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

Renewable Energy Systems 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 11/15/2018 Renewable Energy Systems

U.S. Energy Consumption by Resource Electrical Power (%) Total Energy (%) Petroleum 2 40 Natural Gas 10 25 Coal 55 23 Nuclear 22 7.7 Hydro 3.9 Geothermal 0.2 0.1 Wind Other 0.6 1997 data (Wiser, 2000) 11/15/2018 Renewable Energy Systems

U.S. Fossil Fuel Reserves vs. Energy Consumption 1997 data (Wiser, 2000) Fossil Fuel Resource Reserve (%) Consump-tion (%) Coal 82 23 Natural Gas 1.4 25 Petroleum 1.3 40 Oil Shale 14 Tar Sands 11/15/2018 Renewable Energy Systems

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) 11/15/2018 Renewable Energy Systems

Renewable Energy Systems U.S. Petroleum Use Transportation: 60% Industrial processes: 19% Heating oil: 6% Synthetics/Plastics: 5% Petrochemicals: 5% Electric Power: 5% 1997 data (Wiser, 2000) 11/15/2018 Renewable Energy Systems

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) 11/15/2018 Renewable Energy Systems

Renewable Energy Systems 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) 11/15/2018 Renewable Energy Systems

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 11/15/2018 Renewable Energy Systems

Renewable Energy – Wind Turbine Systems Horizontal Axis Wind Turbines Vertical Axis Wind Turbines 11/15/2018 Renewable Energy Systems

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 11/15/2018 Renewable Energy Systems

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 11/15/2018 Renewable Energy Systems

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 11/15/2018 Renewable Energy Systems

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 11/15/2018 Renewable Energy Systems

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 11/15/2018 Renewable Energy Systems