 2012 is a technology by which sunlight is focused by mirrors or reflective lenses to heat a fluid in a collector at high temperature. Solar Energy Mark Z. Jacobson, Energy & Environtal Science., 2009, 2, 148-173 Solar Thermal (Solar T) or Concentrated Solar Power (CSP): are arrays of cells containing a semiconductor material that converts solar radiation into direct current (DC) electricity. Solar Photovoltaics (Solar PVs):

3. Prof. R. Shanthini Jan 21, 2012 Solar heating capacity was 145 GW-thermal in 2008. Solar Thermal

4. Prof. R. Shanthini Jan 21, 2012 Solar Thermal Active solar water heater Passive solar water heater

5. Prof. R. Shanthini Jan 21, 2012 Solar Thermal Solar heater on roof Solar heater heats up water without involving electricity generation.

6. Prof. R. Shanthini Jan 21, 2012 CSP for electricity generation - parabolic trough http://www.greenrhinoenergy.com/solar/technologies/cst_technologies.php

7. Prof. R. Shanthini Jan 21, 2012 Source: http://en.wikipedia.org/wiki/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. CSP for electricity generation - parabolic trough

8. Prof. R. Shanthini Jan 21, 2012 Steam Turbine Steam Generator Electric Generator Condenser Cooling Tower Thermal oil is circulated in a closed loop Solar Troughs Source: http://www.solarpanelsplus.com/parabolic-trough-collectors/ 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 400 o C). Steam turbine generates electricity (at about 30% conversion efficiency). CSP for electricity generation - parabolic trough

9. Prof. R. Shanthini Jan 21, 2012 - 354 MW installed capacity - power 232,500 homes - have a total of 936,384 mirrors - cover more than 1,600 acres (6.5 km 2 ) - lined up, the parabolic mirrors would extend over 370 km. - 3000 broken mirrors (mostly by wind) per year are replaced Source: http://en.wikipedia.org/wiki/Solar_Energy_Generating_Systems 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. CSP for electricity generation - parabolic trough

10. Prof. R. Shanthini Jan 21, 2012 CSP for electricity generation - solar tower http://www.abengoasolar.com/corp/web/en/technologies/concentrated_solar_power/power_tower/index.html

11. Prof. R. Shanthini Jan 21, 2012 CSP for electricity generation - solar tower

12. Prof. R. Shanthini Jan 21, 2012 - 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 1000 o C. - The fluid is used to heat water and run the steam turbine that produces electricity. Solar Thermal / Concentrated Solar Power http://www.greenrhinoenergy.com/solar/technologies/cst_technologies.php CSP for electricity generation - solar tower

13. Prof. R. Shanthini Jan 21, 2012 Solar Thermal / Concentrated Solar Power Solucar PS10 (in Spain) is a commercial solar thermal power tower-based plant http://en.wikipedia.org/wiki/Solar_power_tower CSP for electricity generation - solar tower

14. Prof. R. Shanthini Jan 21, 2012 - 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 m 2 surface area each - four years to build - cost 35 million Euros - 11 MW installed capacity Facts on Solucar PS10: http://en.wikipedia.org/wiki/PS10_solar_power_tower CSP for electricity generation - solar tower

15. Prof. R. Shanthini Jan 21, 2012 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. Solar Thermal / Concentrated Solar Power http://www.greenrhinoenergy.com/solar/technologies/cst_technologies.php Storage media used are: - pressurized steam - concrete - molten sodium nitrate - molten potassium nitrate - purified graphite CSP for electricity generation - solar tower

16. Prof. R. Shanthini Jan 21, 2012 Mark Z. Jacobson, Energy & Environtal Science., 2009, 2, 148-173 CSP for electricity generation - Dish-Stirling system

17. Prof. R. Shanthini Jan 21, 2012 - 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 650 o C) 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 http://www.volker-quaschning.de/articles/fundamentals2/index.php CSP for electricity generation - Dish-Stirling system

18. Prof. R. Shanthini Jan 21, 2012 PV cell turns sunlight directly into DC electricity. Total of installed PV was more than 16 GW in 2008. Solar irradiance PV module Charge controller DC loads AC loads Inverter Battery Stand Alone System Solar PVs

19. 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%. http://global.kyocera.com/solarexpo/solar_power/mechanism.html

20. Prof. R. Shanthini Jan 21, 2012 How much electricity can we get from solar roof? Solar Energy Roof area (assumed)= 10 m 2 (all covered with PV cells) Solar radiation on earth = 2 – 6 kWh/m 2 /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

21. Prof. R. Shanthini Jan 21, 2012 Photovoltaic Power for Rural Homes In Sri Lanka Solar Energy

22. Prof. R. Shanthini Jan 21, 2012 Solar lantern About Rs 2500/= 7W CFL, 12V Electronics, 10Wp Panel 7Ah MF Battery Backup: 3 to 4 hours Solar Panel Warrantee: 10 years Lantern Warrantee: 1 year Solar Energy

23. Prof. R. Shanthini Jan 21, 2012 Photovoltaic 'tree' Solar PVs

24. 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 sheep are now grazing under and around the 57,912 photovoltaic modules US$87 million Solar PVs

25. Prof. R. Shanthini Jan 21, 2012 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) Solar PVs (completed in 2010 and 2011)

26. Prof. R. Shanthini Jan 21, 2012 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…. Solar PVs

27. Prof. R. Shanthini Jan 21, 2012 Inorganic Solar Cells Bulk 2 nd Generation Thin-film GermaniumSilicon Mono-crystalline Poly-crystalline Ribbon Silicon Amorphous Silicon Nonocrystalline Silicon 3 rd Generation Materials CIS CIGS CdTe GaAs Light absorbing dyes Solar PVs

