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Developing the PTO of the first MW-level Oscillating Wave Surge Converter

Periodic Reporting for period 2 - MegaRoller (Developing the PTO of the first MW-level Oscillating Wave Surge Converter)

Reporting period: 2019-11-01 to 2021-12-31

What is the problem/issue being addressed?
Despite its attractive characteristics, wave power entails significant challenges that have so far prevented it from becoming a mainstream energy source. To date the industrialization of wave energy has been very limited due to technical challenges and limitations in scale resulting in comparatively high cost of electricity production. There are numerous types of wave energy converters (WEC) in development designed to unlock this potential, but the oscillating wave surge converter technology type (OWSC) has distinct advantages over all other solutions and represents the most advanced technical solution for the industrialization of wave energy.

Why is it important for society?
The largest benefit from the installation of a MegaRoller WEC project is the production of clean, renewable electricity that will be fed into the local electricity grid or used for the production of hydrogen or freshwater. In addition, the wave resource can balance lower solar resource in the night time or during winter season in the northern hemisphere.

MegaRoller WEC’s can supply power for industries and enable smoother transition of industries to fully renewable-based operation. For example, water desalination and green hydrogen production industries benefit from the high predictability and consistency of power supply that MegaRoller WEC’s provide.

Significant elements of the MegaRoller WEC device can be manufactured locally through standard steel and concrete manufacturing processes, thereby providing jobs to the local population. Assuming 10 jobs per MW, the deployment of MegaRoller power plants can generate 6,000 jobs by 2030 (600 MW) and 400,000 jobs by 2050 (40,000 MW) in Europe only. These jobs will be centred on the location where the devices are deployed i.e. European coasts, however suppliers in many other European countries will also benefit.

The carbon impact from a MegaRoller WEC device has been assessed to be 33.8g CO2e/kWh, well
below the thresholds set by the EU’s Sustainable Finance Taxonomy. This allows projects using the MegaRoller technology to receive funding from sustainable investment funds and similar facilities.

What are the overall objectives?
The MegaRoller project focused on the design, construction and validation of a high performance, cost-efficient and reliable PTO. The project aimed at reducing the levelized cost of energy (LCOE) of the system below €150 MWh, for the first 10 units deployed, by increasing nominal device capacity, reducing the number of components, increasing the PTO reliability (lower CAPEX, OPEX and higher availability) and reducing power conversion losses.
Overview of results

The main outcome of the MegaRoller project is the new power take-off (PTO) solution for wave energy converters featuring a modular design. The performance of the PTO has been demonstrated and validated in various wave conditions with simulation models.
For the MegaRoller partners the project has resulted in several new innovations and concepts for product and service offerings aligning with the set targets for the project and the broader opportunity in support of the emerging new sustainable wave energy industry. Particularly, notable developments have been made in reducing the costs of oscillating wave surge converter (OWSC) PTO technologies and improving energy capture and conversion of the technology type.

The project has demonstrated that MegaRoller PTO technology is a cost effective, reliable and an efficient technical solution for harnessing larger forces and consequently producing higher power levels when scaled up. Thereby, it is not solely applicable in the oscillating wave surge converter type device but can also be applied to other wave energy converters by enabling larger devices and directly reducing the cost of energy, thus contributing to the development of the entire wave energy industry.
Project results have been disseminated to the relevant stakeholders throughout the duration of the project through various channels. The project has produced in total over 50 publications and open deliverables from the design and development tasks. The majority of these have been presented in technical journals and at European conferences. Description of the research results and associated informational material has been distributed through the MegaRoller website, Zenodo repository, YouTube and conference proceedings targeting a wide range of stakeholder groups.

To manage the innovations and IPR resulting from the project, an innovation strategy was developed. The protection measures for the generated intellectual property are ongoing even after the project has ended. The innovations made during the project included both hardware and software innovations, and they were listed in the IPR registry produced during the project.

An exploitation strategy was developed for the management of project results. The exploitable results, target customers for the developed solution and the exploitation model were identified by each project partner. In addition, a commercial business plan and final modelled levelized cost of electricity were produced, including potential commercial applications of the developed technology, review of the existing markets as well as forecast of future demand for the applications.
Progress of the state of the art
The MegaRoller innovations include modular PTO design, twin drive train, intelligent cylinders, electric central unit, wave-by-wave prediction, wave-by-wave damping, efficient energy storage control, and supervisor controller.

The modular structure allows the modules to be exchanged and adjusted for MegaRoller WEC according to varying wave resource, ambient conditions, and customer requirements. The twin drive train arrangement makes it possible to utilize two PTOs with a single panel and increase the rated power to 1MW. The purpose of the electric central unit is to connect the two PTO units of the MegaRoller and feed the power to the grid. Different intelligent cylinder concepts were designed to remove pressure spikes from the MegaRoller hydraulic cylinder circuit.

A machine-learning algorithm to produce wave-by-wave predictions is integrated in the MegaRoller PTO control systems software to give an input to damping algorithm. The algorithm predictions are used in PTO damping control for optimized power capture. By applying wave-by-wave damping it is possible to capture significantly more energy from the moving panel.

An efficient energy storage control is based on modelling the fill level of the hydraulic accumulators. Based on the information of the incoming waves and the fill level of accumulators, usage of the energy storage can be optimized. Advanced efficiency control is a combination of controlling multiple PTO subsystems in optimized way. The supervisor controller controls site output power and grid support functionality.

Socio-economic impacts
The socio-economic impacts were studied during the project and an environmental and socio-economic impact assessment tool (ESIAT) was developed. The tool renders a complex and extensive document that includes the potential environmental and socio-economic impacts expected from the MegaRoller installation and their mitigation measures. The assessment allows a quick overview of the most significant impacts to which the developers should give greater attention, thus facilitating decision making.
MegaRoller PTO test rig and PTO 3D-model