One thing... there is a whole heck of a lot of energy to be captured offshore. But offshore renewables have proven to be almost as politically challenging as offshore drilling.

Take the famous Cape Wind debacle. It has taken close to a decade to overcome the ire of both conservative and liberal (even Kennedy) opposition to the development of a large scale offshore wind project near the coast of Cape Cod.

So Ocean Power Technologies may be onto something big. Their APB (Autonomous Power Buoy) is barely visible from the shore, has a 30-year life expectancy (about the same as a wind turbine) and is both easier and cheaper to install.

At the Sustainable Energy Expo in Capitol Hill I visited OPT's booth where Debbie Montagna walked me through the revolutionary technology. Right now OPT is manufacturing the 150 kW buoys (2 will be installed later this year) and they are on track to produce a 500 kW buoy in 2010, at which point the technology will become competitive in cost with coal.

Afterwards, I stopped by and talked to Sean O'Neill and Carolyn Elefant, cofounders of the Ocean Renewable Energy Coalition, the trade association for offshore renewable energy companies. They described the array of different ocean technologies that are currently under development. In addition to offshore wind, there are 4 main categories of wave energy technology:

  • oscillating water columns
  • attenuators
  • water buoys
  • tidal technologies (both vertical and horizontal)

This video describes another technology called ocean thermal conversion:

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