EMISSIONS FROM HYDROELECTRIC RESERVOIRS AND COMPARISON OF HYDROELECTRICITY, NATURAL-GAS AND OIL

When reservoirs are created, a small fraction of the flooded organic m atter decomposes into humic acids, carbon dioxide (CO2), methane (CH4) , nitrogen, phosphorus, and other elements. The major greenhouse gases produced are CO2 and CH4. For northern projects, Canadian studies on emissions from hydroelectric reservoirs have reached similar conclusio ns: Emissions, including methane, are less than 35 kg CO2 equivalent p er MWh. Using a typical project in northern Quebec as the basis for an alysis, none of the studies dispute the considerable advantages of hyd roelectricity regarding greenhouse-gas emissions. Taking into account all components of energy systems, emissions of greenhouse gases from n atural-gas power plants are 24 to 26 times greater-than emissions from hydroelectric plants. The Freshwater Institute, in the article publis hed in Ambio suggests that emissions from hydroelectric plants could b e a significant source of greenhouse gases (1). This conclusion does n ot apply to most hydroelectric projects for two reasons: First, the Fr eshwater Institute's studies concerned flooded peatlands and shallow r eservoirs that are not typical of most hydro projects; and second, the Institute analyzed a hydro project with a ratio of flooded area to en ergy production that is 6 to 10 times higher than typical projects in Canada.