Among the energy crops, most frequently used at present is the biomass of Miscanthus grass, Sida and willow. The content of raw ash obtained from 1 ton of biomass of the above plants reached, in kgs, 52.5; 59.5 and 31.5, respectively, and that of ash proper – 14.7; 16 and 17, respectively. Assuming the content of ash of particular energy crops as 100%, in the ash of Miscanthus the content of macroelements was 91.9%, including 38.6% of Ca and 33% of K, that of microelements 4.871%, including 3.126% of aluminium, and the content of and heavy metals 0.556%, including 0.375% of zinc; in the ash of Sida the content of macroelements was 89.5%, including 66.3% of calcium and 11.1% of potassium, that of microelements 1.054% including 0.5% of aluminium and 0.412% of iron, and the content of heavy metals 0.267%, including 0.1% of zinc; in the ash of willow – the content of macroelements was 90.8%, including 40.4% of potassium and 32.3% of calcium, that of heavy metals was 1.483%, including 1.342% of zinc, and the content of microelements and others was 2.663%, including 1.288% of aluminium.