[en] This paper quantifies the benefits attributable to hydroelectric power generation in preventing carbon dioxide emissions from the use of thermal plants. It proposes that utilities and funding agencies consider the societal costs associated with the emission of CO₂ in power system planning. It also suggests that the industrialized countries should consider changing their funding practice and give more appropriate credits for the construction of hydro plants in developing countries, with a view to avoiding the construction and operation of fossil fuelled powerplants. (author)