Stream buoys 02 with details - Streaming power plants 03

Constant hydropower without damming, ecological consequences and danger for fish - that is the promise of a stream buoy from Austria. 16 of these buoys will soon be floating in the Rhine River generating electricity. A single one of them is expected to supply up to 100 households. Drilling work is already underway in the Rhine.

Hydropower is a renewable energy. Water, dammed by dams, can be accessed as needed and is not dependent on weather conditions like wind turbines and solar panels. However, dams also bring problems. In addition to the massive forced relocation of the local population, as in the case of the Chinese Three Gorges Dam, they can throw entire ecosystems out of balance: Fish can no longer reach their breeding grounds, dangerous bacteria accumulate in the stagnant water - not to mention the danger of dam bursts. For reasons such as these, wind turbines and solar plants are primarily installed in Germany.

[Pioneer Fritz Mondl with stream buoys on the Rhine in Germany]

A technology from Austria now promises a comeback for hydropower and has already secured a site on the Rhine near the famous Loreley Rock. The stream buoy does not change the flow behavior of the river, but uses the water flowing through it for constant power generation. "The stream buoy is so far the only small power plant in the world that works and uses the free-flowing current, without any structural intervention in the river, without any dam, without any rake, completely neutral without any danger for all kinds of creatures and inhabitants of the river," Fritz Mondl, inventor of the buoy, told Sputnik.

[Minimum flow velocity: 2m/s - up to 100 households - 3500 kilowatt hours / year - average depth 2.5 to 3m]

With a rated power of 70 kilowatts, the eleven-meter buoy could generate up to 300 megawatt-hours, or supply 70 to 100 households of 3500 kilowatt-hours per year, depending on "site quality." The "quality" primarily refers to the flow velocity, which should be over two meters per second or 7.2 kilometers an hour for a buoy to be economically viable. In addition, the buoy needs a minimum depth of 2.5-3 meters of the average annual water body in which it will be used. At high tide, it automatically rises on the chain that anchors it to the bottom.

[Model "Stream buoy 3" in large rivers with up to 250,000kWh - 350 stream buoys in the Wachau region - 16 stream buoys on the Rhine]

The final "Stream buoy 3" (German: Strom-Boje 3) was originally designed for large rivers such as the Danube or the Inn, emphasizes Mondl. There, it could generate between 200,000 and 250,000 kilowatt hours a year, he says. "In the Wachau, we could make the whole region self-sufficient in electricity with 350 stream buoys," says Mondl. But apart from a prototype buoy that has been in use in the Danube since 2016, no other buoys have made it into rivers in Austria. That's because of the myriad legal requirements, Mondl said. These have turned out to be far less extreme in Germany, which is why the first water park of a total of 16 buoys will be built on the Rhine.

[Rhine: German test program using cameras to monitor fish behavior in the Rhine around a stream buoy]

Or in better words: it's in the making. Because the company "Middle Rhine UG" ("MittelrheinStrom UG") has already had the first eight moorings drilled there and is waiting for the stream buoys, which are to be delivered in half a year, the co-founder of MittelrheinStrom, Norbert Burkart, told Sputnik. However, the power company is expected to receive a pre-series model of the buoy in the near future, with which it will meet the requirements: Among them, fish monitoring with a camera and net to test how the technology affects the Rhine's swimming inhabitants.

"There used to be a lot of ship mills on the Rhine," Burkart says. He was very interested in these mills, he says, and at the same time wondered how the current could be tapped in our time. At the same time, Mondl was enjoying great success with his buoy. From 2010 on, the two companies were in contact about this.

And this is all right, thinks Mondl: "Mr. Burkart can certainly generate 300,000 to 350,000 kilowatt hours a year at the site with his MittelrheinStrom UG." But that might not be the most important thing, after all, the region is well supplied. Such parks make sense above all in connection with the switch to renewable energies, because unlike sun and wind, the water in the Rhine flows constantly. This makes the power buoy "base-load capable" and can provide the basis for power supply even when the weather doesn't play along.

[Costs: 1 stream buoy 350.000€ - with mass production 1 Stromboje 200.000€ - in 9 months the energy is produced, which was necessary for the production of the stream buoy]

Originally, such a stream buoy costs €350,000, but in mass production the price should drop to as low as €200,000, Mondl notes. In terms of profitability, that means "we generate the energy needed to make the power buoy in about nine months." The buoys themselves should be able to operate for at least 25 years. They are made of steel and polyethylene, and maintenance is only required on two replaceable bearings every 100,000 hours of operation, Mondl says.>