Green mass to biogas in Ukraine—bioenergy potential of corn and sweet sorghum

Abstract

In current times, we heavily rely on the use of fossil fuels, which bring negative impacts on climate change; therefore, it is essential to place more focus on all renewable alternatives, especially bioenergy crops. This study is focused on the quantification and evaluation of biogas production from either corn or sweet sorghum, as well as their combination. The field data were obtained from 2013 to 2016 in central Ukraine. The Buswell equation was used for the calculation of the theoretical biogas and methane potential. The results show that corn and sweet sorghum were intercropping and had higher on 8.5–37.8% of green mass, and 9.5–28.7% estimated yield of biogas compared to the single use of these crops. Due to the higher dry matter content, the specific yield of biogas per unit of applied corn silage was higher by 33.7–50.6% compared to sweet sorghum. However, biogas yield was increased by 9.2–13.0% when using a mixture of corn silage and sweet sorghum compared to sweet sorghum alone. Results of biogas and methane yield per unit area show that the highest rates, 10.2 and 5.9 thousand m3/ha, were obtained in the combined growing of hybrids of sweet sorghum Dovista and corn Monica 350. Even though theoretical calculations have some limitations, the gathered results provide essential information on the potential of the examined green mass for biogas potential in Ukraine. Such information are crucial to be known for economic and energy reasons.