Uppsala researchers have high hopes for wave power
Building wave power stations to survive the harsh conditions out at sea has proved difficult. A good many wave power projects have foundered along the way, but not the wave power group at Uppsala University. Its relatively simple method now leads the world and its spin-off company, Seabased, is project-managing several commercial wave power installations.
Wave power has major energy potential; installing it along the coast of Norway could supply the entire Nordic region with energy. However, despite decades of trying, there are few wave power stations in operation. “The various challenges of the technology have stalled quite a few projects,” says Rafael Waters of the wave research group in Uppsala University’s Division of Electricity.
“A well-functioning wave power station isn’t just about producing energy efficiently; power plants must also be able to cope with salt water, harsh winds, high waves, sea currents and becoming a habitat for marine life,” says Waters.
Simple solution wins out
The systems which the wave power groups at Ångström and Seabased are working on are strong because they are simple. A buoy attached to a cable floats on the surface. This then raises and lowers a magnet through a coil in the generator. Unlike other systems, this one is almost totally non-mechanical; there are no axles or gearings to wear out and the system is free-standing on the bottom. This means it can’t drift away and cause damage or incur major repair costs. The whole system can be easily lifted out at the end of its service life and tests show that marine life actually fares better within wave farms than outside them.
“Because we’ve chosen a simple mechanical system, we’ve solved many of the problems that other wave power groups had. Advanced mechanics can’t cope with the stresses or salt water without costly maintenance and stationary power plants can break loose,” says Waters.
That said, using simple mechanics is a double-edged sword. One drawback is that it provides “inferior” power which needs more conversion before it can go onto the grid. So this system is a compromise between energy production and durability. However, Waters believes that although they are sacrificing some of the energy which might be generated, they are conversely building a product with realistic investment costs and low maintenance; an otherwise major cost offshore.
“We’ve also managed to significantly reduce the costs of launching the power plants, which is an important part of commercialisation,” says Waters. We currently position the power plants on the bottom of the ocean using a crane and then lift them up a little bit from the bottom using a tugboat anchor line. Then we take the whole unit to the right spot and lower it to the bottom.”
The cost of progress
Waters has devoted all his time since 2008 to wave power research and is delighted with the progress that’s been made plus the fact that the wave power group at Uppsala University had a major hand in its development.
“The philosophy of the wave power group here in Uppsala was to bring things to fruition quickly, in sharp contrast with the way other research groups have done it. It’s easy to spend ages in the lab, doing small-scale tests in loads of stages. The drawback is that it takes a long time to get out into realistic surroundings. Then they run up against the really big challenges which take time to solve”, says Waters.
There is still a little way to go before the group’s first station can provide power to the grid but they are on the verge of achieving their goal – both they and Seabased have power plants connected and ready to produce green wave power for consumers. But even as this is taking place, there’s another challenge: it’s easier to get money for producing reports, articles and theoretical results than for substations and cables.
“Maintaining the infrastructure is quite costly,” says Waters. “Cables can rub against the seabed in heavy seas and boats can get fouled on them. And sometimes the electrical equipment needs overhauling. This all costs money and it’s hard to get funding. Meanwhile, the renewable energy everyone’s talking about depends on research projects being funded all the way and not just to produce scientific reports and articles.”