Canary islands test site could unlock ocean thermal energy for tropical communities worldwide

A groundbreaking pilot project off Spain’s Canary Islands is testing technology that could revolutionize how tropical islands generate clean electricity. The EU-funded initiative uses ocean thermal energy conversion (OTEC), a promising renewable energy system that harnesses the natural temperature differences in seawater to produce power.

The floating device operates through an elegant closed-loop process: warm surface seawater heats a working fluid like ammonia until it vaporizes and spins a turbine. Cold water pumped up from depths of nearly 2,500 feet then cools the vapor back to liquid form, completing the energy cycle. The system requires at least a 36-degree Fahrenheit temperature difference between surface and deep waters – conditions readily available in tropical and subtropical regions.

What sets OTEC apart from other renewables is its reliability. “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,” explains Andrea Copping, a University of Washington faculty fellow. This consistent energy output could prove transformative for fossil fuel-dependent island communities that currently rely on expensive imported oil and gas.

Though OTEC was first conceived in the 19th century and tested extensively during the 1970s and 80s under President Jimmy Carter’s energy initiatives, modern technology may finally make it commercially viable. For tropical islands struggling with energy security and climate commitments, ocean thermal energy could offer both energy independence and a pathway to dramatically reduce carbon emissions.