Chapter 13 Renewable Energy and Conservation

1. Chapter 13Renewable Energy and Conservation

2. Overview of Chapter 13 • Direct Solar Energy • Heating Buildings and Water • Solar Thermal Electric Generation • Photovoltaic Solar Cells • Indirect Solar Energy • Biomass Energy • Wind Energy • Hydropower • Other Renewable Energy Sources • Geothermal Energy • Tidal Energy • High and Low Technology Energy Solution • Hydrogen and Fuel Cells • Energy Efficiency

3. Direct Solar Energy • Varies with latitude, season, time of day, and cloud cover

4. Heating Buildings and Water • Passive solar energy • system of putting the sun’s energy to use without requiring mechanical devices to distribute the collected heat • Certain design features can enhance passive solar energy’s heating potential • South facing windows (in N. hemisphere) • Well insulated buildings • Attic vents • Overhangs and solar sunspaces

6. Solar sunspace • Utilizes passive solar energy to heat and cool homes • Can be added to existing homes

7. Heating Buildings and Water • Active Solar Energy • System of collecting and absorbing the sun’s energy, and using pumps or fans distribute the collected heat • Most common • Series of collection devices on roofs or in fields • Typically a black panel or plate • Used to heat water

8. Heating Buildings and Water • Solar Thermal Electric Generation • Means of producing electricity in which the sun’s energy is concentrated by mirrors or lenses to either heat a fluid filled pipe or drive a Stirling engine • More efficient than other solar technologies • Benefits • No air pollution • No contribution to global warming or acid precipitation

9. Solar Thermal Electric Generation

10. Photovoltaic Solar Cells • Thin cells are treated with certain metals so that they generate electricity when they absorb solar energy • Convert sunlight directly into energy • No pollution and minimal maintenance • Used on any scale • Lighted road signs • Entire buildings

11. Photovoltaic Solar Cells • Can be incorporated into building materials • Roofing shingles • Tile • Window glass

12. Cost of Electrical Power Plants

13. Indirect Solar Energy • Biomass • Plant materials used as fuel • Ex: wood, crop wastes, sawdust, and animal wastes • Contains energy from sun via photosynthesizing plants • Renewable when used no faster than it can be produced • Can convert to biogas or liquids • Ethanol and methanol

14. Advantages and Disadvantages of Biomass • Advantages • Reduces dependence on fossil fuels • Often uses waste materials • If trees are planted at same rate biomass is combusted, no net increase in atmospheric CO2 • Disadvantages • Requires land, water and energy • Can lead to • Deforestation • Desertification • Soil erosion

15. Indirect Solar Energy • Wind Energy • Electric or mechanical energy obtained from surface air currents caused by solar warming of air • World’s fastest growing source of energy • Wind results from sun warming the atmosphere • Varies in direction and magnitude • New wind turbines harness wind efficiently

16. Wind Energy • Most profitable in rural areas with constant wind • Few environmental problems • Kills birds and bats • No waste- clean source of energy • Biggest constraints • Cost • Public resistance

17. Indirect Solar Energy • Hydropower • Form of renewable energy reliant on flowing or falling water to generate mechanical energy or electricity • Sun’s energy drive hydrologic cycle • Most efficient energy source (90%)

18. Hydropower • Generates 19% of world’s energy • Traditional hydropower • Only suited for large dams • New technology • May be able to utilize low flow waterways • Problems with Dams • Changes natural flow of rivers • Disrupts migratory fish patterns • Potential dam breaks

19. Other Indirect Solar Energy • Ocean waves • Produced by winds • Has potential to turn a turbine- and create electricity • Ocean Temperature Gradients • Use difference in temperature of surface and deep water to create electricity

20. Other Renewable Energy Sources • Geothermal Energy • Energy from the Earth’s interior for either space heating or generation of electricity • From Hydrothermal Reservoirs (left) • Created by volcanoes • Reservoirs used directly for heat or to generate electricity

21. Geothermal Energy • From hot, dry rock • Geothermal heat pumps • Use difference in temperature between surface and subsurface • Great for heating buildings • Expensive installation

22. Other Renewable Energy Sources • Tidal Energy • Form of renewable energy that relies of the ebb and flow of the tides to generate electricity • Typical difference between high and low tide is 1-2 ft • Narrow bays may have greater variation • Energy can be captured with • A dam across the bay • A turbine similar to a wind turbine

23. Hydrogen as a Fuel Source • Advantages to Hydrogen as a fuel source • Very high energy density • Can be produced from any electrical source • Electrolysis (see illustration on next slide) • No greenhouse gases and few other pollutants • Can be use in vehicles • Disadvantages to Hydrogen as a fuel source • Highly volatile (requires special storage) • Relatively inefficient

24. Hydrogen as a Fuel Source-Electrolysis

25. Hydrogen Fuel Cell • Fuel cell • Device that directly converts chemical energy into electricity • Requires hydrogen from a tank and oxygen from the air • Similar to a battery, only the reactants are supplied from outside source

26. Future Applications of Fuel Cells • Vehicles • Not yet commonly available • Hydrogen is not yet readily available as a fuel source • Batteries in cells phones or laptops

27. Energy Consumption Trends and Economics

29. Energy Efficient Technologies • Super-insulated buildings (right) • Energy efficient appliances (ENERGYSTAR) • Compact Fluorescent light bulbs • Condensing furnaces

31. Energy Efficient Technologies • Automobiles – we could do much better, but the foreign manufacturers are already much improved! • USA avg. auto fuel efficiency doubled between mid-1970’s and mid 1980’s, but has actually declined since then!!!!! • Current technology could routinely produce autos that get 60-65 mpg within next 10 years • Aircraft technology • Papermaking industry also much more efficient

32. Cogeneration • Production of two useful forms of energy from the same fuel

33. Energy Savings in Commercial Buildings

34. Saving Energy at Home