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Marine current power station tested in the river Dal

2013-10-21

The power station was lowered using a crane and divers next to the road bridge in the centre of Söderfors.

Uppsala University's run-of-river power station was launched in the river Dal, in central Söderfors. The turbine, generator and foundation were put into place using a crane and divers. “This is like one large laboratory to us. We can now verify the technology,” says Mats Leijon, professor of Engineering Sciences, Division of Electricity.

This has been a very busy period for the research team at the Division of Electricity at the Ångström laboratory. Within the space of a few months, four theses have been presented, and in March the test facility was launched in the flowing waters of the river Dal.

The research looks into how to take advantage of run-of-river power for energy production. There are ten or more comparable test installations around the world, but this specific technology is unique. It is similar to wind power technology, with the difference that the generator is adapted to the slow movement of the water. In truth the technology was designed for the great oceans, where tides can be utilised, but it is now being tested on the river Dal.

“This is like one large laboratory to us. There is a power station further up and one further down the river. We are collaborating with Vattenfall and Fortum and we have access to constant information about the flow of water,” says Mats Leijon.

The power station consists of a turbine and a generator, which via a subsea cable is connected to a measurement hut on land. Divers checked the riverbed before the turbine was lowered into the water.

“It went very well, despite having to dive in freezing cold waters. Everything fell into place perfectly,” says researcher Mårten Grabbe.

The research into run-of-river power has been in progress since 2001 and now the work is beginning to pay dividends in the form of four theses: about the control system, turbine design, generator design and the best placement of the run-of-river power station, based on water flow measurements.

The station has now been lowered into the river Dal and could remain there for at least three years. If it works well, there are plans to apply for yet another power station at the same site, but this lies in the future.

“First, we need to verify the technology. We have made various component experiments, but now we need to test the entire system. This is always very difficult. In the best of all worlds the experiments will also correspond in reality and then we have taken an engineering scientific step,” says Mats Leijon.

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Marine current power station - how it works:

* The kinetic energy of flowing water is converted to electricity by connecting a vertical axis turbine directly to a generator.

* The turbine rotates slowly, 5-30 rpm, and the generator has been adapted to the slow movement of the water. This provides effective electromagnetic energy conversion at the same time as the number of moving parts - that require maintenance - is kept to a minimum.

* The first prototype generator was designed to produce 5 kW at 10 rpm and was completed at the Ångström laboratory in March 2007.