The First Large-Scale Ocean Thermal Energy Generator is Set for Deployment in 2025

On an average day, tropical oceans absorb around 278 petawatt-hours of solar energy. Capturing just 1/4000th of this energy could fulfill global daily electricity needs, and ocean thermal energy conversion (OTEC) offers a potential solution.

Pioneering OTEC Technology

Extracting energy from the temperature contrast between warm ocean surfaces and cold deep oceans is not a new concept. First trialed 142 years ago in 1881, a 22-kilowatt OTEC plant was built in Cuba in 1930. The basic idea is to locate a region with a consistent temperature difference, typically in tropical areas near land, where cold water at approximately 4 °C (39 °F) can be obtained from a depth of around 800 m (2,625 ft), and warm water exceeding 25 °C (77 °F) can be sourced from the surface throughout the year.

A floating barge, moored to the sea floor and equipped with a closed-loop power system using a refrigerant-like liquid, such as ammonia, is then deployed. The warm surface water boils the liquid, expanding it into a gas that drives a turbine to generate electricity. The liquid is cooled and condensed using cold water from the deep ocean, and the cycle repeats. This system produces electricity consistently, making it suitable for baseload usage, with the potential to mitigate rising sea surface temperatures.

However, historical challenges include the significant energy consumption by pumps bringing cold water to the surface, storm vulnerability, biofouling, corrosive seawater, and economic difficulties due to the technology’s early stage. Despite these hurdles, London-based Global OTEC sees an opportunity with recent shifts in the energy economy. They presented a new OTEC barge concept, Dominique, expected to commission in 2025 off São Tomé and Príncipe’s coast.

Paving the Way for Commercial-Scale OTEC Platforms

Dominique is designed to deliver a net output of 1.5 megawatts year-round, covering nearly 17% of the nation’s energy consumption. Global OTEC deems it the “first commercial-scale OTEC platform.” While details on project funding remain unclear, early-generation OTEC barges are projected to have a Levelized Cost of Energy (LCoE) between $150-300 per megawatt-hour, posing challenges in cost competition. Global OTEC envisions larger-scale plants reaching $50/MWh over time, aligning with wind and solar costs.

The journey to achieve this vision is challenging, exemplified by past shelved projects and the Innovation Valley of Death constraints. A 2021 review recognized OTEC’s potential but highlighted infrastructure costs and the harsh marine environment. The remote island locations where OTEC could work often lack the financial means for such initiatives. Despite optimism, success for Global OTEC’s 2025 target is viewed as a long shot.

Read the original article on: New Atlas

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