In spite of everything you've been led to believe by the largely indiscriminate media, the United States of America is and is expected to remain, even as the shale gas mania crests, a net importer of natural gas.
We've cited and linked to gas import/export reports, and projections, made available by the USDOE's Energy Information Administration in previous dispatches touching on that issue; but, the format of EIA tabulations of domestic gas production, domestic usage, and net imports and exports, has changed recently and they no longer lend themselves to efficient excerpt and summary.
But, here is an article that states the situation in rather plain terms:
The US still Imports Natural Gas, so Why the Desire to Export it?; "With U.S. natural gas production having risen more than 25 percent from its nadir in 2005, natural gas producers are pushing for an end to limits on U.S. natural gas exports. The growth in supplies comes primarily from previously inaccessible shale deposits deep in the Earth, a development that has convinced many people that the country is now entering a new era of natural gas abundance. Trouble is, the United States remains an importer of natural gas. Through November 2012 the country imported 12.5 percent of its natural gas consumption for the year, mostly from Canada. That's down from an average of 15.7 percent for the previous 20-year period. But it's not exactly energy independence. So worried are industrial consumers of natural gas about exports pushing up prices and thus their production costs that they've formed an alliance to fight the loosening of export restrictions. The alliance includes utilities dependent on natural gas to fuel electricity generation, chemical companies that use it as a feedstock for making myriad industrial chemicals, and heavy industrial users such Alcoa and Nucor who use natural gas to fire their metal-making operations. (Those who heat their homes and businesses with natural gas also stand to benefit if the alliance prevails.) The members of the alliance have reason to worry since Europeans are paying close to $12 per thousand cubic feet for liquefied natural gas and the Japanese are paying more than $17. Compare that to the U.S. domestic pipeline price for natural gas of just $3.27 as of (February 22, 2013)". - - -
Clearly, the United States of America - - - in spite of all the baloney sandwiches and pie-in-the-sky for dessert we've been force-fed about the shale gas miracle - - - imports a significant portion of the natural gas used by it's residents and it's industries; but, shale gas producers are eager to export some of the gas they produce so that they can benefit from world prices for gas that are, roughly, four times what we pay for it in the United States.
And, since the US already is a net importer of natural gas, the price we all pay for that gas, whether to heat our homes or, via our electric bills, for gas-generated electricity, has, in fact, no where to go but up. Maybe way, way up.
Thankfully, we have employees, genuine patriots, in our United States Government that insulate themselves from the hogwash and remain focused on making certain that we common US citizens will have options, if anyone ever manages to scrounge up the courage to tell us about them, to keep our gas-heated homes, and our electric utilities foolish enough to switch over to gas, up and running and generating electricity that someone besides Donald Trump can afford to buy.
And, those options, of course, are founded on Coal.
As we've seen in many past reports, such as, for one recent example:
USDOE 2013 Coal to 99% Methane | Research & Development | News; concerning: "Coal-Derived Warm Syngas Purification and CO2 Capture-Assisted Methane Production; Final Report; October, 2014; RA Dagle, et. al.; PNNL-23777; Pacific Northwest National Laboratory, United States Department of Energy; Executive Summary: Gasifier-derived synthesis gas (syngas) from coal has many applications in the area of catalytic transformation to fuels and chemicals. ... Systems comprising multiple sorbent and catalytic beds have been developed for the removal of impurities from gasified coal using a warm cleanup approach. By combining syngas methanation, water-gas-shift, and CO2 sorption in a single reactor, single pass yield to methane of 99% was demonstrated";
with apologies for the error in the dating of the title, it is feasible to convert Coal, as established by the United States Department of Energy, through a gasification process, into a product gas that consists, in essence, of nothing but substitute natural gas Methane.
We cite the above work of the USDOE's Pacific Northwest National Laboratory since their Coal gasification development studies have extended beyond that encompassed by ""Coal-Derived Warm Syngas Purification and CO2 Capture-Assisted Methane Production; Final Report". And, we will be addressing that further work in dispatches to follow.
