1. AP Environmental Science: Renewable Energy

3. Renewable Energy Use in the United States

4. Future Fuels

5. Electricity Supply and Demand

6. Examples of Direct Solar Energy Uses Solar space heating Photovoltaic cells Solar-trough collectors

7. Examples of Indirect Solar Energy Uses Wind Water Hydrogen

8. Hurdles in Using Solar Energy Collection Conversion Storage Cost- effectiveness

9. Direct Uses of Solar Energy: Heating = 25% U.S. Energy Budget

10. Direct Uses of Solar Energy - Electricity

11. Passive Use of Solar Energy – Space heating 75% reduction in energy bills

12. Trees and Energy Absorption Significant solar energy is converted to biomass (potential energy) by photosynthesis.

13. Terms and Definitions: Solar Heating Systems Active: moves water or air with pumps and blowers Passive: moves water or air with natural convection currents or gravity

14. Components of Active or Passive Solar Heating Systems? Flat-plate collector Water pump Blowers Heat exchanger Improved insulation Earthen berms

15. Required Components? Flat-plate collector Water pump Blowers Heat exchanger Improved insulation Earth berms Solar hot water Solar space heater Both

16. Solar Energy From the Sun Short wave lengths (sun) are higher energy than long wavelengths (Earth)

17. Electromagnetic Energy Wave energy transmits energy though the vacuum of space to the Earth. We only “see” a small amount of it.

18. Solar Energy Cycle We get 99% of the Earth’s energy from the sun through various pathways.

19. Photosynthesis: Solar Energy Photosynthesis uses solar energy for the electron transport chain to change CO 2  sugar/starch

20. USA Solar Energy Map Some areas that have lots of cloudless sunshine could benefit greatly from solar energy units.

21. Solar Energy Budget Solar energy is either reflected, absorbed in air or absorbed by the Earth.

22. The Hydrologic Cycle is powered by Solar Energy The sun powers the water cycle on Earth

23. Solar Energy  Electric Plant Solar energy electric plants are different only in the energy source.

24. Solar Production of Electricity Photovoltaic cells Solar-trough collectors Converts 22% of incoming sunlight to electrical power at a cost of 8 cents/kwh

25. How Photovoltaic Cells Work Each cell consists of two thin mylar layers. Lower layer has atoms with single electron in outer orbit – easily lost. Upper layer has atoms lacking one electron in outer orbit – easily accepts electrons.

26. How Photovoltaic Cells Work Kinetic energy from sunlight dislodges electrons from lower layer – creates an electric potential between the two layers. The potential provides the energy for an electrical current through the rest of the circuit. Electrons from lower layer flow through a device back to upper side.

27. The Solar-trough Collector

28. How the Solar-trough Collector Works. The curved reflector focuses sunlight on and heats oil in the pipe. Heated oil used to boil water and generate steam for driving a conventional turbogenerator.

29. Disadvantages of Solar Energy Technologies Expense Only works during the day Requires back-up energy sources, e.g., Batteries Some climates not sunny enough

30. Hidden Costs of Traditional Energy Sources Air pollution Strip-mining Nuclear wastes

31. More or Less? The use of solar electrical power will: create ____ reliance on coal or nuclear power. lead to significantly _____ acid rain. produce ____ electrical power for villages in developing countries.

32. Electrolysis

33. Electrolysis (Continued) Water is slightly acidified with a salt (eg. NaCl ) so that it is a good conductor of electricity. Reduction of H 2 O to H 2 occurs at cathode. 2H 2 O + 2e - --> 2OH - + H 2 (g).

34. Electrolysis (Continued) Oxidation of H 2 0 to O 2 occurs at anode. 2H 2 O ---> 4e - + 4H + + O 2 (g). Net cell reaction 2H 2 O ---> 2H 2 (g) + O 2 (g).

35. Fuel Cells What is the fuel in a fuel cell?

36. Fuel Cell Mechanism

37. Fuel Cell Running an Electric motor Notice the only byproduct is water.

38. Fuel Cells: Benefits or Limitations? Substitute for fossil fuels Pollution factor Production technology Portability National distribution system

39. Hydroelectric Plants These electric generation plants use the potential energy of water (via gravity) to run turbines to make electricity

40. Benefits or Drawbacks of Hydroelectric Power? Level of pollution generated Level of environmental degradation Amount of energy produced

41. Benefits or Drawbacks of Hydroelectric Power? Geographical distribution of energy produced Ecological impacts above and below dam Societal disruptions

42. Wind Power Mechanism

43. World Wide Wind Power A good answer to the energy crisis. “The answer my friend, is blowing in the wind…” Peter, Paul and Mary song.

44. USA Wind Power Graph The dots show the current wind generated electricity facilities.

45. Benefits or Drawbacks of Wind Power Size limitations of wind turbines Megawatts of electricity produced Level of pollution generated Level of environmental degradation Geographical distribution of energy produced Aesthetics

46. Examples of Bioconversion

47. Benefits or Drawbacks of Bioconversion Availability of the biomass resource Access to the biomass resource Public acceptance and utilization of biomass energy Past history of human harvests within a maximum sustained yield

48. Additional Renewable Energy Options OTEC (Ocean Thermal Energy Conversion). Temperature differences between surface and 300m deep are used like nature’s heat pump. Geothermal (Greenland) using tectonic heat to make steam. Tidal flow used to turn generators.

49. Benefits or Drawbacks of Geothermal Energy Consistent source Level of pollution Cost-effectiveness Technology required for extraction Geographical distribution of energy produced

50. Benefits or Drawbacks of Tidal Power Consistent source Level of pollution Cost-effectiveness Technology required for extraction Geographical distribution of energy produced

51. Benefits or Drawbacks of OTEC (Ocean Thermal Energy Conversion). Temperature differences between surface and 300m deep are used like nature’s heat pump. Use ammonia as a vaporization/condensation medium. In an average day the heat absorbed by the surface water in only one square mile is equivalent to the burning of 7000 barrels of oil.

52. Aspects of U.S. Energy Policy Mandates to increase fuel efficiency in cars Exploitation of public lands for fossil fuel reserves Subsidies to producers of solar/other renewable energy technology Research and development on alternative energy technologies

53. What can a Government do? 1. Keep prices artificially low 2. Keep prices artificially high 3. Educate Consumers

54. Keeping prices artificially low Encourage use of sustainable/renewable resources R&D subsidies & tax breaks to companies Enact laws that favor R&D

55. Keeping prices artificially high To discourage use of inefficient fuels/ technology Eliminate tax breaks & subsidies Increase gas/ fuel use taxes

56. Educate Consumers Make public aware of benefits of technology benefits of efficiency Long range costs of environmentally harmful products Encourage public to let company executives know about their choices

57. Growing Trends Shifting from supply-side (hard-path) To demand-side (soft path) Large, centralized Macro-power systems To smaller, de-centalized micro-power systems