Just north of Terra Mar Point, a surfing hot spot in the San Diego County town of Carlsbad, the new Poseidon desalinization plant is churning away as it removes brine from seawater—sending the saltless solution through a multistep filtering-and-reverse-osmosis process. The plant, which opened December 2015, will take in 100 million gallons of Pacific Ocean and produce 50 million gallons of potable water per day from it, enough for about 400,000 residents.
This is nothing else like the Poseidon plant in the Western Hemisphere. By using existing infrastructural elements that ring the shores of the Agua Hedionda Lagoon (most of this area is occupied and owned by the Encina Power station and its parent company NRG Energy), Poseidon was able to cut new construction costs that typically make plants like these financially infeasible here.
In a region reeling from drought-fueled anxiety, this kind of cost-saving tactic means all eyes are on the deployment of the Poseidon plant. Detractors say it, and desalinization technology in general, wastes energy, distracts from water conservation as a drought remedy, and endangers sea life when its brine by-product is dumped back into an already salty ocean. Poseidon’s boosters are quick to counter these claims, however, highlighting aspects of the plant that are decreasing overall costs, energy consumption, and environmental degradation. For example, the plant’s siting next to the Encina power station minimizes lengthy underground connections for cooling water and power. The plant uses recovery devices to recuperate pressure from the discharge process, reducing energy consumption by 46 percent, and brine is diluted before going back into the sea (although the dilution process hasn’t satisfied most environmentalists’ concerns).
The plant was realized through a partnership between Boston-based Poseidon Water and the San Diego County Water Authority. Poseidon provided permitting, financing, and design, and SDCWA helped acquire lands and is contracted to buy the entire output of the plant over 30 years. Most other desalinization plants in the United States have been public-sector developments, like the federal government’s Point Loma plant, constructed for the Navy and dismantled in 1964, and Santa Barbara’s city plant, which closed in 1992 when California’s last big El Niño year hit. Attempts to open plants in recent dry years proved cost prohibitive for the public entity.
Projections by the National Oceanic and Atmospheric Association and others forecast drought as the new normal. Implementing new desalinization technologies, materials reuse, public-private partnerships, and energy recovery, these plants may soon become solvent solutions for coastal cities with their eyes on future drinking water sources.