Washington (Platts)--19Sep2012/626 pm EDT/2226 GMT

Significant water use by traditional US energy power generating technologies, including nuclear, coal, natural gas and biomass, are a "major hidden cost" associated with the fuels, Synapse Energy Economics said in a report released Wednesday.

"Too often left out of the equation are a number of important 'hidden' costs, also called 'indirect' or 'externalized' costs, associated with each generation technology," said Geoff Keith, senior associate, Synapse Energy Economics. "These include costs to society such as depletion of water and other resources, air and water pollution, detrimental impacts on human health and the environment, and contributions to global climate change."

These indirect costs for electric generation are important to consumers, "whether or not they can be easily expressed in monetary terms," such as the capital needed to build and operate a power plant, he said.

Coal, nuclear and natural gas-fired generation have the heaviest impact on water supplies, according to the study. The energy research group also examined solar and wind energy in terms of these costs. Coal and nuclear plants also have the largest effect land out of the six fuel sources examined.

Coal and natural gas have the highest climate change costs and coal generation overall incurred the highest costs to address air pollution. Nuclear energy and coal-fired generation ranked the highest in planning and cost risk as well as costs related to subsidies and tax incentives, the study found.

The Synapse Energy prepared the report for the nonprofit, nonpartisan Civil Society Institute and the Environmental Working Group.

The report said coal-fired generation withdraws 500 to 600 gallons of water per megawatt-hour of electricity generated using a closed-loop cooling water system that recyles the water.

Open-looped, or once-through, cooling systems require 20,000 to 50,000 gallons/MWh produced. Coal mining also affects drinking water and coal ash waste fouls water, the study said.

About 62% of the nation's nuclear power plants employ closed-loop cooling systems that withdraw 700 to 1,100 gallons of water per MWh. Open-loop systems take 25,000 to 60,000 gallons per MWh. Water is usually returned to sources at a higher temperature and diminished quality.

Hydraulic fracturing or fracking for shale natural gas can use up to 10 million gallons of water per well, according to EPA estimates in 2010, the report noted. Biomass plants of 50 MW can withdraw 242 million gallons of water per year. Water, estimated between 40,000 and 100,000 gallons, also must be dedicated to raise these energy crops.

--Cathy Cash cathy_cash@platts.com --Edited by Jeff Barber, jeff_barber@platts.com

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