LiftWEC

Innovating to make wave energy viable Innovating to make wave energy viable

Developing Innovative Strategies to Extract Ocean Wave Energy, or the LiftWEC project, is exploring the potential of using lift forces generated by ocean waves as a source of power. Principal Researcher, Matt Folley, seeks to finally prove waves can make sense as the next big renewable.

There have been many attempts and trials to convert energy from the natural power of ocean waves. It is an area of enormous potential because waves are relatively predictable and reliable as natural forces. There is a range of technologies established such as heaving buoys, oscillating water columns, overtopping devices, and line absorbers, among many other methods of capturing energy from waves. However, there is an issue with the majority of ocean wave energy converters because, despite their useful functionality, they have not proved to be commercially competitive with offshore wind, or solar power. However functional a device might be, it has to be cost-effective and make economic sense for wide-scale adoption and to attract industry investment.

“Wave energy is probably thirty years behind wind energy,” began Folley. “If you think about where wind energy was thirty years ago, where there were a few prototypes but limited commercial interest; that’s where wave energy is now. People would treat wind energy back then as a marginal technology but of course, that changed, partly because of the demands from climate change, but also because effort has been spent on developing wind turbines resulting in a significant reduction in cost. This is even more apparent when you see the changes with solar panels. The cost of solar panels has plummeted dramatically in the last ten years, making it more attractive to manufacture and install.”

The power of starting afresh

The LiftWEC project was created to discover new ways to approach the challenge of making wave energy commercially viable and to fulfil its potential as a major renewable, alongside wind and solar.

The engineering design began with ‘a blank canvas’ and the coming together of experts and specialists in related fields, to understand the hydrodynamics involved. The wider goals stretch beyond making a device that works and the aim is to design and engineer a device that is viable in the renewable industry. This goal means considering the environmental impact, the maintenance requirements, and the costs. For a design to be successful it has to operate in the ‘real world’ with a range of considerations beyond functionality.

“A lot of people are trying to do wave energy today, and it feels to me like there are too many ideas and not enough are filtered out. There can be a tendency for inventors to have one idea and focus on developing it, with a blinkered vision, and this may encourage a bias towards its positives, ignoring its flaws. We wanted to avoid that. Following a structured design process, we initially came up with seventeen different concepts which

Wave-tank facilities at Ecole Central Nantes. © Ecole Central Nantes

we narrowed down to four concepts after analysing the ideas in detail, and finally to a single concept to go forward with for detailed engineering.”

Through a process of analysing different ways to extract wave energy in an economically sound way, the research team, derived from a consortium of 10 European universities and companies, has developed a concept for a cyclorotor-based wave energy converter reliant on lift forces from rotating hydrofoils.

These relatively large devices would be positioned underwater, out of sight, and connected to the Grid.

“The major difference to other wave energy converters is that our device couples with the waves through lift forces rather than diffraction or buoyancy forces, and if you look at the history of wave energy, although there have been hundreds of devices invented, the number of devices that have used lift is probably less than half a dozen,” said Folley. “What we tried to do in this research project, is to look in terms of how it can be done most effectively and to reduce the cost to make it competitive with other sources of renewable energy.”

Technology fit for the sea

With a wave energy converter there are core problems to address. One is the device’s survivability and robustness. The advantage with lift-based devices is they have a similar benefit to wind turbine devices, which is they can decouple and stop generating lift in order to survive extreme events, like fierce storms. This sets it apart from many other types of wave energy converters.

“If you look at buoys, oscillating water columns or overtopping devices there is little they can do in extreme conditions, they just have to be built to survive it,” explained Folley. Another issue is the ability to perform essential maintenance for these machines in the sea. It is key to place these devices where there are lots of waves but where there are lots of waves, it makes maintenance very challenging. The biggest issue with maintenance at sea, where people are involved, a game-changing piece of technology development in this field. In the future, with inevitable advances in technology, there is likely to be further progress in providing better solutions to this challenge.

