Tide-riding ‘kite’ powers island grid

This underwater powerstation taps the surging currents beneath the sea's surface.

Tide-riding ‘kite’ powers island grid
Source: Minesto

Energy harvested from the ocean’s tidal streams and currents via a submersible powerplant has delivered electricity to the grid for the very first time.

The Dragon 12 was developed by marine energy company Minesto. Its first megawatt-scale submersible ‘kite’ forms part of an ambitious scheme in the Faroe Islands to reach 100 per cent renewable energy by 2030. 

The vessel was successfully commissioned last month on the independent archipelago during its preliminary phase of operations, delivering the first 1.2 megawatts (MW) of energy to the island's national electricity grid.

Going deeper

With more than 70 per cent of the earth’s surface covered in water, tapping into the powerful force of the ocean holds great potential in the transition to clean energy.

Much of the focus to date has been on capturing energy from waves on the ocean's surface, but overcoming this hostile environment has proved costly owing to the harsh conditions. 

Instead of focusing on the ocean's surface, Minesto’s Dragon 12 generates electricity from undersea tidal streams and ocean currents akin to the way a kite flies through the wind. 

Minesto's 'sea flight' takes place in the depths of the ocean where water is far more dense than air, which substantially concentrates the energy.

"We have reached the most significant milestone in the history of the company by producing electricity to the grid with our mega-watt scale powerplant."

A scaled-up version of its earlier Dragon 4 100kW powerplant, the Dragon 12, spans 12-metres and is anchored to the seabed with a tether that moves along a figure-8 flight trajectory powered by the tidal flow. 

“We have reached the most significant milestone in the history of the company by producing electricity to the grid with our mega-watt scale powerplant,” Dr Martin Edlund, CEO of Minesto said.

“The competitiveness of the Dragon 12 is straight to the point; it’s powerful, cost-effective and feeds predictable electricity to the grid.”

Global reach

According to Minesto, both the functionality and power-generating capability of its technology have been verified by ocean testing at various other scales and locations including a low-velocity tidal energy project in Holyhead Deep in North Wales.

It's also in the process of establishing operations in Taiwan where Minesto is carrying out site development for the first tidal energy arrays in Asia. 

The startup was founded in 2007 as a spin-off from Swedish aerospace manufacturer Saab. It is owned by BGA Invest and Corespring New Technology and is listed on the Nasdaq First North Growth Market in Stockholm.

With operations in Sweden, Wales, the Faroe Islands, Northern Ireland and Taiwan, it has been awarded €40 million from the European Regional Development Fund through the Welsh European Funding Office, European Innovation Council and InnoEnergy.

The tech
Dragon 12 generates electricity from tidal streams and ocean currents using a principle similar to a kite flying in the wind. The wing uses the hydrodynamic lift force created by the underwater current to move the kite. An onboard control system autonomously steers the kite in a predetermined figure-of-eight which pulls the turbine through the water at a flow rate far higher than the actual stream speed. The turbine shaft turns the generator which then sends electricity to the grid via a power cable in the tether and a seabed umbilical that connects to the shore.