Researchers at Technische Universitaet Muenchen (TUM) have developed a small-scale hydroelectric power plant that solves a number of problems. The construction is so simple, and thereby cost-efficient, that the power generation system is capable of operating profitably in connection with even modest dam heights. The system is concealed in a shaft, minimizing the impact on the landscape and waterways. There are thousands of locations in Europe where such power plants would be viable, in addition to regions throughout the world where hydroelectric power remains an untapped resource.
Why so many places to use this idea? The new power plant design is capable of operating economically given a low “head” of water of only one to two meters, just under 80 inches for the non-metric world. This isn’t much water drop.
The power plant, most of which lies concealed below the riverbed, is designed to let fish pass along with the water. The internal design is also remaining concealed with the available photos much less than explanatory. Proprietary for sure, but an idea of the design would be supportive. One assumes the press release is about invitations to see the lab unit in operation.
The idea of low head power has been around since the start of hydro generation. Hydro generation might have peaked at the Hoover Dam where the view from the bottom at the water’s exit up to the top explains “head” rather dramatically. Getting worth while power from a mere two meters or just 7 feet is an accomplishment of note. In reality the device has to be really simple, easy to install and low cost. The power at these water drop levels isn’t like the Hoover Dam by any comparison.
Meanwhile, the good locations for hydroelectric power plants have long since been developed. In a number of newly industrialized nations, huge dams are being discussed that would flood settled landscapes and destroy ecosystems. In many underdeveloped countries, the funds and engineering know-how that would be necessary to bring hydroelectric power on line are not available.
That makes smaller worthwhile. Smaller power stations still require considerable investment and are also deliver negative environmental impacts. Until the TUM design, the use of hydroelectric power in connection with a relatively low dam height meant that part of the water had to be guided past the dam by way of a so-called bay-type power plant – a design with inherent disadvantages. Bar type designs are all single engineered projects, they are still physically quite large with powerhouses, water diversion and watercourse building. Then there is the fish passing by – bar type plants still have gross negative effects on the wildlife.
The TUM model by Prof. Peter Rutschmann and Dipl.-Ing. Albert Sepp at the Oskar von Miller-Institut, the Research Institution for Hydraulic and Water Resources Engineering incurs very little impact on the landscape. Only a small transformer station is visible on the banks of the river. In place of a large power station building on the riverside, a shaft dug into the riverbed in front of the dam conceals most of the power generation system. The water flows into a box-shaped construction, drives the turbine, and is guided back into the river underneath the dam. This solution has become practical due to the fact that several manufacturers have developed generators that are capable of underwater operation – thereby dispensing with the need for a riverbank powerhouse.
Simple – but the TUM team had additional problems to solve: how to prevent undesirable vortex formation where water suddenly flows downward; and how to best protect the fish. Rutschmann and Sepp solved two problems with a single solution – by providing a gate in the dam above the power plant shaft. In this way, enough water flows through to enable fish to pass. At the same time, the flow inhibits vortex formation that would reduce the plant’s efficiency and increase wear and tear on the turbine.
Here is where the scientists come in with grave reality – The core of the concept is not optimizing efficiency, however, but optimizing cost: Standardized pre-fabricated modules should make it possible to order a “power plant kit” just like ordering from a catalog.
Prof, Rutschmann says , “We assume that the costs are between 30 and 50 percent lower by comparison with a bay-type hydropower plant.” The shaft power plant is capable of operating economically given a low “head” of water of only one to two meters, while a bay-type power plant requires at least twice this head of water. Series production could offer an additional advantage: In the case of wider bodies of water, several shafts could be dug next to each other – also at different points in time, as determined by demand and available financing. Investment in hydro generation has entered a new phase, which might not be so noticeable as the huge dams with lakes inundating regions of productive land.
The European Union also has its own environmental issues gathering capital and forcing change. The EU Water Framework Directive stipulates that fish obstacles are to be removed even in smaller rivers. In Germany’s Bavaria alone, there are several thousand existing transverse structures, such as weirs, that will have to be converted, many of which also meet the prerequisites for shaft power plants. Construction of thousands of fish ladders would not only cost billions but would also load the atmosphere with tons of climate-altering greenhouse gas emissions. If in the process shaft power plants with fish gates and additional upstream fish ladders were installed, investors could shoulder the costs and ensure the generation of climate-friendly energy over the long term – providing enough power for smaller communities from small, neighborhood hydroelectric plants.
It all sounds so, well – satisfying. But it’s a long way from a lab demonstrator to a caisson filled with generator equipment installed in a running river or stream and operating for generations. That’s going to require considerable sophistication. Rutschmann notes, “Distributed, local power generation by lower-cost, easy-to-operate, low-maintenance power plants is the only solution. For cases in which turbines are not financially feasible, Rutschmann has already come up with an alternative: “It would be possible to use a cheap submersible pump and run it in reverse – something that also works in our power plant.”
That sounds more practical in the third world. Once the structure is in the generation set could be upgraded as the economics improve. For that matter a full dam isn’t actually needed, just a shaft long enough to get the head or water drop distance far enough to extract the energy.
The TUM idea looks quite good as a starting point for a lot of innovation. Not making huge environment and habitat destruction a part of the energy harvest is another huge bonus. The idea is, well – satisfying. Lets encourage its progress.