14-06-2012, 10:44 AM
Seminar on Hydrogen Fuel Cell Vehicle Study
Hydrogen Fuel Cell Vehicle Study.pdf (Size: 877.02 KB / Downloads: 383)
INTRODUCTION
At the beginning of 2002, the Bush Administration announced the FreedomCAR
initiative, an industry-government cooperative effort, to develop fuel cell vehicles. This
prompted a subcommittee of the POPA Energy and Environment Committee to
commence work on a report about fuel cells and FreedomCAR. The rationale for
preparing such a report is that the topic is an important aspect of the nations energy
policya topic that physicists justifiably feel competent to discuss. Previous POPA
studies have been on nuclear energy, energy supplies, etc. Fuel cells are of interest to the
physics community (e. g., see the recent Physics Today article by Joan Ogden [1]) and
physicists are actively involved in research areas for potential hydrogen storage, such as
carbon nanotubes.
Technical goals are not yet available, but the general goals are [2]:
• Lowering the cost of hydrogen: Currently, hydrogen is four times as expensive
to produce as gasoline (when produced from its most affordable source, natural
gas). The FreedomCAR and Fuel Initiative seeks to lower that cost enough to
make fuel cell cars cost-competitive with conventional gasoline-powered vehicles
by 2010; and to advance the methods of producing hydrogen from renewable
resources, nuclear energy, and even coal.
• Creating effective hydrogen storage: Current hydrogen storage systems are
inadequate for use in the wide range of vehicles that consumers demand.
• Creating affordable hydrogen fuel cells: Currently, fuel cells are ten times more
expensive than internal combustion engines. The FreedomCAR and FUEL
Initiative is working to reduce the cost to affordable levels.
SYSTEM CONSIDERATIONS
In the April, 2002 issue of Physics Today Joan Ogden of the Princeton Environmental
Institute discussed the future of hydrogen as a fuel and described the operation of
hydrogen-oxygen fuel cells. Ogden stated that practical fuel cells2 are up to 60% efficient in converting hydrogen energy into electrical energy (which is the
FreedomCAR target) although not necessarily at the rated power, significantly higher
than the 45% efficiency of using hydrogen in an internal combustion engine. However,
these estimates do not include the losses in producing hydrogen from various
hydrocarbon sources (Fig. 2). Clearly, hydrogen is not a naturally occurring terrestrial
fuel. Rather, it is an energy carrier.
HYDROGEN STORAGE TECHNOLOGIES
Existing and proposed technologies for hydrogen storage include (1) physical storage:
pressurized tanks for gaseous hydrogen and pressurized cryotanks for liquid hydrogen;
(2) reversible hydrogen uptake in various metal-based compounds including hydrides,
nitrides, and imides; (3) chemical storage in irreversible hydrogen carriers such as
methanol; (4) cryoadsorption with activated carbon as the most common adsorbent; and
(5) advanced carbon materials absorption, including carbon nanotubes, alkali-doped
carbon nanotubes, and graphite nanofibers. The U.S. Department of Energy report, A
National Vision for Americas Transition to a Hydrogen EconomyTo 2030 and Beyond,
projects that pressurized tanks will be the predominant hydrogen storage technology until
about 2015, to be supplanted by hydride storage into the early 2020s, then other solid
state storage technologies [23]. They see storage technologies maturing sufficiently for
mass production in the 2020s.