A critical view on the eco-friendliness of small hydroelectric installations

Renewable energy sources are widely perceived as 'clean', 'green', and 'inexhaustible'. In recent years the spectre of global warming and ocean acidification, which has been primarily attributed to fossil fuel burning, has brought renewable energy at the forefront of most climate change mitigation strategies. There is strong advocacy for large-scale substitution of conventional energy sources with the renewables on the premise that such a move would substantially reduce environmental degradation and global warming. These sentiments are being echoed by scientists and policy makers as well as environmental activists all over the world. 'Small hydro', which generally represents hydroelectric power projects of capacities 25 MW or lower, is one of the renewable energy options which is believed to be clean and sustainable even as its bigger version, large hydro, is known to cause several strongly adverse environmental impacts. This paper brings out that the prevailing perception of 'eco-friendliness' of small hydro is mainly due to the fact that it has only been used to a very small extent so far. But once it is deployed at a scale comparable to fossil fuel use, the resulting impacts would be quite substantially adverse. The purpose is not to denegrade small hydro, less so to advocate use of fossil fuels. It, rather, is to bring home the point that a much more realistic and elaborate assessment of the likely direct as well as indirect impacts of extensive utilization of this energy source than has been done hitherto is necessary.