This paper describes the impact on particulate and 'greenhouse gases' emissions of substitution policies implemented by Argentine state-owned electric power stations. Those policies involve the substitution, on the one hand, of hydroelectric and nuclear energy for conventional thermal energy and, on the other hand, of natural gas for fuel oil, diesel oil and coal. As additional investments are required in conventional thermal power stations to prevent environmental pollution, the investment savings generated by substitution policies have been calculated. While the environmental impacts of hydroelectric, nuclear and natural gas facilities is locally significant and is experienced in geographical areas away from cities, there can be no doubt that the substitution policies implemented in the Argentine electricity sector have overall both ecological and economic benefits. (author). 1 ref., 8 figs, 2 tabs.