However, as seen in other reports, such as:
Texaco Coal to Methane & Syngas | Research & Development | News; concerning: "United States Patent 3,951,617 - Production of Clean Fuel Gas; 1976; Inventor: William Crouch; Assignee: Texaco, Inc., NY; Abstract: Production of clean fuel gas having a high heating value by means of two interconnected free-flow noncatalytic partial oxidation gas generators. All of the particulate carbon produced in the effluent gas stream from both generators is recovered and burned as a portion of the feedstock in gas generator two to maximize the methane yield in gas generator one. ... A process for the production of fuel gas comprising ... reacting by partial oxidation a liquid hydrocarbon fuel with a free-oxygen containing gas ... wherein supplemental steam is introduced into the reaction zone ... (and) ... wherein the liquid hydrocarbon fuel ... is selected from the group consisting of asphalt, ... coal tar, coal oil (etc., and) wherein the hydrocarbonaceous fuel ... is ... pumpable slurries of solid hydrocarbonaceous fuels e.g. coal, coke from coal, particulate carbon ... in a liquid hydrocarbon fuel or water, and mixtures thereof. Background: A national dilemma exists as the result of a diminishing supply of natural gas and an increasing demand for it. ... By the subject invention a clean fuel gas having a high heating value may be produced (in a way) to maximize methane yield. ... Optionally, a stream of clean synthesis gas is produced simultaneously with the fuel gas"; and:
Exxon Converts 99% of Coal to Methane | Research & Development | News; concerning: "United States Patent 4,077,778 - Process for the Catalytic Gasification of Coal; 1978; Assignee: Exxon Research and Engineering Company, NJ; Abstract: A process for the production of synthetic natural gas from a carbon-alkali metal catalyst or alkali-metal impregnated carbonaceous feed, particularly coal, by reaction of said feed with water (steam) in the presence of a mixture of hydrogen and carbon monoxide (both made within the system, as noted above, from Coal and Water - JtM), in a series of staged fluidized bed gasification reactors (or gasification zones). ... (A) process for the production of synthetic natural gas by the conversion of a solid carbonaceous feed, in the presence of a carbon-alkali catalyst, by contact of said feed in a gasification zone containing a fluidized bed of char, with steam and a mixture of hydrogen and carbon monoxide gases added to said zone. (Recovering) a gaseous effluent from (the) secondary gasification zone and recovering synthetic natural gas consisting essentially of methane and a synthesis gas comprising hydrogen and carbon monoxide, from said gaseous effluent, recycling the recovered synthesis gases as the hydrogen and carbon monoxide gases supplied to the main and secondary gasification zones ... . Background: Fuel oil and natural gas shortages have sparked renewed world-wide interest in the development of processes that can produce clean synthetic natural gas, or gas of pipeline quality, from carbonaceous solids, particularly coal";
it is also feasible to produce, as a product of Coal gasification, a combination of substitute natural gas Methane along with hydrocarbon synthesis gas - - a blend of Carbon Monoxide and Hydrogen. That fact has multiple, and valuable, implications. For instance, the Methane can be combusted directly for power generation, or exported for other purposes. The syngas can, as well, be combusted for power generation, perhaps to supplement the Methane; or, it can be catalytically, chemically condensed into a full range of gaseous and liquid hydrocarbons, as via, for just one example, the Fischer-Tropsch synthesis.
An indication of those possibilities is provided in our report of:
Eastman Chemical Coal to Liquid Fuel, Chemicals and Electricity | Research & Development | News; concerning, in part: "United States Patent Application 20060149423 - Method for Satisfying Variable Power Demand; 2006; Inventors: Scott Barnicki, et. al., TN; Correspondence (and presumed eventual Assignee of Rights): Eastman Chemical Company, TN; Abstract: A process for satisfying variable power demand and a method for maximizing the monetary value of a synthesis gas stream are disclosed. One or more synthesis gas streams are produced by gasification of carbonaceous materials and passed to a power producing zone to produce electrical power during a period of peak power demand or to a chemical producing zone to produce chemicals such as, for example, methanol, during a period of off-peak power demand. The power-producing zone and the chemical-production zone which are operated cyclically and substantially out of phase in which one or more of the combustion turbines are shut down during a period of off-peak power demand and the syngas fuel diverted to the chemical producing zone. This out of phase cyclical operational mode allows for the power producing zone to maximize electricity output with the high thermodynamic efficiency and for the chemical producing zone to maximize chemical production with the high stoichiometric efficiency. The economic potential of the combined power and chemical producing zones is enhanced";
wherein the syngas could be used to, as circumstances warrant, synthesize valuable liquid fuels, for instance "methanol", or, to generate additional electric power. Again as we will be seeing, the USDOE has been devoting some effort to improving the efficiencies of using Coal-derived syngas as a fuel for electric power generation turbines.
