This drought solution takes less energy than air conditioning

Water is pumped into a field that will be planted with rice on May 8, 2015, in Biggs, Calif.
Getty Images
Water is pumped into a field that will be planted with rice on May 8, 2015, in Biggs, Calif.

California continues to suffer through a fourth year of water shortages, bordered by the largest body of water on earth.

The crisis has encouraged residents to once again wonder if the Pacific Ocean is the answer to the state's water woes. Some are pushing for additional desalination plants like those used in water-starved Israel and Australia to convert ocean water into unlimited fresh water.

Coastal Santa Barbara turned to desalination during a devastating five-year drought in the late 1980s, but by the time a new plant was ready for operation in 1992, heavy rains had returned. The $35 million facility ran for a few weeks before being shuttered.

That's because the desalination process is not only potentially harmful to marine life, but removing salt by pushing salt water through membranes takes far more energy than simply pulling fresh water from inland sources. All that energy use is not only counter to the state's push for lower emissions, but it only seems economical during the worst of a drought. As Santa Barbara reactivates the plant this summer, water bills in the area are expected to increase by 40 percent.

Read MoreDrought to deluge? El Nino's impact on California

Not only is desalination expensive compared to the state's dwindling freshwater supplies, it is more expensive than other drought-year options, like the State Water Project, which pumps water to Southern California from the less parched top half of the state.

Compared to local freshwater sources, desalination is certainly energy expensive. But it's only slightly more costly than other options available during drought conditions. That's why Santa Barbara is spending another $40 million to reopen its plant, and why 17 others are in the works along the state's coast.

In Carlsbad, California, Poseidon Water is opening a $1 billion plant that will be the largest in the U.S. when it is completed in the fall. In a recent Wall Street Journal article, CEO Carlos Riva defended desalination plants against those that worry that they represent a step backward in the state's efforts to reduce carbon emissions, pointing out that the plant will "use less energy than one of the data center that are being built, and nobody claims that they are somehow immoral."

Read MoreCalifornia's drought no match for its tourism industry

According to the Natural Resources Defense Council, data centers are expected to consume 140 billion kilowatt hours of electricity a year by 2020—the output of 34 large coal power plants. According to the Pacific Institute, the Carlsbad plant will take 750 megawatt hours per day, so more than 500 equivalent plants would have to be constructed to match the energy cost of our Facebook and Google habits.

In fact, producing water by desalination requires less energy than many things Americans take for granted—like central air conditioning.

Heather Cooley, water program director at the Pacific Institute, said that while it is true that we can always point to other areas of energy consumption, water policies should be made based on water options available right now to local decision makers.

"It's sort of a slippery slope," she said. "It needs to take into perspective what is available, and from our research there are in many cases cheaper options than desalination available."

That doesn't mean that those alternatives might not be more expensive in a few decades, making desalination a good option for the future, she said.

"We don't have a crystal ball," she said. "We have to think about what our options are right now, recognizing that it could be different in 20 years."

In the end, the biggest risk may be repeating the past. It takes years for desalination plants to overcome regulatory concerns—Poseidon began construction in 2013 after six years of lawsuits about the plant's environmental impact. Even if Californians decide to invest in a network of desalination plants, they could find that by the time they are up and running the state can once again rely on low-cost surface water.

Poseidon overcame that risk with a 30-year contract with the San Diego County Water Authority, but in a few years that expensive desalinated water could leave Californians wishing they'd just hunkered down and left the Pacific Ocean alone.

Most of the desalination projects in the works are long term plans, not just responses to the drought, and that's how it should be, said Cooley.

"It's more a strategy for long-term supply and diversification," she said. "If you build it simply in response to a drought, you run the risk of the drought ending."

UPDATED: This story was updated to include comments from the Pacific Institute.