1. Alternative Forms of Energy Use • Consider advantages and disadvantages of alternative forms of energy • Evaluate if alternative energy sources address the root problem

2. 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

3. 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

4. Sweden’s search for alternative energy • 1980 - 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%

5. 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

6. Yucca Mountain, Nevada

7. 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

8. Biomass = energy obtainedfrom 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

9. 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

10. 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

11. New renewables • Renewables provide only 1% of energy and 18% of our electricity

12. 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

13. 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

14. 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

15. 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

16. The origins of geothermal energy

17. 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

18. Newer alternatives – Future Supports • Hydrogen • Tidal • Future successes depend on government subsidies, politics, and location.