Just a few kilometers away from the famous Lorelei rock, 16 power buoys are set to generate 400,000 kilowatt hours of power annually in the future - as much as a wind turbine. The torpedo-shaped mini hydroelectric power plants are eleven meters long, weigh seven metric tons, and have a rotor diameter of two and a half meters. The Rhine current in the Prinzensteiner Channel, a distributary of the Rhine with no commercial shipping near St. Goar, will drive the rotor, while a generator connected to it will produce the power. Power cables have been secured to the bed of the Rhine, which will transport the power from the buoys to the shore and onto a transformer station located above the high-water mark. From there, another cable transports the power to the grid in the St. Goar district of Fellen.
According to Norbert Burkart und Christian Hanne, the founders of the company Strom-Boje Mittelrhein, the advantages are obvious: There is no need for any major construction works or dams, the turbines make no noise, and there is no negative impact on the Upper Middle Rhine Valley, a UNESCO World Heritage site. Furthermore, there is no downtime - unlike idle wind turbines. Yet isn't there a danger of the fish ending up in the turbines and being shredded by the rotors to some extent?
Both company founders deny this. The propellers only rotate between 60 and 120 times per minute; the oscillations even deter the fish from swimming through the turbines. No problems arose during tests performed by the Austrian buoy manufacturer Aqua Libre. In order to be absolutely sure, a fish monitoring operation has been prescribed for Strom-Boje Mittelrhein using video cameras.
Ann-Sybil Kuckuk from the Rhineland-Palatinate Nature and Biodiversity Conservation Union thinks that large wind turbines in certain locations may even be more dangerous for some creatures, such as red kites and bats. And the huge barriers and hydroelectric power plants pose a danger to the fish, according to Anne Schulte-Wülwer-Leidig, managing director of the International Commission for the Protection of the Rhine in Koblenz, because larger fish such as eels are constantly being injured in them. She says that this is not the case with the power buoys.
In general, there aren't that many places on the Rhine where the mini hydroelectric power plants can be operated anyway - partly because the current must be strong enough to operate the plants, but also due to the fact that they must not interfere with shipping, which would be the case with the buoys, as they normally operate just beneath the surface of the water. And the small power plants are also equipped to deal with extreme weather situations: During flooding, they do not rise beyond a certain height thanks to the chains that anchor them. Larger debris simply floats over them, although the design of the buoys means that even a collision with a fully grown tree trunk is not likely to cause any damage, according to the manufacturer. If the water level is extremely low, on the other hand, they simply remain on the bed.
The pre-production buoy cost 275,000 euros, with the models for regular operation set to be somewhat less expensive. The head of Germany's nationwide "Fluss-Strom" technological expertise network, engineer Mario Spiewack, can even envisage the mini power plants working well all over the world on a decentralized basis in regions with no power supply. After all, they are certainly quieter and eco-friendlier than diesel generators. In any case, we are interested to see how things will develop. Perhaps one day the buoys will be so small and well developed that we will be able to use them to generate power in our ponds at home. But plenty of water will undoubtedly flow along the Rhine before that day comes.