Edinburgh Researcher Helping Ocean Desalinate Itself
by EcoGeek.org on 11. 9.06
If we need power to turn the ocean into tap water, why not let the ocean provide the energy? Stephen Salter at Edinburgh University is working toward that possibility his Edinburgh Duck, a wave powered desalination plant. The device would work by using the force of the ocean to lower the pressure within the device, creating water vapor even at low temperatures. No electricity is generated or needed, no membranes need to be cleaned or replaced, the device simply sucks water vapor from the seawater, condenses it, and then uses the power of the waves to pump it back to shore via it's tube-like tethers.
Right now the device pumps only air, and not even very much air at that, but Salter says the concept could be expanded to create Ducks up to ten meters in diameter that would pump out 2000 cubic meters of water every day, enough fresh clean water for roughly 20,000 people (not including agriculture.)
Detractors say that there is no way to scale up the Edinburgh Duck to the levels of performance seen in electric desalination plants. But we say that the Ducks can be decentralized and used locally only where they're most needed. Plus they don't pump out huge quantities of super concentrated salt water or require hundreds of megawatts per day to perform.
See Also, ::Treehugger picks: Wave and Tidal Power, ::Wave Power: Spotlight on Ocean Power Delivery Ltd
Pictured above is a scale model of the desalinization duck (left), and a 1976 image of a energy-producing duck design (right).
Via ::NewScientist
I feel like there's a big "but..." missing from the story. The New Scientist article says this guy made a similar contraption for generating electricity 30 years ago...what happened to that?
Coal was cheap why would anyone care 30 years ago?
I thought making the oceans more saline by taking water out of it was incredibly dangerous to existing ecosystems?
@eric: It's a question of scale more than anything. There are some plants in the Middle East that desalinate more than a billion liters of water a day. That causes serious ecological problems. But 20,000 liters a day would probably not even be locally measurable.
It causes problems? Is there any real evidence of that? I find that a bit hard to believe. Rivers dump way more fresh water into the ocean in a day.
This might not be suitable for a city, but there's a HUGE amount of smaller scale development spread out along the coasts--especially in Europe. The scale of this contraption would be perfect for a lot of resort towns in Spain, where holidaymakers and farmers are tussling over the little available water.
@anonymous: There are definitely real problems with high salt concentrations coming out of desalination plants. It's not fresh water that's the problem, though any large scale change to an ecosystem could upset an ecosystem.
Desalination plants don't expel fresh water, they expel extremely salty water, and life in general has a hard time dealing with water that is saltier than oceans, just because life hasn't had a lot of exposure to water that is saltier than the oceans. Not, at least, on this planet.
Whoops you are right. I definitely meant the salty water. I'm sure it could be alleviated by releasing the water over an area, say a few miles of pipes.