March 10, 2022

Mitsui O.S.K. Lines Will Launch a Practical Application of "Ocean Thermal Energy Conversion (OTEC)"

OTEC is a form of renewable energy that uses the point where the temperature of seawater varies greatly between the surface and deep layers of the ocean to generate electricity. The goal is to operate a power plant with an output of 1,000 kilowatts scale around 2025. By utilizing existing facilities, the cost of power generation will be lower than that of offshore wind power. If it can be deployed in many locations, it will lead to diversification of energy sources.

The New Energy and Industrial Technology Development Organization (NEDO) estimates that the potential power generation capacity of the method amounts to 47 billion kWh per year. This represents approximately 5% of domestic power generation. This is the first large-scale practical application in Japan. Research has also been conducted at Hawaii State in the U.S., Malaysia, and other countries.

In April, Mitsui O.S.K. Lines will begin operating facilities owned by Okinawa Prefecture. Warm seawater evaporates CFC substitutes and turns the turbine. The steam is cooled with cold seawater and reused. Mitsui will build a 1,000-kilowatt scale power plant based on its operations. Construction costs are expected to run into the billions of yen.

Cost has been an issue for ocean thermal energy conversion. This time, the company plans to use water intake pipes for aquaculture and other industries to reduce the cost of power generation to about 20 yen per kilowatt-hour. Ministry of Economy, Trade and Industry estimates that it will be lower than offshore wind and oil-fired power as of 2030. The system will be used as a stable power source, taking advantage of the fact that the amount of electricity generated does not fluctuate even in bad weather.

Marine energy has lagged behind solar power and wind power in utilization, and if popularized, it will become a new energy resource.