And, there are even other possibilities for maximizing the value of Coal-derived mixed Methane and Syngas streams, in more advanced Coal gasification and power generation technologies, as disclosed in excerpts from the initial link in this dispatch to:
"United States Patent 8,920,526 - Production of Methane-rich Syngas from Hydrocarbon Fuels
December 30, 2014
Inventors: Nicholas Siefert, et. al., PA and Morgantown, WV
Assignee: United States Department of Energy, Washington, DC
Abstract: The disclosure provides a gasification process for the production of a methane-rich syngas at temperatures exceeding 700 C through the use of an alkali hydroxide MOH, using a gasification mixture comprised of at least 0.25 moles and less than 2 moles of water for each mole of carbon, and at least 0.15 moles and less than 2 moles of alkali hydroxide MOH for each mole of carbon. These relative amounts allow the production of a methane-rich syngas at temperatures exceeding 700 C by enabling a series of reactions which generate H2 and CH4, and mitigate the reforming of methane. The process provides a methane-rich syngas comprised of roughly 20% (dry molar percentage) CH4 at temperatures above 700 C, and may effectively operate within an IGFC cycle at reactor temperatures between 700-900 C and pressures in excess of 10 atmospheres.
Government Interests: The United States Government has rights in this invention pursuant to the employer-employee relationship of the Government to the inventors as U.S. Department of Energy employees and site-support contractors at the National Energy Technology Laboratory.
(The above "IGFC cycle", i.e., "Integrated Gasification Fuel Cell cycle", is one point where this technology differentiates itself from the others, similar, about which we've reported. As can be learned via:
Integrated Gasification Fuel Cell Cycle - Wikipedia, the free encyclopedia; "Lower-temperature fuel cell types such as the proton exchange membrane fuel cell, phosphoric acid fuel cell, and alkaline fuel cell require pure hydrogen as fuel, typically produced from external reforming of natural gas. However, fuels cells operating at high temperature such as the solid oxide fuel cell (SOFC) are not poisoned by carbon monoxide and carbon dioxide, and in fact can accept hydrogen, carbon monoxide, carbon dioxide, steam, and methane mixtures as fuel directly, because of their internal shift and reforming capabilities. This opens up the possibility of efficient fuel cell-based power cycles consuming solid fuels such as coal and biomass, the gasification of which results in syngas containing mostly hydrogen, carbon monoxide and methane which can be cleaned and fed directly to the SOFCs without the added cost and complexity of methane reforming, water gas shifting and hydrogen separation operations which would otherwise be needed to isolate pure hydrogen as fuel. A power cycle based on gasification of solid fuel and SOFCs is called an Integrated Gasification Fuel Cell (IGFC) cycle; the IGFC power plant is analogous to an integrated gasification combined cycle power plant, but with the gas trubine power generation unit replaced with a fuel cell (high temperature type such as SOFC) power generation unit".
We'll be treating the differentiations between IGFC and IGCC Coal utilization technologies in more detail in reports to follow, especially as they relate to co-generation technologies for producing both electric power and hydrocarbon fuels from Coal in one combined process as developed by the USDOE and others.
But, note, herein, that even though we prefer to emphasize the potential for generating both Methane and Hydrocarbon Synthesis Gas, "syngas" from Coal, and the multiple uses to which those products can be put, the USDOE herein is emphasizing the use of both of them, as generated from Coal, in Solid Oxide Fuel Cells.
The use of Syngas alone in SOFC's results in the generation of excess heat, which must be removed. To mitigate those, what the USDOE refers to as "parasitic" power drains for cooling, it is proposed herein to react Methane and Syngas together in an SOFC, with the net effect being that the SOFC runs cooler in the first place.
