Solar Power & Energy Independence

1. Solar Power & Energy Independence

2. Overview • Solar Energy Potential • Non-Electric Solar Power • Technologies • Implications for Energy Independence • Solar Generated Electricity • Technologies • Distribution Approaches • Implications for Energy Independence

3. Solar Energy Potential • As of February 2006, Photovoltaic technology accounted for less than 1% of worldwide electricity generation. • The amount of solar energy that reaches the Earth’s surface every hour is greater than humankind’s total demand for energy in one year

4. Non-Electric Solar Power Solar Water Heating Passive Solar Heating/Lighting

5. Solar Water Heating

6. Solar Water Heating • Advantages • Replacing or supplementing other water heating methods: natural gas, electricity • Disadvantages • More expensive in cooler climates

7. Passive solar heating can use overhangs to shield the home from the sun in the summer, and warm the home when the sun is lower in the winter sky Passive Solar Heating/Cooling

8. Solar Heating/Cooling

9. Non-Electric Solar Power & Energy Independence • Lowered Energy Consumption • Broadening of Energy Portfolio • Reduced Need for Fossil Fuel Imports

10. Solar Generated Electricity Concentrating Solar Power Photovoltaic (PV) Cells

11. Require Direct Sunlight Concentrating solar power systems cannot reflect diffuse sunlight, making them ineffective in cloudy conditions Two Approaches Power Tower Parabolic Trough Concentrating Solar Power • Direct normal solar resource in the Southwest. Image courtesy of “Tackling Climate Change In the US: Potential Carbon Emissions Reductions from Energy Efficiency and Renewable Energy by 2030” (Charles F. Kutcher ed.). Darker colors signify greater solar radiance.

12. CSP Potential - Direct normal solar resource in the Southwest, filtered by resource, land use, and topology. Image courtesy of “Tackling Climate Change In the US: Potential Carbon Emissions Reductions from Energy Efficiency and Renewable Energy by 2030” (Charles F. Kutcher ed.) Existing US Generation Capacity (2003) = 1,000 GW Total Potential CSP Generation in Southwest = 7,000 GW

13. Solar One (CA) Steam Heat Transfer 10 MW Solar Two (CA) Molten Salt Heat Transfer 10 MW Solar Tres (Spain) Molten Salt Heat Transfer 15 MW Power Tower

14. Solar Two

15. Parabolic Trough • Sunlight focused on heat transfer fluid (HTF), which then runs steam turbine

17. Parabolic Trough Generating Plant Image of parabolic trough power plant in Kramer Junction, CA, which supplies power for the greater Los Angeles area. This plant, in conjunction 4 other parabolic trough plants in California, can produce as much as 354MW of electricity.

18. Photovoltaic Cells

19. Photovoltaic Potential • “The basic resource potential for solar PV in the United States is virtually unlimited compared to any foreseeable demand for energy.” • Paul Denholm, Robert Margolis, & Ken Zweibel, “Potential Carbon Emissions Reductions from Solar Photovoltaics by 2030,” in Tackling Climate Change In The US: Potential Carbon Emissions Reductions From Energy Efficiency And Renewable Energy By 2030, p.99 (Charles F. Kutcher, ed., 2007) • PV is flexible enough that it can be adapted for use in many areas.

20. Basic process by which a photovoltaic cell converts absorbed sunlight into electricity “Photons” knock electrons free from the silicon structure, freeing them to enter electric current and power a “load” (like a light bulb) Photoelectric Effect

21. Solar Generated Electricity Distribution Approaches • Centralized (CSP) • Advantages and Disadvantages • Distributed (PV Roof Installations) • Advantages and Disadvantages • Distributed PV Generation & Energy Independence

22. Advantages Traditional model of distribution No fuel costs Disadvantages Non-Constant Power Vulnerability Centralized This PV Array is part of the Sacramento Municipal Utility District, generating 3.2 MW, enough for 2,200 homes.

