A small floating pilot device deployed off the Canary Islands could one day prove pivotal to unlocking clean energy for tropical island and coastal communities by harnessing seawater heat. At least, that’s the hope of the EU-funded project that’s using a system known as ocean thermal energy conversion, or OTEC. Experts are hot on OTEC, a century-old theoretical means of extracting energy from the oceans. In a closed-loop system, warm surface seawater passes through a heat exchanger to evaporate a working fluid, such as ammonia, which vaporizes to turn a turbine. Then, cold deep-ocean water is pumped up from a depth of around 750 meters (nearly 2,500 feet) as a coolant to return the gas to liquid form, completing the cycle. For the process to function, a temperature difference of 20° Celsius (36° Fahrenheit) or more is needed between surface and deep waters. “The potential for OTEC to provide power and other value-added streams is really high in the tropical and subtropical areas,” says Andrea Copping, a faculty fellow at the University of Washington in the U.S. “You really are talking about base load power, so 24/7 power, which is more than you can say, really, about pretty much any other renewable.” This is by no means a new technology or idea. OTEC was first conceived as a way to produce electricity in the 19th century. Fast forward to the 1970s and ’80s, and a host of tests were being performed. U.S. President Jimmy Carter pushed forward the idea of…This article was originally published on Mongabay

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