Abstract
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.
