[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

dam-l Water power 'fuels climate change'


BBC Online, 31 May 2000
http://news.bbc.co.uk/hi/english/sci/tech/newsid_771000/771465.stm

Water power 'fuels climate change'

By environment correspondent Alex Kirby

   Hydro-electric power, often proclaimed as one of the greenest ways of
generating energy, can be more polluting than coal.
   This is because the reservoirs that power the dams can trap rotting
vegetation, which emits large amounts of greenhouse gases.
   But establishing just how much pollution a particular reservoir will
cause is very difficult, because they vary widely.
   The announcement of this cause of climate change comes shortly before the
next round of negotiations on how to tackle it.
   The discovery of the full greenhouse potential of hydro-electric schemes,
published in New Scientist magazine, was made by the World Commission on
Dams (WCD).

Clean claim

   The commission, a group of scientists, engineers and environmentalists,
is supported by the World Conservation Union and the World Bank, which is
the single biggest funder of large dams.
   Supporters of dams argue that they should qualify for support as a clean
technology under the 1997 Kyoto Protocol on tackling climate change.
   Many scientists believe there is strong evidence to suggest that the
earth's atmosphere is warming, and that human activities - chiefly the
burning of fossil fuels - are a significant cause.
   The WCD will report its findings at a meeting in the German city of Bonn
in June to discuss the Clean Development Mechanism, a key part of the Kyoto
Protocol.
   It says the decay of forests submerged when reservoirs are flooded
produces only a fraction of the two gases involved, carbon dioxide (CO2) and
methane.
   Much more is produced by organic matter washed into the reservoir from
further upstream, a process which may continue for the lifetime of the
reservoir.
   Methane is 20 times more potent as a greenhouse gas than CO2. It is given
off by stagnant water, while running water, which contains oxygen, produces
CO2.

Extensive problem

   So a reservoir will produce more methane than the river which ran before
the dam was built.
   The WCD, which believes the problem is far more widespread than first
thought, says the reservoirs that appear most at risk are shallow ones in
the tropics which have not been cleared of biomass before they were flooded.
   It says one particular cause for concern is the Balbina reservoir in
Brazil, which in parts is only four metres deep.
   Its generating capacity is 112 megawatts, and it is estimated to produce
three million tonnes of CO2 annually over its first 20 years.
   A coal-fired power station of the same capacity would produce 0.35m
tonnes of CO2 a year.
   In French Guyana the Petit-Saut reservoir, which has a similar capacity
and powers the launch site for Europe's Ariane rocket, is expected to
produce 0.9m tonnes of CO2 annually in its first 20 years.

Huge variation

   The WCD has looked at only a few dams in four countries, and thinks there
will be many similar examples.
   But it says one study of nine Brazilian reservoirs found their greenhouse
emissions varied per unit of electricity by a factor of 500.
   It says: "There is no justification for claiming that hydro-electricity
does not contribute significantly to global warming."

BBC Online, 31 May 2000
http://news.bbc.co.uk/hi/english/sci/tech/newsid_771000/771465.stm



--







Doris Shen
International Rivers Network 

1847 Berkeley Way
Berkeley, CA 94703
doris@irn.org   
tel: 510.848.1155 ext. 317      
fax: 510.848.1008
IRN http://www.irn.org IRN China Page http://www.hk-sanxia.org

To learn how you can help stop financing of Three Gorges Dam 
and other destructive projects by Wall Street investment banks 
http://www.floodwallstreet.org