Germany challenges the status quo with 124 invisible turbines under a river capable of generating energy even when there is no sun or wind; they are installed in 3 months and cost 88% less than a hydroelectric plant.
Germany has just opened a curious door in the energy transition. On the Rhine, near Sankt Goar, Rhineland-Palatinate has authorized a system with 124 floating turbines called Energyfish, designed to produce electricity from the river's current itself, without a dam, without a reservoir, and almost invisible from the shore. Currently, three are in operation, and the next step will be to install another 21 before completing the swarm.
The main conclusion is simple. This alone will not replace solar, wind, or large-scale hydroelectric power, but it does point to one of the missing pieces in many electrical grids. The river keeps moving at night, when solar panels no longer generate electricity, and also when the wind decides to stop. In practice, we are talking about small, local, and constant renewable energy. And that shows.
Energy fish under the Rhine
The name sounds almost like a fairy tale, but the device is quite concrete. Each Energyfish measures about 2.8 meters long, 2.4 meters wide, and 1.4 meters high. It weighs around 80 kilos, has a maximum power of 6 kilowatts, and an average of nearly 1.8 kilowatts.
The technology harnesses the kinetic energy of the water. The rotors spin with the current, the generator converts that motion into electricity, and the energy is taken to land to be injected into the grid. There is no need to build a barrier in the middle of the river or modify the riverbed.
That is why they talk about almost invisible turbines. They do not disappear, of course, but they remain largely submerged and are discreet from the outside. For a city along the river, it is not the same to look at a large concrete structure as to see the water flow as always.
The value of producing at night
The great appeal of this system is not in a single turbine. An isolated unit contributes little in terms of the electrical grid. The key lies in the swarm, that is, in gathering many small machines so that the result begins to make sense.
According to the Ministry of Environment of Rhineland-Palatinate, 100 Energyfish can produce around 1.5 gigawatt hours per year. That would be enough to supply between 400 and 500 four-person households. In Sankt Goar, with 124 units planned, the figure exceeds 460 households.
Katrin Eder, the state's Minister for Climate, Environment, Energy and Mobility, summed it up with a very visual phrase: "124 of these fish in the Rhine can supply about 465 local households with climate-neutral electricity." It is not an entire city, but it is not trivial either.
Without a dam and with less impact
The important difference with a traditional hydroelectric plant is that here no wall is erected. Dams can complicate the lives of migratory fish, because they block passage and alter the river. In the Middle Rhine, the ministry itself cites species such as barbel and nase.
The Technical University of Munich has analyzed the ecological compatibility of this technology with measurements from sensor fish, ARIS sonar, and GoPro camera observations. The ministry states that the study detected no injuries or negative changes in fish behavior in the analyzed stretch. An important nuance should be added: the project's own fact sheet notes that Energyminer is listed as a client of that evaluation.
This does not turn the technology into a magic solution. It means that, under the conditions studied, the results are promising. For any future expansion, each river, each species, and each stretch will need to be examined with a magnifying glass. Not all riverbeds behave the same.
Not every river works
Here is the less spectacular but most important part. For the numbers to work, depth, space, and adequate current speed are needed. In the Sankt Goar stretch, the Rhine reaches between 1.5 and 2 meters per second, conditions that the ministry considers ideal for this type of installation.
Additionally, the turbines cannot interfere with navigation. Nor do they have the power of a large conventional hydroelectric plant. Boris Lehmann, from the Technical University of Darmstadt, described it as a useful complement, not a total substitute. As he explained to ZDF, the set can provide a "serious" amount of energy when many units are grouped together.
The company also assures that the Energyfish are prepared for floods and ice. In such cases, they can automatically sink to the riverbed to allow floating debris to pass and continue operating. It is an interesting technical promise, although the real test always comes with years of operation, maintenance, and storms.
A scale test
Sankt Goar is more than just a striking installation. Energyminer presents it as its step from prototype to a decentralized infrastructure that can be replicated in other suitable locations. Richard Eckl, the company's co-CEO, said it directly: "St. Goar is our scale test."
The timeline will be gradual. First, three units have entered, then another 21 will arrive, and later the set will be completed to 124. This pace makes sense, because it is not just about putting machines in the water. They also need to be connected, monitored, measured for effect, and checked to see if production remains as expected.
At its core, this news is about something very simple. The energy transition does not depend on a single brilliant technology, but on many pieces that fit together well. Solar panels on rooftops, wind turbines where the wind blows, batteries, smarter grids, and perhaps small electric "fish" in rivers with enough force.
The official press release about the authorization of the first Energyfish swarm power plant has been published by the Ministry of Agriculture, Viticulture, Environment and Forests of Rhineland-Palatinate.
