New Approach to Grid-friendly Water Technology

Modular Desalination Is a Potential Next Step, with Applications from the Industrial Scale to the Village-microgrid Level

The process of desalination isn't nearly as energy-intensive as it was just a decade ago, thanks to newreverse-osmosis plant designsandnano-structured membranesthat have drastically improved the energy efficiency of turning salt water into fresh water. Pairing solar, wind and other renewable energy with desalination is a potential next step, with applications from the industrial scale to the village-microgrid level.

But there is a catch.The most efficient desalination technologies produce poor quality water when they vary the pressures or throughputs, which means they need a steady and predictable supply of electricity. Solar panels can't provide that, absent diesel generators or batteries, which add cost and complexity.

A desalination system that can follow the ups and downs of local green power could allow more projects to flourish without those constraints -- and taken to bigger scales, it could turn constant-energy desalination plants into "demand response desalination" systems. Down in La Paz, Mexico, semi-retired inventor Jan Kunczynski has quietly been testing a potential solution to this challenge over the past decade -- and now he's formed a company,Sisyan LLC, to bring the concept to a broader audience.

It's a similar concept to using lots ofsmart thermostats,water heaters,commercial refrigeratorsand other on-or-off electricity loads to follow the ups and downs of intermittent supply of wind and solar power in stepwise fashion. In this case, Sisyan has put three 3-horsepower modules together, each using avariable frequency drivethat can maintain consistent pressure on each unit within a certain operating range at about 22 kilowatts. If total power supply falls below that minimum range, Sisyan turns off one of the units and directs the remaining power to the still-operating units, keeping them running at optimal capacity.

But beyond that, the same modular concepts could be applied to the larger-scale desalination plants that are now being built in Israel and the Middle East, where they're a critical source of fresh water, he said. It could also be applied in drought-stricken California, which "could be the next Israel" in terms of its need for desalination, he said.

California, of course, is also the epicenter of distributed solar power, as well as host to a range of initiatives meant to incorporate this intermittent resource into the grid. That includesdemand response-- the ability to ramp power consumption up and down at a site to help the grid manage peak loads or variations in supply -- as well as newflexible, fast-ramping resourcesto help the state manage the "duck curve" distortions of its daily grid demand-supply balance.

Source: GreenTech Media

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• Innovation
• Technology
• Desalination