Energy & Water – How U.S. Energy Choices Affect Fresh Water Supplies
Water and energy, energy and water – two resources that we might like to think of as being separate, but which are actually interdependent in a way that can cause concern regarding the long-term sustainability of this dependence.
For every kilowatt-hour (kWh) of electricity that is generated in the United States, water is consumed. For the average Austin household (using about 1,000 kWh per month), this will result in a monthly consumption of 426 gallons of water if that electricity comes from a coal plant and 223 gallons if it came from a natural gas plant. And that’s just consumption (aka evaporation, in the case of power plants) – a LOT more water will pass through the power plant for cooling.
How much is “a LOT”?
Throughout the U.S., “a LOT” translated to hundreds of BILLIONS of gallons of water.
According to a report released at the end of November by The Worldwatch Institute:
The production and use of energy requires both the withdrawal and consumption of water and represents one of the largest demands on fresh water in the United States. In 2005, U.S. power plant cooling systems withdrew 143 billion gallons of fresh water per day, accounting for 41 percent of domestic fresh water withdrawals. Mining and fuel extraction withdrew an additional 2 billion gallons per day. Fresh water in turn requires energy to be pumped, treated, and transported before it can be used.
This report, titled “How Energy Choices Affect Water Supplies: A Comparison of U.S. Coal and Natural Gas” was written by friend and colleague, Emily Grubert, and hery co-author Saya Kitasei. Their work discusses how our energy choices affect fresh water supplies in the United States. In this report, Grubert and Kitasei state that:
Declining water availability is already limiting energy choices. Over the past decade, concerns about water availability have halted power plant construction or operation in the U.S. states of Arizona, California, Colorado, Georgia, Massachusetts, Missouri, New Mexico, North Carolina, Pennsylvania, Rhode Island, South Dakota, Tennessee, Texas, and Washington. As state and local governments around the country plan their electricity generation mix for the coming years, they will need to consider the water dimension of their decisions.
This report discusses the effects of coal versus natural gas on U.S. fresh water supplies, but for those of us who might be includes to favor nuclear as a good alternative to these two fuel resources – a factoid.
A nuclear power plant will consume about 600 gallons of water per megawatt-hour (MWh) of electricity generated (0.6 gal/kWh). That’s 1.4 times the amount of water consumed by a coal plant (2.7 times the amount of water consumed by a natural gas plant).
To compare the economic and environmental tradeoffs of different fuels we use to generate electricity in Texas, check out the Texas Interactive Power Simulator (TIPS) website.