Like some others (see SiliconBeat's posting today, for instance), I was struck by the Wired Magazine article on Common Heritage Corp. and their technology for ocean thermal energy conversion (OTEC). The article doesn't really describe the technology, but in a nutshell OTEC uses the heat of surface ocean water to boil a liquid like ammonia with a low boiling point. Then the ammonia vapor thus produced runs a turbine, just like a steam engine would. Finally, cold deep ocean water is used to re-condense the ammonia back into a liquid for re-use. At least that's this layman's take on it. Other benefits besides power generation include fresh water production via condensation off the cold water pipes, and the use of deep-sea nutrients brought up in the process. NREL has a good description of the technology, which has been around for quite a while and has enjoyed federal and state government funding for R&D at various stages.
According to Carl Hoffman, the author of the Wired story, a very private venture capital firm out of Memphis, TN named Alpha Pacific has funded CHC to the tune of $75M. If accurate (there doesn't appear to be any more information about Alpha Pacific or the round anywhere to be found), that would be a huge bet on this technology, amidst a lot of secrecy. The only thing missing is a catchy code name for the technology, something like "Ginger," perhaps.
Another backer of OTEC technology is the Abell Foundation, through their investment in Sea Solar Power (SSP). SSP was supposedly unsuccessful in its attempts in the late 1990s to raise a very large amoung of funding, but has been moving forward with a couple of demonstration projects with support from Abell.
Meantime, wave power -- the use of the motion of ocean waves to power generators -- has apparently been making some progress as well. The world's first commercial wave power farm is apparently going to be constructed in Portugal by Ocean Power Delivery, a Scottish company. The cost appears to be about $4.4M per MW (as point of comparison, a wind farm costs about $1.3M per MW, according to the AWEA), but it's a good start. Ocean Power Delivery is backed by cleantech VCs such as Norsk Hydro Technology Ventures, Sustainable Asset Management (SAM), and Carbon Trust, among others.
At the same time, another Scottish wave power startup, Wavegen, has run into a bit of trouble and required rescue via trade sale to Voith Siemens Hydro.
Another technological approach being considered by ocean power startups is the installation of water-driven turbines directly into rivers or ocean currents. Several such demonstration projects have been proposed or have already been successfully tested.
Clearly, it is very early days for ocean-based power, with a lot more ups and downs to come (no wave-power pun intended). However, the long-term potential is there, and it will be interesting to follow the development of these technologies going forward.