Oceans

\ Marine Systems
	Qunicy Mass tide mill c. 1900	One of thousands of tide and wind mills once dotting the coasts of North America and Europe.
	The tidal barrage at St. Malo, France	This modern tide mill uses twenty-four 10-megawatt bulb-type turbine generators. Built in 1965, the barrage hasn't missed a tide for more than 38 years.
	Georges Claude. who also invented neon signs, built an experimental open-cycle OTEC system at Matanzas Bay, Cuba, in 1930.	The system used a low pressure turbine with amonia as a working fluid and produced 22 kilowatts of electricity. In 1935, Claude constructed another open-cycle plant aboard a 10,000-ton cargo ship moored off the coast of Brazil. Weather destroyed both plants. Worse, Claude was never able to achieve energy break even.
	Ocean thermal energy conversion system experiments have been successful at the Institute of Ocean Energy, Saga University, Japan.	Scientists have surpassed engineering expectations by producing well over 30 percent net power during continuous operating tests. Initially, these systems were expensive because the low boiling point working fluid was Freon inside corrosion-resistant titanium shell-and-tube heat exchangers. More recently, IOE scientists have been working on lower cost materials and working fluids, such as amonia-water mixtures.
	In 1979, a plant on the Kona coast of Hawaii produced a net of 15 Kw from a gross of 53 Kw.	One estimate of cost per installed kilowatt is around $1,500, on a par with coal and hydroelectric power and far lower than nuclear or gas fired electrical generation. However, long term large scale demonstration of the technology has taken place only on a limited scale.
	Experiments with aquatic biomass at the US National Renewable Energy Labs (NREL).	Unfortunately, research on renewable energy in the US has been held back by politics.
	Modern day kelp harvester operating off California coast.	Yet as early as 1918, the Pasteur Institute of Paris, France demonstrated that 10 gallons of ethanol could be produced per ton of seaweed. Imagine what that could mean.
	Could these kinds of systems begin to entirely replace petroleum?	Large scale biorefining could involve an integrated marine farm approach, as this diagram from a 1979 study by the Institute of Gas Technology demonstrates. The methane product could be converted to convenient liquid fuels (methanol, ethanol etc) through oxygenation.
		To replace all petroleum used today (27 billion barrels / year) with fuel from kelp would be an enormous undertaking, requiring perhaps 8 million square miles -- an area equivalent to 12% of the Pacific Ocean. While terrestrial biomass resources would be inadequate, marine biomass is a holds the promise of large scale sustainable fuel systems development.