While the greenhouse gas emission reductions of switching from coal to natural gas have been well documented, less attention has been paid to their effects on water.  Worldwatch Sustainable Energy Fellow Saya Kitasei and I recently coauthored a briefing paper comparing the lifecycle impacts of natural gas-fired and coal-fired electricity on fresh water in the United States. We looked at water consumption from mining and drilling in a few different resource basins, including regions where natural gas is produced by more water intensive methods like hydraulic fracturing or coal seam dewatering. We also looked at water consumption in processing, transportation, and at the power plant itself, along with pollution controls and waste disposal for those sites.

Perhaps unsurprisingly, we concluded that the biggest consumptive use of water comes at power plants, where water is routinely used as a coolant. Natural gas-fired power plants generally use less water for cooling for two major reasons. First, natural gas-fired power plants are often more efficient than coal-fired power plants, so less heat needs to be dissipated. Second, natural gas can be burned directly in a turbine (unlike coal, which is solid), and gas turbines are air-cooled. So power plants running gas turbines (including combined cycle plants, which run natural gas through a gas turbine, then use the waste heat to boil water and run a steam turbine) use less water for cooling than plants with steam turbines.

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EIA Reports Increased U.S. Natural Gas Reserves

Last week, the US Energy Information Administration (EIA) announced that proved reserves of natural gas in the U.S. have risen to their highest level in 40 years, reaching 284 trillion cubic feet at the end of 2009. US natural gas proved reserves are now at their highest levels since 1971.

Why do domestic natural gas reserves matter? 284 trillion cubic feet of natural gas is enough to power every American household’s electricity consumption, for over 73 years.* While estimates of the emissions reductions that could be induced by natural gas vary—anywhere from a 50% reduction to a 22% reduction in greenhouse gas emissions as compared to coal, depending on the criteria used–the takeaway is clear: plentiful domestic natural gas resources can decrease U.S. reliance on foreign oil.

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