Development of a small size gas engine using biomass gaseous fuel (combustion characteristics of low calorific gaseous fuels)

Biomass resource is one of the attractive alternative fuels. It is efficient method to use it in distributed power generation system with gas engine because it disperses. However, its calorie is low, and gas composition is affected by resource, gasification method and gasifying conditions, it will change momentarily during engine operation. Gas engine is needed to be stable and high thermal efficiency operation under these fluctations. The objective of this study is to develop a small size gas engine system for biomass gaseous fuel. In this paper, effect of fuel composition on combustion was clarified by engine experiment with low calorific gaseous fuel. Diluted fuel made longer combustion duration and lower thermal efficiency, but it was not necessarily in lower calorie fuel. It was also confirmed that spark timing control against fuel composition fluctuation was efficient method to keep high thermal efficiency.