Wave power startup Nemos is launching a full scale pilot project in the North Sea next year – and it says that with help from its technology partners, its system may be more efficient and more durable than many competitors.
The waterborne components of the system are little more than a long float and a three-point mooring. When a wave lifts the float, it pulls on its anchor lines. Unlike lines used for conventional anchors, though, two of these lines are running rigging: they are led through sheaves to an adjacent tower, where generators are mounted above the waterline. The lines exert force to turn the generators.
A wind turbine tower makes a good base for mounting the system, and as it already has a power cable to shore, the firm believes that Nemos will make a cost-effective complement to existing installations.
The Nemos team has worked for several years to address the inevitable challenges for installing such a system below the surface – notably biological fouling and line wear – and they suggest that extensive testing has substantially addressed these problems.
A 1:5 scale device has been in operation in Denmark since 2014, and Nemos says that the full-scale generator system – including a 40-ton generator unit, years in the making – will be installed at a North Sea facility next year.
Marine equipment supplier MacGregor has designed custom winches to handle the lines; they can be used to adjust the orientation of the float to match the waves, and to pull it fully beneath the surface in the event of a storm – addressing one of the most challenging problems for wave power systems, the question of survivability in severe weather.
Nemos claims that the system is up to 80 percent efficient, compared to 50 percent for traditional designs.
Separately, MacGregor says that it has the contract for supplying mooring systems to Statoil's Hywind project, the first ever floating, deepwater offshore wind farm. “We are very pleased with this contract awarded to MacGregor. We are excited that high quality oil and gas suppliers in both Norway and Scotland are able to capture the growing opportunities offered through new renewables growth," said Stephen Bull, Statoil’s Senior Vice President for Offshore Wind.