Note: Descriptions are shown in the official language in which they were submitted.
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RENEWABLE ENERGY OPERATED HYDROGEN REFORMING SYSTEM
Related Applications
The present invention claims priority to U.S. Provisional Patent Application
Serial Number 60/449,131 entitled "RENEWABLE ENERGY OPERATED
HYDROGEN PRODUCTION SYSTEM", filed February 21, 2003 and U.S. Provisional
Patent Application Serial Nmnber 60/445,485 entitled "RENEWABLE ENERGY
OPERATED HYDROGEN 'PRODUCTION SYSTEM", filed February 6, 2003, the
contents of which are herein incorporated by reference.
Field of the Invention
The present invention relates to a hydrogen reforming plant for producing
hydrogen. More particularly, the present invention relates to a hydrogen
production
plant that utilizes a renewable energy source for hydrogen compression and
energy
storage.
Background of the Invention
Hydrogen is an ideal candidate for replacing fossil fuel because it can be
readily
made available from domestic renewable resources. Hydrogen is also
nonpolluting,
storable, transportable and clean, making it a valuable fuel. However, the
lack of cost-
effective hydrogen storage and transport, particularly for an onboard
vehicular system, is
a major impediment to its widespread use. Improvements in the energy densities
of
hydrogen storage systems, reductions in cost, and increased compatibility with
available
and forecasted systems are required before viable hydrogen energy use will be
realized.
One .traditional means for generating hydrogen involves electrolysis. In this
process, an electrical current is applied to split water into hydrogen at a
cathode and
oxygen at an anode. However, hydrogen production using electricity by
electrolysis is
expensive.
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The storage of hydrogen fuel also .poses many problems. To store.hydrogen, the
hydrogen must be stored under pressure, at low temperature, or both, which may
require
a significant amount of energy to create sufficiently high pressures and low
temperatures. The requirement of additional energy for storage reduces the
efficiency
and effectiveness of producing and storing hydrogen.
Summary of the Invention
The present invention provides a system and method for utilizing a renewable
resource, such as wind energy or solar energy, for the compression or
refrigeration of
hydrogen as means for energy storage. The compressed hydrogen may comprise a
form
of mechanical energy storage and furthermore gains an added value as a
transportable
fuel for vehicle use.
According to one aspect of the invention, a hydrogen production system is
provided. The hydrogen production system includes a reformer for producing
hydrogen
from a hydrocarbon fuel, a compressor for compressing the hydrogen produced by
the
reformer into a compressed state, a renewable energy source for converting a
renewable
resource into electricity for powering the compressor and a storage device for
storing the
compressed hydrogen from the compressor.
According to another aspect of the invention, a hydrogen production system
comprising a catalytic reformer, an electric source, a compressor and a
storage device is
provided. The catalytic reformer produces hydrogen from a hydrocarbon fuel
using one
of an endothermic reforming process and steam generation. The electric source
provides
thermal energy for at least one of the endothermic reforming process and the
steam
generation. The compressor compresses the hydrogen produced by the reformer.
The
storage device stories the compressed or liquefied hydrogen from the
compressor.
According to another aspect of the invention, a hydrogen production system
comprising a catalytic reformer, a compressor and a storage device is
provided. The
catalytic reformer produces hydrogen from a hydrocarbon fuel and the
compressor
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compresses the hydrogen produced by the reformer into one of a compressed and
a
liquefied state. The storage device stores the compressed or liquefied
hydrogen from the
compressor. The compressed hydrogen is pumped to a hydrogen tank of a vehicle
and
stored as a mechanical energy source and a chemical energy source.
According to yet another aspect of the invention, a hydrogen production system
comprising a reformer, an electrolyses, one or more compressors, one or more
renewable
energy sources and one or more storage devices is provided. The reformer
produces
hydrogen from a hydrocarbon fuel. The electrolyses,produces additional
hydrogen by
electrolysis. The compressors compress the hydrogen produced by the reformer
and the
electrolyses and the renewable energy sources convert a renewable resource to
electricity
for powering the electrolyses and the compressor. The storage devices store
the
compressed hydrogen from the compressor.
Brief Description of the Figures
Figure 1 is a schematic view of a hydrogen production system according to an
illustrative embodiment of the invention.
Figure 2 illustrates the on-board components of a hydrogen-powered vehicle
suitable for implementing an illustrative embodiment of the invention.
Figure 3 is a schematic view of a hydrogen production system providing levered
production of hydrogen using the combination of a chemical reformer and
electrolysis
according to one embodiment of the present invention.
