InfinityWEC Solution
InfinityWEC is a novel 500 kW point absorbing Wave Energy Converter (WEC). It is both highly efficient in capturing energy, and robust enough to operate reliably and survive the harshest marine conditions. Cost efficiency is achieved by its modular design and the easy handling, allowing for road transportation and requiring a minimum of offshore operations.
A. PTO with Instant Force Control
A combination of ball screw actuators and a hydrostatic pre-tension system provides instant force control in the power take-off (PTO), enabling advanced control algorithms to increase energy output, reduce loads and improve reliability.
Ball screws convert linear motion and force into high speed rotatory input to direct drive generators/motors, providing high efficiency, high power density and high reliability.
The PTO hull is split in two halves, being pushed together by the surrounding water pressure close to the seabed. This way half of the PTO control force is provided “for free”, reducing cost and improving overall efficiency.
Optimal Force Control
Predictive optimal control of the PTO force to maximize power output in every individual wave.
Depending on wave resource, the annual energy production is increased 25-50% compared with sea state tuned (non-predictive) optimal control.
B. Concrete Buoy
Buoy made as a honeycomb structure consisting of thin walls of high-performance concrete and EPS cores. Compared to steel:
- Same weight, 4x lower cost, 3x lower CO2 footprint
- Manufactured on site, 10x faster
- Unsinkable, solid structure
C. End-stop Spring
Soft end-stop spring in the form of a pre-charged gas accumulator integrated with the hydraulic cylinder used to adjust for tidal variations.
- Maximum end-stop force reduced to half
- Power produced also in storm conditions
D. Easily Deployed Anchor
Concrete anchor cage, easily deployed and then filled with ballast through a down pipe from a transportation vessel.
- Manufactured on site
- Low cost
InfinityWEC Wave Farms
A wave farm consists of multiple InfinityWEC´s arranged in star shaped 6 MW clusters á 12 WEC units. This topology is area efficient, provides good access to all WEC´s for service vessels, and the total length of the power cables are relatively short. In the wave farm below, three cable hubs are connected on a string cable to a central substation for the wave farm, where power is transformed to higher voltage and exported. A total of 21 clusters arranged in seven strings provides a total power rating of 126 MW, with an electrical infrastructure very similar to an offshore wind farm.
The system is installable with a minimum of complicated offshore operations and no diving or heavy lifting are necessary offshore. An anchor cage is lowered to the seabed with a crane and filled with 500 ton high density ballast from an installation vessel. The 100 ton buoy and 30 ton PTO are towed separately to the installation site. The PTO is first connected to the power cable retrieved from the cable hub with ROV, then lowered in a vertical position and connected to the anchor. The buoy is finally connected by pulling the upper mooring rope from the PTO through the center of the buoy and locking it with a pin from the top.
Road Map
We follow the staged development method set out by the international marine energy community
OHT is since 2017 developing the novel InfinityWEC wave energy converter with advanced force control and with AI capabilities. We have an extensive know-how in the wave power application and patent protection covering all aspects of the InfinityWEC system. To mature the concept we have developed tools to accurately assess dependencies between design and the overall life cycle cost of the system. We believe in using numerical models to time and cost efficiently simulate the behavior, loads and performance of the system, and to verify them with limited and controllable physical tests. This ensures we are on track to a commercially viable system before we move into large scale prototypes and testing.
We are currently preparing for sea trials of a fully operational InfinityWEC in scale 1:3 on the west cost of Sweden.
In 2025 we plan to start the sea trial project of a full-scale 500 kW InfinityWEC, after which the system is validated and certified, to be followed by first commercial installations.