Energy Recovery Thirsty for New Desalination Markets

The desalination guru company, Energy Recovery, has a parched throat for other things...

The Norwegian-American-Kuwaiti company – which held one of the few IPOs in greentech last year – today unfurls the PX-300, a larger, fine-tuned version of its energy capture devices for desalination plants. The PX-300 can process 300 gallons per minute, or more than its earlier versions.

The new device will likely be deployed in arrays in the large seawater desalination plants being currently constructed or planned in Australia, the Middle East and China where the flow can reach tens of thousands of gallons per minute. Energy Recovery commands approximately 70 percent of the market for its component, said Richard Stover, the company's CTO.

Resorts on the Red Sea and Baja are big purchasers of the systems. "In some of these places, there is no infrastructure," said Stover, adding that the company is also examining new markets.

Energy Recovery wants to start making equipment for brackish water desalination plants, which are more common in the U.S., as well as the emerging forward osmosis systems championed by, among others, Yale spin-out Oasys.

It is also working with Starkraft Energi in Norway to generate power through osmosis. Starkraft, optimistically, believes it could generate most of Norway's power through osmotic pressure gradients created where Norway's many streams and rivers meet the sea. The initial stage of a pilot will begin later this year.

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Energy Resources in a lot of ways can be considered the weirdo 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, he said. 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 Research's pressure harvesting technique drops it to 2 kilowatts per cubic meter. The system is also 97 percent efficient on average, which in turn makes the reverse osmosis process 60 percent efficient. Turbine systems – which convert hydraulic power to mechanical power and then to electricity – can't match that, he argued.

- Brewskie