While wind and solar power are on the rise, ocean energy is a largely untapped resource. A Swedish company is hoping to change this with a kite-mounted turbine that ‘flies’ in submarine currents.
Swedish company Minesto has recently signed an agreement to install their underwater kite technology to provide power to the Faroe Islands – a self-governing Danish territory located in the North Atlantic Ocean between Iceland and Norway.
The technology works on the principle of hydrodynamic lift, with the ocean’s underwater currents providing an upward force on the kite’s wings. As the tethered kite steers in a figure eight, water drives the turbine mounted on its nose to generate electricity.
Minesto will install two of their underwater kites, which have the poetic name of Deep Green, in late 2019 and 2020.
CNBC reported the CEO of SEV – Faroe Islands’ main power generator and supplier – saying tidal energy at the right cost could be an important part of the energy puzzle for the subpolar territory.
“As a remote island society, we don’t have the option of buying electricity from neighbouring countries,” said SEV’s CEO Hakun Djurhuus.
From the air to the sea
The Deep Green tidal kite technology has been under development for more than a decade, since Saab engineer Magnus Landberg thought up the concept while studying long carbon fibre blades for wind turbines.
Landberg was searching for a relatively lightweight solution with high power output, and discovered that a turbine would be smaller, lighter and cheaper if driven by tidal currents, as water is hundreds of times denser than air.
“Then I realised that the cross arm and tower could be even lighter if a high-speed turbine and a generator were attached directly to the blade,” Landberg said on the Minesto website.
Landberg’s invention, originally dubbed Enerkite, was further developed by masters students at Chalmers University of Technology in Sweden before being patented by Minesto in 2007.
Minesto has developed two models of its Deep Green tidal kite, which is able to operate in low-velocity (1.2-2.4 m/s) tidal currents. The DG500 has a 12 m wingspan, weighs 10 tonnes, and is rated up to 500 kW. The company is nearing the completion of its first commercial-scale demonstration plant at Holyhead Deep in Wales. After initial testing, Minesto plans to install multiple kites to build a 10 MW demonstration array, which will be expanded to an 80 MW commercial array.
In the Faroe Islands, Minesto will install its smaller DG100 model, which has a wingspan of 4-5 m and supplies up to 100 kW per kite.