The InfinityWEC wave energy converter has been upgraded with an innovative solution which uses hydrostatic pressure to provide a constant pre-tension force in the power take-off (PTO), reducing size, weight, complexity, and ultimately cost of electricity production (LCoE).

In the upgraded InfinityWEC design, the PTO hull is split into two halves, with the top half moving up and down with the buoy, while the bottom half is fixed to the anchor. Similar solutions have been used by pressure-modulating wave energy converters, to extract energy from the variation in pressure below waves, close to the surface. InfinityWEC however, is a point-absorbing wave energy converter, with a buoy on the surface driving the PTO positioned close to the seabed. At 70 m depth, the high pressure of the water provides a 100-ton pre-tension force with only a 1.6 m diameter PTO hull. A patent application has been filed for the innovation.

“The new pre-tension solution is a further improvement of the InfinityWEC wave energy converter, reducing the weight of the PTO by approximately 40%,” says CEO Mikael Sidenmark. “We take advantage of the water pressure outside the PTO to generate the constant pre-tension force, which in combination with ball screw actuators provides instant force control with very high efficiency. This enables wave-by-wave tuned force control, improving the annual energy production by up to 30% compared to sea-state tuned control.”

Ocean Harvesting is preparing for sea trials of InfinityWEC at scale 1:3, to be performed off the west coast of Sweden. The sea trial project, to validate the performance in a real sea environment, will be conducted between February 2023 – June 2025. Results will be used to further develop and improve the full-scale system with regards to energy yield, system efficiency, availability, and ultimately affordability.

On 14 November, Ocean Harvesting was awarded a 2 MEUR grant from the Swedish Energy Agency for the project. To complete the project financing, the Company is now raising 3 MEUR in equity investment at a pre-money valuation of 7 MEUR.

The grant is for the project ”InfinityWEC wave energy converter – Validation through sea trials at scale 1:3”, to be performed off the west coast of Sweden.

The sea trials will validate the performance in real sea environment and the results will be used to further develop and improve the full-scale system with regards to energy yield, system efficiency, availability, and ultimately affordability. The project is implemented in cooperation with RISE Research Institutes of Sweden and will be executed during the period March 2023 – June 2025. Ocean Harvesting follows the staged validation framework for ocean energy technologies set out by Ocean Energy Systems (IEA).

Offshore oil & gas platforms require constant power supply and decarbonization of this power is a high priority. A case study with Lundin Energy Norway has shown that wave power is highly competitive with offshore wind power, both in terms of levelized cost of energy and providing a more stable power supply that requires only half as much power balancing.

To assess the sizing and power balancing requirements of the oil & gas platform, a one-year time series with sea state data was analysed. A design for a 100 MW wave farm was developed for on- and off-grid installations. The output power profile was compared with the output power profile from an equivalent wind farm and wind data for the same place and time period. The more consistent nature of waves was evident and wave power provided a significantly more stable power production.

An off-grid wind farm installation requires ⁓50% more energy storage compared to wave power, both in terms of power and energy capacity, and twice as much energy pass through the storage to balance the output. The cost for balancing the produced power is therefore considerably lower with wave power, by reducing both the cost of the energy storage system and the loss of produced electricity occurring when the energy storage is used.

Hydrogen was identified as the most viable solution for long-term seasonal balancing in an off-grid installation, due to the large quantities of storage required. It can also be noted that using depleted gas fields to provide hydrogen storage is considered an interesting opportunity for oil & gas companies to continue generating value from such assets.

“In addition to the very promising findings of this case study, it has also made it possible for Ocean Harvesting to develop a comprehensive array and system design, a handling plan, and a life cycle cost assessment for a 100 MW wave farm, all of which will be very valuable going forward towards sea trials and commercialization,” says Mikael Sidenmark, CEO.

InfinityWEC is based on the following Design Principles, to achieve high performance, low cost and to be prepared for high volume production and roll-out

Ocean Harvesting has filed a new patent application for an improved pre-tensioning system in the power take-off, replacing customized components in the previous design with standard components. This is the sixth patent family protecting the InfinityWEC technology and its novel power take-off and concrete buoy.

