Global production of biomass and biofuel are growing rapidly, due to the increases in the price of fossil fuels, growing environmental concerns, and considerations regarding the security and diversification of energy supply. However, the production of biomass energy crops and removal of biomass residues from forest and agricultural systems for energy production can result negative environmental, economical, or social impact. Therefore, sustainable development of biomass and biofuel are the major issue in order to increase the production of biomass and biofuel. This paper aims to review the current assessment study on sustainable development of biomass and biofuel, especially about social impact which is not widely known comparing with environmental and economical impact. Furthermore, the key factor of social impact assessment on sustainable biomass and biofuel development is analyzed in order to apply the result of assessment for development of biomass and biofuel certification and planning of energy policy.

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Willingness to pay for environment soundness in voluntary base by Japanese people was analyzed. The analysis was based on two mail surveys. Respondents were asked their willingness to pay for green electricity through dichotomous choice with follow up questioning by the first survey launched in 2000. In the second survey launched in 2001-2002, respondents were asked their willingness to pay for small co-generation systems installed at their residences. The difference in the amounts of willingness to pay was small between the two surveys. The amounts of willingness to pay were estimated to be about 1,900 yen a month for a household in both surveys. Effects to willingness of household income and other factors were evaluated. The estimated parameters suggested that the household income affects the willingness, but the relationship was not so simple. As the income increased, the willingness increased stepwise and the household could be divided into three classes. The knowledge and support willingness for the reduction of green house gases emission arranged in Kyoto protocol were questioned moreover, and the relationship between those answers and willingness to pay for environmentally sound goods was revealed to be strong.

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Food waste as biomass resources is discharged by about 20 million ton per year in Japan. To reduce and recycle food waste is social demand today. However, the food waste that is not recycled is as much as 16 million ton, only a small part of food wastes being recycled. The main reason for this low recycle rate is its high moisture content. Drying the food waste requires more energy than the waste itself possesses, which makes energy use of food waste difficult. To circumvent this problem, supercritical water can be applied. In supercritical water, the organic compounds are gasified easily into hydrogen and methane. For this process, drying is not necessary since the reaction takes place in water. In this study, we developed continuous-flow equipment for gasifying food waste in supercritical water with nickel catalyst, which is known to promote water-gas shift reaction. First, we gasified glucose to determine the reactor characteristics of the equipment. Then based on this result, we successfully gasified model food waste of 1 wt%-dry matter at 723 K, 25 MPa. It was found that application of enzyme is effective for smooth feeding of food waste.

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