A German company has switched on what it calls the world's first approved swarm power plant, a cluster of small underwater turbines anchored in the Rhine that pull electricity straight from the river's current. The operator, Energy Miner, calls each turbine an energy fish, and the plan is to grow the swarm in this stretch of river to 124 of them. The appeal is twofold. The system produces base-load power, meaning it generates electricity continuously rather than only when the sun shines or the wind blows, and the company puts the price at around 8 cents per kilowatt hour. That figure is what makes this more than a science project. It sits right alongside wind and solar, which is rare for a new generation technology making its first real-world appearance.
To see why this matters, it helps to know where hydropower sits today. Around 15 percent of the world's electricity already comes from hydro, and one estimate puts the global potential of flowing water at roughly 5.42 petawatt hours a year, close to a fifth of total demand, even after excluding sites that are ecologically or economically unworkable. The catch has always been that big hydro means dams, and the easy dam sites in countries like Germany and the United States are largely used up. The energy fish is interesting precisely because it avoids that ceiling. It needs no dam and reportedly no concrete foundations, which opens up rivers that could never host a conventional plant. On cost, the video lays out the comparison plainly: large solar farms run about 4 to 7 cents per kilowatt hour and rooftop solar lands around 6 to 14 cents, so the river turbines are in the same neighborhood. Energy Miner also leans on a set of environmental selling points. The turbines need no dam, so they do not block fish migration the way a barrage does, grills keep larger fish out while smaller ones pass through the slow-spinning rotors, and roughly 90 percent of each unit sits underwater, which keeps the swarm nearly invisible from the bank.
Each energy fish works like an underwater wind turbine, using the same lift principle a wing relies on, with the current spinning a rotor that drives a generator. A unit weighs about 80 kilograms and measures roughly 2.8 by 2.4 by 1.4 metres, and it needs at least a metre of water depth and a flow of at least 1 metre per second, with peak output at 2.5 metres per second. Three turbines are running so far, and the company says 100 of them should produce about 1.5 gigawatt hours a year. The host does not skip the caveats. The studies on fish safety lean on lab and modelling work rather than direct field measurement at the plant, turbine noise has no published data yet, and the turbines do slow the river slightly, which is itself a change to the ecosystem. He also flags that drought could cut output, as low rivers have already done to nuclear plants in France. Potential is the open question. Hydropower is considered close to tapped out across much of the West, yet the energy fish could open river stretches that conventional plants cannot touch. The flow has to cooperate, though. The Elbe, one of Germany's largest rivers, averages about 0.83 metres per second, below the threshold the turbines need, even if some faster sections would qualify.
Bottom line: This is the rare clean-energy story where the economics are not the weak point. Constant power at solar-competitive prices, with no dam and a small physical footprint, is a genuinely useful combination, especially for places with the right river flow and no room for more solar or wind. The honest limits are real: it only works where the current is fast enough, the fish and noise data needs proper field study, and droughts are a growing risk. But the worst case is a niche technology that quietly powers a handful of locations cheaply, and that is still a win. Watch whether Energy Miner can scale past a few turbines without the ecological numbers turning sour.