Feature ArticleMinesto's Marine Power Plant Producing Electricity in Northern Ireland
By Anders Jansson
The Deep Green power plant has attracted much attention lately from the global marine energy industry and the media.
Deep Green deployment in Strangford Lough.
The power plant, which looks like an underwater kite, is now producing electricity in the waters off the coast of Northern Ireland. The ongoing ocean trials verify ocean currents as a commercially viable renewable energy source.
Invented by an engineer at Swedish aircraft manufacturer Saab in 2001 and spun-off into marine energy company Minesto (Fr'lunda, Sweden) in 2007, Deep Green has now taken a further step toward commercialization by starting to produce electricity in Northern Ireland's Strangford Lough.
The Deep Green power plant comprises a wing and a turbine, which is secured to the seabed with a tether and moves at high speeds in an eight-shaped path in the tidal or ocean current. The turbine can reach a speed 10 times higher than the speed of the ocean current.
The unique ability to increase the relative flow by a factor of 10 makes it possible to produce electricity from low-velocity tidal and ocean currents, 1.2 to 2.5 meters per second, where no other known technology operates cost effectively. The power output is increased by a factor of 1,000, since the velocity and power has a cubic relationship.
Using a 1:4 scale prototype, the breakthrough ocean trials of the Deep Green power plant in Strangford Lough proved cost-effective power production from slow currents could be obtained using a surface-mounted installation. The concept, as it appears now in Northern Ireland, is directly transferable to full-scale commercial installations in ocean currents.
The ocean trial verifies the ability to unlock ocean currents as a competitive renewable energy source and greatly expands the potential for marine energy worldwide. The sea trial in Northern Ireland measures long-time performance of Deep Green for valuable insights for the first full-scale installation of Deep Green, planned for 2015 in the U.K.
High Efficiency and Low-Cost Offshore Operations
Deep Green is quite different than other marine power plants. Its size and unique design, which allow it to operate in low-velocity currents, bring several advantages when compared to other marine power plants, which are generally larger and designed to operate in stronger currents, or so-called hot spots.
With a wingspan of 12 meters and a turbine diameter of 1 meter for a 0.5-megawatt power station, the Deep Green device is comparatively small. Deep Green weighs a mere 7 tonnes for a 0.5-megawatt plant, and is 10 to 25 times lighter per megawatt than competing technologies designed for the hot-spot sites (2.4 meters per second and above).
If the design of competing tidal energy devices, using the same principle as horizontal axis wind power stations, could be adapted to the slower currents, a rotor diameter of 32 meters would be needed to produce 0.5 megawatts of electricity. This is due to the fact that the energy is directly proportional to the inflow area multiplied by the inflow velocity to the power of three (E~A*v3).
The small size and light weight of Deep Green make it possible to use smaller boats and equipment for installation, service and maintenance. Also, in high-velocity currents, boats can only operate for a maximum of three hours per day. Possible Deep Green sites are accessible up to 14 hours per day, so costs for offshore operations thereby decrease quite drastically. To continue this article please click here.
Anders Jansson is co-founder and CEO of Minesto, an energy technology company in the field of marine energy, with a patented and proven technology (Deep Green) to harvest energy from low-velocity tidal and ocean currents. He has eight years of experience developing and commercializing marine energy technology, both as an entrepreneur and business leader, with a background from Chalmers University of Technology.