Detailed Description of the Invention
The present invention provides an efficient, low cost hydrogen production
system that utilizes renewable energy sources. The invention will be described
below
relative to an illustrative embodiment. Those skilled in the art will
appreciate that the
present invention may be implemented in a number of different applications and
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embodiments and is not specifically limited in its application to
the;particular
embodiment depicted herein.
As used herein, the term "renewable source" or "renewable energy source"
refers
to any energy source with a natural replenishment rate that augments its own
stock (or
biomass) at a non-negligible rate. Renewable resources are generally capable
of being
replenished at least as fast as the renewable resource is used, although .this
need riot be
the case. Renewable sources include, but are not limited to, wind, solar
energy,
geothermal energy, biomass, wasted wave energy and hydro energy. In contrast,
raoyaretzewable energy sources draw on finite resources that will eventually
dwindle.
The term "renewable energy converter" refers to a system or device that
converts
a renewable resource to another form of energy, such as electricity.
The term "reforming", and the like, refers to a chemical process that reacts
hydrogen-containing fuels in the presence of steam, oxygen or both into a
hydrogen-rich
gas stream.
The term "electrolysis", and the like, refers to an electrochemical process
that
dissociates water into hydrogen and oxygen using electricity.
The term "compress", and the like, refers to a process of increasing the
pressure
of hydrogen to make the hydrogen suitable for storage. The term "liquefy", and
the like,
refers to a process of compressing hydrogen, which may incorporate
refrigeration to
reach a lower temperature, into a liquefied state and is intended to be
included in the
term "compress".
Figure 1 illustrates a hydrogen production system 100 according to an
illustrative embodiment of the invention. The system 100 comprises a fuel
reformer '10
for producing hydrogen by converting an input fuel, fed from an input fuel
supply 15,
into a hydrogen gas in a process known as "reforming". The system includes a
hydrogen compressor 20 for compressing the hydrogen gas produced by the
reformer 10
into a compressed or liquefied state by increasing the pressure and/or
reducing the
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temperature of the hydrogen. The system 100 further includes a hydrogen
storage
device 30 for storing the hydrogen after compression. The storage device 30
can include
any appropriate storage media suitable for storing or transporting hydrogen.
A renewable energy converter, such as a windmill 40, photovoltaic cell or
other
source l~nown in the axt; is used to convert a renewable source, such as wind,
solar
energy, a geothermal resource, biomass, waste, wave energy and hydro energy,
to
electricity to power the hydrogen compressor 20. The use of a renewable source
to
provide the necessary energy for compressing the hydrogen into a state
suitable for
storage and transport in accordance with the teachings of the invention,
coupled with use
of thermal reforming for the hydrogen production, significantly reduces the
overall cost
involved in producing and storing hydrogen. The illustrative hydrogen
production
system 100 further produces hydrogen with little or no emission produced as a
byproduct. The hydrogen production system 100 is further capable of at least
partial or
total sequestration of carbon dioxide (C02), which provides additional
environmental
benefits.
The rate of hydrogen generation from the system 100 may be regulated
according to the power available from the renewable energy converter 40,
resulting in a
more efficient, cost effective and capacity augmented hydrogen generation and
storage
system 100 based on renewable energy.
The reformer 10 may comprise catalytic reformer that produces hydrogen from a
hydrocarbon fuel using one of an endothermic reforming process and steam
generation.
For example, the reformer may be a steam reformer, autothermal reformer,
partial
oxidation reformer or other suitable device known in the art for separating
hydrogen
from hydrocarbons, for example, in a hydrocarbon fuel, to produce hydrogen,
such as
the autothermal cyclic reforming (ACR) process developed by General Electric
Energy
and Environmental. The input fuel that the reformer 10 uses to produce
hydrogen may
comprise a hydrocarbon fuel, such as, but not limited to, natural gas
(methane), liquid
and gaseous hydrocarbon fuels, and carbonous fuels, such as coal.
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In an illustrative embodiment of the present invention, the hydrogen can be
inexpensively produced by a thermal reforming process using natural gas at
less than
i
half of the price of producing hydrogen by electrolysis: Another advantage of
the use of
a reformer 10 using natural gas to produce hydrogen is that,the natural gas
may be
already available on site. In the present invention, the on-site generation of
hydrogen
using a continuous pipeline supply of natural gas, or by other known means for
delivering available hydrocarbon fuel using existing infrastructure, reduces
the needs for
massive on-site storage and fleets of hydrogen trucks, which tend to impose
sensitive
safety considerations and inhibit wide adoptions of the bulk usage of
hydrogen.