23. Advantages Net-metering Grid Storage Flexibility Reduced vulnerability to terrorist attack Almost no maintenance Negligible environmental impact Domestic Production (?) Disadvantages Cost Extensive Individual Investment Low Conversion Efficiency CCR’s Intermittency Distributed Solar (PV)

24. Net-Metering • Peak generation from PV occurs during the day • Net-metering allows users to “bank” electricity they generate, and credit it against the electricity they use • Most states won’t pay users if they generate more electricity than they use, but they can “zero-out” their accounts • As of 2007, net-metering is offered to some degree in 41 states and D.C. • California, New York, Texas • Net-metering is offered in Illinois by one or more individual utilities • EPAct of 2005 requires all states to offer net-metering by 2008

25. Grid-Connected PV

26. Stand-Alone Water pumps Fans Battery Backup Isolated Areas Generator Backup Hybrid Remote applications Grid Connected Grid storage Utility Scale Easy & Quick to build PV Flexibility

27. PV Applications

28. Reduced Vulnerability • Roof-by-roof power generation makes it too difficult for one strike to have a crippling effect • Vulnerability of centralized generation was illustrated in the August 2003 US blackout • caused by a series of “tripped” generation facilities and transmission lines • Within the first 2 hours: • 3 Coal Fired Power Plants • 9 Nuclear Power Plants • 5 Major Transmission Lines • Estimated loss from the August 2003 blackout has been placed at $5-6 billion.

29. Distributed Solar Power and Energy Independence • The ultimate in Energy Independence – self-sufficiency • Consumers becoming “producers”

30. PV Disadvantages • Price • Efficiency • Community Associations – CCR’s • Intermittency

31. Price • Still not “price-competitive” with traditional sources of electricity • “If you don't include the environmental costs of coal-fired electricity when comparing them with solar, it becomes very difficult. [Saving money] is not what motivates me and if that's all that motivates the consumer, then perhaps solar isn't for them.” • Dr. Richard Corkish, University of New South Wales, School of Photovoltaic and Renewable Energy Engineering • “Paying for Itself” • Ability of a PV system to “pay for itself” depends on the size of the installation, electricity demands it is meeting. • Residential PV system may “pay for itself” within first half of its estimated lifespan (30 years)

32. Price Reductions • Goals for DOE’s Solar America Initiative for cost reduction in PV Residential (2-4kW) Systems: • 2015 = 10-12 cents/kWh • 2030 = 6-8 cents/kWh • $148M in 2007 Funding for Solar America Initiative to spark R&D

33. Efficiency • Conversion Efficiency – the percentage of solar energy shining on a device that is converted into electrical energy • Typical Efficiencies • Single Crystalline Silicon = 14% • Thin Film = 7%

34. CCRs • As of 1999, 42 Million Americans lived in community associations • Many of these communities seek to establish aesthetic uniformity, protecting homeowner and developer investment and lessening the risk of undesirable activities in the community • The Declaration of Conditions, Covenants, and Restrictions are one method used to ensure that homes retain a common design theme w/in a community

35. Prior Approval of Architectural Committee Explicit Restrictions on Placement of Solar Equipment Height Restrictions Restrictions on secondary buildings or structures Requirements that utilities be screened Restrictions on the placement of improvements Specifications regarding roofing materials Restrictions pertaining to architectural style Typical CCR Provisions Restricting Solar Systems

36. Architectural Restrictions • Arizona HOA is battling resident over black solar collector which doesn’t match his light-brown roof • Some state laws have attempted to limit the ability of CCRs to restrict solar improvements

37. Intermittency • Obviously, solar power requires sunlight to generate power • This means that: • No power is can be generated at night • Power generation may be reduced by cloud cover • However, PV will still work with overcast skies • Generation techniques requiring direct sunlight (CSP) are ineffective w/o optimum conditions • Solutions: • Generators, Batteries, Hybrid Facilities • Hydrogen

38. Hydrogen • Hydrogen can be used as an energy carrier • Hydrogen can be created from water through a process called “electrolysis” • DC current is used to split water into hydrogen and oxygen • Energy from renewable sources, like solar power, can be used to manufacture hydrogen • Commercial feasibility of solar generated hydrogen is far off

39. Solar Power and Energy Independence • Lessen Reliance on Fossil Fuel • Stabilize Energy Costs • Re-conceptualize Distribution of Energy • End-user production • Distributed system lessens large-scale vulnerability • Production Method for Hydrogen Economy