Next step is scale 1:3 sea trial for which we are now raising 3 MEUR in private financing, read more.

To finance sea trials with wave energy converter InfinityWEC at scale 1:3, Ocean Harvesting is raising 3 MEUR in equity investment at a pre-money valuation of 7 MEUR. This investment will be combined with public financing for the project. The sea trials are planned to be completed by the end of 2024, after which commercialization of the technology will be initiated with sea trials of full-scale systems.

A transition to 100% renewable energy is necessary to mitigate climate change. Solar and wind energy are driving the transition but will not be sufficient given the enormity of the task and geographical, space and other constraints. Much more renewable energy will be needed. Wave energy is a vast, unexploited resource for renewable electricity generation. It can furthermore add substantial value by reducing variations in electrical grids with a high degree of renewables, and thereby reduce the amount of energy storage needed to balance electricity supply and demand.

InfinityWEC can unlock the potential of wave power through its advanced power take-off and control system, which tunes to every individual wave to produce electricity efficiently in all sea states. Furthermore, a unique end-stop function ensures both survival and continuous, reliable power production even in the harshest wave conditions. The novel buoy design is made with high strength concrete, with weight similar to a conventional steel hull, but at a quarter of the cost, a third of the CO₂ footprint, and one tenth of the manufacturing time. In all, the exceptional performance and reliability, using proven subsystems and a modular design, make InfinityWEC a highly competitive solution for the future global energy market.

Ocean Harvesting is preparing for sea trials of InfinityWEC at scale 1:3 to be performed off the west coast of Sweden. The sea trials will validate the performance in real sea environment and the results will be used to further develop and improve the full-scale system with regards to energy yield, system efficiency, availability, and ultimately affordability.

Ocean Harvesting follows the staged validation framework for ocean energy technologies set out by Ocean Energy Systems (IEA). InfinityWEC has with simulations and physical tests in a test rig in scale 1:10 and in a wave tank been successfully verified with regards to critical functionality of the power take-off and control system, sea-keeping and survival functions in extreme conditions, and the power production performance. The technology is on track towards a competitive cost of energy at 100 EUR / MWh already at 100 MW installed capacity, and < 35 EUR / MWh at large scale deployment, with the added value of reducing the need for energy storage to balance supply and demand of electricity.

The market for InfinityWEC ranges from utility-scale wave farms to off-grid applications such as oil & gas platforms, island communities, green hydrogen production and aquaculture.

Karlskrona/Gothenburg, Sweden; 6 May, 2022

Ocean Harvesting is developing a novel concrete hull for the prime mover (buoy) of the InfinityWEC wave energy converter, using high strength concrete with low environmental footprint and excellent durability. The solution allows for large scale production and results in a buoy with a weight similar to a conventional steel hull, but at 1/4 of the cost and 1/3 of the CO2 footprint.

Highly flowable concrete is poured into a mould with void fillers, forming the concrete shell and the internal honeycomb structure, one of the strongest structures in nature. Most of the raw materials will be sourced locally at the installation site, where the buoy is cast in a process common in civil engineering. The buoy will be towed or shipped to the installation site and linked to the InfinityWEC PTO system with a mooring rope, which enables quick and diverless attachment and detachment of the buoy from the PTO system during installation and maintenance operations.

The RISE (Research Institutes of Sweden) department for Infrastructure and Concrete Technology has developed a unique high-performance concrete mix for the buoy, as part of the joint industry project WECHull. To facilitate a thin-walled, lightweight structure and easy, rapid manufacturing, alternative reinforcement measures were investigated, evaluating the use of fibres of different types (carbon, aramid, glass, steel and biomass), as well as polymer reinforcement with carbon-textile grids. By using recycled aggregates and replacing more than 50% of the cement content, InfinityWEC’s buoy is aligned with the European Circular Economy Action Plan.

The next development stage for Ocean Harvesting is a sea trial of InfinityWEC at scale 1:3, a project planned to start in November 2022. The sea trial will demonstrate the InfinityWEC technology and its control system, and their performance in the real sea environment. This is a critical step towards the final validation stage of the system at full scale and the commercialization of the technology.

