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© 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
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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
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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%
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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
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Yucca Mountain, Nevada
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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
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Biomass = energy obtainedfrom organic material
Large variety of productionsAdvantages
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
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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
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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
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New renewables
• Renewables provide only 1% of energy and 18% of our electricity
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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
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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
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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
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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
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The origins of geothermal energy
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Geothermal RedefinedEnhanced 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
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Newer alternatives – Future Supports
Hydrogen
Tidal
Future successes depend on government subsidies, politics, and location.
