Abstract:
Environmental concerns and the increasing demand for transportation energy have led to increased production and utilization of biofuels worldwide. Biofuels are perceived to provide clean and green energy. Globally, bioethanol is the most widely used biofuel. This study considered the production of bioethanol from sugarcane molasses. The production of bioethanol from molasses does not pose threat to food security as molasses is a by-product in the manufacture of sugar from the sugarcane. This study aimed to determine the environmental impacts associated with production bioethanol from sugarcane molasses in Kenya from a lifecycle perspective. The environmental impact categories evaluated included Global Warming (GHG emissions), Acidification, Eutrophication, Human Toxicity, Ecotoxicity and Photochemical oxidant Formation. Data was collected in all stages of the life cycle of bioethanol production. These include sugarcane cultivation, harvesting, transportation, cane milling, bioethanol conversion and wastewater treatment. The data was collected during field visits at Mumias Sugar Company and Spectre International. In the study, an inventory analysis was performed which involved quantification of emissions from each stage using models and emission factors from literature. Emissions were also obtained from Ecoinvent databases for the major processes as well as their supporting processes. Economic allocation was used to partition emissions and resources between molasses and sugar. A life cycle impact assessment (LCIA) was performed in Chain Management by Life Cycle Assessment (CMLCA) software. The characterization method that was used to calculate the environmental impacts of bioethanol was the CML-IA. Low values of Global Warming Potential (GWP), Acidification Potential (AP), Eutrophication Potential (EP), Human Toxicity Potential (HTP) and Photochemical Ozone Creation Potential (POCP) were obtained in this study. Emissions emitted due to fossil fuel use, production and use of agrochemicals were found to be the major contributors to environmental impact. The study recommends use of cane trash, bagasse and stillage as supplement fertilizer and boiler fuel. This will reduce dependency on fossil fuels and chemical fertilizers which impacts negatively on the environment.
