Ocean thermal energy conversion

Energy from the deep

Ocean thermal energy conversion (OTEC) technology exploits the temperature gradient between surface seawater (at around 25 °C) and the much colder water (around 5 °C) found at depths of 1,000 metres or more. This difference in temperature exists naturally in tropical waters, where OTEC can be used to generate electricity all year round. OTEC can generate power continuously 24 hours a day, 7 days a week, and could therefore replace fossil energy and eventually make a major contribution to meeting the increasing electricity demand from tropical countries, helping them to achieve energy self-sufficiency at a future date. This innovative solution is a practical, green alternative to fossil fuels like gas and coal, which are still used in very large quantities in isolated locations not connected to continental power distribution networks.

An international ambition led by the French overseas departments and communities

The goal of DCNS is to demonstrate the feasibility of this technology in tropical waters around the world, and the French overseas departments and communities expressed their interest in it as early as 2008. In the same year, DCNS responded with an initial pre-feasibility study conducted on the island of Martinique. This first research contract has since been followed by a series of others, signed with La Réunion, Tahiti and Martinique. The contracts signed with the island La Réunion have resulted in the installation earlier in 2012 of a land-based prototype. In Tahiti, DCNS has already presented the results of a feasibility study conducted earlier this year, and the Group has signed two agreements with Martinique, the second of which covers the detailed specification and options for a future power plant.

Paving the way for standard turnkey power generating plants

DCNS is now the preferred partner of the French overseas departments and communities for the development of an ocean thermal energy conversion (OTEC) industry sector.

In 2009, DCNS signed an agreement with the La Réunion Regional Council for the construction of an OTEC land-based prototype, which is, in effect, a scale model of the energy generation system for a future OTEC generating plant. The system simulates the inputs of warm and cold water required for its operation. This land- based prototype is primarily a research and development resource whose main purpose is to test key elements of the energy generating system (heat exchangers, thermodynamic cycles, etc.). It also sets out to optimise the technological and financial challenges posed by OTEC technology. The OTEC land-based prototype was built and qualification tested at the DCNS Nantes-Indret centre, before being transported to La Réunion university of Saint- Pierre for commissioning at the beginning of 2012.

Paving the way for turnkey OTEC power generating plants

The cold water pipe (-1000m) is one of the major technological challenges of OTEC. DCNS is taking up this challenge with an ambitious R&D program in 2013. The achievement of this milestone will enable the Group to bid for turnkey floating generating power systems in 2014. DCNS will also bid for turnkey on-shore generating power systems, currently under development, in 2013.