Our point is that some portion of the Syngas, perhaps with the co-product Methane, can be directed to an SOFC for generation of electricity. Another, perhaps variable, portion of the Syngas could be directed to a hydrocarbon synthesis process, such as the Fischer-Tropsch synthesis, for the production of liquid hydrocarbons; or, to a Methane synthesis reactor, more about which we will be documenting in reports to follow, for the production of even more Methane. And, all of the Methane could be directed, not to the specified SOFC, but, to a power plant already built to utilize shale or other natural gas but, which, due to rising prices for those fuels, can no longer supply affordable electricity, without some form of subsidy, to it's customers.)
Claims: A method for the production of a methane-rich syngas comprising: generating a slurry, where the slurry is comprised of a carbonaceous fuel, water, and an alkali hydroxide MOH, where M is an alkali metal cation of Potassium, Sodium, Lithium, ... or mixtures thereof, and where the slurry is comprised of at least 0.25 moles and less than 2 moles of the water for each mole of carbon, and where the slurry is comprised of at least 0.15 moles and less than 2 moles of alkali hydroxide MOH for each mole of carbon, and where the slurry is at a slurry temperature such that the water is in the liquid phase; transferring the slurry to a gasification zone and subjecting the slurry to a gasification temperature and a gasification pressure, where the gasification temperature is at least 700 C, and where the gasification temperature is greater than the molten temperature of a molten carbonate M2CO3, thereby generating gasification gases comprised of H2 and CH4 and thereby generating the molten alkali carbonate M2CO3; and separating at least some portion of the gasification gases from the molten alkali carbonate M2CO3, thereby generating the methane-rich syngas, where the methane-rich syngas is the at least some portion of the gasification gases.
The method ... where the gasification pressure is at least 10 atmospheres.
(This is a high-temperature and, perhaps more importantly, high-pressure process. So it should be noted that the capital expense needed to build a plant to carry out a process like this would be significant. Likely, though, not as significant as the cost of yet another US Navy destroyer or other ship needed in some numbers to keep the OPEC shipping lanes open and the Persian Gulf area peaceful enough to keep pumping oil. Since the co-produced Coal syngas generated herein could be used in a Fischer-Tropsch process, as we will be documenting in yet more reports to follow concerning the USDOE's work, to make substitute petroleum liquid fuels, that comment isn't inappropriate.)
The method ... where the alkali hydroxide MOH is at least 5 mol % Potassium Hydroxide, and where the slurry is comprised of at least 0.5 moles and less than 1.5 moles of alkali hydroxide MOH for each mole of carbon.
The method ... where the carbonaceous fuel is coal,
and where the ... the methane-rich syngas is comprised of at least 15 vol % CH4 and less than 10 vol % CO2.
(The co-production of CO2 shouldn't be seen as a drawback to this process. As seen, for only one more recent example out of now many in:
"US Patent Application 20140272734 - Electrochemical Device for Syngas and Liquid Fuels Production; 2014; Inventors: Robert Braun, William Becker, and Michael Penev, CO; (USDOE National Renewable Energy Laboratory and Colorado School of Mines); Abstract: The invention relates to methods for creating high value liquid fuels such as gasoline, diesel, jet and alcohols using carbon dioxide and water as the starting raw materials";
the technology now exists to start treating Carbon Dioxide as a valuable raw material resource from which, in processes driven by environmental, so-called "renewable", energy, we can synthesize even more hydrocarbon fuels, such as "gasoline" and "diesel".)
The method ... where for each 1 mole of Potassium Hydroxide the alkali hydroxide is comprised of between 0.9 and 1.1 mole of Sodium Hydroxide and between 0.9 and 1.1 mole of Lithium Hydroxide.
The method ... where the carbonaceous fuel is coal, and the gasification temperature is less than 900 C, and the gasification pressure is at least 20 atmospheres.
The method ... where subjecting the slurry to the gasification temperature and the gasification pressure occurs in a co-current gasification zone, and where separating at least some portion of the gasification gases from the molten alkali carbonate M2CO3 occurs in a separation vessel through buoyancy and gravity effects on the at least some portion of the gasification gases and the molten alkali carbonate M2CO3.