According to one embodiment, the reformer 10 comprises a steam reformer,
which converts methane (and other hydrocarbons in natural, gas) into hydrogen
and
carbon monoxide by reaction with steam over a nickel catalyst. Conventional
steam
reformers currently in wide cormnercial use comprise a reformer section
consisting of a
catalyst material, which promotes the reforming reaction and a burner to
supply heat for
the endothermic reforming reaction. A steam source is typically comlected to
the
reformer section to provide steam by vaporizing water.
For improved environmental performance of the system, the renewable energy
converter may function as an electric source for providing thermal energy for
an
endothermic reforming process andlor steam generation. The heating requirement
for
the thermal reforming process can be supplied with the electricity derived
from a
renewable source using the renewable energy converter 40 or the heating
derived by
consuming hydrogen produced by the hydrogen production,system 100. According
to
one embodiment, the thermal energy for the endothermic reforming process
performed
by the reformer 10 may also be supplied from a renewable energy converter,
such as the
renewable energy converter 40 shown in Figure 1, in electrical or thermal
forms. For
example, electricity derived from the renewable energy source may be used to
supply
heat to produce steam for a steam reforming process. The use of renewable
energy to
supply heat to the thermal reforming process also presents advantages over
electrolysis,
including increased efficiency.
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In another embodiment, the reforming process can also be carried out utilizing
renewable energy in an electrical discharge plasma process, such as that
marketed by
Warigtec ofNew'Jersey. In such as process, the reformer 10 produces hydrogen
using
electricity derived :from the renewable energy source by performing an
electric discharge
plasma process to reform a hydrocarbon fuel into hydrogen.
According to another embodiment, the reformer 10 comprises a tubular reformer
containing multiple tubes, which are normally made of refractory metal alloys.
Each
tube,contains a packed granular or pelletized material having a suitable
reforming
catalyst ~as a surface coating. The tube diameter typically varies from
between 9 cm and
16 cm, and the heated length of the tube is normally between 6 and 12 meters.
A
combustion zone is provided external to the tubes, and is typically formed in
the burner.
The tube surface temperature is maintained by the burner in the range of
900°C to ensure
that the hydrocarbon fuel flowing inside the tube is properly catalyzed with
steam at a
temperature of between about 500°C and about 700°C. This
traditional tube reformer
relies upon conduction and convection heat transfer within the tube to
distribute heat for
reforming. Examples of suitable plate-type reformers for thermal enhancement
are also
described in U.S. Patent Numbers 5,858,314, 5,693,201 and 6,183,703, the
contents of
which are herein incorporated by reference.
The compressor 20 may comprise any suitable device known in the art for
compressing hydrogen gas into a compressed or liquefied state suitable for
storage,
using energy derived from a renewable source. According to one embodiment, the
compressor 20 operates by increasing the pressure of the hydrogen gas. The
compressor
20 may comprise a mechanical compressor, a thermal hydride compressor, a
magnetic
compressor, a magneto-caloric compressor or other suitable device known in the
art.
Powered by energy produced by the renewable energy converter 40, the
illustrative
compressor 20 compresses and stores the hydrogen at a pressure of up to 50,000
psi.
The hydrogen gas may also be liquefied for bulk storage under a cryogenic
state at a
temperature of between about 15-35°K.
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In one application, the compressed hydrogen formed using a renewable. source
and the renewable energy converter 40 is a form of mechanical energy storage
and
furthermore gains an added value as a transportable fuel for vehicle use. In
addition to
providing a source of chemical energy, the compressed hydrogen may also
provide a
source of mechanical power that is stored in the hydrogen during the
compression
process. The energy content of the high-pressure hydrogen state of 10,000 psi
can reach
a ratio of 1:2 between the compression energy and the chemical component.
Mechanical
energy for compression, if utilized and recovered thermodynamically or
electrochemically, represents a significant increase of energy density in the
hydrogen
fuel for transportation use.
The renewable energy converter 40 may comprise any suitable device that
converts a renewable source, such as wind energy, solar energy, a geothermal
resource,
biomass, waste, wave energy, hydro energy and so on, into electricity for use
by the
compressor 20. According to the present invention, the electricity derived by
the
renewable energy converter 40 may also be supplied to the, reformer 10 to
enhance the
reforming process. Suitable renewable energy converters include, but are not
limited o,
windmills, which convert wind energy to electricity and photovoltaic devices,
which
convert solar energy to electricity.
The hydrogen gas can be dispensed from the storage tank 30 through a dispenser
or from the tank itself to any suitable device or system, such as a hydrogen
consumption
device. The thus-produced hydrogen may be used as a mechanical energy source
andlor
.a chemical energy source for the hydrogen consumption device.
According to one practice, as illustrated in Figure 2, the hydrogen
consumption
device is a hydrogen-powered fuel cell vehicle 200 having an on-board fuel
cell 250 that
produces electricity to power the vehicle from the electrochemical reaction
between a
hydrogen-containing fuel and oxygen from the air. The mobile vehicle may be a
truck,
bus, automobile, marine vessel, submarine, airplane and spacecraft, train or
the like.
