Nuclear fusion, geothermal power, and deep ocean electricity are all possibilities. Japan has successfully tested an ocean turbine that harnesses ocean currents to generate limitless renewable energy. It’s the latest moonshot technology that could one day provide endless green energy and a completely new ocean-based industrial sector.
IHI Corp., a Japanese heavy machinery manufacturer, has been working on a subsea turbine that captures the energy in deep ocean currents and converts it into a consistent and reliable source of electricity for more than a decade.
The massive machine resembles an airplane, but instead of jets, it has two counter-rotating turbine fans and a center ‘fuselage’ that houses a buoyancy adjustment mechanism. The 330-ton prototype, known as Kairyu, is planned to be anchored to the seafloor at 30-50 meters (100-160 feet).
The proposal for commercial production is to locate the turbines in the Kuroshio Current, which runs along Japan’s eastern coast and is one of the world’s strongest and transmit the electricity via seabed cables.
“In terms of accessibility in Japan, ocean currents have an advantage,” said Ken Takagi, an ocean technology policy professor at the University of Tokyo Graduate School of Frontier Sciences. “Europe, which is exposed to prevailing westerly winds and is located at higher latitudes, is more geographically adapted to wind power.”
As per NEDO, Japan’s New Energy and Industrial Technology Development Organization, the Kuroshio Current may generate up to 200 gigawatts or nearly 60% of the country’s current generating capacity.
Ocean currents have the advantage of being stable. They have a capacity factor of 50-70%, compared to roughly 29% for onshore wind and 15% for solar, because they flow with little variation in speed and direction.
The Demonstration Study
IHI and NEDO conducted a three-and-a-half-year demonstration study of the technology in February. Its crew put the system to the test in the waters off the coast of the Tokara Islands in southwestern Japan, dangling Kairyu from a ship and transferring power back to it. The ship was first driven to create an artificial current, and then the turbines were hanging in the Kuroshio.
The prototype was found to be capable of producing the predicted 100 kilowatts of reliable electricity, and the entity is now planning to scale up to a complete 2-megawatt system, which may be operational in the 2030s or later.
However, the Japanese company has a long way to go. Installing a system underwater is far more difficult than installing one on land.
“Unlike Europe, which has a lengthy history of oil exploration in the North Sea,” Takagi explained, “Japan has minimal expertise with offshore construction.”
Building a system that can resist the harsh conditions of a deep ocean current while also reducing maintenance expenses is a huge engineering challenge.
“There aren’t a lot of alternative energy sources in Japan,” he remarked. “Some may reject this as a pipe dream, but we must do everything possible to achieve carbon neutrality.”
With the cost of wind and solar power and battery storage falling, IHI will need to show that ocean current power project costs are competitive. With large-scale implementation, IHI hopes to generate power for 20 yen per kilowatt-hour.
In Japan, solar costs around 17 yen per watt, whereas offshore wind costs between 12 and 16 yen per watt. IHI also stated that it undertook an environmental evaluation before launching the project. The test results will determine any potential impact on the marine environment and the fishing industry.
Deep ocean currents, if scaled up, could play an important role in delivering green baseline electricity in the worldwide attempt to phase out fossil fuels.
According to Angus McCrone, a former BloombergNEF chief editor, and maritime energy analyst, IHI’s work might help Japan’s engineering take the lead with government assistance.
“Japan may profit from being a technology leader in this area,” he said, adding that IHI must make a compelling case.