The document discusses various sources of renewable energy and energy efficiency. It covers: 1) Energy efficiency and the benefits of reducing energy waste 2) Solar energy sources like passive and active solar, photovoltaic cells, and high temperature systems 3) Hydropower from dams, tides, waves and solar ponds 4) Wind power and its pros and cons 5) Biomass from burning wastes and crops 6) Geothermal energy and its limited suitable sites 7) The solar-hydrogen revolution for storing energy It emphasizes that humanity will ultimately need to rely on renewable sources as coal and uranium are finite.

1. Chapter 20 Energy Efficiency & Renewable Energy

2. Where are we going? 1. Energy efficiency 2. Solar energy 3. Hydropower 4. Wind Power 5. Biomass 6. Solar–hydrogen revolution 7. Geothermal 8. Sustainability © Brooks/Cole Publishing Company / ITP

3. 1. Energy Efficiency percentage of energy input that does useful work in an energy conversion system Fig. 20–4 © Brooks/Cole Publishing Company / ITP

5. Net Energy Efficiency Fig. 20–5 © Brooks/Cole Publishing Company / ITP

6. Net Energy Efficiency Fig. 20–5 © Brooks/Cole Publishing Company / ITP

7. Energy Waste 43% in U.S. Fig. 20–2 © Brooks/Cole Publishing Company / ITP

11. 2. Solar Energy © Brooks/Cole Publishing Company / ITP

12. Costs Fig. 20–15 © Brooks/Cole Publishing Company / ITP

13. Passive Fig. 20–16 sunlight captured directly & used for space heating © Brooks/Cole Publishing Company / ITP

14. Suitability Fig. 20–19 best when more than 60% of daylight hours sunny © Brooks/Cole Publishing Company / ITP

15. Active Fig. 20–17 uses fans or pumps to distribute heat © Brooks/Cole Publishing Company / ITP

17. Photovoltaic Cells (PVs) Fig. 20–23 © Brooks/Cole Publishing Company / ITP

18. Fig.20–23 © Brooks/Cole Publishing Company / ITP

19. High Temperature Systems Fig. 20–21 © Brooks/Cole Publishing Company / ITP

22. 4. Wind Fig. 20–29 © Brooks/Cole Publishing Company / ITP

25. 5. Biomass Fig. 20–31 © Brooks/Cole Publishing Company / ITP

28. 6. Geothermal Fig. 20–35 © Brooks/Cole Publishing Company / ITP

30. 7. Solar – hydrogen revolution Fig. 20–33 © Brooks/Cole Publishing Company / ITP

32. In the long run, humanity has no choice but to rely on renewable energy. No matter how abundant they seem today, eventually coal & uranium will run out. –– Daniel Deudney & Christopher Flavin © Brooks/Cole Publishing Company / ITP