The method ... further comprised of transferring the methane-rich syngas to the anode of a high temperature fuel cell, such as a solid oxide fuel cell.
The method ... where subjecting the slurry to the gasification temperature and the gasification pressure occurs in a reaction zone, and further comprised of transferring heat or gas or a combination thereof from the anode tail-gas of the solid oxide fuel cell to the reaction zone.
A method for the production of a methane-rich syngas comprising: generating a mixture comprised of coal, water, and an alkali hydroxide MOH, where M is an alkali metal cation of K, Na, Li, or mixtures thereof, where the alkali hydroxide MOH is at least 5 mol % KOH, where for each 1 mole of KOH the alkali hydroxide is comprised of between 0.9 and 1.1 mole of NaOH and between 0.9 and 1.1 mole of LiOH, and where the mixture is comprised of at least 0.25 moles and less than 2 moles of the water for each mole of carbon, and where the mixture is comprised of at least 0.15 moles and less than 2 moles of alkali hydroxide MOH for each mole of carbon; subjecting the mixture to a gasification temperature and a gasification pressure, where the gasification temperature is at least 700 C and less than 900 C, and where the gasification temperature is greater than the molten temperature of a molten carbonate M2CO3, and where the gasification pressure is at least 10 atmospheres, thereby generating gasification gases comprised of H2 and CH4 and thereby generating the molten alkali carbonate M2CO3; and separating at least some portion of the gasification gases from the molten alkali carbonate M2CO3 and withdrawing the methane-rich syngas, where the methane-rich syngas is comprised of at least 15 vol % CH4 and less than 10 vol % CO2, thereby generating the methane-rich syngas, where the methane-rich syngas is the at least some portion of the gasification gases.
The method ... where generating the generating the mixture comprised of the carbonaceous fuel, the water, and the alkali hydroxide MOH is comprised of: generating a slurry, where the slurry is comprised of the coal, the water, and the alkali hydroxide MOH, and where the slurry is comprised of the at least 0.25 moles and the less than 2 moles water for the each mole of carbon, and where the slurry is comprised of the at least 0.15 moles and the less than 2 moles of the alkali hydroxide MOH for the each mole of carbon, and where the slurry is at a slurry temperature such that the water is in the liquid phase; and transferring the slurry to a gasification zone at the gasification temperature and the gasification pressure, and heating the slurry in the co-current gasification zone to the gasification temperature, thereby generating the mixture comprised of the carbonaceous fuel, the water, and the alkali hydroxide MOH (and) subjecting the mixture to the gasification temperature and the gasification pressure occurs in a co-current gasification zone, and where separating at least some portion of the gasification gases from the molten alkali carbonate M2CO3 occurs in a separation vessel through buoyancy and gravity effects on the at least some portion of the gasification gases and the molten alkali carbonate M2CO3.
The method ... further comprised of transferring the methane-rich syngas to the anode of a high temperature fuel cell, such as a solid oxide fuel cell.
The method ... further comprised of transferring heat or gas or a combination thereof from the anode tail-gas of the solid oxide fuel cell to the co-current reaction zone.
(For more info on "solid oxide fuel cell"s, see:
Solid oxide fuel cell - Wikipedia, the free encyclopedia; A solid oxide fuel cell (or SOFC) is an electrochemical conversion device that produces electricity directly from oxidizing a fuel. Fuel cells are characterized by their electrolyte material; the SOFC has a solid oxide or ceramic electrolyte. Advantages of this class of fuel cells include high efficiency, long-term stability, fuel flexibility, low emissions, and relatively low cost. The largest disadvantage is the high operating temperature which results in longer start-up times and mechanical and chemical compatibility issues".
