OREANDA-NEWS. Kobe Steel, Ltd. has developed a high heat transfer titanium sheet called HEET™ for use in plate heat exchangers, one of the important applications of commercially pure titanium sheet. Kobe Steel has supplied this material for use in the heat exchangers of an ocean thermal energy conversion (OTEC) power system in a demonstration project in Kumejima, Okinawa Prefecture.

The high heat transfer titanium sheet enhances the heat transfer performance by more than 20 percent. Moreover, the new sheet is environmentally friendly and conserves resources. It is the first time that HEET™ has been applied in an OTEC power system. This HEET™ application is hoped to make large advances in lowering the power generation cost to verify the practical use of OTEC power generation, which is attracting attention as a renewable source.

OTEC power generation utilizes the temperature difference between deep seawater and surface water. Warm surface seawater is pumped through a heat exchanger where a low-boiling-point fluid, such as ammonia, is vaporized. The resulting steam drives a turbine to generate electricity. Cold deep seawater goes through a second heat exchanger to condense the vapor back to liquid. OTEC is drawing attention as a renewable source of energy that efficiently uses the heat energy in the ocean.

Electricity generated in the demonstration project is supplied to a power company, a world first. The OTEC power system successfully started generating electricity on March 30 and commenced verification tests in April. Stability tests of the heat cycle, validation of controllability, and performance tests of the heat exchangers are also being conducted. Aiming to commercialize the OTEC power system in the future, the project is examining ways to reduce power generation costs and is looking to set up an OTEC power system in the Okinawa area.