Potential For OTEC (Ocean Thermal) In India

By Narsi Santhanam • Sep 11th, 2010 • Category: Uncategorized

Ocean Thermal Energy Conversion (OTEC) utilizes the energy potential created by temperature difference between sun-warmed surface water and colder parts at the bottom to generate electricity.

OTEC uses this natural temperature gradient to drive a turbine, which is connected to a generator. It is desirable that the temperature difference between the warm surface water and the cold deep water be at least 20 degrees C.

This is what Wikipedia has to say about OTEC: “The total energy available is one or two orders of magnitude higher than other ocean energy options such as wave power; but the small magnitude of the temperature difference makes energy extraction comparatively difficult and expensive, due to low thermal efficiency. Earlier OTEC systems had an overall efficiency of only 1 to 3% (the theoretical maximum efficiency lies between 6 and 7%). Current designs under review will operate closer to the theoretical maximum efficiency. The energy carrier, seawater, is free, though it has an access cost associated with the pumping materials and pump energy costs. Although an OTEC plant operates at a low overall efficiency, it can be configured to operate continuously as a Base load power generation system. ”

Examining the future of Ocean Thermal Energy Conversion

Tuesday, 17 June 2008

Although it may seem like an environmentalist’s fantasy, experts in oceanic energy contend that the technology to provide a truly infinite source of power to the United States already exists in the form of Ocean Thermal Energy Conversion (OTEC). Despite enthusiastic projections and promising prototypes, however, a lack of governmental support and the need for risky capital investment have stalled OTEC in its research and development phase. Regardless, oceanic energy experts have high hopes. Dr. Joseph Huang, Senior Scientist at the National Oceanic and Atmospheric Administration and former leader of a Department of Energy team on oceanic energy, told the HPR, “If we can use one percent of the energy [generated by OTEC] for electricity and other things, the potential is so big. It is more than 100 to 1000 times more than the current consumption of worldwide energy. The potential is huge. There is not any other renewable energy that can compare with OTEC.” The Science of OTEC French physicist George Claude first explored the science of OTEC in the early twentieth century, and he built an experimental design in 1929. Unfortunately for Claude, the high maintenance needed for an OTEC plant, especially given the frequency of storms in tropical ocean climates, caused him to abandon the project. Nevertheless, his work demonstrated that the difference in temperature between the surface layer and the depths of the ocean was enough to generate power, using the warmer water as the heat source and the cooler water as a heat sink. OTEC takes warm water and pressurizes it so that it becomes steam, then uses the steam to power a turbine which creates power, and completes the cycle by using the cold water to return the steam to its liquid state. .

Power from the sea

Second time around…

Ocean heat may be used to generate electricity

Jan 7th 2012 | SAN FRANCISCO | 

EVEN by the standards of American bureaucracy, an organisation that operated for 13 years without achieving anything is impressive. Yet that was the fate of the Ocean Thermal Energy Conversion (OTEC) permit office, which opened its doors in 1981 and closed them in 1994, having issued not a single OTEC permit.

The office was part of NOAA, America’s National Oceanic and Atmospheric Administration—a marine counterpart of the country’s space agency, NASA. And the idea of OTEC was to exploit the difference in temperature between the top of the ocean and the bottom, in order to drive turbines and generate electricity. The incentive was the oil-price spike of the 1970s. But once that incentive went away, so did interest in alternative sources of power and, eventually, so too did the office.

Alternative power sources are back in fashion, though, and OTEC is one of them. A range of companies, from giants such as Lockheed Martin to minnows like the Ocean Thermal Energy Corporation of Lancaster, Pennsylvania, are working on the technology, and this time it might actually come to pass. Most of the bits and pieces required can be borrowed from other areas of engineering, such as deepwater oil drilling. And the idea of a power station whose fuel is free is attractive, as long as the capital cost is not too high.

Scouring the Tropics for Thermal Energy | Renewable Energy News Article

The world's largest untapped source of solar energy doesn't lie on the vast sands of the Sahara or even atop the high chaparral of the desert Southwest. Instead, it stretches across at least 23 million square miles of earth's tropical oceans; the uppermost layers of which make a prime natural source of thermal energy.

Regardless of time of day or cloud cover, Ocean Thermal Energy Conversion (OTEC)promises to harness this thermal sea-based resource year round.
OTEC production converts heat energy from seawater into kinetic energy using the ocean’s naturally steep temperature gradient.  It’s this juxtaposition of tropical (and sometimes subtropical) subsurface seawater at temperatures typically above 80 degrees F. and below 40 degrees F. that makes OTEC possible.