Analyses of life cycle inventory and business potential of the BLUE Tower process energy system using waste mushroom bed materials

Since the enactment of the Kyoto Protocol, renewable energy technologies have been an attractive subject in Japan. Especially, technologies related to biomass resource use are promising as waste materials in local areas can be reduced or recycled, and the system can turn a profit. In this paper, we describe the biomass energy systems of a cogeneration system (CGS) and a bio-hydrogen production system (B10-H₂) that effectively uses the waste material of a mushroom bed from the viewpoints of CO₂ emission mitigation and business potential. CO₂ emission mitigation was estimated using Life Cycle Assessment (LCA) methodology. Additionally, the moisture content of the biomass materials and/or the transportation distance were considered applying the Monte Carlo simulation. In the case of a processing fee of 15,000 yen/t and a subsidy rate of 50%, CO₂ emissions and energy costs were as follows: CO₂ emissions and the power price through CGS were 20.3 to 34.2 g-CCVMJ and 11.5 to 16.8 yen/kWh. On the other hand, in the case of the B10-H₂ production system, they were 31.9 to 45.8 g-CO₂/MJ and 61 to 81 yen/Nm³.