Desalination plants powered by solar thermal are being tested in California in agricultural areas far from the ocean. Water used for crops can be filled with salts, and the problem gets worse over. The Water FX Aqua4 provides clean water from “wastewater, drainage water, runoff, saline groundwater and industrial process water. The remaining brine is concentrated into solid byproducts for resale.” The system is a highly efficient, scalable solar still that produces 30x more clean water than by natural evaporation.
A pilot project in Australia by Carnegie Wave Energy plans to produce zero emission energy using their CETO wave energy technology to run a desalination plant.
CETO harnesses the enormous renewable energy present in our ocean’s waves and converts it into two of the most valuable commodities underpinning the sustainable growth of the planet; zero-emission electricity and zero-emission desalinated water.
Unlike other wave energy systems currently under development around the world, the CETO wave power converter is the first unit to be fully-submerged and to produce high pressure water from the power of waves.
Opponents of desalination in Santa Cruz CA object to an environmental report for a $129 million desal plant. They say water conservation measures and improved water management could hold water consumption at current levels so the plant would not be needed.
I’m completely in favor of water conservation. However, California is in a drought, climate change is making the water situation worse, and the population is growing. San Diego is currently building a huge desal plant. If California wants to guarantee plentiful water then it will need many more desal plants. That in turn means more power plants, as desal uses considerable amounts of electricity.
There are no easy answers here. However, the NIMBY, slow growth view of desal opponents is no solution.
Energy is the biggest cost for desalination plants, sometimes 50%, more than with importing water from elsewhere and much more than wastewater recycling. California has seventeen proposed desalination plants. San Diego has started construction of the biggest desal plant in the Western Hemisphere. California absolutely needs much more water, but where will the energy come from? On hot summer days California already faces the possibility of power shortages. This will be exacerbated by the San Onofre nuclear plant being closed, quite possibly permanently.
While the projects may ease water strains for area utilities, they’ll increase suppliers’ exposure to variable energy prices…
“While you may be improving your water reliability, you may be increasing your vulnerability to energy price changes over time.”
Energy and water are inextricably linked in California and the Southwest, where one of the biggest uses of electricity is for pumping water and large amounts of water are used for cooling in the generation of power. Seventeen desal plants would hugely help California’s ongoing water shortages. Running them though would require gigawatts of electricity that California simply doesn’t have, and this shortage is made worse by California’s plan to have 33% in-state renewable energy by 2020.
When completed, the Carlsbad desalination plant will convert 50 million gallons of water a day into drinking water, about 7-10% of San Diego’s needs, and will be the biggest desal plant in the Western Hemisphere.
Water from the plant will cost about double what the Los Angeles Metropolitan Water District charges. However, it guarantees San Diego will always have at least some water. 100 millions gallon a day will be pumped in from the ocean, filtered to 50 million gallons of drinking water, with the brine then being diluted and pumped back into the ocean.
Modern desal systems use 50% less electricity than previous methods. Even with that though, desalination still uses lots of power. As always, electricity and water are inextricably bound in California.