Dr Markus Mueller
It has been estimated that marine energy could supply the electricity demands of the United Kingdom twice over, and yet wave power – one of the various forms of marine energy – remains largely overlooked as a renewable source. In comparison to solar panels or wind turbines, the technology for extracting energy from waves is relatively under-developed.
A collaborative project between mathematicians and engineers from the University of Exeter and Tel Aviv University now claims to have found a way to modify existing wave energy converters (WECs) to effectively double the amount of energy they are able to extract. The research paper, published in the journal Renewable Energy
, describes the team’s effort to improve the efficiency of point absorbers by introducing a mechanism to control the device based on predictions about incoming waves.
In my opinion, the problem is that in the UK there is a lot of focus on wind and solar in terms of renewable energy, but the awareness doesn’t yet exist that wave and tidal energy have great potential and are very reliable.
Dr Markus Mueller
I spoke to Dr Markus Mueller, from the Environment and Sustainability Institute at the University of Exeter's Cornwall Campus, about the immense potential of marine energy sources and how difficult it is proving to get the industry moving in the direction of wave power. I began by asking why, if marine energy has so much potential in the UK, it has not as yet been developed further.
"I suppose it is mainly for political reasons," Dr Mueller remarked. "The potential is there but so far the technology has not been made economically viable. Devices like the wave buoys we are working on have existed for 30 or 40 years now. The idea is very simple – it is basically a buoy bobbing up and down in the waves and driving a converter – but the problem is with infrastructure.
"Infrastructure is quite expensive because there are all sorts of factors which come into play in a marine environment. It only becomes economically viable when you have farms with a large number of devices but, before that can happen, investment and research is required into the issues which would be faced by such farms."
Dr Mueller went on to explain the main challenges involved in efficient wave energy capture with regard to those devices which are currently commercially available.
"The way existing devices work is that they are put into the sea and their mode of energy extraction is based on those statistical properties which the sea usually exhibits. In reality, the devices will never face waves which represent statistically average values of, say, amplitude and frequency."
I asked how the system developed and tested by Dr Mueller and his colleagues tackles the efficiency issue, and how it copes in an often hostile marine environment.
"Our research involves taking buoys which companies are already producing and optimising the way that they work. The idea we employ is that when you can predict what the waves will do in the next 30 seconds, you can actively optimise your wave energy converter (WEC) to get the most energy from the wave.
"We can shut it down when the weather is too rough, and it can be predicted whether or not a wave might cause damage and then shut down accordingly. It also actively engages the internal parameters of the wave so that it can adapt to extract the most energy in light of the amplitude and frequency."
The application of mathematical models proves that the system of anticipating incoming waves is much more efficient than working from an average without the ability to actively control, intervene with or optimise the device’s operation. As well as increasing efficiency, damage is much less likely when the device responds appropriately to each wave.
Dr Mueller explained that although the algorithms they use in their predictions cannot get it right all of the time, for shorter periods it is possible to get an accurate picture of what will happen in the following 30 seconds.
I asked what more can be done to allow wave power to play a more significant role in the UK renewable energy sector and how we can make sure it gets the attention it deserves.
"More research on wave farm issues is needed, because there may be problems with interactions between wave energy buoys and other devices, for example. There might also be security issues. You want to have optimum use of your infrastructure; for example you want to have as many buoys as possible, so you need an optimum arrangement. If you know that storms or waves usually come from the west you would arrange the WECs in such a way that the most possible energy is harvested.
"In my opinion, the problem is that in the UK there is a lot of focus on wind and solar in terms of renewable energy, but the awareness doesn’t yet exist that wave and tidal energy have great potential and are very reliable. Tidal streams and waves are constant. When big companies and governments invest a lot of money in infrastructure, only then will it become economically viable to harvest wave energy. From the political point of view, that is the main issue. One has to be bold; take some decisions and make an investment."