1. A TECHNOLOGICAL ADVANCE
French Patent FR
A TECHNOLOGICAL ADVANCE
for Ocean Thermal Energy
Conversion
Inventors : Fabrice Pélestor - Josselyne Guevara - Sébastien Boisson -

2. Abstract of the patent
OTEC new technology without pumping The seawater pumping pipe of the depths, about 1000 m long, is the current technological lock of the OTEC (abandonment of the project of OTEC of 16 MW in Martinique of Navals Group). Our patent avoids this technological lock. It is that of a frigories elevator : a container is filled with a material in the liquid state whose property is to have a solidification temperature, or melting, variable according to the composition of the material : the Phase Change Materials (PCM). The container filled of PCM is lowered by ballasting to a depth where the temperature of the sea water is sufficiently cold. When the material became solid and accumulated cold, it is raised by deballasting to the surface where the water is hot. So we have a cold body in a hot environment, which allows the production of electricity by a thermal machine. There are no more pipes or pumping seawater ! It is important to note that our invention is based on the principle of latent heat : the solidification, or fusion, of a body absorbs a lot of frigories. The latent heat, used here, must not be confused with the heat capacity of a body which is its usual cooling, without passing from a liquid state to a solid state. Note that it has been proposed in the past to use Phase Change Materials but only for their ability to change volume during solidification. As they were not used for their latent heat of fusion (not adequate), but for their variation of buoyancy, they could not allow our thermal energy extraction technology of the sea. The Phase Change Materials allowing to accumulate cold by latent heat at precise temperature appeared recently. This physical principle makes it possible to be able to separate the power plant producing electricity and containers filled with MCP, allowing to have a continuous production of electricity by synchronization of several containers alternately on the surface and at the bottom. This technology will provide electricity, water, hydrogen even far from the coast. A reconversion of obsolete oil platforms may be considered. Pre-sizing calculations show significant efficiency, they were published in the first patent. This technology has never been tested.

3. Physical Data Water H2O Tfusion = 0 °C , L= 333 kJ/kg
(Latent Heat)
Phase Change Material Tfusion , L ≈ 200 kJ/kg*
Ton Oil Equivalent ≈ calories$ cal. / kg ≈ kJ/kg
‘ Phase change material based cold thermal energy storage: materials, techniques and applications-a review,
International Journal of Refrigeration (2016)
$ : Universalis Encyclopedia
Stored Energy
1 kg PCM ≈ 4,35 kg oil

4. Principle of OTEC
Use the difference in temperature between warm surface water (20 °C ↔ 32 °C) and cold deep water ( < 0°C ↔ 10 ° C)

5. Technology used since 1926 industrial & economic failure
1) Cold water collecting tubes  maximum 1000 m long and big diameters does not hold
2) Pumping of cold water
constantly uses 20 to 35% of the produced electrical energy
3) Ecological risk* of disturbance
natural flows on a large scale
4) Ecological risk of modification
ocean biotope (fishing)
* 500 to 1500 years to renew
naturally the water of the depths!

6. Latent heat (frigories) taken in the ocean = energy
Patent principle
no pipe
Container
of PCM
Surface temperature
Liquid PCM
Latent heat (frigories) taken in the ocean = energy
rise to
start the melting
descent to start
solidification
Ballasting
up and down
Deep temperature
Solidified PCM

7. Technological and environmental risks removed
Ballasting technique → « sea proven »
(submarine, off-shore)
Very low energy spent (ballasting technologie)
No pipe : the technologicals locks disappears
No pumping → 25% of the energy gained
Disappearance of environmental and ecological impact
In accordance with the evolution of the regulations

8. advantages and disadvantages
→ Continuous production of electricity
→ Safe from naturals disasters as storm or cyclone
→ Purchase of MCP : only once
→ 25% more electricity than other OTEC
→ No purchase of pumps or hoses
No maintenance of pumps and hoses
→ No depth limitation :
choice of the best exploitation sites on the planet → increased production
→ Reconversion of offshores equipments (oil rig …)

9. oil age ecological age of hydrogen
Prospective
Implantation possible far from consumptions sites
H2 manufacturing and transport by super tanker of the LNG type
oil age ecological age of hydrogen
Possibility of melting the PCM
near the  magma of the ocean ridges
 ( m) and its solidification at
surface
In very great depths where the temperature is less than 0, possibility of using fresh water as PCM : negligible PCM cost !
however, the surface temperature must be compatible

10. Conclusions Sustained financial investments !
Matures technologies → no industrial risk
Continuous production of electricity
Respect the environment
Almost inexhaustible energy
Sustained financial investments !