© 2011 Pearson Education, Inc. Alternative Forms of Energy Use Consider advantages and disadvantages of alternative forms of energy Evaluate if alternative energy sources address the root problem

© 2011 Pearson Education, Inc. Alternatives to fossil fuels Our global economy is powered by fossil fuels  These fuels also power ⅔ of electricity generation Fossil fuels are limited and pollute  We need to shift to resources that are less easily depleted and environmentally gentler

© 2011 Pearson Education, Inc. Conventional alternatives Most common: Nuclear, hydroelectric, and biomass  They are renewable and pollute differently (often in less harmful ways) Assessment:  More expensive in the short term when external costs are not included in market prices  They exert less environmental impact These are intermediates along a continuum of renewability

© 2011 Pearson Education, Inc. Sweden’s search for alternative energy Sweden’s people voted to phase out nuclear energy Government promoted hydroelectric, biomass, and wind power Favor reductions in fossil fuel use so public support for nuclear power has increased Now nuclear supports 33%

© 2011 Pearson Education, Inc. U.S. storage of high-level radioactive waste Waste is held at 125 sites in 39 states 161 million citizens live within 75 miles of nuclear waste

© 2011 Pearson Education, Inc. Yucca Mountain, Nevada

© 2011 Pearson Education, Inc. Dilemmas in radioactive storage… Advantages to Yucca Mountain  Waste in a central repository can be heavily guarded  Remote location  Geologic activity minimal ? Disadvantages to this site  Transportation of waste  Fissures in rock can change during seismic activity  Fairness to local residents

© 2011 Pearson Education, Inc. Biomass = energy obtained from organic material Large variety of productions Advantages  Many forms and uses available  Available on a small scale that meets local needs  Considered carbon neutral  Uses “waste” Disadvantages  Overharvesting causes deforestation, erosion, and desertification  Deprives soil of nutrient recycling – need more fertilizers  Heavily populated arid regions are most vulnerable  Produces particulates and indoor air pollution

© 2011 Pearson Education, Inc. Ethanol – Food or oil? Ethanol = a biofuel made by fermenting carbohydrate-rich crops  Ethanol is added to U.S. gasoline to reduce emissions  E-85 is a newer fuel with 85% ethanol (flex-fuel) Advantages  Non-toxic & biodegradable  Cleaner burning Disadvantages  Corn based fuel competes with land used for food, requires major inputs  Increase price of food  Increase land use change

© 2011 Pearson Education, Inc. Hydropower = kinetic energy of moving water turns turbines Advantages  No carbon emission  renewable  High efficiency (10:1) Disadvantage  Damming causes damage (submerged habitat, downstream doesn’t receive sediment and nutrients)  Many MEDC rivers already dammed

© 2011 Pearson Education, Inc. New renewables Renewables provide only 1% of energy and 18% of our electricity

© 2011 Pearson Education, Inc. Solar – diverse production Types:  Passive: structure that maximizes solar input  Materials that absorb and slowly reemit heat  Active: heating air or water for use in buildings  Roof top solar collectors  Concentrating: magnifying rays to a single point  Solar cookers, troughs  Photovoltaic cells: directly create energy that can be stored

© 2011 Pearson Education, Inc. Solar – miniscual production Widely used?  Not in MEDCS – accounts for only 1% of electricity production Advantages  Utilizes our most renewable resources – THE SUN  Local power generation  No emissions Disadvantages  LOCAL POWER GENERATION?  Incoming radiation is not even across the globe  Daily and seasonal differences  VERY expensive set-up costs

© 2011 Pearson Education, Inc. Wind – indirectly solar Growing steadily – doubles each 3 years  Prices continue to fall Advantages  Variety of scales  Very efficient (EROI 23:1)  Farm-land use and more jobs Disadvantages  Expensive to set-up  Not reliable or always local  Wind energy may need lengthy transportation  Ecological effects

© 2011 Pearson Education, Inc. Geothermal = thermal energy from beneath the Earth’s surface Radioactive decay of elements under extremely high pressures deep inside the planet generates heat  Which rises through magma, fissures, and cracks  Or heats groundwater, which erupts as geysers or submarine hydrothermal vents Geothermal power plants use hot water and steam for heating homes, drying crops, and generating electricity Geothermal energy provides more electricity than solar  As much as wind

© 2011 Pearson Education, Inc. The origins of geothermal energy

© 2011 Pearson Education, Inc. Geothermal Redefined Enhanced geothermal systems (EGS)  Deep wholes are drilled for cold water to be pumped in and heated, water withdrawn to generate electricity  Advantages: many locations, immense energy reserves  Disadvantage: can trigger earthquakes Ground source heat pumps (GSHPs)  geothermal pumps heat buildings in the winter by transferring heat from the ground to the building, cool in summer

© 2011 Pearson Education, Inc. Newer alternatives – Future Supports Hydrogen Tidal Future successes depend on government subsidies, politics, and location.