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Editor's Note: This excerpt concerning "the four most fundamental technological
and economic challenges" to hydrogen-fueled transportation appears in The
Hydrogen Economy: Opportunities, Costs, Barriers, and R&D Needs (The
National Academies Press, 2004), pages 116-117. The report is available
online.
Abbreviated excerpt
To develop and introduce cost-effective, durable, safe, and environmentally
desirable fuel cell systems and hydrogen storage systems. To develop the infrastructure to provide hydrogen for the light-duty-vehicle
user. To reduce sharply the costs of hydrogen production from renewable energy
sources, over a time frame of decades. To capture and store ("sequester") the carbon dioxide by-product of hydrogen
production from coal.
Full excerpt
Research and Development Priorities
There are major hurdles on the path to achieving the vision of the hydrogen
economy; the path will not be simple or straightforward. Many of the
committee's observations generalize across the entire hydrogen economy: the
hydrogen system must be cost-competitive, it must be safe and appealing to the
consumer, and it would preferably offer advantages from the perspective of
energy security and CO2 emissions. Specifically for the
transportation sector, dramatic progress in the development of fuel cells,
storage devices, and distribution systems is especially critical. Widespread
success is not certain.
The committee believes that for hydrogen-fueled transportation, the four most
fundamental technological and economic challenges are these:
To develop and introduce cost-effective, durable, safe, and
environmentally desirable fuel cell systems and hydrogen storage systems.
Current fuel cell lifetimes are much too short and fuel cell costs are at
least an order of magnitude too high. An on-board vehicular hydrogen storage
system that has an energy density approaching that of gasoline systems has not
been developed. Thus, the resulting range of vehicles with existing hydrogen
storage systems is much too short.
To develop the infrastructure to provide hydrogen for the
light-duty-vehicle user. Hydrogen is currently produced in large quantities
at reasonable costs for industrial purposes. The committee's analysis indicates
that at a future, mature stage of development, hydrogen (H2) can be
produced and used in fuel cell vehicles at reasonable cost. The challenge with
today's industrial hydrogen as well as tomorrow's hydrogen is the high cost of
distributing H2 to dispersed locations. This challenge is especially
severe during the early years of transition, when demand is even more
dispersed. The costs of a mature hydrogen pipeline system would be spread over
many users, as the natural gas system is today. But the transition is difficult
to imagine in detail. It requires many technological innovations related to the
development of small-scale production units. Also, nontechnical factors such as
financing, siting, security, environmental impact, and the perceived safety of
hydrogen pipelines and dispensing systems will play a significant role. All of
these hurdles must be overcome before there can be widespread hydrogen use. An
initial stage during which hydrogen is produced at small scale near the small
user seems likely. In this case, production costs for small production units
must be sharply reduced, which may be possible with extended research.
To reduce sharply the costs of hydrogen production from renewable energy
sources, over a time frame of decades. Tremendous progress has been
made in reducing the cost of making electricity from renewable energy sources.
But making hydrogen from renewable energy through the intermediate step of
making electricity, a premium energy source, requires further breakthroughs in
order to be competitive. Basically, these technology pathways for hydrogen
production make electricity, which is converted to hydrogen, which is later
converted by a fuel cell back to electricity. These steps add costs and energy
losses that are particularly significant when the hydrogen competes as a
commodity transportation fuel—leading the committee to believe that most
current approaches—except possibly that of wind energy—need to be
redirected. The committee believes that the required cost reductions can be
achieved only by targeted fundamental and exploratory research on hydrogen
production by photobiological, photochemical, and thin-film solar processes.
To capture and store ("sequester") the carbon dioxide by-product of
hydrogen production from coal. Coal is a massive domestic U.S.
energy resource that has the potential for producing cost-competitive hydrogen.
However, coal processing generates large amounts of CO2. In order to
reduce CO2 emissions from coal processing in a carbon-constrained future, massive amounts of CO2 would have to be captured and safely
and reliably sequestered for hundreds of years. Key to the commercialization of
a large-scale, coal-based hydrogen production option (and also for
natural-gas-based options) is achieving broad public acceptance, along with
additional technical development, for CO2 sequestration.
For a viable hydrogen transportation system to emerge, all four of these
challenges must be addressed.
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