Water & Energy: Plan Recalculates Water’s Energy Use

11 Sep 2014

While energy regulators grapple with putting a dollar amount on the energy saved from water efficiency measures, big questions remain as to the amount of power consumed by energy-intensive groundwater pumping, use of which increases during dry periods. The latest partial update of the California Water Plan released Sept. 10 estimates that the water sector consumes about 12 percent of the state’s energy.

That includes 19 percent of electricity supplies, 32 percent of its natural gas and an unknown amount of crude and diesel. “The amount of crude oil is infinitesimally small,” compared to what is used by the transportation and heating sectors, said Andrew Schwartz, Department of Water Resources’ senior water resources engineer.

The California Energy Commission reported in 2005 that more than 80 billion gallons of diesel fuel were used annually by the water sector for pumping (not 80 percent as incorrectly reported in the Sept. 5 issue of Current.) But the Department of Water questions that figure.

“It’s all assumptions,” noted Schwartz.

The amount of water pumped, the depth from which it is extracted, and the fuel used to lift it up to the surface are big unknowns.

Those numbers are not reported, nor required to be.

Also unknown is the efficiency of the pumps being used. All those factors determine the amount of power used.

The Water Plan update breaks down the water sector’s 12 percent of the state’s energy use as follows: • About 10 percent of the energy is used by industrial, commercial and residential users for heating, cooling, pressurizing and industrial processes.

• The other 2 percent is used to move the flow long and short distances and treat it.

Of that energy used to transport water supplies, the 600-mile-long California Water Project, which conveys water from the Bay Delta to Southern California, uses about 0.3 percent—between 3,500-4500 GWh/year.

Half of the water project energy demand is met by the project’s hydropower.

The bulk of the 2 percent of the power used to transport and treat water—1.7 percent—is used to power the other water systems.

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