Field experiments were conducted from 2008-2010 in Warmińsko-Mazurskie voivodship to analyze the yields of various energy crops. The highest average fresh biomass yields came from maize, lucerne mixed with timothy grass, purple clover mixed with timothy grass, and sweet sorghum. When ranked by dry organic matter yield, maize, miscanthus, lucerne mixed with timothy grass, sida hermaphrodita, and sweet sorghum had the highest yields. The biogas yield varied greatly between crops, with C4 grasses like maize and miscanthus producing the most biogas per hectare. While C4 gr