Energy Efficiency and Renewable Energy Chapter 16 G. Tyler Miller’s Living in the Environment 13th Edition

Key Concepts Improving energy efficiency Solar energy Hydropower (flowing water) Wind Biomass Hydrogen fuel Geothermal Decentralized power systems

Doing more with less Energy efficiency is the percentage of total energy input into an energy conversion device or system that does useful work and is not converted to low-quality heat.

The Importance of Improving Energy Efficiency 84% of all commercial energy produced in the U.S. is wasted! Fig. 16-2 p. 381

The Importance of Improving Energy Efficiency Lower life cycle cost Initial cost plus lifetime operating cost Net energy efficiency Total amount of useful energy available minus the amount of energy used (First Law of Thermodynamics) automatically wasted (Second Law of Thermodynamics) unnecessarily wasted. Least Efficient Incandescent light bulb (5%) Internal combustion engine (10-15%) Nuclear power plants (8-14%)

REDUCING ENERGY WASTE AND IMPROVING ENERGY EFFICIENCY Four widely used devices waste large amounts of energy: Incandescent light bulb: 95% is lost as heat. Internal combustion engine: 94% of the energy in its fuel is wasted. Nuclear power plant: 92% of energy is wasted through nuclear fuel and energy needed for waste management. Coal-burning power plant: 66% of the energy released by burning coal is lost.

Efficiencies (fig. 16-4 p. 382)

Electricity from Nuclear Power Plant 95% Waste heat Uranium mining (95%) 54% Waste heat Uranium processing and transportation (57%) 17% Waste heat Power plant (31%) Waste heat 14% Transmission of electricity (85%) 14% Resistance heating (100%) Uranium 100% Electricity from Nuclear Power Plant Passive Solar Sunlight 100% 90% Waste heat Energy Efficiency

Could we save energy by recycling energy? No Second Law of Thermodynamics

Ways to Improve Energy Efficiency In Our Homes Insulation Eliminate air leaks Air-to-air heat exchangers Industry Cogeneration Two useful sources of energy are produced from the same fuel source Efficient electric motors High efficiency lighting Increased fuel economy

Saving Energy in Existing Buildings About one-third of the heated air in typical U.S. homes and buildings escapes through closed windows and holes and cracks. Figure 17-11

WAYS TO IMPROVE ENERGY EFFICIENCY Average fuel economy of new vehicles sold in the U.S. between 1975-2006. The government Corporate Average Fuel Economy (CAFE) has not increased after 1985. Figure 17-5

Increased Fuel Economy Rechargeable battery systems Hybrid electric-internal combustion engine Fuel cells

Hybrid Car (Electric – Internal Combustion Engine) Fuel tank B Electric motor C Battery bank D B Regulator E D Transmission F E F A C Fuel Electricity

Fuel Cell Cars A B C D E Fuel Electricity Fuel cell stack Fuel tank Turbo compressor B D Traction inverter D E Electric motor / transaxle C E A Fuel Electricity

H2 O2 H2O 1 3 1 2 2 3 4 4 Cell splits H2 into protons Hydrogen gas and electrons. Protons flow across catalyst membrane. Hydrogen gas 3 1 O2 2 React with oxygen (O2). 2 3 Produce electrical energy (flow of electrons) to power car. 4 H2O 4 Emits water (H2O) vapor.

The Solar-Hydrogen Revolution Extracting hydrogen efficiently Storing hydrogen Fuel cells

Fuel Cells Advantages Energy efficiencies of 65-90% No moving parts Quiet Emit only water and heat More reliable Disadvantage Cost

Using Solar Energy to Provide Heat and Electricity Passive solar heating Active solar heating

Using Solar Energy to Provide High-Temperature Heat and Electricity Solar thermal systems

Using Solar Energy to Provide High-Temperature Heat and Electricity Photovoltaic (PV) cells

Using Solar Energy to Provide High-Temperature Heat and Electricity

Producing Electricity from Moving Water Large-scale hydropower Small-scale hydropower Pumped-storage hydropower

Producing Electricity from Moving Water Tidal power plant Wave power

Producing Electricity from Heat Stored in Water Ocean thermal energy conversion (OTEC) Saline solar ponds Freshwater solar ponds

Producing Electricity from Wind Fig. 16-28 p. 402 Fig. 16-29 p. 402

Producing Energy from Biomass Biofuels Biomass plantations Crop residues Animal manure Biogas Ethanol Methanol

Geothermal Energy Geothermal reservoirs Dry steam Wet steam Hot water Fig. 16-36 p. 409 Dry steam Wet steam Hot water Molten rock Hot dry-rock zones

Geothermal Reservoirs Fig. 16-37 p. 410

Entering the Age of Decentralized Micropower Current Centralized power systems Future Decentralized power systems Micropower systems Fig. 16-40 p. 411 Fig. 16-39 p. 411

Solutions: A Sustainable Energy Strategy