By Michael Kanellos
Energy Recovery (ERII), the Oakland, Calif.--based maker of advanced desalination equipment, has signed a contract to install its PX Pressure Exchanger systems in a new desalination plant in Tenes, Algeria. The plant itself will generate 52.8 million gallons of fresh water a day and marks the tenth project in the country for Energy Recovery. In all, those plants generate 422.7 million gallons a day.
And San Diego is trying to build one. There's American ingenuity for you.
Energy Recovery in a lot of ways can be considered the iconoclast of desalination. Reverse osmosis desalination is effectively an energy-intensive pressure play: Water gets forced through a fine membrane that removes seawater. Energy Recovery's machines do not remove salt. Instead, they harness the pressure in the wastewater stream that flows from reverse osmosis systems and then feed it to the pressurizing machines at the front of the process, thereby lowering the total energy required.
Exploiting this pressure drastically reduces the amount of energy required to purify water, which in turn lowers the cost. Energy costs have been the Achilles' heel of desalination.
It took around 20 kilowatt hours per cubic meter to desalinate water with traditional multi-stage systems. Reverse osmosis membranes dropped that to 8 kilowatts to 10 kilowatt hours per cubic meter.
Putting a turbine in the waste stream and turning the pressure into waste stream drops it to 5 kilowatts to 6 kilowatts per cubic meter.
Energy Recovery's pressure harvesting technique drops it to 2 kilowatts per cubic meter. The system is also 97 percent efficient on average.
The company also had one of the few IPOs last year.