Western Isles (Picture: Neil Kenhead)
Stand on a beach in the Western Isles looking out at the Atlantic and it’s easy to see why for over a century people have dreamed of harnessing the power of our seas. The wave energy here is some of the most intense in the world, with the potential to provide the UK with 40 terrawatt hours (TWh) of electricity each year – over 10 per cent of current demand.
Given such a spectacular natural resource, alongside our nation’s engineering capacity and expertise in marine operations, it would be a tragedy if we were not at the forefront of global efforts to develop the technologies to turn this potential into reality.
Thankfully, the Government sees it this way too, and deserves credit for the policies it has put in place. As a result, there are now five different full-scale prototype wave devices operating in UK waters and scores of earlier stage concepts. A number of international firms are choosing to come to the UK to develop their technology.
How close are we to generating power from the waves?
Taken at face value, Government and industry statements over the last two years suggest rapid progress is being made. They talk of successful sea trials, large engineering companies entering the market, and imminent plans to deploy the first multi-device ‘test arrays’ – all critical steps towards commercialisation.
But scratch beneath the surface, and the picture is more complex. These claims are made under the banner of ‘marine energy’ which includes not only wave but also tidal stream technologies like the Atlantis tidal turbine, pictured below.
Whilst in the past it has made sense to lump these together for the purposes of policy and advocacy, they actually face different challenges and are now developing at different rates. Wave technologies, whilst still making progress, are not keeping pace with tidal stream technologies, and require a more tailored approach to support their development.
Wave and tidal: unique forms of energy
This is in part due to the very different forms of energy embodied in the tides and waves. When tides are funnelled through topographical features such as narrow channels the resulting currents are fast, predictable and linear. The resource is similar in nature to wind, and so are the technological solutions to harnessing it.
By contrast wave energy moves in a circular motion and can vary massively in size and strength. It is unique and as a result the technologies here do not benefit from years of innovation and learning in other areas. There are fundamental challenges to designing devices which are capable of both extracting this energy and surviving in very rough seas.
Wave energy: a wide variety of possible solutions
So whilst tidal stream technologies have now converged around a horizontal-axis turbine design similar to wind turbines, there are still a wide variety of different wave energy solutions being developed. No consensus has emerged. This means fewer big companies are involved, a specialist supply chain will struggle to develop, and investors holding back because it’s impossible to judge who the eventual winners might be.
Pelamis’s ‘sea snake’ has faced technical problems
What’s more, when it comes to harnessing wave energy further away from shore (the lion’s share of the UK’s wave energy resource), there remains considerable doubt within the industry as to whether the current leading offshore wave devices are utilising approaches that will ever be capable of generating power at reasonable cost. The Pelamis ‘sea snake’, for example, has suffered a number of technical problems over the years.
It is unsurprising then, that of the five multi-device test arrays recently awarded EU and UK Government funding, four were tidal stream projects. Only one wave project was chosen, which involves deploying Aquamarine’s nearshore device – a big step forward but not one which brings us closer to the ultimate prize of offshore wave power.
What next for wave energy?
The different rates of progress over the last few years are now creating tension, which could threaten the development of wave energy unless greater differentiation is made in policy.
First, we still need to push the leading wave devices to test array stage. Even if ultimately unsuccessful, the learning and experience gained would benefit the industry as a whole. Given that most current marine energy array funding is being directed towards tidal devices, ring-fenced allocations are needed to take wave technologies to this stage.
Second, under the Renewables Obligation both wave and tidal energy currently benefit from the same revenue levels for their electricity. Yet the higher costs associated with wave devices mean wave projects will require higher levels in order to be viable. The upcoming setting of strike prices under the Government’s Energy Market Reforms offers a chance to put this right.
Third, it is critical that early stage innovation funding continues. In particular, there must be a renewed effort to ensure the best of the less advanced wave energy concepts, which have the potential to deliver competitive costs of energy in the long-term, have the chance to prove themselves as full-scale prototypes in open sea conditions.
In short, we must stop treating wave and tidal stream technologies in the same way. To realise the potential of wave energy, our approach must be as unique as the energy itself.
