Dear EarthTalk: Many people oppose dams because they
change the flow of rivers and affect the migrating
patterns of fish and other species, but aren't they
also a great renewable energy source?
- Ryan
Clark, Milton, Wash.
Hydroelectric dams are among the greenest and
most affordable electricity sources in the world -
and by far the most widely used renewable energy
sources - but they also take a heavy environmental
toll in the form of compromised landscapes,
ecosystems and fisheries. Hydroelectric dams have
been an important component of America's energy mix
since the powerful flow of rivers was first
harnessed for industrial use in the 1880s. Today
hydroelectric power accounts for seven percent of
U.S. electricity generation - and some two-thirds of
the country's renewable power - according to the
U.S. Geological Survey.
Globally, about 19 percent of electricity comes from
hydroelectric sources. The U.S. Energy Information
Administration reports that China is the world's
largest producer of hydroelectricity, followed by
Canada, Brazil and the U.S. Some two-thirds of the
economically feasible potential for hydro power
remains to be developed around the world, with
untapped resources most abundant in Latin America,
India and China.
Of course, despite the
inexpensive and emissions-free power, many
environmentalists consider hydroelectric dams to be
man-made abominations that prevent salmon and other
fish from swimming upstream, divert otherwise
natural riparian settings, and fundamentally change
the character of surrounding ecosystems. Green
groups including American Rivers, Defenders of
Wildlife, Earthjustice, the Endangered Species
Coalition, Friends of the Earth, National Wildlife
Federation and the Sierra Club are pushing the
federal government to mandate the removal of four
dams along the Snake River in Washington State that
help the region have the lowest power-related carbon
footprint in the country. The dams have decimated
once teeming salmon runs, and upstream forest
ecosystems have suffered accordingly.
But the Bonneville Power Administration, the
quasi-federal utility that runs the dams and
distributes the electricity they produce, says that
keeping them going is crucial even as wind plays an
increasingly larger role in the region's electricity
mix. Since hydro power can be generated and released
when most needed, it is an important resource for
backup power when intermittent sources like wind
(and solar) aren't available.
The scheduled removal of two century-old dams on
the Elwha River in Washington State's Olympic
National Park beginning in 2011 may well serve as
test cases for larger dam removal projects in the
Pacific Northwest and beyond. Planners hope wild
salmon numbers will rebound as a result, and that
other wildlife - such as bald eagles and black bears
- will follow suit.
President Obama has committed $32 million to
modernize existing hydropower dams, increase
efficiency and reduce environmental impacts.
"There's no one solution to the energy crisis, but
hydropower is clearly part of the solution and
represents a major opportunity to create more clean
energy jobs," U.S. Secretary of Energy Steven Chu
told reporters last year. "Investing in our existing
hydropower infrastructure will strengthen our
economy, reduce pollution and help us toward energy
independence."
CONTACTS: U.S. Geological Survey, www.usgs.gov;
U.S. Energy Information Administration,
www.eia.doe.gov; Bonneville Power Administration,
www.bpa.gov.
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