Recently, the need has grown stronger for municipal solid waste incinerators (MSWI) that reduce energy and resource use and help prevent global warming in order to contribute to the advancement of societies with low-carbon emissions and sustainable material cycles. In this study, we compiled and evaluated operation data from MSWIs in order to develop an evaluation method for their adoption for such societies. From these results, we found benchmark indicators such as the amount of input energy, the ratio of output energy (electric power sold, heat supply), and the ratio of discharged residue. We evaluated 97 MSWIs with high power generation efficiency using these benchmark indicators. The results showed the value of using these benchmark indicators. In addition, we proposed a method for scoring and showing the results to make them easily understood.

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Biomass utilization technologies are demanded as effective means of greenhouse gas emission reduction. Over a long term, we evaluated gasification methanol synthesis technologies that use wood biomass, such as scrap wood, for the purpose of demonstrating its technical reliability and stability in operation. The demonstration produced approximately 5,000L of methanol during a total of 2,500 hours operation, including 1-month of continuous operation. Operation was stable and could produce approximately 40-50L of methanol per day during the 1-month of continuous operation. We were able to confirm the stability and reliability of the facilities. The methanol produced was as clear as water and no contaminants were seen. The purity was stable at approximately 95% and other than methanol was mainly water. In the methanol synthesis reaction, even with the same H₂/CO ratio, the higher the CO concentration the more the rate of methanol transformation from CO increased. The partial pressure of H₂ was also important for increasing the rate of methanol transformation from CO.

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In recent years, various organic wastes, including kitchen garbage, have been used as raw materials for compost. Therefore, the evaluation of compost quality has become more important. Maturity is one of the most important qualities of compost. However, no generic single index or standardized method to combine several indices has been established to evaluate the maturity of various types of composts. In this study, the integration of several maturity indices was examined as an alternative method to the traditional approach of developing a single index.
A variety of compost samples of different raw materials and maturity degree were collected and used for the measurement of several maturity indices. In some cases, the comparison of multiple indices for the same compost sample did not result in consistent evaluations. Principal component analysis, which is one method to integrate data with multiple indices, was applied to find integrated indices, and the first principal component and the distance were proposed as integrated indices and evaluated. These indices surpassed the inadequate evaluation from multiple single indices described above, and they can be thought to be more wide use for the evaluation of compost maturity.

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In agriculture, most stems and leaves are disposed of as waste after harvesting. In this study, we aimed to demonstrate the effectiveness of tomato stems and leaves as a pellet material, and investigated the suitable moisture percentage of the stems and leaves, as well as measured heat values and conducted combustion tests in order to pelletize tomato stem and leaf wastes. When the wastes of tomato stems and leaves that were pelletized were 11% wet, then the pellets were approximately 8% wet. Although 100% of the tomato pellets could not be combusted continuously due to residual combustion ash, it was possible to combust them by mixing 80% wood pellets and 20% tomato pellets. The low heating value of the mixture of 80% wood pellets and 20% tomato pellets was 17.0MJ/kg, which was the same level as just wood pellets. This indicates that tomato pellets can be utilized as an energy source.

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Currently in Japan, there is a critical need for appropriate disposal management of vast amounts of disaster waste generated by the Great East Japan Earthquake that occurred on March 11, 2011. As matters now stand, although waste is being collected from across the devastated areas of eastern Japan and moved to primary and secondary provisional waste yards, sufficient practical waste disposal work is still not being carried out and it is necessary to propose waste disposal guidelines for speedy rehabilitation and reconstruction. In this study, we quantified the environmental impact with respect to the tsunami debris generated by the Great East Japan Earthquake (the quantified environmental impact is defined as the severity of environmental impact) and further, by incorporating a timescale, we discussed appropriate disposal flow from both the enviro-economic and time-axis viewpoints. As a result, we conclude that promotion of broad-based disposal and waste reuse is important from the comprehensive aspect of environmental impact and time.

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