Re: electricity power station and environment

Electric power stations come in several forms:
     hydro (water-powered)
     fossil-fuel burning (coal, oil, natural gas)
     nuclear

Each of these types has its own environmental impacts.

Hydro usually uses water held behind large dams.  These dams often
interfere with fish migration and breeding, and halt the seasonal 
variations in water level, with accompanying sediments, that often 
enrich flood plains below the dam. These impacts are primarily local.

Fossil fuel burning plants have the greatest environmental impact of
all types at the present time.  All fossil fuels, when burned, produce
large amounts of carbon dioxide, a "greenhouse" gas.  This contributes
to global warming, which has the potential for producing large-scale
changes in climate and flooding coastal areas.  In addition, burning of 
coal and fuel oil produces sulfur oxides, which are a major factor in
causing acid rain.  So the impacts of fossil fuel burning are felt on
a global scale.

Nuclear plants appear environmental friendly on the surface.  They produce
no carbon dioxide or sulfur oxides, and do not interfere with local
waterways.  The potential danger, however, exists in escape of radiation
through some accident, as happened 10 years ago in Chernobyl in the
Ukraine.  Also, society has not yet dealt with the problem of long-term
storage of the highly radioactive wastes produced by this process.