The world’s oceans are an energetic place, and military-industrial giant Lockheed Martin said today it has been granted $1.2 million by the Department of Energy to demonstrate that ocean thermal energy conversion is possible. Although the ocean often doesn’t feel very warm, the temperature gradient between the warm, sun-soaked surface and the frigid, dark depths provides enough of a differential to run a heat engine. The idea has been kicking around for over a century but has never been scaled. Lockheed Martin helped build the largest ocean thermal energy conversion system to date back in the 80s, but it only ever produced 50,000 watts, or .05 megawatts.
For those who aren’t so up on their thermodynamics, whenever you have a temperature gradient, there is accessible energy to be had. Ocean thermal energy conversion (OTEC) works best when there’s a temperature difference of at least 20 degrees Celsius. Waters of two different temperatures are pumped through a heat exchanger which vaporizes and then condenses the water, producing energetic steam in the process.
Lockheed will work on the problem of getting that cold, deep water up to the surface. The small-scale OTEC system Lockheed had previously help design in Hawaii used a polyethylene pipe that was 2,150 feet long and 2 feet in diameter to draw up cold water. Under terms of the grant, Lockheed will demonstrate cold water pipe fabrication using modern fiberglass and low-cost composite material manufacturing methods.
Harnessing ocean thermal energy is likely farther out than both wave and tidal energy systems. But if scaled, it could provide consistent base-load energy and help tropical islands, like Hawaii, attain energy independence, a serious issue in a world of petropolitics.
Images courtesy of NREL.