The method of potential ecological effects assessment understood as decreasing of atmospheric air pollution that results from usage of wood willow biomass as the alternative fuel to coal was presented in the paper. The publication has methodical character and its research base is composed of the set-aside lands in Poland in provinces perspective, obtained from Central Statistical Office of Poland. Ecological effects expressed as not emitting potentially to atmospheric air carbon dioxide in the amount of 13,828,553 tons during a year and sulphur dioxide in the amount of 103,714 tons during a year as well as significant decrease of potential emitting nitric oxide by about 26,274 tons during a year were determined as a result of surveys. Obtained ecological effects are particularly significant in terms of improving atmospheric air quality in our country and also for the sake of necessity to increase the share of energy from renewable sources in the structure of consumption of primary media in Polish energy balance.