Riding the waves in the wild west

Not many companies admit that they are cowboys in a wild-west industry. But, as Dr Will Bateman admitted, that is where his company Ccell finds itself. It does not mean that the wave energy sector cannot foster innovation, and Bateman believes he has made a breakthrough

Over recent months the renewable wave sector has seen its two biggest players sink below the waves. Pelamis went into administration and has failed to find a buyer, while Aquamarine has downsized considerably and its future remains uncertain. Hopefully both of these companies, or at least their staff and technology, will live to fight another day, but in the meantime it leaves a void.

Will Bateman, whose company's technology is very much still in the early stages of development, gave his view on the state of the market: "Solar has been done, costs are coming down but it is really tinkering around the edges. Wind energy is still in the learning curve, has in general settled on the three blade turbines and all they are doing now is making their devices bigger. If you look at those two sectors there are now big multinational OEMs involved in making them on a massive scale. Wave energy as a whole is the wild west industry of the 21st century, certainly of the renewable energy sector. It is new territory."

In other words the market is left to much smaller companies looking to make a name for themselves. Playing the role of sheriff in this analogy are such organisations as the Scottish Wave Energy, the National Renewable Energy Centre, WaveHub and the European Marine Energy Centre in Orkney. But these organisations provide the sector with support rather than structure, leaving the door open for small companies to come in and make a splash.

Although following a cautious development schedule, Bateman believes his technology is set to do just that. The main reason for that is that he believes, in terms of the fundamental technology required to harness wave energy, that others have got it wrong.

There are several different ways of trying to capture wave movement and convert it to electricity (for example, see Eureka February 2015 for a report on Wello's 'Penguin'), but a common approach, and the method used by Aquamarine, is to have a flat paddle that is pushed forward and backwards by the waves, effectively then converting this into a linear flow that can be used to power a generator.

The logic behind this is that the particles in water move approximately in an elliptical way, allowing the symmetrical paddle to be pushed back and forth. However, Bateman questioned this for a number of reasons. Firstly the amount of turbulence created around the edges of the paddle makes movement less efficient due to counter-flows that act against the motion of paddle. Secondly was the notion that as the paddle sweeps through the water it must displace water and in doing so it created waves, which dissipate the energy we're trying to capture. If all the wave energy was being captured then it would theoretically leave a flat calm behind it.

Most significantly is that the flow of energy in waves goes in predominantly one direction. As Bateman explains "Waves derive there energy from wind blowing across the water far off land. The waves and their energy flows through the sea and eventually meet land where is it dissipated as breaking waves on the beach. Except near vertical rock faces, you don't see the wave energy travelling away from a beach."

"So why then are we building a symmetric system," asked Bateman, "when it is an asymmetric problem? So I thought if I am going to make an asymmetric solution then naturally I am going to make a curve." Dr Bateman explained, that while a curved paddle displaces the same volume of water as a flat paddle when it moves, the curved surface that is closes to the shore, dissipates smaller waves which reduces energy dissipation by a factor of four. That was my Eureka moment."

Bateman continued: "So what we did was take that to UCL and ask them to test it and from there it has snowballed. At first a student rigged up a flat panel and a curved panel with identical dampers from a car boot, and the curved one moved 40% more. So I got a patent on the curved paddle."

The proving and prototyping phase is proving to be a lengthy one and started with more thorough tests at UCL using different shapes. Bateman said: "The results were categoric. We were probably able to generate two to three more times power from a curved paddle rather than flat.

"The last year has been spent proving the physics. The commercial side of me says we have got something that works go and get it in the water. The rational side says until we need to know exactly the physics behind it, why it is better than everything else – and we believe this to be the most efficient device on the planet by a significant margin – until we can do that our ability to innovate is only as strong as our current knowledge is."

Not all progress has been smooth. Tests last year in a giant water tank in Plymouth involved covering the device in a grid of pressure sensors, designed to test the water pressure on the paddle. Bateman said: "In Plymouth we weren't actually successful with the pressure tests. We got some indicative results but there was too much noise in the signals. There was a lot we underestimated, the sensors themselves weren't accurate enough, we were getting too much noise on the connections, but it was the first big test we've done. We had modelled the pressures with our CFD but we wanted to actually capture that physically. You learn more from your failures than you do from your successes they say, so we learnt vast amounts in Plymouth last year!"

The CFD modelling is done in the open source package OpenFOAM, which includes a turbulence feature.

The next iterations of the design are being put to test just off the coast of Cumbria, which are on a larger scale – approximately 4m high. One of the important aspects here was to establish that the design could be made easily and partnering a ship repair company, MPM, it has passed this test. Small companies like Ccell need to build up expertise around them. Bateman said: "What we are trying to do is to find people who have an interest in doing some research or developing new capabilities that matches with something we need. Hopefully there is a meeting of minds and we can go off and do something clever with them."

MPM's devices have been constructed in steel, which the company is comfortable working with, while previous lab version had been made in aluminium. An anticipated tie up with the National Composites Centre in Bristol shows the direction Bateman is looking at following. He commented: "Composites come with a whole host of benefits - corrosion proof, super light, strong and it also allows double curvature. The flip side is that making a prototype in composite typically means making a mould, which can be very expensive. We are looking at a range of options including computerised 3D milling to make mould and 3D printing of models."

Along with material and mechanical design it is also vital to create the most efficient way of converting the energy and also controlling the panel so that it is always in the right position to be efficient, and this is an area that Bateman again expects to rely on the help of others in his unofficial consortium, notably in this case the Universities of Bath and Exeter. "We will only be as successful as the people we involve and bring in around us," he added.

The next phase of the project should raise the technology readiness levels from around five to nearer seven or eight and by 2017 it is anticipated that five devices will have been deployed in the water at least one of them for over a year.

It is an exciting market yet one that awaits the breakthrough, with several small companies like Ccell leading the charge to identify a winning technology. Bateman concluded: "If anyone gets their device to work then they go from being worth thousands of pounds to billions because there is so much coastline."