Swedish startup Minesto has developed a subsea ‘kite’ style mini power plant that generates renewable energy from tidal streams and ocean currents.
How It Works
The ‘wing’ technology, described by Minesto as a kind of “subsea kite” and a “powerful, lightweight, and modular power plant” which can be made with a wingspan ranging from 4.9 – 12m and weighing from 2.7 – 28 tonnes. Anchored to the seabed by a long cable tether, it sits in the sea and ‘flies’ across the main flow direction of the tidal streams and currents just like a kite flies in the air.
The wing technology uses the hydrodynamic lift force created by the underwater currents to move the kite around and its onboard control system autonomously steers the kite (using rudders and elevators) in a predetermined figure-of-eight trajectory. This has the effect of pulling kite and its turbine through the water at a flow that’s several times higher than the actual stream speed. This maximises the power it can generate and reduces the size of the kite and rotor required to collect the energy compared with a fixed turbine.
The turbine shaft inside the kite turns the generator which outputs the electricity to the grid via a power cable in the tether and a seabed umbilical to the shore.
Harnessing A Reliable And Inexhaustible Resource
As highlighted by Minesto on its website, a balanced renewable energy mix is needed for the world to move towards a sustainable future energy system. Tidal streams and ocean currents are reliable and inexhaustible, available all over the globe, and are a rich source of energy that can be converted to a reliable and local source of renewable energy. This is why an easy to deploy and effective technology that can harness and use this endless resource (such as a simple kite system technology) could be a low cost and effective way to produce renewable (green) energy anywhere around the world (the ocean covers 71 per cent of the earth’s surface).
Also, unlike wind and solar, tidal streams and ocean currents are predictable, i.e. they’re caused by the gravitational forces exerted on the earth by the moon and are continuous and directional. This reduces risk and makes it easier in terms of control for the deployment of tidal power technology, such as Minesto’s wing/kite design.
The fact that the kites are a modular design which can be easily latched and unlatched (via the tether) to the seabed anywhere means that the system is easily scalable, simply by using hundreds of them across an area.
Real World Applications
So far, Minesto reports that its wing subsea power generators have been delivering electricity to the Faroe Islands’ power grid since 2020 and, in 2022, Minesto commissioned the first power plant in Vetmannasund, Faroe Islands.
What Does This Mean For Your Organisation?
As Minesto rightly says, the world’s very necessary shift away from fossil fuels for power will involve developing and scaling a mix of innovative renewable energy solutions that make the most of existing natural resources such as wind, water, and sun. Also, with the UK being an island nation subject to tidal activity, in world where more roughly 71 per cent of the surface of the planet is covered by ocean, with its strong, constant, predictable tides, it does seem to be an area with the ability to supply vast amount of naturally generated energy if the right technology is deployed.
The advantages of the wing idea are that it can be easily and relatively cheaply deployed around the world, is scalable simply by multiplying the number used, can be placed far enough below the surface so as not to become a hazard or eyesore, and the technology is ready to go now. That said, these are relatively small turbines and even with many of them, there’ll still be a need for a mix of other ideas and solutions to harness the power of the waves.
These ideas will need to be part of wider mix of sustainable and renewable energy generating schemes that between them can offer enough power to seriously cut carbon emissions. Furthermore, they’ll need to supply the considerable energy needs of homes and businesses, provide power that’s affordable, have a low environmental impact, and thereby help the world to meet its climate targets as quickly as possible while still supporting the growth of the world’s economies.
As Minesto says, its wing solution ads a “step of energy conversion” that “expands the global tidal and ocean currents’ extractable potential.”