And, keep in mind that SOFC's can be operated "in reverse", so to speak, with the result being, as in:
USDOE Idaho Lab Recycles More CO2 | Research & Development | News; concerning: Model of High Temperature H2O/CO2 Co-electrolysis; 2007;G. Hawkes, J. O'Brien, C. Stoots, Stephen Herring, Joe Hartvigsen; OSTI ID: 912896; Report Number: INL/CON-07-12092; DOE Contract: DE-AC07-99ID-13727; Research Organization: Idaho National Laboratory (INL); Sponsoring Organization: USDOE; Abstract: A three-dimensional computational fluid dynamics (CFD) model has been created to model high temperature co-electrolysis of steam and carbon dioxide in a planar solid oxide electrolyzer (SOE) using solid oxide fuel cell technology. A research program is under way at the Idaho National Laboratory (INL) to simultaneously address the research and scale-up issues associated with the implementation of planar solid-oxide electrolysis cell technology for syngas production from CO2 and steam. Various runs have been performed under different run conditions to help assess the performance of the SOE. This paper presents CFD results of this model compared with experimental results. The Idaho National Laboratory (INL), in conjunction with Ceramatec Inc. (Salt Lake City, USA) has been researching for several years the use of solid-oxide fuel cell technology to electrolyze steam for large-scale nuclear-powered hydrogen production. Now, an experimental research project is underway at the INL to produce syngas by simultaneously electrolyzing at high-temperature steam and carbon dioxide (CO2) using solid oxide fuel cell technology. A strong interest exists in the large-scale production of syngas from CO2 and steam to be reformed into a usable transportation fuel";
the conversion of Carbon Dioxide and Water into more hydrocarbon synthesis gas. And, as in our above citation of our report concerning "US Patent Application 20140272734 - Electrochemical Device for Syngas and Liquid Fuels Production; 2014; Inventors: Robert Braun, William Becker, and Michael Penev, CO; (USDOE National Renewable Energy Laboratory and Colorado School of Mines)"; at least some of the needed energy to drive the reverse SOFC reaction can be provided by renewable sources.)
Background and Field: The disclosure relates to a gasification process for a carbonaceous fuel for the production of a methane-rich syngas at molten bed temperatures exceeding 700 C through the use of an alkali hydroxide MOH, where M is an alkali cation of K, Na, Li, or a mixture thereof, using a gasification mixture comprised of at least 0.25 moles and less than 2 moles of water for each mole of carbon, and at least 0.15 moles and less than 2 moles of alkali hydroxide MOH for each mole of carbon. The process provides a methane-rich syngas comprised of roughly 20% (dry molar percentage) CH4 ... .
Gasification is a process that converts organic or fossil based carbonaceous materials into carbon monoxide, hydrogen, carbon dioxide and methane. This is achieved by reacting the material at high temperatures without combustion, with a controlled amount of oxygen and/or steam, to generate a resulting gas mixture of H2 and CO called syngas. Syngas is combustible and often used as a fuel or as an intermediate for the production of other chemicals such as methane, methanol, synthetic diesel and dimethyl ether in catalytic processes.
A significant use of syngas is as a fuel for fuel cells, which utilize hydrogen and oxygen to produce direct current electricity.
In addition to electricity, fuel cells produce water, carbon dioxide, heat and, depending on the fuel source, very small amounts of nitrogen dioxide and other emissions. The energy efficiency of a fuel cell is generally between 40-60%, or up to 85% efficient if waste heat is captured for use. Additionally, because fuel cells generate electricity while keeping the fuel and air separated, the CO2 generated in the anode of the fuel cell is not diluted with nitrogen, making about 100% capture of CO2 within the system both technically and economically viable.
A Solid Oxide Fuel Cell (SOFC) is a specific type of fuel cell which offers particular advantage. SOFCs use a solid material, typically yttria-stabilized zirconia, as the electrolyte, and the solid material construction allows geometries outside of the flat plane configurations of other types of fuel cells. The SOFC operates at very high temperatures, typically between 500 and 1000 degrees Celsius (C), and are capable of internally reforming light hydrocarbons such as methane, propane and butane. As a result, SOFCs can be run on a variety of fuels other than pure hydrogen gas, provided the fuel selected contains hydrogen atoms. The high SOFC temperatures also incur other advantages, such as: a) the ability to incorporate bottoming cycles to generate further power from high temperature exhaust stream, b) the capability to water-gas-shift CO into H2 fuel, c) the capability to steam reform hydrocarbons into H2 and CO, and d) the capability to catalyze the electrochemical reactions using non-noble metals, thus eliminating the need for expensive electro-catalysts, such as platinum. A primary disadvantage in SOFC operation is the necessary cooling load of the fuel cell due to the exothermic electro-chemical reaction between hydrogen and oxygen ions. In terms of overall system efficiency, the parasitic cooling load typically manifests as compressive and pumping power cost expended for supply of cooling air flow. A reduction in cooling requirements therefore has direct improvement on the operating efficiency of the SOFC.
