Via the Environmental Research Web, an interesting analysis of the watergy nexus:
Almost 13% of US energy (12.3 quadrillion BTU) goes towards collecting and preparing water for its intended end use. That makes water one of the largest energy consumers in the nation, according to Kelly Twomey Sanders and Michael Webber from the University of Texas at Austin, US.
“About 5.4 quadrillion BTU (more than 40% of the total) is dedicated to producing electricity for water-treatment facilities, electric water heaters, and other electric devices such as appliances, which by itself is about the same amount of energy consumption for electric lighting in the commercial and residential sectors,” Twomey Sanders told environmentalresearchweb. “Despite this equivalency, more policy attention is dedicated to replacing lighting fixtures than to mandating more efficient water heaters or to fixing leaky pipes.”
Twomey Sanders and colleague Michael Webber hope that by filling in an important knowledge gap their findings will lead to more discussion on achieving energy efficiency through the water sector. “While energy–water nexus practitioners have touted water conservation as a means of conserving energy, without a national estimate of water-related energy use it is difficult to quantify these potential savings,” said Twomey Sanders.
The team found that roughly 46 quadrillion BTUs of the 98 quadrillion US energy consumption in 2010 went to water-related purposes. The bulk was consumed in making steam for electricity generation, space heating and use in industrial processes. Direct water services, including water for drinking, bathing, pressurized water for cleaning, and appliances such as dishwashers and clothes washers, and direct steam use, such as steam injection in industrial processes and steam stripping, together took up 12.3 quads of energy.
The concept of the “energy–water nexus” – the principle that it takes water to produce energy and energy to produce water – has gained increasing attention in the past five years. “However, to date, more analysis has been devoted to quantifying the water embedded in different forms of energy at the national level than to the amount of energy that is used to treat, heat, pump, pressurize and cool water for a variety of end uses,” said Twomey Sanders.
The researchers employed data from the US Energy Information Administration, the US Department of Energy, the Electric Power Research Institute (EPRI) and private sources. California has led the way in accounting water-related energy use. Massachusetts, Wisconsin, Iowa and New York have also begun to quantify their water and wastewater utility energy consumption at a state level. “We decided to pursue the approach of using a bottom-up detailed inventory of energy use for water simply because no top-down national statistics were available with suitable fidelity,” said Twomey Sanders.
Water-related energy use in the US is expected to rise as states such as Texas, Florida, Arizona and California are forced to use more energy-intensive technologies such as desalination plants and interbasin water pipelines to provide enough water for their populations.
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