Water Consumption: Nat Gas Greener Than Coal

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"Natural gas doesn't get a totally free pass. . ."

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.

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, as power plants running gas turbines use less water for cooling than plants with steam turbines.

Water withdrawals (water that is taken from a source, used, and returned) and water quality impacts are also important. Based on our research, coal mining seems to be more harmful to water quality than natural gas drilling, too.

Coal-fired plants prove themselves more dirty on a number of other water related fronts. The emissions from coal-fired power plants are worse in terms of generating acid rain. Also, coal mining is often associated with dewatering. It can take years to restore the groundwater table near mines, as this disrupts hydrology.

Although coal is dirtier, natural gas doesn't get a free pass. Hydraulic fracturing has been employed for decades. The fracturing usually occurs thousands of feet below usable water sources, which are protected by cement casings. In general, the process is safe to groundwater if it's done correctly.

We're hoping to do some more work on the water impacts of natural gas versus coal a priority is looking more closely at issues of water quality and localized impacts of resource extraction in different areas of the United States.

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