Wacky Cleantech Ideas: Electricity from the Seashore

Lyngby, Denmark—As long as rivers flow into the sea, we potentially can get cheap power with almost no effort.

That’s the view from Scandinavia, where some scientists and start-ups are turning their attention to generating power from osmotic pressure.

It works as follows. Fresh water from streams and rivers comes tumbling toward a tank of sea water filled by the ocean. Before it falls into the sea, though, it must pass through a membrane. The membrane eliminates any impurities and lets only the tiny water molecules get through.

When fresh water enters the tank filled with sea water, it decreases the salt concentration in the seawater and increases the overall pressure. (You can get a more full description from Rolf Aaberg from Norway’s Starkraft Energi here.). The pressure can then be harnessed to run a turbine.

“You have the potential of approximately 2,000 terawatt hours a year globally. Any place you have a stream going into the sea you have potential energy,” says Peter Holme Jensen, a microbiologist turned CEO of a water purification company in Lyngby called Aquaporin. Aquaporin is looking at this market, but Jensen said it is in the very experimental stage.

The sun, meanwhile, keeps the whole process going by evaporating seawater, which later turns to rain to fill streams. Like coal and wind, osmotic power is indirect solar energy.

It is one of those zany ideas—like nuclear fusion, piezoelectrics and self-powered hydrogen plants—that is on the fringe now but could pay off massive dividends in the future. A longshot, yes, but who knows. If someone in 1944 told you that a bunch of Europeans were in the New Mexico desert building a bomb that could flatten a city, you probably would have scoffed.

Others are working on different passive ocean power concepts.  John Craven in Hawaii wants to exploit sea-based heat exchangers to generate air conditioning. The heat exchanger, a tube, would fill with frigid water thousands of feet below the surface. When that cold water gets toward the surface, it radiates cool.

But if osmotic power sounds easy, how come we aren’t doing it now? Getting adequate pressures is difficult. It has also been tough finding a durable membrane that won’t foul.

That is where Aquaporin says it can play a part. The company, along with Novozymes, is devising a water purification membrane based around a protein called an aquaporin. Aquaporins sit in channels in living cells: they eject impurities but let water pass. (Read more here.). Novozymes is working on developing a synthetic aquaporin while Aquaporin the company is working on arrays and membranes. (That’s an artists’ rendering of an aquaporin, by the way.)

The companies will first sell membranes to the semiconductor industry, which buy membranes to turn very clean water into almost absolutely pure water. Later, it will move into the mass water market and in the meantime continue to work on the energy concept.

“We could have energy as long as the sun shines,” Jensen said.

The Scandinavian countries, by the way, are pushing cleantech hard. Denmark, Sweden and Finland are trying to commercialize their university research more and large local established companies like Danfoss and Dong Energy are concocting spin-outs. Will all of these things make it? No, but it shows that, in greentech, you are going to continue to see a lot of activity overseas. It probably won’t be like the IT revolution where most of the important companies came from the U.S. or the east coast of Asia.

Other interesting Danish start-ups: fabric that can replace steel from PolyPower and an LED growing system.