“Our current maintenance policy is to return it to base as that seems most viable. It may be in twenty years’ time that remotely operated vehicles or ROVs, latch

LiftWEC has a profound understanding of why wave energy converters have historically failed to develop

into large offshore farms. The project is taking a broader view of all the factors that need to be satisfied for adoption by the sector, as well as choosing a novel solution that bucks the trends that have not previously translated to industry.

is of course risk to life. LiftWEC’s solution would be to tow the devices back to port to be worked on in safety. Using knowledge gleaned from other projects means it is now possible to disconnect such a device in 15 minutes, on to these devices and crawl around to fix them. If ROVs were deployed in the future, it could dramatically change the landscape for offshore wave energy making it significantly cheaper and commercially viable.”

Results from a 3D CFD model for LiftWEC showing vortex shedding at end of hydrofoils. © Gerrit Olbert, TUHH

Developing Innovative Strategies to Extract Ocean Wave Energy Project Objectives

The LiftWEC project aims to develop understanding of how best to extract wave energy using wave-induced lift forces and to design a novel wave energy converter based on this understanding leading to the identification of a viable renewable energy technology.

Project Funding

3.4 Million Euros

Project Partners

• Queen’s University Belfast • Technical University of Hamburg • Innosea Ltd • Maynooth University • Aalborg University • University College Cork • Strathclyde University • Julia F. Chozas Consulting • Wavec/ offshore renewables • Ecole Central Nantes

Contact Details

Project Coordinator, Dr Carwyn Frost Lecturer & MRG Lab Manager School of Natural and Built Environment QUB Research Portal Research Gate T: +44 (0) 28 9097 4012 E: c.frost@qub.ac.uk W: https://liftwec.com/ : https://www.youtube.com/ watch?v=CJjVeFMwlDA.

Dr Matt Folley Dr Carwyn Frost Dr Paul Lamont-Kane

Dr Matt Folley is the principal researcher in the LiftWEC project having worked in the research and development of wave energy converters, from conceptual design to fullscale prototypes, for over 30 years. Dr Carwyn Frost is an academic in the offshore renewable energy sector, facilitating lab and field scale testing and measurement campaigns for the development of renewable technologies. Dr Paul Lamont-Kane is a research fellow at Queen’s University Belfast and is working on developing the fundamental hydrodynamic understanding of the LiftWEC concept.

Testing the LiftWEC prototype at Ecole Central Nantes. © Ecole Central Nantes

Always seeing the bigger picture

After the initial design phase, numerical modelling was the crucial next step. There were many different models. There were highresolution models that took days to run and produced all the details of the vortex shedding and the lift generation, a model around potential flow solutions and an engineering design model. By validating those numerical models, the team could generate performance data for different wave scenarios and also for different dimensions of the device, to understand more completely how the device works and which configurations were optimal. However, with the wider perspectives of the project focused on commercial viability, there needed to be a holistic approach with every change.

“If for example, they said increasing the length ten metres would increase power capture by fifteen per cent but then the structural people come in and said it will increase the cost by twenty per cent, then that’s when the development is not going in the right direction. Unfortunately, there is not always sufficient focus on how power capture and costs change with dimensions so that novel concepts cannot be truly optimised. What we are trying to do is avoid that pitfall. It makes it more complicated during development but produces a more economically viable result.

There is a delicate balancing act with the developing technology and dimensions of this machine.

The physical modelling involved testing a small-scale model in a two-dimensional configuration and a larger-scale model in a three-dimensional configuration. A special water tank was used for the simulation of ocean waves in a controlled environment. This way performance could be measured and assessed much faster than if the device was in situ in an ocean environment.

LiftWEC has a profound understanding of why wave energy converters have historically failed to develop into large offshore farms. The project is taking a broader view of all the factors that need to be satisfied for adoption by the sector, as well as choosing a novel solution that bucks the trends that have not previously translated to industry.

The resulting wave energy converter appears robust and effective and a promising new direction as an ocean-based renewable. The testing and engineering of this device may well pave the way to large-scale energy harvesting from our seas. There is more to be done. Further optimisation of the concept has to be worked on in line with the wider aims of the project. Every detail, configuration and environmental parameter must be thoroughly investigated. Ongoing marginal changes, paired with the potential of newly developed materials and technologies, could lead to the first major success story for wave energy harvesting.