According to one embodiment, the hydrogen formed according to the teachings of
the
invention may be pipe transported to users. Alternatively, the hydrogen from
the
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hydrogen storage tank 30 of the hydrogen production system 100 maybe vehicle
transported to users.
The renewable energy provided by the renewable energy converter 40 can also
~ be used for hydrogen liquefaction for an increased range of commercial
distribution.
This economically viable model is 'applicable for the size of a filling
station or for the
central hydrogen production with proper siting considerations. An area with
ample
wind, solar or hydropower, in addition to a supply of readily available
natural gas, liquid
hydrocarbons or other carbonous solid fuels, provides a desirable location for
the
renewable energy powered hydrogen reformer station 100 of the present
invention.
Refernng again to Figure 2, in one embodiment, the compressed hydrogen
formed using renewable energy sources may be pumped to the hydrogen tank 210
of the
vehicle 200 in the form of stored mechanical energy, which can then be
converted to
shaft power. The converted shaft power may be used for direct propulsion of
the vehicle
or for electrical generation using an electrical generator 220 and in turn to
provide
propulsion to the vehicle. The stored high-pressure hydrogen produced
according to the
teachings of the present invention can also be used for direct electrical
power generation
in a high-pressure fuel cell for the Rill utilization of the mechanical and
chemical
energies associated with the stored hydrogen. As the compression pressure
increases for
improved energy density for hydrogen storage, the mechancal energy related to
the
pressure becomes comparable to the chemical energy of the fuel. An efficient
vehicle
design therefore utilizes the mechanical energy stored in the fuel due to
compression. A
small size expander 240, of turbo or reciprocating machinery, can be used to
generate
shaft power that in turn can provide mechanical or electrical energy to
supplement the
propulsion of the vehicle 200.
The use of renewable energy in hydrogen production for hydrogen reforming
and/or compression according to the teachings of the invention provides an
economic,
clean and transportable hydrogen fuel with enhanced energy density in storage.
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According to another application, shown in Figure 3, the present invention
provides a hydrogen production system 3,00 for mixed used of conventional
hydrocarbon
fuel with one or more renewable energy converters 340. For example, according
to one
embodiment, conventional chemical reforming may be used for leveled hydrogen
generation capacity, together with electrolysis using electricity derived from
renewable
energy sources. As shown, the hydrogen. production system 300 of Figure 3
includes an
input fuel supply 315 for providing a hydrocarbon fuel to a reformer 310,
which reforms
the hydrocarbon fuel into hydrogen. The renewable energy converter 340
converts a
renewable energy source into electricity to power an electrolyser 350, which
produces
hydrogen using the electricity generated by the renewable energy converter
340. The
hydrogen from both the reformer 310 and the electrolyser 350 are provided to a
hydrogen compressor 320, which compresses the hydrogen gas provided by the
reformer
310 and the electrolyser 350 into a compressed state. As shown, the compressor
320
may be powered using additional electricity derived from the renewable energy
converter 340. The system 300 further includes a hydrogen storage device 330
for
storing the hydrogen after compression. The storage device 330 can include any
appropriate storage media suitable for storing or transporting hydrogen.
W an illustrative embodiment, .the reformer 310 contributes over 50% of the
hydrogen produced by the system 300 on an average time basis, while the
electrolyser
350 produces, on average, less than about 50% of the hydrogen produced by the
system
300. However, one skilled in the art will recognize that the invention is not
limited to
this allotment, and that the electrolyser 350 and the reformer 310 may produce
any
suitable portion of the hydrogen produced by the system 300.
The hydrogen production system 300 of Figure 3 compensates for the natural
fluctuations of the availability of the renewable energy supply, i.e. the
daily, seasonal or
weather variations of wind and solar intensity. As shown, the system 300
improves the
plant utilization, efficiency and the associated economics, by supplementing a
hydrogen
r
reforming operation using conventional hydrocarbon fuels. The mixed use of
conventional hydrocarbon fuel together with a renewable energy sources
provides an
optimal balance among economic, environmental benefits;and commercial
dependability.
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The present invention has been described relative to an illustrative
embodiment.
Since certain changes may be made in he above constructions without departing
from
the scope of the invention, it~is intended that all matter contained in the
above
description or shown in the accompanying drawings be interpreted as
illustrative and not
in a limiting sense.
It is also to be understood that the following claims are to cover all generic
and
specific features of the invention described herein, and all statements of the
scope of the
invention which, as a matter of language, might be said to fall therebetween.
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