Drought solution has high costs
As surely as the hot, dry Santa Ana winds bring blue skies to the coast and wildfires to the hills, severe California droughts bring calls to build desalination plants up and down the seashore.
All that ocean water, begging to be converted to fresh and pumped into our pipelines, would solve our water supply problems instantly and permanently, boosters say. In the coming months, the drumbeat will only get louder. That’s not only because the current drought is the longest and most severe in memory, but because a $1-billion desalination project scheduled to start operating in Carlsbad this fall will be attracting lots of attention. The plant, the largest of its kind in the U.S., is designed to provide San Diego County with about 50 million desalinated gallons a day, about 7% of its water needs.
“A lot of people are watching what’s going to happen in Carlsbad,” says Peter MacLaggan, the executive overseeing the project for its developer, privately held Poseidon Water. “They’re going to base their future decisions on the success of this project.”
That could be a mistake. MacLaggan himself doesn’t expect desalination to be “a major component in our lifetime” of the state’s overall water supply, although Poseidon has proposed to build a second desalination plant, in Huntington Beach. That plant is still awaiting approval from the California Coastal Commission.
Enthusiasm for desalination tends to overlook its high costs, which stem in part from its enormous energy demand and weighty environmental footprint. The modern process, known as reverse osmosis, involves forcing seawater at high pressure through a membrane that screens out the salt, leaving behind a heavily brackish residue.
In Southern California, which has become more dependent on fossil-fueled electric generation since the shutdown of the San Onofre nuclear power plant, Carlsbad arguably will be moderating the effects of climate change on the region while also contributing to the greenhouse gas emissions that help cause it. (MacLaggan says Poseidon will buy carbon credits and restore local wetlands to offset the plant’s environmental impact.)
“There are definite advantages to seawater desalination,” says Heather