A System Analysis of Greenhouse Gas Reduction for the Bio-cycle Project in Kyoto

Nakamura, K.; Hori, H.; Deguchi, S.; Hirai, Y.; Sakai, S. (2008) Proceedings of the 5th International Conference on Combustion, Incineration/ Pyrolysis and Emission Control, pp. 767-772

The biomass available in Kyoto City was estimated to be 2.02 × 106 t-wet/yr (0.14 × 106 kL/yr oil equivalent), of which waste paper, waste timber, food waste, unused forest tree, and sewage sludge account for the largest amounts on an energy basis. Based on Kyoto's regionally specific biomass potential and its historic use of biomass, we started the "Kyoto-Bio-Cycle Project" in 2007. The objective of this project was to synergistically enhance the effects of greenhouse gas (GHG) countermeasures, through greening of necessary materials such as methanol and the cyclic use of byproducts, with "Kyoto City's project for the manufacture of biodiesel fuel from used cooking oil" as the core activity. Two technologies are being developed as part of the project. One is technology to synthesize methanol with the gas generated from the gasification of woody biomass. Through the use of this biomass-derived methanol ("green" methanol), totally carbon-neutral BDF can be manufactured from waste cooking oil and previously unused poor quality oils and fats. The other technology is a high efficiency biogasification system that treats food waste, waste paper, and waste glycerin. This system can improve the production rate of biogas and reduce the residue produced in fermentation tanks through the introduction of hyper-thermophilic hydrolysis in the thermophilic dry anaerobic fermentation process. Our system analysis indicated that, by collecting and recycling plastic packaging waste and introducing these new technologies in Kyoto City, GHG emissions would be reduced by 60% as compared to the current method of incinerating waste wood, cooking oil, and other combustibles such as plastics. Additionally, if these demonstration technologies were used throughout Japan, we estimated the reduction effect to be 3.5 X 106 t-CO2/yr (equivalent to 1/20 of Japan's GHG emission reduction target of 6%).


biodiesel fuel; methanol synthesis; anaerobic fermentation; thermophilic hydrolysis; greenhouse gas reduction