Thermoeconomic analysis of a small-size biomass gasification plant for combined heat and distributed power generation

This paper presents the analysis of the thermoeconomic performance of an integrated atmospheric biomass gasifier internal combustion engine and microturbine cycle for heat and distributed power generation. The gasifier technology considered is based on the atmospheric updraft fixed-bed configuration: the gasifier performance was predicted at on-design with a 1-D model, which was previously verified with experimental measurements. The economic situation considered is the Italian scenario, updated to September 2005. In this scenario the electricity from renewables, such as biomass, and heat for domestic heating are awarded the so-called "green certificates", which provide an additional income for the thermal plant for the first eight years of operation. The results show that the reference case of 600 kWe is too small for actual commercial operation, and is of interest only for demonstration purposes. Instead, sizes over 2 MWe are economically sustainable, although their sustainability strongly depends on the district-heating operating hours and the local cost of biomass. Detailed analysis and boundary values are provided.