Patent Application
20060207178
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.
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.
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.
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 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 electrolyser, 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 electrolyser produces additional hydrogen by electrolysis. The compressors compress the hydrogen produced by the reformer and the electrolyser and the renewable energy sources convert a renewable resource to electricity for powering the electrolyser and the compressor. The storage devices store the compressed hydrogen from the compressor.
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 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 not be the case. Renewable sources include, but are not limited to, wind, solar energy, geothermal energy, biomass, waste, wave energy and hydro energy. In contrast, nonrenewable 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 ton 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”.
A renewable energy converter, such as a windmill 40, photovoltaic cell or other source known in the art, 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 (CO2), 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.
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 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 commercial 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 connected 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 and/or steam generation. The heating requirement for the thermal reforming process can be supplied with the electricity derived from a 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
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 Wangtec of New 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. Pat. Nos. 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 gasp 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 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.
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 to, 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 and/or a chemical energy source for the hydrogen consumption device.
According to one practice, as illustrated in
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.
Referring again to
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.
According to another application, shown in
In 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 allotments 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
The present invention has been described relative to an illustrative embodiment. Since certain changes may be made in the 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.
The present invention claims priority to U.S. Provisional Patent Application Serial Number 60/449,131 entitled “RENEWABLE ENERGY OPERATED HYDROGEN PRODUCTION SYSTEM”, filed Feb. 21, 2003 and U.S. Provisional Patent Application Ser. No. 60/445,485 entitled “RENEWABLE ENERGY OPERATED HYDROGEN PRODUCTION SYSTEM”, filed Feb. 6, 2003, the contents of which are herein incorporated by reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US04/03439 | 2/6/2004 | WO | 5/11/2006 |
| Number | Date | Country | |
|---|---|---|---|
| 60445485 | Feb 2003 | US | |
| 60449131 | Feb 2003 | US |
