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Hydrogen Production andDelivery
Overview
The production and transportation of hydrogen in acost
effective, environmentally friendly manner isone of the major
challenges to the development ofthe hydrogen economy.
The production of hydrogen is an energy intensiveprocess. The
energy needed to produce hydrogencan be obtained from traditional
fossil fuels, nuclearenergy and renewable energy sources.
Hydrogen may be produced at large-scale centrallocations and
then transported to multiple end usedestinations. Alternatively, it
can be produced on-site at small-scale decentralized locations
closer tothe point of use.
Hydrogen has the highest energy content per unit ofweight of any
known element. It is also the lightestelement. As a result, it is
characterized by lowvolume energy density, meaning that a given
volumeof hydrogen contains a small amount of energy.This presents
significant challenges to transporting,delivering and storing the
large quantities ofhydrogen that will be necessary in the
hydrogenenergy economy.
How is Hydrogen Produced?
About 95% of the hydrogen we use today comesfrom processing
natural gas. The remainder isproduced using electrolysis a process
that splitswater into its individual components, hydrogen
andoxygen. Some of the specific technologies used toproduce
hydrogen include:
Steam reforming converts methane (andother hydrocarbons in
natural gas) intohydrogen and carbon monoxide by reactionwith steam
over a nickel catalyst. The carbonseparated from the hydrogen in
the reformingprocess may be captured and sequestered toavoid damage
to the environment.
Electrolysis uses direct electrical current tosplit water into
hydrogen at the negativeelectrode and oxygen at the positive
electrode.
Steam electrolysis (a variation onconventional electrolysis)
uses heat, instead of
electricity, to provide some of the energyneeded to split water,
making the processmore energy efficient.
Thermochemical water splitting useschemicals and heat in
multiple steps tosplit water into its component parts.
Photocatalytic systems use specialmaterials to split water using
onlysunlight.
Photobiological systems usemicroorganisms to split water in
thepresence of sunlight.
Biological systems use microbes tobreak down a variety of
biomassfeedstocks into hydrogen.
Thermal water splitting uses a veryhigh temperature
(approximately1000C) to split water.
Gasification uses heat to breakdownbiomass or coal into a gas
from whichpure hydrogen can be extracted.
In some countries, major industries such assteel production,
petroleum refining and sodaproduction produce excess hydrogen that
maybe used in the initial stages of the hydrogeneconomy.
How is Hydrogen Delivered?
Hydrogen is currently transported by pipelineor by road via
cylinders, tube trailers, andcryogenic tankers, with a small
amountshipped by rail or barge.
Due to the energy intensive nature and thecost associated with
hydrogen distribution viahigh-pressure cylinders and tube trailers,
thismethod of distribution has a range limited toapproximately 200
km.
For longer distances of up to 1,600 km,hydrogen is usually
transported as a liquid insuper-insulated, cryogenic,
over-the-roadtankers, railcars, or barges, and then
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vaporized for use at the customer site. This isalso an energy
intensive and costly process.
Pipelines, which are owned by hydrogenproducers, are limited to
small areas wherelarge hydrogen refineries and chemical plantsare
concentrated. A large pipeline systemdedicated to transporting
large volumes of
hydrogen does not yet exist.
The Challenges
Due to its unique properties high energycontent per unit of
weight coupled with lowvolumetric energy density the
production,transportation and storage of hydrogenpresents unique
challenges.
Two fundamental questions are how muchenergy is required to
extract hydrogen fromnaturally occurring, stable hydrogen-rich
compounds and whether hydrogen should beproduced at large-scale
central locations thatwill require the development of a
dedicatedinfrastructure to store and transport it to enduse
destinations. Both of these questionsdemand close evaluation of the
related social,economic, and environmental costs andbenefits
associated with developing ahydrogen production and
transportationinfrastructure.
In addition, breakthroughs are necessary inmaterial science to
reduce the cost oftransporting hydrogen over long distances.
Another option is to produce hydrogen atdecentralized locations
closer to end useapplications. This approach requires
theexamination of other technical and social
questions related to the production andstorage of hydrogen.
It is likely that hydrogen production,transportation, and
storage will use bothdecentralized and centralized
approaches.Developing the infrastructure necessary toproduce, store
and deliver the large quantitiesof hydrogen necessary for the
future hydrogeneconomy is one of the major challengesaddressed by
the IPHE.
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The IPHE partners are working to develop the infrastructure
necessary to produce, storeand deliver the large quantities of
hydrogen that will be essential to the future of the
hydrogen economy. For more information, please visit the IPHE
website at:
www.iphe.net.
