The Water Footprint of Energy

You may not realize it, but when you use energy, you're also using water – lots of it.

Electricity and Water Use

In the US, 90 percent of electricity is generated by thermoelectric power plants. These fossil- or nuclear-fueled facilities boil water for steam to turn turbines and generate electricity. Once the steam is used, it has to be cooled so it can be used again. Many thermoelectric power plants rely on “once-through” cooling technology where millions of gallons of water are withdrawn daily, before being dumped back into whatever body of water they were withdrawn from at a higher temperature.

Thermoelectric power plants account for 45 percent of total water withdrawals in the US, including freshwater sources like lakes and rivers, and saline sources, such as oceans and estuaries.

About 43 percent of power plants in the US still use once-through cooling systems. Plants that use less water-intensive “closed-cycle” systems (where cooling water is recycled) or “dry-cooled” systems (where air is used for cooling instead of water) make up the other 57 percent.

Once-through cooling system withdrawals can have devastating impacts on aquatic ecosystems. As water is drawn into the plant for cooling purposes, fish, fish eggs and other aquatic life can be injured or killed in the process. In addition, when the cooling water is put back, it is typically warmer than when it was withdrawn, potentially damaging aquatic life through “thermal pollution.” Many plants across the US have reported returning water to its source with temperatures above 90 degrees Fahrenheit, and some reported temperatures above 110 degrees Fahrenheit.

There are many energy options available today, both large- and small-scale, that require significantly less water than thermoelectric power plants. Switching to clean and sustainable energy sources like wind and solar power is an important step towards reducing our energy-related water use.

Transportation and Water Use

Producing and refining oil also requires lots of water. In fact, researchers at the Lawrence Berkeley National Laboratory estimate that the US withdraws 1 to 2 billion gallons of water each day to refine nearly 800 million gallons of petroleum products like gasoline.

Corn-based ethanol, which some tout as an eco-friendly alternative fuel, is not so water-friendly. At 10 to 324 gallons of water per gallon of corn ethanol produced, it uses more water than gasoline, which requires 3 to 6 gallons of water per gallon.

Using Less Water

Driving less, carpooling and using public transportation are all good ways to reduce fossil fuel use and save water. So too is using energy more efficiently at home by switching to energy- (and water-) efficient appliances and light bulbs and turning off electronics when they're not being used. Energy- and water-efficient appliances play a critical role because saving water saves energy, which reduces the strain on water resources even further. It also helps in the fight to clean our air and slow climate change.

Small efforts to conserve energy and water really add up, and we each have the power to save.