New Energy World™
New Energy World™ embraces the whole energy industry as it connects and converges to address the decarbonisation challenge. It covers progress being made across the industry, from the dynamics under way to reduce emissions in oil and gas, through improvements to the efficiency of energy conversion and use, to cutting-edge initiatives in renewable and low-carbon technologies.
Power from the deep sea
5/5/2026
8 min read
Feature
In the 1870 classic novel 10,000 Leagues under the sea, Jules Verne ponders the possibility of generating electricity by exploiting temperature differences in seawater. Now, the idea has been put into practice for the first time in a physical prototype offshore the Canary Islands. It makes continuous renewable energy by exploiting the temperature difference of seawater at the surface and deep in the ocean. Energy Institute Senior Content Office Kristy Jooste reports.
Global OTEC, a UK-based developer of ocean thermal energy conversion (OTEC) technology, has announced the completion of the offshore installation of its prototype platform, named ‘Don’, in the Canary Islands. The company describes the structure as the world’s first purpose-built offshore platform designed to harness continuous renewable energy from ocean temperature differentials.
The OTEC system actually makes energy using a coolant with a low boiling point in a closed-loop Rankine cycle, like a refrigerator. It’s a multi-step process, according to Global OTEC. First, it draws in warm surface seawater (of around 26°C) which has been heated by the sun’s rays. This warm water is used to evaporate the working fluid. This produces a vapour which spins a turbine to produce electricity using a generator. At the same time, cold deep water (of around 4°C) is drawn up through a pipe from the depths of the ocean. The cold water cools the vapour, turning it back into a liquid which can then be immediately reused. Power is exported via a subsea cable. (See Box for more information.)
While the process has previously been demonstrated in small-scale onshore facilities, commercial scaling has been hindered by the technical requirements and costs associated with the long piping systems needed to reach sufficient heat from land. According to Global OTEC, moving operations offshore reduces the required length of piping by approximately 80% compared to onshore installations. The company aims to provide a baseload power alternative for tropical island nations, many of which currently rely on imported diesel and heavy fuel oil.