Burning Methane Could Improve Hydro-Electric Power
by Matthew Sparkes, London, UK on 05.10.07
Hydro-electric dams can often cause significant damage to the environment by releasing methane into the atmosphere. Bacteria break down organic matter on the bottom of lakes and reservoirs, producing the natural gas. When intake pipes for hydro-electric plants suck this methane rich water or matter up, they release the gas into the air. It’s the reason for much controversy surrounding what is often thought of as a green source of power. In fact, some critics believe that certain dams contribute more to climate change than a fossil fuel plant would.
However, hydro-electric power could be about to become a lot greener. Scientists in Brazil claim that capturing and burning this surplus methane is possible, and are developing a prototype to do just that. If it works, then it’s estimated that the technique could lower emissions by the equivalent of a years total of fossil fuel consumption in the UK. Some dams with an especially heavy methane problem could increase their output by up to 50%.
Dr Ramos of the National Space Research Institute, where the research originated, told the BBC, "we cannot hide from this problem; you have to address it. In fact, it's better to recognise there is a problem today, and to use this methane that is there as a commodity, harvest it to produce energy." :: BBC
They need a gigantic pool-cleaning robot !
They could vaccuum all the gunk off the bottom and use it as fertilizer.
Very cool technology.
About methane, I've always wondered why they don't clear cut areas and remove the organic matter before flooding it. Maybe before we knew about global warming it didn't seem to make sense, but now I hope that new hydro projects will do that.
Hmmm... clear cutting to be more enviromentally friendly.
That's funny.
"Hmmm... clear cutting to be more enviromentally friendly.
That's funny."
In the context of leaving that organic matter to rot at the bottom and release large quantities of methane, that's certainy funny but eco-friendly ;)
A major public fallacy has developed as a result of reporting on the reservoir/methane connection. Northern temperate zone lakes, as one normally encounters in Minnesota through Maine and into Canada, are thermally stratified through the middle to end of summer, with coldest water found on the bottom. Logs which sunk into these lakes the 1880's are sitting there "water logged", and only barely decayed upon the surface, such that they can be extracted and cut for timber. The marls on such lakes can be several meters deep, reflecting a very slow decay rate indeed. Significant methane production occurs only late July through early October, unlike in more southerly lakes and reservoirs which are much warmer. It is also important to keep in mind that the acid environments found in northern peat/cranberry bogs is such that decay is also very much inhibited, such that methane formation is suppressed.
Finally, we should be aware that siltation of reservoirs comes not only from what is left behind during construction but also from siltation caused by upstream logging and sloppy farming practices that cause soil erosion and silt transfer. Eventually, many of these reservoirs become so silt filled they must either be drained and dredged or abandoned. The preferred management technique then ought to be one of watershed stabilization first, and methane capture second.
Brazilian people in the north where two hydroelectric dams are being proposed are very much against the projects because dams produce stagnant water and malaria. I don't think scientists in Brazil are considering the potential harm of these dams.
adrianakau@aol.com
Regarding the idea to clear areas prior to flooding: I understand the ideas behind this suggestion, but there are two key issues.
Firstly, the areas flooded are often huge, and the definition of organic matter includes everything organic - trunks, leaf litter, etc. clearing would involve leveling a huge area *and* removing the organic matter from the ground (which would mean a fair amount of the top layer of the floor of previously untouched areas). It would take a lot of money and a hell of a lot of (fossil) fuel to clear these massive areas.
Secondly, the issue is not only existing organic matter, but ongoing organic contributions. At its most obvious, this includes any leaves or branches that fall into the water of the dam or (perhaps more importantly) any of the many tributaries whcih carry water and anything in it to the dam. In addition, though, the fact that the water level in a dam rises and falls, often over shallow regions (which cover a large area of land) means that during low level times, rich soil is exposed, leading to a lot of growth on those areas. When the rains come and the level rises, this organic matter is flooded, often dies, and begins to rot, releasing methane.