Renewable Energy Systems

1. Renewable Energy Systems ME 252 Thermal-Fluid Systems G. Kallio

2. Introduction • Renewable energy is energy obtained from sources that are essentially inexhaustible, as opposed to energy obtained from fossil fuels (coal, petroleum, natural gas), of which there is a finite supply. • Renewable energy technologies generally include: • Solar electric, or photovoltaic (PV) • Solar thermal • Wind turbines • Geothermal • Biomass • Fuel cells that use renewable hydrogen • Small hydroelectric • Ocean energy Renewable Energy Systems

3. U.S. Energy Consumption by Resource 1997 data (Wiser, 2000) Renewable Energy Systems

4. U.S. Fossil Fuel Reserves vs. Energy Consumption 1997 data (Wiser, 2000) Renewable Energy Systems

5. Fossil Fuel - Petroleum • Total world reserves (known & recoverable): 1035 billion barrels • Total world demand: 25.7 billion barrels/year • Years to depletion: 1035/25.7 = 40 years 1997 data (Wiser, 2000) Renewable Energy Systems

6. U.S. Petroleum Use • Transportation:60% • Industrial processes: 19% • Heating oil: 6% • Synthetics/Plastics: 5% • Petrochemicals: 5% • Electric Power: 5% 1997 data (Wiser, 2000) Renewable Energy Systems

7. Fossil Fuel – Natural Gas • Total U.S. reserves (known & recoverable, including coal bed methane): 361 trillion ft3 • Total U.S. demand: 22.3 trillion ft3/year • Years to depletion w/o imports: 361/22.3 = 16 years 1997 data (Wiser, 2000) Renewable Energy Systems

8. Fossil Fuel - Coal • Total U.S. reserves (known & recoverable): 434 billion tons • Total U.S. demand: 978 million tons/year • Years to depletion w/o imports: 434/0.978 = 444 years 1997 data (Wiser, 2000) Renewable Energy Systems

9. Renewable Energy – Solar Systems • Solar Electric, or Photovoltaic (PV), Systems • Solar Thermal Systems • Concentrating solar for power generation • Passive solar for space heating/cooling and daylighting • Active solar water heating and space heating/cooling Renewable Energy Systems

10. Renewable Energy – Wind Turbine Systems • Horizontal Axis Wind Turbines • Vertical Axis Wind Turbines Renewable Energy Systems

11. Renewable Energy – Geothermal Systems • Space Heating - direct use of hot water • Electrical Power Generation – steam power plant • Ground-Source Heat Pumps – utilizes constant temperature of soil or surface water Renewable Energy Systems

12. Renewable Energy – Biomass Systems • “Biomass” refers to any plant-derived organic matter • Biomass solid fuels include wood waste, ag waste, animal waste, municipal waste, and aquatic plants • Biomass liquid and gaseous fuels include ethanol, methanol, biodiesel, methane, and hydrogen • Combustion of biomass fuels is used in electric power generation, process heating, and vehicle propulsion Renewable Energy Systems

13. Renewable Energy – Hydrogen Fuel Cell Systems • Renewable sources of hydrogen include water (by electrolysis) and reforming biomass fuels • Fuel cells efficiently convert chemical energy into electricity with little or no pollutant emissions and without the limitation of the 2nd Law of Thermodynamics Renewable Energy Systems

14. Renewable Energy – Hydroelectric Systems • Renewable hydroelectric typically refers to small plants (< 30MW) due to their minimal impact on fisheries and downstream water quality • Not all hydroelectric systems require dams; a diversion facility channels a portion of the river through a canal or penstock Renewable Energy Systems

15. Renewable Energy – Ocean Energy Systems • Tidal Energy – uses traditional hydroelectric technology to produce electricity from an elevated, dammed tidal basin • Wave Energy – difficult to harness • Ocean Thermal Energy Conversion (OTEC) – natural-occurring temperature difference used as a heat engine Renewable Energy Systems