Karlskrona/Gothenburg, Sweden; 5 May, 2022

Ocean Harvesting has successfully completed the testing of a prototype in scale 1:10 of the power take-off (PTO) and the control system for the wave energy converter InfinityWEC. The design, build and testing in the rig was part of a project co-financed by the Swedish Energy Agency.

To obtain a realistic load on the machinery, a scaled hydrodynamic model of a full-size wave energy converter (WEC) was used in combination with the physical PTO prototype and a real-time control system in a hardware-in-the-loop (HIL) configuration. A control system has been developed for both the PTO and the HIL rig, which in combination with the physical representation of the PTO, with all essential functionality included, demonstrates that the technology works as intended.

The project validated that all critical parts of the PTO could be built with standard components. The full-scale design aims to use standard components with high availability from suppliers, to minimize risks, shorten development time and reduce the costs of the final product.

The control system developed for the project is based on a modern software architecture using OOP (object-oriented programming) and TDD (test-driven development). It is based on Beckhoff PLCs and TwinCAT software, which is a suitable and cost-effective solution both for HIL testing and for large-scale offshore deployment of wave energy converters in wave farms. The developed software will be transferred to and further developed in the full-scale development phases of InfinityWEC.

The test rig will have continued use as a development platform to evaluate advanced reactive control strategies and design principles, to further refine InfinityWEC’s capability to extract maximum power from every individual wave.

The next development stage for Ocean Harvesting is a sea trial of InfinityWEC at scale 1:3, a project planned to start in November 2022. The sea trial will demonstrate the InfinityWEC technology, control system and its performance in a real sea environment, a critical step towards the validation stage of the system at full scale and commercialization of the technology.

Ocean Harvesting Technologies (OHT) has commissioned a Hardware in the Loop (HIL) test rig at scale 1:10 to validate the InfinityWEC power take-off (PTO) with instant force control capabilities.

The test rig simulates the buoy motion with force feedback from the PTO system, and will be used to validate the complete functionality of the PTO and control system as in a complete WEC for real sea conditions. The functionality includes (i) instant force control capability in combination with efficiency and constraint-aware predictive control, amplifying energy capture, and (ii) a soft two-stage end stop, holding the buoy submerged through the crest of large waves to ensure both survival and continued, reliable power production even in the harshest conditions. The test rig will later be used as a platform to develop and evaluate AI-based control strategies and design principles, to further refine InfinityWEC’s capability to capture maximum power from each wave. The project is co-financed by the Swedish Energy Agency and will be completed by February 2022.

The developed control system will be used in the sea trial of a complete InfinityWEC system at scale 1:3, to take place on the Swedish west coast. The sea trial project is planned to start in 2022 and key suppliers are Sigma Energy & Marine, Acumo/NSK, and Beckhoff, among others. RISE Research Institutes of Sweden is partnering in the project and will be responsible for validation of the integrity of the hull that includes sustainable high performance concrete and biofouling as outcomes in the research project WEChull, financed by the Swedish Energy Agency.  

The sea trial in scale 1:3 will demonstrate that InfinityWEC is on track towards LCoE 100 EUR / MWh at 100 MW installed capacity and < 35 EUR / MWh at 5 GW installed capacity. System performance will be tested in real sea conditions and results will be used to validate and calibrate the simulation tools to predict energy yield, ownership cost, affordability, availability and process efficiency. The commercial-scale single device demonstration is planned to start in 2024, to be followed by array installations on commercial terms. The road map to commercialization follows the staged development process recommended in the Ocean Energy Systems (OES) framework, a technology collaboration program by the International Energy Agency (IEA).

OHT is, furthermore, performing a feasibility study on how a wave farm installation could provide electricity to one of Lundin Energy Norway’s oil & gas platforms. The study includes sizing and specification of the wave farm, energy storage, handling procedures and a life cycle cost assessment. OHT also participates in three joint industry collaborative projects led by RISE: WECHull (hull materials), Seasnake (dynamic power cables) and NextWave2 (sensor technology and algorithms for wave prediction).

OHTs technology is protected by five patent families filed since 2017, covering all vital aspects of the power take-off and control system, the buoy design and general arrangements.