One method of reducing SOFC cooling requirements is to use the internal reforming capabilities of the electrocatalysts engendered by the high operating temperatures. Endothermic reforming of hydrocarbons such as CH4 can serve as an effective heat sink to the exothermic H2 oxidation within the fuel cell, and significantly reduce stack thermal management load. As a result, use of a methane-rich syngas as an SOFC fuel carries distinct advantages. However, generation of a methane-rich syngas through gasification has been problematic at the typical SOFC operating temperatures, temperatures above 700 C, because of rapid methane reforming and oxidation in typical coal gasifiers. Correspondingly, the realizable efficiency of combined cycle concepts such as the Integrated Gasification Fuel Cell (IGFC) have suffered. In order to achieve high IGFC efficiencies, it is desirable that the gasification process and the SOFC operation occur at commiserate temperatures, and additionally desirable that the gasification process delivers a methane-rich syngas product, in order to exploit the endothermic reforming reactions discussed above that minimize the amount of coolant or cooling air.
A gasification system capable of generating a methane-rich syngas at the high operating temperatures of an SOFC would provide distinct advantage. The advantage of a methane-rich syngas would additionally accrue to the gasification operation itself, since methanation is a highly exothermic reaction and can be utilized to supply all or a large portion of the energy required for the endothermic steam-coal reactions, and greatly mitigate the need for oxygen, and hence greatly mitigates the need for supporting air separation units in gasification operations. In addition, since higher temperatures means faster steam-gasification kinetics, then higher reactor temperatures imply smaller reactor sizes per unit of syngas exiting the reactor.
It is also understood that the reactivity of carbonaceous materials such as graphite and coal char towards CO2 and steam is strongly enhanced by the presence of alkali metal salts such as Li2CO3, (etc.,). The exact role that the salts play in these processes is not completely understood, however whatever the detailed mechanism of the catalytic process is, the overall rate of gasification is enhanced through contact between the alkali metal catalyst and the carbon. Generally, molten catalyst salts are better able to penetrate the coal structure and, hence, improve accessibility of the unavailable carbon sites in the interior of the coal/char. ... It would be advantageous to provide a gasification process whereby catalytic gasification using an alkali metal catalyst could generate a methane-rich syngas within the SOFC operating temperature range. It would provide further advantage if the catalyst were an alkali hydroxide, so that a substantial amount of CO2 generated as a result of the gasifier process could be captured within the reactor. The exothermic capture reactions, along with the exothermic methanation reactions, mean that the gasifier can be operated without any input of oxygen or external heating. Additionally, by eliminating the requirement for oxygen to maintain the temperature of the reactor, a larger amount of methane can be generated in the gasifier.
(Eliminating the need for air separation units to provide enriched Oxygen to the gasifier would help to reduce the overall capital expense and costs of operation, in addition to enabling the formation of a "larger amount of methane".)
Summary: The disclosure provides a gasification process for the production of a methane-rich syngas at temperatures exceeding 700 C through the use of an alkali hydroxide MOH using a gasification mixture comprised of at least 0.25 moles and less than 2 moles of water for each mole of carbon, and at least 0.15 moles and less than 2 moles of alkali hydroxide MOH for each mole of carbon. Preferably, the gasification mixture is comprised of at least 0.5 moles and less than 1.5 moles of alkali hydroxide MOH for each mole of carbon. These relative amounts allow the production of a methane-rich syngas at temperatures exceeding 700 C by enabling a series of reactions which generate H2 and CH4, and mitigate the steam-reforming of methane. The particular molar relationship of the gasification mixture prevents the alkali hydroxide MOH from capturing all gaseous carbon species. If not enough alkali hydroxide catalyst is used, then the process requires the input of oxygen, which can oxidize methane. If too much alkali hydroxide is used, then the methane and higher hydrocarbons are steam-reformed, and there isn't enough hydrocarbons in the syngas to provide cooling downstream in the SOFC. If not enough water is used, then the initial steam-coal gasification reaction cannot proceed. If too much water is used, then the methane and higher hydrocarbons are reformed, and there isn't enough hydrocarbons in the syngas to provide cooling downstream in the SOFC
The carbonaceous fuel is a fuel or gasifiable material which contains carbon in an elemental or chemically combined form. The alkali hydroxide MOH and subsequently formed alkali carbonate M2CO3 act to catalyze the carbon-steam reaction, generating CO and H2. The water gas shift reaches equilibrium rapidly at the gasification temperature, and acts to balance the concentrations of CO, H2O, CO2, and H2, in conjunction with methanation reactions. The alkali hydroxide MOH in the molten state acts to remove to some portion of CO2 and form molten alkali carbonate M2CO3, however, the molar relations of the gasification mixture limit the alkali hydroxide MOH and H2O actions maintain a concentration of C and H2O such that reverse methanation is greatly mitigated.
