Environmental Engineering Reference
In-Depth Information
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The U.S. Department of Energy (USDOE) focuses on hydrogen-production
technologies that result in near-zero net greenhouse gas emissions and use
renewable energy sources, nuclear energy, and coal (when combined with
carbon sequestration). To ensure sufficient clean energy for our overall
energy needs, energy efficiency is also important.
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Hydrogen can be produced via various process technologies, including
thermal (natural gas reforming, renewable liquid and bio-oil processing,
and biomass and coal gasification), electrolytic (water splitting using a vari-
ety of energy resources), and photolytic (splitting water using sunlight via
biological and electrochemical materials).
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Hydrogen can be produced in large, central facilities (50 to 300 miles from
point of use) or in smaller semi-central facilities (located within 25 to 100
miles of use), or it can be distributed (near or at the point of use).
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To be successful in the marketplace, hydrogen must be cost competitive
with the available alternatives. In the light-duty vehicle transportation mar-
ket, this competitive requirement means that hydrogen needs to be available
untaxed at $2 to $3 per gasoline gallon equivalent (GGE). This price would
result in hydrogen fuel cell vehicles having the same cost to the consumer
on a cost-per-mile-driven basis as a comparable conventional internal-com-
bustion engine or hybrid vehicle.
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The USDOE is engaged in the research and development of a variety of
hydrogen production technologies. Some are further along in development
than others—some can be cost competitive for the transition period (begin-
ning in 2015), and others are considered long-term technologies (cost-com-
petitive after 2030).
Infrastructure is required to move hydrogen from the location where it is pro-
duced to the dispenser at a refueling station or stationary power site. Infrastructure
includes the pipelines, trucks, railcars, ships, and barges that deliver fuel, as well
as the facilities and equipment required to load and unload them. Delivery technol-
ogy for a hydrogen infrastructure is currently available commercially, and several
U.S. companies are delivering bulk hydrogen today. Some of the infrastructure
is already in place because hydrogen has long been used in industrial applica-
tions, but it is not sufficient to support widespread consumer use of hydrogen as an
energy carrier. Because hydrogen has a relatively low volumetric energy density,
its transportation, storage, and final delivery to the point of use represent signifi-
cant costs and result in some of the energy inefficiencies associated with using it
as an energy carrier.
Options and trade-offs for hydrogen delivery from the production facilities to
the point of use are complex. The choice of a hydrogen production strategy greatly
affects the cost and method of delivery; for example, larger, centralized facilities
can produce hydrogen at relatively low cost due to economies of scale, but the deliv-
ery costs are higher than for smaller, localized production facilities. Although these
smaller production facilities would have relatively lower delivery costs, their hydro-
gen production costs are likely to be higher, as lower volume production means
higher equipment costs on a per-unit-of-hydrogen basis.
