Small-scale biomass gasification CHP utilisation in industry: energy and environmental evaluation

Biomass gasification is regarded as a sustainable energy technology used for waste management and producing renewable fuel. Using the techniques of life cycle assessment (LCA) and net energy analysis this study quantifies the energy, resource, and emission flows. The purpose of the research is to assess the net energy produced and potential environmental effects of biomass gasification using wood waste. This paper outlines a case study that uses waste wood from a factory for use in an entrained flow gasification CHP plant. Results show that environmental impacts may arise from toxicity, particulates, and resource depletion. Toxicity is a potential issue through the disposal of ash. Particulate matter arises from the combustion of syngas therefore effective gas cleaning and emission control is required. Assessment of resource depletion shows natural gas, electricity, fossil fuels, metals, and water are all crucial components of the system. The energy gain ratio is 4.71MJ_delivered/MJ_primary when only electricity is considered, this increases to 13.94MJ_devlivered/MJ_primary if 100% of the available heat is utilised. Greenhouse gas emissions are very low (7-15gCO-e/kWh_e) although this would increase if the biomass feedstock was not a waste and needed to be cultivated and transported. Overall small-scale biomass gasification is an attractive technology if the high capital costs and operational difficulties can be overcome, and a consistent feedstock source is available.