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Technologies · ocean energy

The cold of the deep sea. The heat of the surface water.

Two complementary processes to exploit the ocean resource: cool without a compressor (SWAC) and produce electricity from a thermal gradient (OTEC).

The principle

A vast, natural, under-exploited resource.

Our work relies on a technique that cools with sea water and generates electricity by exploiting natural physical phenomena: the thermal stratification of the ocean and salinity gradients.

  • Very low environmental impact : No fluorinated-gas emissions, controlled thermal discharge, careful integration with the marine environment.
  • Lifespan up to 50 years : Infrastructure designed as marine works, far longer than conventional cooling.
  • −90 % electricity consumption : Versus a classical compression chiller, on the cooling share of the building.
  • Continuous energy : Largely independent of surface weather: the deep ocean stays cold.
  • Green energy : Natural, renewable, local. No combustion, no high-GWP refrigerant.
  • Decoupled from energy markets : Cost is essentially pumping, sheltered from electricity price shocks.
  • No fluorinated gas : No HFC/HCFC on the primary loop. Naturally aligned with the F-Gas schedule.
  • Suited to bad-grid sites : Ideal where electricity is expensive and carbon-intensive: overseas territories, islands, remote zones.

Where the ocean can cool and generate

The tropics, natural ground for SWAC and OTEC

Both technologies need cold deep water within reach of the coast. OTEC also needs a temperature difference of at least 20 °C between surface and depth, which mainly limits it to tropical and island areas.

Project

Réunion Island

Our project at the CHU Sud Réunion hospital in Saint-Pierre: cooling a hospital with cold water from the Indian Ocean.

Shaded band: the tropics, as an indication. Feasibility is always checked site by site (seabed depth, distance to cold water, needs on land).

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Two processes

SWAC for cooling. OTEC for electricity.

The first directly uses the coolness of deep water. The second uses the temperature gap between surface and depth to spin a turbine.

SWAC · cooling

Cool with marine free-cooling.

5°C deep sea water enters a titanium heat exchanger which cools the building's chilled-water loop. No main refrigeration compressor, only pumps. Typical system COP: 20 to 30.

  • Suited to coastal and island sites with quick access to cold deep water
  • Ideal for hospitals, hotels, data centres, urban districts
  • Cooling capacities of 5 to 50+ MW per loop
  • Our reference: CHU Sud Réunion, targeting −90 % electricity consumption
OTEC · electricity

Generate electricity from a thermal gradient.

An OTEC plant is a heat engine driven by the temperature difference between warm surface water (~26°C) and cold deep water (~5°C). The gap evaporates then condenses a working fluid that drives a turbine.

  • Continuous energy: the ocean does not switch off at night
  • Co-valorisation possible: aquaculture from the nutrient-rich upwelled water
  • Relevant in tropical zones with strong thermal delta (≥ 20°C)
  • Mature technology brick, integrable into an island energy mix
Keywords

Technical glossary.

SWAC Sea Water Air Conditioning

A system using deep sea water as a direct cold source (free-cooling) to meet cooling needs, from a few buildings up to a whole district. Often deployed in "bad-grid" zones where electricity is expensive and carbon-intensive.

OTEC Ocean Thermal Energy Conversion

A thermal plant fed by the temperature difference between warm surface sea water and cold water pumped from depth, producing electricity. The upwelled sea water can be revalorised for aquaculture.

Is your site coastal or insular?

A SWAC pre-feasibility study can be launched in 4 to 6 weeks.

See the SWAC offerDiscuss a study