Hydrogen as Future Energy Carrier - Hydrogen Fuel Cells for Road Vehicles - page 34

high energy densities typical of the traditional liquid fuels (gasoline, diesel, LPG)
used to feed internal combustion engines in passenger cars. Hydrogen infra-
structure scenarios are briefly reported in Sect. 2.2 , while Sect. 2.3 analyses the
potentialities of different on-board storage technologies.

2.1 Hydrogen Production

One of the advantages of using hydrogen as energy carrier is that all primary
resources such as fossil fuels, renewable energy sources (solar, wind, hydro,
geothermic, biomass) and nuclear power could be used for its production [ 4 ]. In
particular, it can be extracted from any substance containing hydrogen atoms, such
as hydrocarbons, water and even some organic matter. Thus, the different tech-
nologies utilize mainly these compounds as starting materials for the final H 2
molecule formation. In addition it can be readily produced from synthesised
hydrogen carriers such as methanol, ammonia and synthetic fuels.
In Table 2.1 , the contributions of the different sources to the current worldwide
hydrogen production are summarized, together with the available technologies
used for each raw material.
Almost half of the hydrogen used worldwide comes from steam reforming (SR)
of natural gas (48%), as it is the most economical route from hydrocarbon feed-
stock. The other contributions to hydrogen production are based mainly on partial
oxidation of refinery oil (about 30%) and coal gasification (18%), whereas only 4%
of the produced hydrogen derives by water electrolysis. The hydrogen is mainly
used to make ammonia for fertilizers, in refineries to make reformulated gasoline,
and also in the chemical, food and metallurgical industries.
The pathways involving fossil fuels (natural gas, refinery oil and coal) that
provide for almost 96% of the total production of hydrogen, release carbon dioxide
in the atmosphere.
Innovative strategies able to capture and sequestrate carbon dioxide emissions,
so-called Carbon Capture and Sequestration (CCS) technologies, are the object of
several analysis and heated debate. CCS technologies should be applied for an
environmental-friendly diffusion of fossil fuel-based H 2 production methods, but
they are presently in the embryonic stage of development and certainly would
involve a great growth of costs.

Table 2.1 World hydrogen
production capacity from
different sources

Raw material Technology %

Natural gas Catalytic steam reforming 48

Refinery oil Partial oxidation 30

Coal Gasification 18

Water Electrolysis 4

Adapted from [ 5 ]