Near the German town of St. Goar on the river Rhine, KSB Aktiengesellschaft, has put two river turbines into operation. These convert the energy of the river water into electric power and feed that into the power supply system. To do this, there is no need for any water to be impounded or diverted.
Obviously they do not generate as much electricity as a traditional hydro power scheme with a head of water driving a Frances turbine but the environmental impact is much reduced. KSB haven’t indicated the power output from their turbines but I wouldn’t expect them to be any more than a couple of hundred watts, possibly enough to power a small house or two, or perhaps some more if they are passivhauser.
As an isolated installation, they do not affect fish nor do they affect navigation on the river although the aggregate effect of several installations has not been fully assessed. Depending on the layout of turbines, flows across the river or along the river may be affected especially during storm flows where the effect of the turbines could lead to flooding or scour of the river bed and an accumulation of poorly sited turbines could have an effect on the riparian ecosystem. Such large numbers of turbines would be required to have a significant impact on reducing our dependence on fossil fuels. KSB note that “In Germany alone, one could potentially generate hydropower in the range of 6.8 TWh per year – without cross-structures, i.e. without major changes to the natural landscape.” (compare with Germany’s total electricity consumption of half a million TWh per year) which would require around 4000 200W turbines.
Installation of a river turbine made by KSB in an arm of the river Rhine at St. Goar.
I don’t like to be dismissive of what is clearly a renewable energy source with limited environmental impact which can generate a constant base load of electricity, but unless our total electricity consumption drops dramatically, it will remain little more than a token gesture. However, there may be an opportunity to develop this concept in developing countries, particularly in remote areas, where grid connections are unavailable and demand can be limited.