The gasification process disclosed effectively operates within an IGFC cycle, or an IGCC cycle if 100% CO2 capture is not required. The IGFC cycle is enhanced by operation with methane-rich syngas by the methane reforming which occurs within the operating temperature and pressure conditions of the SOFC, reducing the burden on parasitic heat removal process associated with maintaining the operating temperature of the SOFC. An additional advantage of the process is the generation of the methane-rich syngas at elevated pressures, which significantly aids integration into an IGFC, where the SOFC may operate at pressures in excess of 5 atmospheres".
Again, as per our introductory and inserted comments, this is really all about a perhaps more efficient process of generating electricity from Coal, wherein a Coal-derived synthesis gas is reacted in a Solid Oxide Fuel Cell, SOFC, for the purposes of power generation.
Methane co-produced in the Coal gasification is also fed, along with the syngas, to the SOFC, since the Methane serves as a heat sink in the SOFC reactions, thus making it unnecessary to arrange for cooling of the SOFC, with the attendant costs of that cooling.
However, other possibilities and potentials are also inherent in the process. As seen in our above citation of our report concerning Eastman Chemical's "United States Patent Application 20060149423 - Method for Satisfying Variable Power Demand", the technology disclosed by our subject could be utilized in a process of what was at least once known as "polygeneration", another example of which is disclosed in our report of:
USDOE Coal to Gasoline, Diesel and Electricity Profitable | Research & Development | News; concerning: "'Baseline Technical and Economic Assessment of a Commercial Scale Fischer-Tropsch Liquids Facility'; DOE/NETL-2007/1260; Final Report for Subtask 41817.401.01.08.001; April 9, 2007; NETL Contact: Michael Reed; Senior Systems Analyst, Office of Systems Analyses and Planning; National Energy Technology Laboratory; Economic and national security concerns related to liquid fuels have revived national interest in alternative liquid fuel sources. Coal to Fischer-Tropsch fuels production has emerged as a major technology option for many states and the Department of Energy. This report summarizes the preliminary results of an NETL study to assess the feasibility of commercial scale, coal-to-liquids production using a high Btu Midwestern Coal. The conceptual design uses high sulfur bituminous coal to produce distillate and naphtha liquid pools via indirect coal liquefaction (F-T process). With the addition of additives, the distillate can be converted to a saleable diesel fuel. The naphtha liquids can be shipped to a refinery for upgrading into gasoline ... . The plant produces a net power output of 124 MWe which can be exported to the grid";
wherein the initial products of Coal gasification can be directed into, depending on need and best economic value, the production of electricity and hydrocarbons in variable amounts. We'll treat that topic more fully in reports to follow, but caution anyone researching the topic to be aware that the terms "cogeneration" and "polygeneration", as applied to Coal-based systems like the ones discussed herein, have of late been largely perverted and are being applied to less-meaningful concepts such as the "cogeneration" of heat energy, along with electricity, in Coal gasification processes - as self-evident as such potentials would seem to be.
We, here, see the process of our subject, "United States Patent 8,920,526 - Production of Methane-rich Syngas from Hydrocarbon Fuels", as inherently more meaningful than that, and will be referring back to it in reports to follow concerning the further development of advanced Coal utilization technologies related to it by, among others, the United States Department of Energy.