Roles and Challenges of Waste Biomass Utilization to Carbon Neutral Society

Abstract

This article aimed to summarize the roles and challenges of waste biomass utilization to carbon neutral society. As of 2015, 250 million tons of waste and unused biomass was generated in Japan, of which 70.6% were recycled. Historically, waste biomass, as a renewable energy, is expected to reduce greenhouse gas （GHG） emission and contribute to the development of a sustainable society and revitalization of the regional economy. Carbon neutral society is one of the elements of a new concept of Regional Circular and Ecological Sphere （R-CES）, which was proposed under the 5th fundamental environmental plan in 2018. Utilization of waste biomass plays a major role in the development of R-CES. Under the mid- and long- terms scenario in waste sector for achieving a carbon neutral society proposed in August 2021, material replacement with biomass based materials and energy recovery with high efficiency from waste biomass were introduced as non-energy and energy originated CO₂ reduction measures, respectively. The challenges of estimating GHG emission and reduction on the basis of waste biomass utilization in carbon neutral society are; 1）shifting from energy based substitutions to material based ones with high added values, 2）having a more exact understanding of fossil derived carbon fraction contained in waste biomass, and 3） describing carbon stocks and flow, which may become complicated in the future.