cause an explosion (Furat et al. 2020). Therefore, as with all fuels, hydrogen as a fuel
poses some degree of danger, and the safe use of any fuel focuses on avoiding
situations where there are the three combustion factors: ignition, oxidant, and fuel
(Furat et al. 2020). Some of the hydrogen properties, however, require additional
engineering controls to ensure their safe use, for example, a wide range of flammable
air concentrations (4–75%) and lower ignition energy (only one-tenth of fired
energy) (Tabkhi et al. 2008). Additionally, when choosing materials, the embrittlement of metal hydrogen and the potential for material damage at the leakage point
require consideration for the hydrogen storage cycle (Ayas et al. 2015; Liu et al.
2017). Key elements are training in safe storage and handling procedures to ensure
the safe use of hydrogen (Robertson et al. 2015; San Marchi et al. 2017), a detailed
understanding of the hydrogen properties, and the implementation of safety features
in hydrogen systems. The US Department of Energy reported on its website (Furat
et al. 2020): “As more and more demonstrations of hydrogen take place, the
hydrogen safety record will expand and set the expectation that hydrogen will be
as safe as today’s common fuels.”
4.5 Hydrogen Properties
At a higher heating value, the hydrogen energy content is 141,8 MJ/kg at 298 K, and
the lower hydrogen heating value is 120 MJ/kg at 298 K which is much higher than
other fuels (e.g., at 298 K gasoline 44 MJ/kg) (Vincent and Bessarabov 2018; Parra
et al. 2017). However, liquid hydrogen has a lower energy density volume than
hydrocarbon fuels such as gasoline by about a factor of four (i.e., 8 MJ/L density,
while oil is 32 MJ/L density) (Parra et al. 2017). Though hydrogen gas has a high
weight-by-weight energy density but a low volume-by-volume energy density
compared to hydrocarbons, it therefore requires a larger storage tank. Hydrogen is
a flammable gas with a relatively low ignition temperature, which creates a significant portion of the risk associated with its use; however, due to its small molecule
size and destructive potential (hydrogen embrittlement), it has the capacity to escape
through materials, which can lead to mechanical deterioration and failure to the point
of leakage in some products (Furat et al. 2020; Zainul et al. 2020; Broom and Webb
2017; Matthias et al. 2019).
4.6 Renewable Biomass Sources for Biohydrogen
Production
There are five major types of renewable energy sources, biomass, flowing water,
electricity generation, wind, and sun, within the earth (Kiriaki et al. 2020). Those
renewable energy sources can be used as the raw material for producing bioenergy.
4 Biohydrogen Production from Biomass
83
poses some degree of danger, and the safe use of any fuel focuses on avoiding
situations where there are the three combustion factors: ignition, oxidant, and fuel
(Furat et al. 2020). Some of the hydrogen properties, however, require additional
engineering controls to ensure their safe use, for example, a wide range of flammable
air concentrations (4–75%) and lower ignition energy (only one-tenth of fired
energy) (Tabkhi et al. 2008). Additionally, when choosing materials, the embrittlement of metal hydrogen and the potential for material damage at the leakage point
require consideration for the hydrogen storage cycle (Ayas et al. 2015; Liu et al.
2017). Key elements are training in safe storage and handling procedures to ensure
the safe use of hydrogen (Robertson et al. 2015; San Marchi et al. 2017), a detailed
understanding of the hydrogen properties, and the implementation of safety features
in hydrogen systems. The US Department of Energy reported on its website (Furat
et al. 2020): “As more and more demonstrations of hydrogen take place, the
hydrogen safety record will expand and set the expectation that hydrogen will be
as safe as today’s common fuels.”
4.5 Hydrogen Properties
At a higher heating value, the hydrogen energy content is 141,8 MJ/kg at 298 K, and
the lower hydrogen heating value is 120 MJ/kg at 298 K which is much higher than
other fuels (e.g., at 298 K gasoline 44 MJ/kg) (Vincent and Bessarabov 2018; Parra
et al. 2017). However, liquid hydrogen has a lower energy density volume than
hydrocarbon fuels such as gasoline by about a factor of four (i.e., 8 MJ/L density,
while oil is 32 MJ/L density) (Parra et al. 2017). Though hydrogen gas has a high
weight-by-weight energy density but a low volume-by-volume energy density
compared to hydrocarbons, it therefore requires a larger storage tank. Hydrogen is
a flammable gas with a relatively low ignition temperature, which creates a significant portion of the risk associated with its use; however, due to its small molecule
size and destructive potential (hydrogen embrittlement), it has the capacity to escape
through materials, which can lead to mechanical deterioration and failure to the point
of leakage in some products (Furat et al. 2020; Zainul et al. 2020; Broom and Webb
2017; Matthias et al. 2019).
4.6 Renewable Biomass Sources for Biohydrogen
Production
There are five major types of renewable energy sources, biomass, flowing water,
electricity generation, wind, and sun, within the earth (Kiriaki et al. 2020). Those
renewable energy sources can be used as the raw material for producing bioenergy.
4 Biohydrogen Production from Biomass
83