LIFECYCLE GREENHOUSE GAS EMISSIONS AND ENERGY BALANCES OF SUGARCANE MOLASSES

Abstract

Many countries have promoted biofuels to address energy security, environmental concerns as well as to improve the socio-economic well-being of rural people. This paper evaluates lifecycle net greenhouse gas (GHG) emissions, energy consumption and energy balances in the production chain of sugarcane molasses-based bioethanol in Kenya. Sugarcane molasses-based bioethanol production involves sugarcane cultivation, cane milling, bioethanol conversion, co-generation and wastewater treatment. The study used economic allocation to partition GHG emissions and energy inputs between sugar and molasses. The lifecycle GHG emissions were estimated at 270.87 gCO2eq per litre of bioethanol produced. The total energy consumption was evaluated to be 22.39 MJ per litre of bioethanol produced. The energy balances calculated values per litre of bioethanol were; net energy value (NEV) = -1.19 MJ, net renewable energy value (NREV) = 19.75MJ and net energy ratio (NER) = 14.62. The negative value of NEV indicates that to produce a litre of bioethanol require greater energy than its energy content. The high positive values of NREV and NER indicate a low amount of fossil fuels are required to produce a litre of bioethanol. Sensitivity analysis on the effects of bioethanol yield and price of molasses on GHG emissions and NER was performed. The study found GHG emissions and NER to be sensitive to bioethanol yield and price of molasses. The results of this study were compared to results of molasses based bioethanol obtained in other countries.