Page 286 - Alternative Energy Systems in Building Design

260 FUEL CELL TECHNOLOGY

and is significantly more expensive to manufacture than internal combustion engines.
However, it is expected that recent advancements in new technologies will reduce the
cost of fuel cell system production significantly.
In some fuel cell technologies, hydrocarbon fuels are used in their pure form, which
makes the systems price-competitive with internal combustion engines. Significant
advantages of fuel cell use in automotive applications include the facts that fuel cells
have a superior power-to-weight ratio, are much more efficient than internal combus-
tion engines, and produce no harmful emissions. In view of the depletion of natural
hydrocarbon fossil fuels and the recent cost increase of gasoline, fuel cell technology
will soon prove to be an economically viable alternative to conventional internal com-
bustion engines and gas turbines used in electrical power generation.

SAFETY CONCERNS

Even though the autoignition temperature of hydrogen is somewhat higher than that of
most hydrocarbons, hydrogen’s lower ignition energy makes the ignition of a
hydrogen-air mixtures more likely; therefore, air-hydrogen mixtures must be designed
with extreme care. The condensed and solidified atmospheric air or trace air accumu-
lated in manufacturing contaminates liquid hydrogen and may create a mixture that
could detonate readily at the same explosive power as TNT.
Flames in and around a collection of pipes or structures also can create turbulence
that causes detonation. In general, the containment of hydrogen owing to leakage, dif-
fusion, and buoyancy is very hazardous; therefore, containment becomes quite diffi-
cult. Intrinsically, hydrogen diffuses extensively, and in the event of accidental
spillage, liquid hydrogen becomes extremely combustible.

Hydrogen Economy

A hydrogen economy is defined as the energy needed for use as fuel in automobiles or
electric power production by stationary-type fuel cells, which are primarily combus-
tion processes derived from the reaction of hydrogen molecules (H ) with oxygen. The
2
main purpose of hydrogen is for use as a fuel to minimize the use of carbon-based fos-
sil fuels and reduce carbon dioxide emissions. Another important principal goal of
hydrogen fuel use is to replace dependency on petroleum.

HYDROGEN INFRASTRUCTURE
A hydrogen infrastructure essentially consists of an industrial hydrogen pipeline that
can transport hydrogen to filling stations. A vehicular highway accommodated with
hydrogen pipelines and filling stations will form a hydrogen highway. In such an infra-
structure, filling stations located on peripheral roads will be supplied via hydrogen
tanks, hydrogen tube trailers, liquid tankers, or onsite hydrogen-production facilities.
Owing to hydrogen’s embrittlement of steel, natural gas pipes must be coated from
within with special carbon-fiber materials.