Laws of Thermodynamics

1. Laws of Thermodynamics • 1st law: Conservation of Energy • Energy cannot be created nor destroyed • Energy can be transferred from one system to another • 2nd law: • Energy transfer must only have one direction • Entropy (disorder) increases over time • 3rd law: • Absolute zero is achieved when all kinetic energy stops

2. SO….. • 1st law of Thermodynamics • Explains how we can convert energy from chemical or mechanical energy to usable electric energy • windmill animation • 2nd law of Thermodynamics explains WHY energy efficiency can be so low

3. Renewable Energy

4. Solar • Solar energy is harnessing energy from the sun’s rays • Passive Solar – Placing buildings strategically to take advantage of the sun’s heat • Example: Log Homes • Active Solar – uses solar panels to convert energy into a usable form such as electricity

5. Single solar cell Solar-cell roof – + Boron enriched silicon Roof options Junction Phosphorus enriched silicon Panels of solar cells Solar shingles Fig. 17-17, p. 398

6. Benefits of Solar: • Readily available • Renewable • Fairly simple system • Pollution free energy source • Can sell back extra energy to the power company • Drawbacks of Solar: • High start up cost for active solar energy system • Location dependent (Seattle would not be a good city for solar energy)

7. Core Case Study: The Coming Energy-Efficiency and Renewable-Energy Revolution • It is possible to get electricity from solar cells that convert sunlight into electricity. • Can be attached like shingles on a roof. • Can be applied to window glass as a coating. • Can be mounted on racks almost anywhere.

8. Core Case Study: The Coming Energy-Efficiency and Renewable-Energy Revolution • The heating bill for this energy-efficient passive solar radiation office in Colorado is $50 a year. Figure 17-1

10. Passive Solar Heating • Passive solar heating system absorbs and stores heat from the sun directly within a structure without the need for pumps to distribute the heat. Figure 17-13

11. Direct Gain Ceiling and north wall heavily insulated Summer sun Hot air Super- insulated windows Warm air Winter sun Cool air Earth tubes Fig. 17-13, p. 396

12. Greenhouse, Sunspace, or Attached Solarium Summer cooling vent Warm air Insulated windows Cool air Fig. 17-13, p. 396

13. Earth Sheltered Reinforced concrete, carefully waterproofed walls and roof Triple-paned or superwindows Earth Flagstone floor for heat storage Fig. 17-13, p. 396

14. Trade-Offs Passive or Active Solar Heating Advantages Disadvantages Energy is free Need access to sun 60% of time Net energy is moderate (active) to high (passive) Sun blocked by other structures Quick installation Need heat storage system No CO2 emissions Very low air and water pollution High cost (active) Very low land disturbance (built into roof or window) Active system needs maintenance and repair Moderate cost (passive) Active collectors unattractive Fig. 17-14, p. 396

15. Cooling Houses Naturally • We can cool houses by: • Superinsulating them. • Taking advantages of breezes. • Shading them. • Having light colored or green roofs. • Using geothermal cooling.

16. Wind • Wind energy is converted into a usable energy form by using wind turbines www.windenergyplanning.com www.lacoastpost.com

17. Wind Power • Benefits of Wind Power: • Readily available • Can sell back extra power • Pollution free energy source • Drawbacks of Wind Power: • Disrupts migration patterns • Turbine farms are not aesthetically pleasing • Turbines are expensive • Good for specific locations only

18. Hydro • Hydro power is mechanical energy derived from water • Most hydropower is generated by damming rivers • Using waves or ocean currents is being researched as a source of hydropower www.southeastasia.biz

19. Three Gorges Dam in China www.livescience.com

20. Three Gorges Dam • 1.5 miles long • 574 feet deep • $23 billion • 13 cities and 1,300 villages were flooded

21. www.howstuffworks.com

22. Benefits of Hydropower • Readily available • No pollution produced • Constant source of power • Drawbacks of Hydropower • Damming rivers disrupts ecosystems, causes sediment to build up and disrupts the natural flow of a river

23. Geothermal • Geothermal energy uses natural underground heat sources • When heat escapes the earth in the form of steam, the steam is used to turn a steam turbine which converts the heat energy into electrical energy

24. Benefits of Geothermal: • When drilled correctly, little pollution is produced • Takes up a relatively small area, does not disrupt the landscape • Drawbacks of Geothermal: • Can only be used in a limited capacity • Very location specific • May run out of steam • May release hazardous gasses or minerals if drilled improperly

25. Biomass • Biomass is burning biomass fuel in a specialized burner. Steam generated turns a steam turbine which turns mechanical energy into electrical energy

26. Biomass at the Denver Zoo! • Trash and animal waste is converted into pellets • The pellets are put into a gassifier and heated to 400 degrees! • When hot enough, a gas is emitted that is converted by micro gas turbines into electrical energy • Denver Zoo

27. Benefits of Biomass • Less waste in landfills Readily available • Drawbacks of Geothermal • Not currently available on a large scale basis

28. USING RENEWABLE SOLAR ENERGY TO PROVIDE HEAT AND ELECTRICITY • The European Union aims to get 22% of its electricity from renewable energy by 2010. • Costa Rica gets 92% of its energy from renewable resources. • China aims to get 10% of its total energy from renewable resources by 2020. • In 2004, California got about 12% of its electricity from wind and plans to increase this to 50% by 2030.

29. Energy Efficiency – renewable energy sources • Solar • Wind • Hydro • Biomass • Geothermal

30. USING RENEWABLE SOLAR ENERGY TO PROVIDE HEAT AND ELECTRICITY • Denmark now gets 20% of its electricity from wind and plans to increase this to 50% by 2030. • Brazil gets 20% of its gasoline from sugarcane residue. • In 2004, the world’s renewable-energy industries provided 1.7 million jobs.