The content of carbon and hydrogen in grass biomass and its influence on heating value

Carbon (C), hydrogen (H), and oxygen (O) are the main chemical elements that determine the heating value of fuels. By combustion of biomass, C and H oxidize in an exothermic reaction. The carbon content in biomass is considerably higher (~45 %) than the hydrogen content (~6.5 %). In contrast, the heating value of H is approximately seven times higher than that of C. The more hydrogen per carbon, the lower the oxidation state and the more energy that will be released during the oxidation reaction, which is characterized by C/H ratio. In our study, the highest carbon content was detected in the mixtures (1/3) of tall fescue with osier (46.6 %) and reed canary grass with grey alder (46.9 %), whereas the lowest values were detected in the mixtures (3/1) of tall fescue with hybrid aspen (43.7 %) and reed canary grass with osier (43.4 %). The highest hydrogen content was found in timothy (5.93 %) and birch (6.83 %). In grass biomass, H content was on average 6 % lower than in wood biomass.