Hydropower Plants – Garbage Disposals for Creeks and Rivers
Bernhard O. Voelkelt
Garbage, that is carelessly thrown out of a car window, that is lost during a stroll through nature, or that is deliberately disposed off in the environment, does not stay stationary. Wind, rain, animals and human beings move garbage. In particular small, round and light refuse is quick to travel until it reaches a waterway. A creek, a river, and a stream, the grey-brown waters cloak the garbage until it reaches a hydropower plant.
Along the way, garbage passes many stations where it can cause damage to the environment. Yes, even animals are at risk of injury or death by carelessly dumped trash. The toad inside a 5 gallon plastic canister – the lid is open but out of reach; the trout stuck inside a plastic ring of 1 inch diameter; or, the hedgehog trapped inside an open food can, are evidence of the potential dangers. Unfortunately, not enough stomachs of wild animals are examined to determine if the animals ate garbage and had suffered from the consequences.
With their water-rakes, that are purchased primarily to hold back floating waste and natural products – leaves, branches, tree trunks, hydropower plants function like giant garbage funnels and filters. Once floating waste reaches a typical bypass hydropower plant, there are only two paths for it to continue it’s travels. One way is dictated by the main current of the water and leads directly to the power plant’s rake. The second route leads through the “rest water exit” in the weir and into the original river bed. One can safely assume that about 90-95% of the floating waste reaches the power plant.
For a power plant operator there are two options to get a grip on the garbage situation. The first is to cumbersomely separate the landed material by hand into groups of bio-degradable, recyclable, and non-recyclable waste. The second option is to guide the floating garbage to the spill weir with the help of floating barriers – such as entire trunks of Douglas Fir, in order to keep it at a distance and in the river.
Addendum - 2011
The great Atlantic and Pacific Garbage Patches http://en.wikipedia.org/wiki/Great_Pacific_Garbage_Patch receive some of their plastic trash from rivers discharging waste into the oceans. This could be mitigated to an extend by society giving support and a special mandate to power plants to collect drifting garbage.