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Hydrogen Production
In hydrogen production there are four considerations:
• The process used – electrolysis, reformation,
partial oxidation or gasifi cation;
• The source of the hydrogen - water, fossil fuels,
biomass or landfi ll gas;
• The source of power in the process – nuclear,
renewable energy, grid electricity or fossil
feedstock; and
• The byproducts of production – COx and SOx
emissions or nuclear waste.
Each of these considerations brings with it a set
of trade-offs and policy implications. While economic
realities and market forces will guide what forms of
hydrogen production will be used, existing policies and
new initiatives will create the rules under which the
market will operate and affect how hydrogen competes.The differing benefi ts of each source of hydrogen to
policy goals such as energy independence or reduced
emissions will drive policymaking. Lifecycle analysis
such as described later in this report benchmarks the
relative benefits of different hydrogen production
methods compared to gasoline and other fuel options.
Electrolysis, at its simplest, breaks water
molecules down into hydrogen and oxygen gas
molecules by running an electric current through a
cathode and anode present in water. Often a catalyst
is used to speed the chemical reaction. The electricity
can come from fossil power plants, renewable energy
sources, or nuclear energy. In 2002, about 4 percent of
the world’s hydrogen was produced using electrolysis.
This form of production can be prohibitive in
terms of capital and energy costs. Controlling these
costs is essential for electrolysis to become a viable
option for a hydrogen fuel infrastructure.
Two processes use fossil fuels to extract
hydrogen: steam reformation and partial oxidation.
Steam methane reforming uses high temperatures to
extract hydrogen from natural gas, propane, biogas,
landfi ll gas, or methane. In the process, carbon dioxideis a byproduct. Steam methane reforming can be done
at a number of scales, from large centralized production
to small, onsite DG units. In this process, the methane
or CH4 in natural gas is heated in the presence of a
catalyst to create a chemical reaction that removes an
initial amount of hydrogen. The resulting components
are then mixed with steam in order to generate greater
concentrations of hydrogen while producing CO2 as
the waste product. In the process of partial oxidation,
the fuel source is combined with pure oxygen or air
at high pressures and temperatures. The source may
be oil, gasoline, methanol, or biomass. During the
process, some of the fuel content is burned in order
to create steam and high temperatures to produce
hydrogen, carbon monoxide, carbon dioxide and
smaller contaminants. The hydrogen is then separated
out and used for desired applications. Heat from the
processes during partial oxidation is controlled using
steam, and any byproducts are used to run gas turbines
in combined cycle systems to improve overall efficiency.
The carbon dioxide produced is greater than natural gas
steam reformation and can be captured.
Biomass and landfi ll gases are possible
approaches for using existing domestic sources of fuel
for hydrogen. A number of different research and
development programs, some at the demonstration
stage, have provided examples of hydrogen production
using partial oxidation of biomass sources. These
sources include agricultural products like corn, animal
waste, and organic trash. While in most cases this
hydrogen has a higher production cost than natural gas
steam reformation, it can provide an additional revenue
stream and reduce disposal costs and excess material.
Altogether this makes the production of hydrogen a
potentially positive venture in these circumstances. Since approximately half of most trash going into landfills is
made up of organic material, trash may become a source
of hydrogen for municipalities and counties looking to
reduce transportation and landfill costs associated with
solid waste disposal. Agricultural companies can use
excess crops or crop byproducts to create hydrogen
either directly or as a byproduct of fertilizer production.
Biomass and landfill production of hydrogen creates
CO2, and landfills also must remove sulfur and other
impurities before production of hydrogen through the
use of scrubbers or other separation technology.
The large quantities of coal available in the US
have led many to look at generating hydrogen from
that source. In a process called coal gasifi cation, coal
is subjected to high temperatures and mixed with steam
and oxygen. This creates a reaction that generates
hydrogen, carbon monoxide and various impurities.
The H2 and CO mixture is cleansed of impurities and
mixed again with steam at lower temperatures to create
pure H2 and CO2 gas. The hydrogen is separated for use
and the CO2 is either vented or captured. No coal plants
currently exist beyond the demonstration phase that are
designed to optimally generate hydrogen and separate
CO2. The U.S. Department of Energy (US DOE)
has funded a project called FutureGen, an integrated
gasification combined cycle (IGCC) coal plant that
will be a test bed for coal gasifi cation technology and
hydrogen production with carbon capture and minimal
production of other harmful gases.
Steam reformation, coal gasifi cation, and partial
oxidation all generate emissions of carbon dioxide,
carbon monoxide, and other environmentally harmful
substances, a major concern for environmentalists,
since the overall advantages of hydrogen as a clean fuel
would be signifi cantly reduced. Those proponents of
using fossil fuels like coal for production of electricity
or hydrogen believe that one solution is through carbon
sequestration. In carbon sequestration, carbon dioxide
created as a result of hydrogen production from fossil
fuels is pumped into the ground to prevent its release
into the atmosphere. This process captures CO2
emissions during production and stores them in various
locations, such as depleted oil or gas fi elds, deep coal
beds, deep saline aquifers, or deep ocean fields. If
successfully developed, this technology would allow
hydrogen production from current natural resource
supplies while maintaining the environmental integrity
of hydrogen as a clean end-use fuel.
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