It is estimated that between 30.000 and 90.000 TW/h year of power are extractable without having negative impacts on the thermal characteristics of the oceans, according to 2014 JRC Ocean Energy Report.
Ocean thermal energy conversion (OTEC) captures the temperature difference between cooler deep and warmer shallow ocean water to produce electricity.
There are three kinds of OTEC systems: closed-cycle, open-cycle, and hybrid.
OTEC plants can be based onshore (land-based and near-shore) or offshore. OTEC technology is most suitable for the equatorial areas.
The first OTEC plant that generated electricity was built in 1978. ‘Mini-OTEC’ had 50 kW of capacity, and it represented a closed-cycle OTEC system.
There are several larger OTEC projects being planned currently – most of which are of 10 MW in capacity.
OTEC plants rely on already-developed and proven technology from conventional steam power plants, with marine components such as floating platforms or mooring systems that are available from other offshore industries, it is stated in JRC’s report.
The most expensive components of an OTEC plant are the platforms, heat exchangers and pipework.
According to JRC, the respective share of each of the components depends on the specific plant layout and type, but can reach up to 50 percent of the cost for the heat exchangers in the case of large-scale plants, and 50 percent for pipework in the case of small land-based plants.
Graphics: Bluerise/OES (areas suitable for OTEC deployment)/2014 JRC Ocean Energy Report