San Diego, California authorities approved construction of a $320 million seawater desalination yesterday in a massive-scale attempt to stave off the state’s infamous droughts. According to the Pacific Institute, the plant will be the first large-scale desalination system on the West Coast and the biggest operation in the Western hemisphere. The plant, set to be built near Carslbad, CA, will filter 50 million gallons of water each day. When the plant is complete, it will filter 100 million gallons of water daily for nine water agencies in San Diego County.
Water infrastructure company Poseidon Resources will build the plant with reverse osmosis, a process that removes salt by filtering it through tiny membranes. It’s a controversial process, mainly because of concerns about cost and energy use–a 25 million gallon a day plant costs up to $100 million. The system also raises questions about the impact on fish from the pumping process as well as ecosystem changes caused by the return of leftover brine to the ocean. Poseidon plans to create 55 new acres of coastal wetland, but the California Coastal Commission has suggested that it isn’t enough.
Poseidon’s reverse osmosis system isn’t the only option for seawater desalination. Yale spin-pff Oasys is working on a forward osmosis process, and start-ups including Porifera and NanoH20 plan on putting synthetic proteins into membranes that eject salt.