I sincerely doubt it's OTEC. Although one of the only OTEC attempts was performed on a barge about that size, it was performed off Hawaii, where the surface waters are warm and to deep waters are cold - you don't have that contrast in SF or Maine, so it would make no sense. Even in Hawaii, the Carnot (=theoretical maximum) efficiency is only around 6%, which translates to a practical efficiency of maybe 3%, at best. What this means is that, in order to produce any appreciable amount of power, you have to pump an enormous quantity of water to extract the heat from, which means gigantic pumps, a gigantic heat exchanger, and the need for thermal reservoirs that can sustain the recycling of that water (i.e., massive, deep ocean waters with good currents). The Hawaii barge-OTEC drew water from 2,200 feet at 2700 gpm, and only produced 55 kW, while eating up 40 kW in pumping energy (net 15 kW) - that gives an idea of the size of equipment that would be needed.
Sorry - OTEC gets me going. I've had to explain to island politicians too many times, after being visited by sham OTEC salesmen promising "free energy from the ocean". Free, my ***.
