1880s technology could provide a virtually unlimited supply of energy to tropical island nations. The technology, known as ocean thermal energy conversion (OTEC), was first discovered by French physicist Jacques Arsene d’Arsonval in 1881.

By harnessing the temperature difference between warm surface water and cold deep ocean water, OTEC can generate electricity. The process involves transferring heat from warm surface waters to create steam, which then drives a turbine to produce electricity. As the steam cools and condenses upon contact with cold seawater, the energy cycle is completed.

Since warm surface water is only found in tropical regions, OTEC energy production is limited to the tropics.

A renewable energy source, OTEC has the capacity to generate 7,000 GW of power globally per year. This is enough to satisfy the energy needs of the entire planet.

However, technological barriers have prevented OTEC from becoming mainstream. Less than 200 households worldwide are currently powered by OTEC, according to TNW.

A major obstacle for OTEC is the need for a continuous supply of cold water from depths of around 1,000 meters. This necessitates the construction of expensive, large-scale, storm-resistant metal pipes. For example, scaling up the Kumejima OTEC plant in Japan to 1 MW could cost up to $80 million for the pipe alone.

OTEC’s high costs have led climate activists to predict that OTEC will never become a major energy source.

Global OTEC’s exciting breakthrough

Nonetheless, a UK-based startup called Global OTEC is determined to prove the skeptics wrong. The company is developing a modular and cost-effective offshore rig named Dominique (pictured above).

Global OTEC opted for a floating barge design due to the challenges associated with onshore OTEC plants.

Onshore plants require extensive piping fixed to the seabed for water intake and discharge. In contrast, offshore rigs only need a single large cold-water pipe extending into the deep ocean.

According to Dan Grech, CEO and founder of Global OTEC, the Dominique offshore rig reduces piping costs by 95 percent or more.

This week, Global OTEC announced that Dominique will be used at a pilot project in São Tomé and Príncipe.  The project is expected to launch in late 2025. It’s the first commercial-scale OTEC project in world history.

Global OTEC estimates that Dominique could eventually replace 10 GW of diesel across 32 countries.

OTEC could generate even more energy if combined with floating solar panels. A 2008 study found that adding floating solar panels could quadruple an OTEC system’s energy efficiency. This is because solar panels increase the temperature difference between warm and cold ocean water.

Image Source: The Energy Year