لخّصلي

a European and global level, thus allowing safe development, introduction and
daily operation of hydrogen-fuelled vehicles on public roads and their associated
hydrogen refuelling stations [9]. A generic risk-based maintenance and inspection
protocol for hydrogen refuelling stations has also been developed. A study has
been undertaken to define the potential for the introduction of environmentally
friendly hydrogen technologies in stand-alone power systems (H-SAPS). Barriers
and potential benefits of promoting new technological applications on a wide
scale and the market potential for SAPS have been widely analysed in select cases
of existing small- and medium-sized systems with power rating from 8 to 100 kW
(Gaidouromantra, Kythnos Island, Greece/PV-diesel-battery/∼8 kW; Fair Isle,
UK/wind-diesel/∼100 kW; Rauhelleren, Norway/diesel/∼30 kW; Rambla del
Aqua, Spain/PV-battery/∼11 kW) [10]. On the basis of the analysis, several
interesting observations have been made. In order to introduce hydrogen energy
technologies in autonomous power systems, a renewable energy source should be
incorporated and in addition it should always be overdimensioned to cover power
demand and use an excess electricity to produce hydrogen. It was shown that
the replacement of conventional power sources with hydrogen is probably more
economically viable in power systems having year-round load demand than those
having seasonal power demand (power systems with seasonal power demand
require seasonal energy storage; thus water electrolyser and hydrogen storage
should be overdimensioned). The cost of fossil fuels in remote locations is higher
(due to the increasing costs of fuel transportation); therefore the replacement
of conventional power equipment by hydrogen energy equipment is expected
to be beneficial from the financial point of view. Furthermore, such systems can
successfully be used in short to medium market niche applications and have
certain environmental advantages, especially in remote communities [10]. It is
expected that hydrogen may play a considerable role in the future global energy
systems. As stated by MacCurdy [11], “The degree of civilization of any epoch,
people, or group of peoples, is measured by ability to utilize energy for human
advancement or needs.” Growing interest of hydrogen in transportation sector
has been recognized and hydrogen-powered fuel cell vehicles (FCVs) are demonstrated
successfuly in Asia, the United States and Europe. Hydrogen-fuelled cars
are reported to be about 1.5–2.5 times more efficient than gasoline-advanced cars
on a TtW basis (tank to wheels) and produce no emissions, thus offering good
performance; a distance of 500 or more kilometres can be refuelled within a few
minutes [12]. A very famous example is theBMWseven series with a compressed
hydrogen tank and with more than 35 years of experience in hydrogen usage
(Figure 1.1).
As transitioning to hydrogen fuels and fuel cells still remains a challenge, there
may be a need for an intermediate phase, where both hydrogen and conventional
fuels are used together in the same vehicle. As stated, “The solution to meet this
transitional requirement is the manufacturing of bi-fuel vehicles running on both
hydrogen and gasoline using current internal combustion engine technologies …
This bi-fuel approach will stimulate the creation of a hydrogen-refuelling network
thus allowing for a full transition to a hydrogen powered vehicle economy” [13].