Power Generation

Abstract

A process for gasifying waste material and producing energy which comprises contacting a solid organic waste material containing at least 10 weight percent oxygen with steam in the presence of an alkali metal carbonate catalyst at an elevated temperature to obtain a gas, combusting at least a portion of said gas to obtain combusted gases, and expanding the combusted gases through a turbine to rotate the turbine. Preferably, the energy of the rotating turbine is used to drive an electricity generator. It is strongly preferred to use a potassium carbonate catalyst in the gasification of the oxygen-containing waste material. Preferably feedstocks include ordinary municipal refuse or garbage having the requisite oxygen content and usually having a more preferred oxygen content above at least 20 weight percent oxygen.

Parent Case Text

CROSS REFERENCES

This application is a Continuation-in-Part of Ser. No. 34,834, filed May 5, 1970, entitled "Catalytic Hydrogen Manufacture," the disclosure of which application is incorporated by reference in the present patent application.

Description

BACKGROUND OF THE INVENTION

The present invention relates to the gasification of carbonaceous solid waste material containing a minimum amount of combined oxygen; and the present invention also relates to the generation of energy by combustion of gases obtained in the gasification of the waste material and preferably expanding the combusted gases through a turbine.

Various gasification methods have been suggested for carbonaceous matter. Among these methods are steam-hydrocarbon reforming, partial oxidation of hydrocarbons, Lurgi heavy hydrocarbons gasification, the traditional steam, red-hot coke reaction, modified methods of reacting carbonaceous matter with steam and oxygen, such as described in U.S. Pat. No. 1,505,065, coal gasification and lignite gasification.

The two leading processes, that is, the two processes which are most frequently used to generate hydrogen, are steam-hydrocarbon reforming and partial oxidation of hydrocarbons.

In typical steam reforming processes, hydrocarbon feed is pretreated to remove sulfur compounds which are poisons to the reforming catalyst. The desulfurized feed is mixed with steam and then is passed through tubes containing a nickel catalyst. While passing through the catalyst-filled tubes, most of the hydrocarbons react with steam to form hydrogen and carbon oxides. The tubes containing the catalyst are located in a reforming furnace, which furnace heats the reactants in the tubes to temperatures of 1,200.degree.F. - 1,700.degree.F. Pressures maintained in the reforming furnace tubes range from atmospheric to 450 psig. If a secondary reforming furnace or reactor is employed, pressures used for reforming may be as high as 450 psig to 700 psig. In secondary reformer reactors, part of the hydrocarbons in the effluent from the primary reformer is burned with oxygen. Because of the added expense, secondary reformers are generally not used in pure hydrogen manufacture, but are used where it is desirable to obtain a mixture of H.sub.2 and N.sub.2, as seen in ammonia manufacture. The basic reactions in the steam reforming process are:

C.sub.n H.sub.2n.sub.+2 +nH.sub.2 0.revreaction.nCO+(2n+1)H.sub.2

C.sub.n H.sub.2n.sub.+2 +2nH.sub.2 0.revreaction.nCO.sub.2 +(3n+1)H.sub.2

e.g., methane-steam:

CH.sub.4 +H.sub.2 0.revreaction.CO+3H.sub.2

and,

CH.sub.4 +2H.sub.2 0.revreaction.CO.sub.2 +4H.sub.2

In typical partial oxidation processes, a hydrocarbon is reacted with oxygen to yield hydrogen and carbon monoxide. Insufficient oxygen for complete combustion is used. The reaction may be carried out with gaseous hydrocarbons or liquid or solid hydrocarbons, for example, with methane, the reaction is:

CH.sub.4 + 1/20.sub.2 .revreaction.2H.sub. 2 +CO

With heavier hydrocarbons, the reaction may be represented as follows:

C.sub.7 H.sub.12 +2.8 O.sub.2 :2.1 H.sub.2 .revreaction.6.3 CO+0.7 CO.sub.2 +8.1 H.sub.2

Both catalytic and noncatalytic partial oxidation processes are in use. Suitable operating conditions include temperatures from 2,000.degree.F. up to about 3,200.degree.F. and pressures up to about 1200 psig, but generally pressures between 100 and 600 psig are used. Various specific partial oxidation processes are commercially available, such as the Shell Gasification Process, Fauser-Montecatini Process, and the Texaco Partial Oxidation Process.

There is substantial carbon monoxide in the hydrogen-rich gas generated by either reforming or partial oxidation. To convert the carbon monoxide to hydrogen and carbon dioxide, one or more CO shift conversion stages are typically employed. The CO shift conversion reaction is:

CO+H.sub.2 O.fwdarw.H.sub.2 +CO.sub.2

This reaction is typically effected by passing the carbon monoxide and H.sub.2 O over a catalyst such as iron oxide activated with chromium.

