Steve Thomas is the host of Planet Green's Renovation Nation, a program that focuses on making green renovations to homes across the country. In his regular column on PlanetGreen.com, Steve goes behind the scenes of the show and offers additional tips and insight on green renovation.

One of the interesting things we did while we were in Hawaii was take a look at a technology called OTEC, Ocean Thermal Energy Conversion. The concept has been around for a long time. The idea is that you have warm water on the top and cold water on the bottom. You take the expanding vapor that comes off the hot water on top, then you cool it with the cold water and that causes a contraction. So you have push on the top and pull on the bottom and that drives the turbine.

Hawaii has plentiful warmth and plenty of water, being in a tropical ocean. By their calculations, you could satisfy all of Hawaii's energy needs by building somewhere around 11 OTEC units and scattering them around on floating platforms. Then pipe the power to shore. For about 11 billion dollars they could have free power.

Right now, their energy bill per year from fossil fuels is about 7 billion. Even if you factor in cost overruns, you've got a pretty short payback period for absolutely clean energy. That really got my attention.

They were in the process of building a new demonstration plant. They built one plant back in the seventies to prove the concept. Now they are thinking about building a small-scale but fully functional plant.

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