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Spotted: Ocean thermal energy conversion (OTEC) is a form of hydropower that generates electricity by harnessing the temperature differences (thermal gradients) between ocean surfaces and deep ocean waters. While research into this method began in the 1970s, progress has stalled – until now.

Recently, a project led by the Guangzhou Marine Geological Survey in China successfully completed sea trials of a floating OTEC 20-kilowatt device that generated power over almost five hours, with a maximum power output of 16.4 kilowatts. 

The successful 10-day trial focused on developing key technologies involved in OTEC, such as deep-sea thermal insulation water intake, cold-water pipeline installation, and more accurate estimation of ocean temperature differentials. The project also added considerable practical experience to what has up to now been largely theoretical work.

However, China is not the only country moving ahead with this technology. UK-based firm Global OTEC Resources recently received its first certificate of approval for the installation of a cold-water riser—a pipe used to transport seawater from the ocean to a seawater tank (and vice versa) from an offshore OTEC platform. This is a key design certification in the company’s plans to deploy a 1.5-megawatt commercial-scale OTEC platform in the African island nation of São Tomé and Príncipe by 2025.

Other companies, including Makai Ocean Engineering Bluerise, NELHA, and the Bardot Group are also developing OTEC technology. However, progress has been slow, due to the expense of the technology and the limited number of areas where it can be used.

If successful, OTEC could join energy innovations spotted in the Springwise archive such as microgrids and energy harvesting from raindrops as a future source of sustainable energy.

Written By: Lisa Magloff