The global movement of the seas through tidal streams and ocean currents generates a rich supply of energy that may be transformed into a dependable and local renewable energy source.
Aiming to further this mission, Swedish firm Minesto has now completed onshore testing on its 1.2 MW Dragon 12 tidal energy kite system. The system will be directly transferred to the Faroe Islands in Denmark for installation and commissioning.
Minesto was established in 2007 as a spin-off from the Swedish aerospace company Saab. Since then, Minesto has successfully developed its technology, holding 92 patents in 12 patent portfolios covering all key markets. Minesto successfully commissioned the first Dragon Class power plant at Vetmannasund, Faroe Islands, in 2022.
According to the firm, its kite system technology is a lightweight, flexible, and scalable solution to harvest tidal energy, which unlocks a predictable renewable energy resource.
Novel system
Tidal streams and ocean currents, unlike wind and sun, are predictable. Tides are caused by the moon's gravitational effects on the Earth. Seawater's continuous, directed movement caused by gravity, wind, and water density is referred to as an ocean current, which is often perennial.
Minesto's invention utilizes these tidal streams and ocean currents to generate power using a proprietary and unique technique comparable to a kite flying in the wind.
The firm's power plant comprises a wing that houses a turbine directly connected to a generator in a nacelle. The control system directs the kite's trajectory by manipulating the rudders and elevators at the back of the kite. The tether holds the tether as well as communication and power lines. The tether is attached to the seabed foundation via a simple connection that is locked and unlatched for installation and retrieval.
The kite is moved by the wing's utilization of the hydrodynamic lift force provided by the underwater stream. An onboard control system autonomously controls the kite in a predefined figure-of-eight trajectory, dragging the turbine through the water at a water flow several times greater than the stream speed.
The turbine shaft drives the generator, sending power to the grid via a cable in the tether and a seabed umbilical to the coast. According to Minesto, the subsea kite is intended to fly in the opposite direction of the main flow, attaining a relative speed several times that of the current rate. Compared to a stationary turbine, this speed increase minimizes the size of the kite and rotor necessary to capture energy. As a result, it is inexpensive to install, run, and maintain.
Sustainable solution
The technology offers its Dragon Class kites to generate power at low-flow locations while being cost-effective, with stream flows as low as 1.2 m/s. The firm also claims that its power plant weighs up to 15 times less per MW than competing technologies.
Apart from being completely submerged below the water surface with minimal environmental impact, Minesto says that "small, cost-efficient vessels and equipment are used for installation, service, and maintenance. The simple recovery concept enables service and maintenance on shore," said the firm's website.
Minesto in the Faroe Islands is one of the world's most ambitious energy transformation plans, aiming for 100% renewable energy by 2030. Minesto revealed a comprehensive proposal for large-scale construction of tidal energy arrays in the Faroe Islands in April 2022. The large-scale buildout strategy calls for the building of tidal kite arrays, each with a capacity of 20-40 MW, in four verified locations.
Minesto cites Hestfjord, Leirviksfjord, Skopunarfjord, and Svinoyarfjord as excellent arrays and its current grid-connected location in Vestmannasund. According to it, the collections would serve 40 percent of the Faroe Islands' rising electricity usage with a combined capacity of 120 MW tidal energy, creating an estimated 350 GWh annually.
The firm says the project is on track after extensive subsystem verification and testing at the Minesto workshop in Göteborg was accomplished. "After service and upgrades the 100kW Dragon 4 is in stable electricity production mode at the site in Vestmanna," said a statement.
Originally published on Interesting Engineering : Original article