Big problems require large scale innovative solutions. ElectronRun has so far covered solar proposals for the energy needs of the EU and the US. Now OTEC artificial energy islands come as another large scale idea whose main energy source is water temperature differences. The idea is that when we have a difference of about 20 degrees Celsius between warm sea surface water and cold water from large depths, it is possible to drive turbines for energy production.OTEC means Ocean Thermal Energy Conversion and is a method that was thought by French physicist Jacques-Arsene d’Arsonval. In fact, Georges Claude, a French inventor, proved the validity of the theory with his tests in the 1920s, but unfortunately did not manage to develop further.
There is two OTEC cycle types. The closed cycle uses ammonia that is vaporised by warm surface water, then drives turbines for energy production and is finally converted to liquid by cold water. The open cycle has an extra advantage, that of producing huge amounts of drinking water. There is quite a few ocean areas that offer the minimum required temperature differences, mostly around the equator.
The modern version of OTEC involves the creation of massive concrete islands that will be floating energy production facilities. Thanks to the size and area of those islands, OTEC will be supplemented by energy produced from waves, wind and sun. These additional energy sources will ensure that an island will be completely energy independent.
The idea goes even further to combine many polygonal islands, to create larger islands with higher energy outputs. The facilities will be run by qualified personel living on the islands in shifts, much like ship crews. Additional islands could be used as tanker docks -to transfer fresh desalinised water to the mainland- plant growing areas or even better hydrogen production facilities via electrolysis for the hydrogen economy of the future.
It is estimated that a single island can produce 250 MW, about 50 thousand islands would cover all worldwide energy needs. The OTEC project is now developed by architect and engineer Dominic Michaelis, his son architect Alex and Trevor Cooper-Chadwick of Southampton University. It will be launched this year at Virgin Earth Challenge, Richard Branson’s competition for global warming solutions.
In any case, despite proof that OTEC works, it is a complex project combining not one but four forms of energy sources and is therefore in need of prototype work. The fact that a module can be duplicated without practical limitations is an advantage not only technically but also financially, as construction costs could be more easily harnessed. Solar and wind projects already start to contribute to our energy needs so it is highly unlikely that OTEC would be called to cover all our energy needs. However, the proximity of certain countries to deep waters near the equator makes it a very attractive proposition for consideration.
Link : Electronrun