28. Prof. R. Shanthini Jan 21, 2012 Inorganic Solar Cells Bulk GermaniumSilicon Mono-crystalline Poly-crystalline Ribbon Silicon Amorphous Silicon Nonocrystalline Silicon 3 rd Generation Materials CIS CIGS CdTe GaAs Light absorbing dyes CdTe (cadmium telluride) is easier to deposit and more suitable for large- scale production. China’s 2000 MW PV plant will use this technology. Cd is however toxic. 2 nd Generation Thin-film Solar PVs

29. Prof. R. Shanthini Jan 21, 2012 Inorganic Solar Cells Bulk GermaniumSilicon Mono-crystalline Poly-crystalline Ribbon Silicon Amorphous Silicon Nonocrystalline Silicon 3 rd Generation Materials CIS CIGS CdTe GaAs Light absorbing dyes GaAs (gallium arsenide) is highly toxic and carcinogenic. When ground into very fine particles (wafer-polishing processes), the high surface area enables more reaction with water releasing some arsine and/or dissolved arsenic. 2 nd Generation Thin-film Solar PVs

30. Prof. R. Shanthini Jan 21, 2012 Inorganic Solar Cells Bulk GermaniumSilicon Mono-crystalline Poly-crystalline Ribbon Silicon Amorphous Silicon Nonocrystalline Silicon 3 rd Generation Materials CIS CIGS CdTe GaAs Light absorbing dyes Processing silica (SiO2) to produce silicon is a very high energy process, and it takes over two years for a conventional solar cell to generate as much energy as was used to make the silicon it contains. Silicon is produced by reacting carbon (charcoal) and silica at a temperature around 1700 deg C. And, 1.5 tonnes of CO 2 is emitted for each tonne of silicon (about 98% pure) produced. 2 nd Generation Thin-film Solar PVs

31. Prof. R. Shanthini Jan 21, 2012 2 nd Generation Thin-film Inorganic Solar Cells Bulk GermaniumSilicon Mono-crystalline Poly-crystalline Ribbon Silicon Amorphous Silicon Nonocrystalline Silicon 3 rd Generation Materials CIS CIGS CdTe GaAs Light absorbing dyes Germanium is an “un-substitutable” industrial mineral. 75% of germanium is used in optical fibre systems, infrared optics, solar electrical applications, and other speciality glass uses. Germanium gives these glasses their desired optical properties. Germanium use will likely increase with solar- electric power becomes widely available and as optic cables continue to replace traditional copper wire. Solar PVs

32. Prof. R. Shanthini Jan 21, 2012 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 Source: Graedel, T.E. and Klee, R.J., 2002. Getting serious about sustainability, Env. Sci. & Tech. 36(4): 523-9 Solar PVs

33. Prof. R. Shanthini Jan 21, 2012 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) Calculation of United States’ Sustainable Limiting Rate of Germanium Consumption: Source: Graedel, T.E. and Klee, R.J., 2002. Getting serious about sustainability, Env. Sci. & Tech. 36(4): 523-9 Solar PVs

34. Prof. R. Shanthini Jan 21, 2012 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) Calculation of United States’ Sustainable Limiting Rate of Germanium Consumption: Source: Graedel, T.E. and Klee, R.J., 2002. Getting serious about sustainability, Env. Sci. & Tech. 36(4): 523-9 Solar PVs

35. Prof. R. Shanthini Jan 21, 2012 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. Calculation of United States’ Sustainable Limiting Rate of Germanium Consumption: Source: Graedel, T.E. and Klee, R.J., 2002. Getting serious about sustainability, Env. Sci. & Tech. 36(4): 523-9 Solar PVs

36. Prof. R. Shanthini Jan 21, 2012 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. http://www.ucsusa.org/clean_energy/technology_and_impacts/impacts/environmental-impacts-of.html

37. Prof. R. Shanthini Jan 21, 2012 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. http://www.ucsusa.org/clean_energy/technology_and_impacts/impacts/environmental-impacts-of.html

38. Prof. R. Shanthini Jan 21, 2012 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. http://www.ucsusa.org/clean_energy/technology_and_impacts/impacts/environmental-impacts-of.html

39. Prof. R. Shanthini Jan 21, 2012 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. http://www.ucsusa.org/clean_energy/technology_and_impacts/impacts/environmental-impacts-of.html

40. Prof. R. Shanthini Jan 21, 2012 £5.5 million 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. Solar Energy

41. Prof. R. Shanthini Jan 21, 2012 Photovoltaic Power for Rural Homes In Sri Lanka Solar Energy

42. Prof. R. Shanthini Jan 21, 2012 Technological status“niche” markets Average growth10.6% per year Total share of global energy mix 0.06% of electricity in 2008 0.54% of electricity in 2035 (potential) Source: International Energy Outlook 2011 Solar Power

43. Prof. R. Shanthini Jan 21, 2012 Source: International Energy Outlook 2011 Total solar electricity generation projection: Average growth is 10.6% per year

44. Prof. R. Shanthini Jan 21, 2012 Source: International Energy Outlook 2011 World electricity generation projection:

45. Prof. R. Shanthini Jan 21, 2012 Comparison of Technologies: TechnologyAvailable energy (PWh/yr) Technical potential energy (PWh/yr) Current installed power (GW) Current electricity generation (TWh/yr) Hydroelectric16.5< 16.57782840 Solar PV14900<30008.711.4 CSP9250 – 11800 1.05 – 7.80.3540.4

46. Prof. R. Shanthini Jan 21, 2012 - 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) RE technology options: Anything else?