Energy Efficiency and Renewable Energy Chapter 16 G

Energy Efficiency and Renewable Energy Chapter 16 G. Tyler Miller’s Living in the Environment 13 th 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 1) does useful work and 2) 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)

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

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

Ways to Improve Energy Efficiency In Our Homes ü Insulation ü Eliminate air leaks ü Air-to-air heat exchangers Industry ü Cogeneration – Two useful sources of energy are produced from the same fuel source ü Efficient electric motors ü High efficiency lighting ü 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 Ø Rechargeable battery systems Ø Hybrid electric-internal combustion engine Ø Fuel cells

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

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

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

The Solar-Hydrogen Revolution Ø Extracting hydrogen efficiently Ø Storing hydrogen Ø 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 Ø Passive solar heating Ø Active solar heating

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

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

Using Solar Energy to Provide High. Temperature Heat and Electricity

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

Producing Electricity from Moving Water Ø Tidal power plant Ø Wave power

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

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

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

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

Geothermal Reservoirs Fig. 16 -37 p. 410

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

Solutions: A Sustainable Energy Strategy