Technical and economic analysis of different cogeneration systems for energy production from biomass

This paper compares the results of a techno-economic performance analysis of seven plants for energy production from biomass with the aim of identifying the most effective solution. Small (≤250 KWe) and micro (≤100 KWe) size plants were investigated: 50 kWe diesel internal combustion engine coupled with a gasifier and 35 kWe Stirling engine coupled with a gasifier with an overall efficiency of 41.1% and 87.5% respectively, two biomass cogenerators, one of 25 kWe and the other of 100 kWe, 250 kWe Otto internal combustion engine coupled with a gasifier and 250 kWe diesel internal combustion engine coupled with a gasifier and 238 kWe biomass ORC plant. The technical analysis provided calculations for specific biomass consumption, electricity generation, heat produced and overall system efficiency. The economic evaluation was carried on through a discounted cash flow analysis. Data were provided by literature, analysis of case study at Italian and European level, and directly by the manufacturers of cogeneration systems. The results showed that a combined heat and power (CHP) generator is the best solution because it is economically viable with a high NPV and a PBP of five years and also technically performing with a global efficiency of 78.2% and a low biomass consumption.