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D. Hara et al.
35.1 Introduction
Hydrogen is an attractive fuel alternative to fossil fuels and electricity for mobility
technology. It has been estimated that the entire hydrogen demand of the world will
expand from seven trillion Japanese yen in 2015 to 160 trillion Japanese yen in 2050
(NIKKEI BP Clean Tech Institute 2013). Moreover, it has also been reported that
fuel cell vehicles (FCVs) will account for approximately 60.00% of the hydrogen
demand in 2050 (NIKKEI BP Clean Tech Institute 2013). This supports the high
expectations for hydrogen as a fuel for mobility.
Hydrogen can be produced from local resources including biomass with low
energy density, scattered around an area. That is, biomass-derived hydrogen can
contribute to local production for local consumption as well as the abatement of CO 2
emissions. In addition, hydrogen can be stored in tanks by various storage methods
and efficiently converted into power using Fuel cell (FC) systems. FC systems can
also be operated using hydrogen fuel from renewable sources. For these reasons,
the promotion of FC mobility such as vehicles, forklifts, and assisted bicycles, is
potentially considerably significant.
In this study, several FC utilization paths for mobility, including biomass derived
hydrogen (Bio-H 2 ) production and storage, were assessed using life cycle assessment
(LCA). Exergy analysis has also been employed because a biomass energy system
involves heat loss due to thermodynamic irreversibility throughout the process and
mobility should occur under atmospheric conditions. That is, it is necessary to identify
the less effective subsystem.
Therefore, hydrogen fuel of woody biomass feedstock or sewage sludge origin was
included in this study. As noted in our previous studies, the CO 2 equivalent intensity
of Bio-H 2 use had lower global warming potential (GWP) that of woody biomass
use (Kondo et al. 2018). Moreover, on-site hydrogen production using sewage sludge
shows good potential due to the beneficial environmental impacts of both feedstock
characteristics and lack of hydrogen transportation.
After production, hydrogen has to be stored in a tank under high- or low-pressure
conditions. Considering the environmental impacts of this step, we focused on a
storage system under a lower pressure condition. That is, a suitable utilization system
using metal hydride (MH) was discussed. The energy density, on the basis of the total
weight of H 2 being stored, is an important issue. Compared to a conventional lithium
ion (Li-ion) battery, a higher compression storage tank might be necessary for the
use of H 2 . Inversely, the higher compression status results in damaging eco-burden
because of the larger compression power. This implies that a lower pressure condition
is preferable. MH is one candidate to replace a Li-ion battery and/or a compression
storage tank and can mitigate GWP.
In impact analysis as part of LCA, the abiotic depletion potential (ADP) is an
important index. The rare metals, platinum and/or nickel and others, used in FC
systems impact the ADP index of the system. In addition, according to previous
research, the ADP and other environmental impact categories are similar in terms of
platinum’s placement in each impact category (Duclos et al. 2017). That is, platinum
D. Hara et al.
35.1 Introduction
Hydrogen is an attractive fuel alternative to fossil fuels and electricity for mobility
technology. It has been estimated that the entire hydrogen demand of the world will
expand from seven trillion Japanese yen in 2015 to 160 trillion Japanese yen in 2050
(NIKKEI BP Clean Tech Institute 2013). Moreover, it has also been reported that
fuel cell vehicles (FCVs) will account for approximately 60.00% of the hydrogen
demand in 2050 (NIKKEI BP Clean Tech Institute 2013). This supports the high
expectations for hydrogen as a fuel for mobility.
Hydrogen can be produced from local resources including biomass with low
energy density, scattered around an area. That is, biomass-derived hydrogen can
contribute to local production for local consumption as well as the abatement of CO 2
emissions. In addition, hydrogen can be stored in tanks by various storage methods
and efficiently converted into power using Fuel cell (FC) systems. FC systems can
also be operated using hydrogen fuel from renewable sources. For these reasons,
the promotion of FC mobility such as vehicles, forklifts, and assisted bicycles, is
potentially considerably significant.
In this study, several FC utilization paths for mobility, including biomass derived
hydrogen (Bio-H 2 ) production and storage, were assessed using life cycle assessment
(LCA). Exergy analysis has also been employed because a biomass energy system
involves heat loss due to thermodynamic irreversibility throughout the process and
mobility should occur under atmospheric conditions. That is, it is necessary to identify
the less effective subsystem.
Therefore, hydrogen fuel of woody biomass feedstock or sewage sludge origin was
included in this study. As noted in our previous studies, the CO 2 equivalent intensity
of Bio-H 2 use had lower global warming potential (GWP) that of woody biomass
use (Kondo et al. 2018). Moreover, on-site hydrogen production using sewage sludge
shows good potential due to the beneficial environmental impacts of both feedstock
characteristics and lack of hydrogen transportation.
After production, hydrogen has to be stored in a tank under high- or low-pressure
conditions. Considering the environmental impacts of this step, we focused on a
storage system under a lower pressure condition. That is, a suitable utilization system
using metal hydride (MH) was discussed. The energy density, on the basis of the total
weight of H 2 being stored, is an important issue. Compared to a conventional lithium
ion (Li-ion) battery, a higher compression storage tank might be necessary for the
use of H 2 . Inversely, the higher compression status results in damaging eco-burden
because of the larger compression power. This implies that a lower pressure condition
is preferable. MH is one candidate to replace a Li-ion battery and/or a compression
storage tank and can mitigate GWP.
In impact analysis as part of LCA, the abiotic depletion potential (ADP) is an
important index. The rare metals, platinum and/or nickel and others, used in FC
systems impact the ADP index of the system. In addition, according to previous
research, the ADP and other environmental impact categories are similar in terms of
platinum’s placement in each impact category (Duclos et al. 2017). That is, platinum