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Electric Energy Resources
Global View
Electricity can be generated from a wide range of energy resources. Customarily, these resources provide energy in the form of heat to operate turbine generators. In the case of hydro, wind and tidal resources, kinetic energy can be transformed into electricity. Direct conversion of sunlight into electric energy is possible in photovoltaic systems, the newest electric generating technology.
However, more electricity is generated worldwide from coal than from any other resource. Unfortunately, burning coal creates more carbon dioxide per kilowatt-hour than other fossil fuels. Coal creates more pollution of other kinds as well. Limiting the amount of coal burned to generate electricity is a top priority of any strategy to reduce global warming.
Note – Hydroelectricity data in the chart includes small amounts of other renewables such as wind, solar, geothermal and biomass.
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United States
Energy used to generate electricity in the US has grown remarkably, increasing fivefold in the last 50 years. The Energy Information Administration projects that this growth will continue. Since the mid-1970s, hydroelectricity has remained relatively unchanged as no major new dams have been constructed. Nuclear power has increased as plants become more reliable. The use of natural gas has doubled since 1990, but the use of petroleum has fallen due to higher fuel prices.
Coal provides the majority of electricity in the US, accounting for 90% of all coal burned in the US. Currently all of the carbon dioxide generated from coal combustion is emitted into the atmosphere. Technology to separate CO2 from exhaust and sequester it permanently is under development, but whether this technology becomes viable remains to be seen. Estimates of carbon recovery technology costs would raise the cost of coal-fired electricity substantially.
For the foreseeable future, significant reductions in carbon dioxide emissions from the electricity sector must be obtained by decreasing the amount of electricity required and by increasing the fraction generated from renewable energy resources – solar, wind, geothermal and biofuels.
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California
California has the most diverse portfolio of energy for electricity generation of any region in the world. Renewable energy resources – solar, wind, geothermal and biofuels – account for over 10% of all electric energy. State law requires this fraction to increase to 20% by 2013. Legislation increasing this to of 33% by 2020 is currently being considered.
Nevertheless, the state currently is dependent on fossil fuels for 60% of its electricity. The large percentage of electricity from natural gas makes the state vulnerable to high gas prices. Coal accounts for over 20% of the state’s electricity supply. Little of this is generated in California, however, but is imported from neighboring states.
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