Environmental benefits including carbon dioxide emissions reduction effects of fuel cell vehicles (FCV) and sucrose- and starch-based bio-ethanol fuel production are evaluated in this paper, together with an exploration of their potential adverse environmental side-effects, taking into account that FCV technologies will change as we learn more about them, and that fuel production is dependent on regional cultivation conditions. Three variations of life cycle impact assessment methodologies are applied: EPS 2000, Eco-indicator 99, and LIME ver. 1. Results of the assessments include: (1) while the net environmental benefit of a 90 kW-capacity FCV fueled by hydrogen produced from natural gas evaluated with EPS 2000 is negative even on an assumption of optimistic technological learning meeting the platinum requirement, the negative result can be reversed by a reasonable shift of hydrogen source and vehicle downsizing; and (2) regarding bio-ethanol production, although it seems difficult to achieve a net positive environmental benefit under any actual farming conditions according to the assessments with Eco-indicator 99 and LIME ver. 1, increasing crop yield with moderate additional fertilizer use is expected to increase the net environmental benefit. The paper also notes a concern about a global phosphorus supply problem that might be caused by a large-scale bio-crop plantation induced by a stringent carbon emissions target.

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An economic evaluation for the feasibility study on energy production by supercritical water gasification (SCWG) with layer poultry manure suspended activated carbon catalyst was conducted. Two systems, basic and improvement, were designed. The basic system is considered only energy product usage by the product gas is converted to electricity. The improvement system is involved by-product utilization processes of SCWG effluent, resulting recycle of activated carbon catalyst and recover of calcium phosphate, ammonium sulfate and potassium sulfate. The material and economic balance of the basic and improvement system was estimated. Under the conditions assumed here, economic balance of the basic system is negative even large scale. In case of the improvement system, profitable line was 35.5 t/d scale of layer poultry manure feed.

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