Kairyu, the giant underwater turbine that Japan hopes will become the “future of energy”

The Asian country announced that it has successfully completed the testing phase (three and a half years) of Kairyu, a superturbine with which it hopes to transform the production of electricity in its territory… and in the world.

The project is pioneer in the use of ocean currents to generate energy and its designers assure that it is one of the most powerful and least used natural sources currently in use, so they foresee that it could become part of the “future of energy”.

And it is that although the sun -used for solar panels- sets and the winds -used for wind turbines- vary, the sea currents follow a constant flow almost permanently, hence the companies behind the project call a truly “inexhaustible” source.

The great challenge for decades for the Japanese was how to design a generator capable of withstanding the strong currents that pass near their coasts.

Since 2017, the company IHI Corporation merged with technology New Energy and Industrial Technology Development Organization (NEDO) to test designs.

They finally managed to make a model work for more than three years: Kairyu.

The generator was able to produce 100 kilowatts of power constantly during that period, so now the companies will launch an even bigger project.

It is an extension of Kairyu to turn it into a gigantic structure weighing 330 tons that will seek to generate 2 megawatts of energy.

They predict that it will be operational, if finally feasible, by 2030.

How is Kairyu?

Kairyu, whose name means “ocean current” in Japanese, features a 20-meter-long structure flanked by a pair of similarly sized cylinders.

Each of the cylinders has a power generation system connected to an 11 meter long turbine.

The device will be connected to the bottom of the sea by a kind of anchor and a power cablewhich will also serve to transport the generated energy to the mainland.

As explained on its IHI Corporation website, the design means that the device can be moved, raised or lowered, to find the orientation of the current that is most efficient for electricity generation.

Kairyu was designed to float about 50 meters below sea level and its mechanism, say the manufacturers, is based on the fact that, when directed towards the surface, the resistance created provides the necessary movement to move the turbines.

The blades they have rotate in the opposite direction, which together with a series of position sensors make the device remain relatively stable despite the dramatic movements of the water in that area.

And it is that the superturbine will be placed in the so-called Kuroshio currentan ocean current that flows from the east of the Japanese coast in a northeasterly direction at a speed of 1 to 1.5 meters per second.

The company behind the project estimates that if the energy present in the stream could be harnessed in further Kairyu developments, it would be possible to generate around 200 gigawatts of electricity, an amount that represents the 60% of what the country currently consumes.

A problem for Japan

Japan is a country highly dependent on imported fossil fuels for power generation.

According to official data, the country imports more than 99% of crude oil and about 98% of natural gas he consumes, mostly from the Middle East.

Although it has numerous nuclear power plants, this form of generation has become widely unpopular in the country after the Fukushima accident in 2011, one of the worst in history.

If before that year nuclear energy represented a third of all that produced in Japan, today it is less than 4%.

Fossil fuels are now the source from which it is obtained the third part of energy consumed by Japan, although in recent years the country has also begun to experiment with natural sources, which currently account for 18% of generation, according to official data.

However, the country faces a “natural enemy” for a greater commitment to renewable sources: its own geography.

Being a mountainous archipelago, Japan does not have large spaces that can be used for wind turbine fields or solar panels and, being distant from other nations, it is more difficult for it to buy energy in other territories.

However, something that it has due to its geography are wide coastal areas and strong sea currents in its surroundings, hence the use of these has been in projects of several companies for decades.

The challenges

Although it is the first major project that seeks to generate electricity from ocean currents, it is not the first to try to use the movements of the sea for electricity generation.

Last year, the UK launched the so-called Orbital O2a turbine that generates energy from the tides and has been capable of producing 2 megawatts of electricity.

Although Japanese media have been optimistic about Kairyu, they also acknowledge that the challenges ahead are enormous.

Despite global interest in this relatively underutilized renewable energy reservoir, previous attempts to extract electricity from the tides, waves and currents of the open ocean have ended in failure.

Among the main obstacles it faces are the High costs of the construction of a structure of this type and its placement in the open sea, the environmental problems it can generate and the dangers of the proximity between the coastal areas and the electrical network.

The very physical characteristics of sea currents are a problem for the idea: they tend to be stronger near the surface, which is also the area where the power of the typhoons that generally affect Japan every year and that could affect the turbine.

Although the test of more than three years managed to maintain a stable power flow, its generation capacity is still very small compared to other renewable energy sources that have experienced greater technological development in recent years.

Experts on the subject interviewed by Bloomberg indicated that Japan it also does not have the experience in offshore constructionwhich also leaves doubts about the feasibility of the project, which requires work on the seabed.

Being far from the coast and in conditions that are often hostile due to currents, there are also fears that its installation, operation and maintenance entail excessively high costs that could, in turn, be reflected in the prices of the energy that it sells to users.

The manufacturers, however, are hopeful that it will be a first step towards the future with which they seek to open the doors to an unexplored energy source.

“NEDO hopes that the generation of electricity by ocean currents will become a new source of renewable energy”, indicates the company.