Production of hydrogen and other gases from waste substances produced in the manufacture of paper from wood chips, and the like has been discussed in the literature as, for example, in U.S. Pat. No. 3,317,292. In the manufacture of paper, wood chips are digested, for example, with an aqueous calcium sulfide liquid thereby forming calcium lignin sulfonate waste product in solution, leaving wood pulp behind. As disclosed in U.S. Pat. No. 3,317,292, the waste substances containing lignin-derived organic components can be converted to a gas mixture comprising hydrogen by contacting the waste material with steam in a reaction zone at an elevated temperature at least of the order of several hundred degrees centigrade. The sulfide waste liquor produced in the manufacture of paper from wood chips and the like is a relatively well-defined waste material consisting mostly of lignin-type organic compounds and certain inorganic components, including at least 5 weight percent sulfur calculated as the element sulfur but present usually in the form of sulfur compounds.

The use of catalysts such as potassium carbonate has been disclosed for the reaction of carbon with steam to form hydrogen as is discussed, for example, in Journal of the American Chemical Society, Vol. 43, page 2055 (1921). However, the use of catalysts such as potassium carbonate to catalyze the reaction of organic material containing substantial amounts of oxygen, particularly waste or garbage-type material with steam to form hydrogen does not appear to be disclosed or suggested in the prior art.

U.S. Pat. No. 3,471,275 discloses a method for converting refuse or garbage-type material to gases such as gases rich in hydrogen. According to the process disclosed in U.S. Pat. No. 3,471,275, the refuse is fed to a retort and heated therein to a temperature between about 1,650.degree.F. and 2,200.degree.F. The retort is externally heated. According to the 3,471,275 patent process, steam is not generally added to the retort. Any steam which is added to the retort according to the process disclosed in the 3,471,275 patent is added to the bottom of the retort so that steam would flow counter-current to the waste material which is introduced to the retort at the top of the retort. No catalyst is used in the 3,471,275 patent process.

As indicated previously, the present invention in addition to gasification relates to the production of energy by combusting the gases obtained from gasification and then expanding the gases through a turbine. Gas turbines are described in Perry's Chemical Engineer's Handbook, Fourth Edition, at page 24-77 to 24-80. As indicated in Perry's Handbook, gas turbines can use a wide variety of fuels. Major fuel limitations are that it does not (1) form ashes which deposite on the blades and interfere with operation, (2) contain dust which will erode the blades, and (3) contain uninhibited vanadium. Gas turbines are now operating on fuel gas (natural and refinery), blast-furnace gases, fuel oils (including heavy residuals), and at least one coal-burning gas turbine is operating.

As described in a report titled: "New Fossil-Fueled Power Plant Process Based on Lurgi Pressure Gasification of Coal" by Paul F. H. Rudolph delivered at an ACS meeting on May 27, 1970, coal burning gas turbines are used at Lunen in West Germany to drive electricity generators. As disclosed in that report, carbon or coal can be gasified in the presence of oxygen and H.sub.2 O at a temperature of 790.degree.C. (1,454.degree.F.). Gases from the gasification zone, which consist of CO, are purified to remove coal dust and fly ash and also many other impurities such as vaporized ash, alkali, and chlorine which are detrimental to the operation of gas turbines. After purification of the gases from the gasification step, the gases are then combusted with air and then expanded through a gas turbine which turbine is used to drive an electricity generator. The amount of air introduced to the combustor chamber is adjusted so that the outlet temperature from the combustor and the inlet temperature to the gas turbine is about 820.degree.C. (1,508.degree.F.).

The Rudolph report is directed to the gasification of coal and also mentions that other gasification plants are used to gasify similar material such as sub-bituminous coal and lignite. The Rudolph report does not disclose the gasification of high oxygen content organic waste material in the presence of alkali metal catalysts. The Rudolph report is hereby incorporated by reference into the present patent specification.

SUMMARY OF THE INVENTION

According to the present invention, a process is provided for gasifying waste material and producing energy which process comprises contacting a solid organic waste material containing at least 10 weight percent oxygen with steam in the presence of an alkali metal carbonate catalyst at an elevated temperature to obtain a gas, combusting at least a portion of said gas to obtain combusted gases and expanding the combusted gases through a turbine to rotate the turbine.

An important feature of the present invention is that the invention provides a process to convert large quantities of waste material, such as municipal garbage, which currently presents a difficult disposal problem, to valuable energy, preferably electrical energy.

I have found that solid organic waste material containing at least 10 weight percent oxygen is converted at an unexpectedly high rate to combustible gases and that the defined organic feed material is converted at an unexpectedly high rate to combustible gas when the conversion is carried out in accordance with the present invention. We have found that the rate of conversion of the organic feed material is particularly fast when a potassium carbonate catalyst is used to accelerate the reaction rate.

The reason for the fast reaction rate for the formation of combustible gases in the process of the present invention is not completely understood, but it is believed that an important factor is the oxygen content of the organic feed material in the process of the present invention. The organic feed material, which in this specification is to be understood to contain hydrogen, as well as carbon, must contain at least 10 weight percent oxygen which can be contrasted to the essentially nil amount of oxygen present in hydrocarbon feedstocks to synthesis gas-producing processes such as steam-light hydrocarbon reforming or hydrocarbon partial oxidation. The presence of oxygen in the organic feed material in the process of the present invention may contribute to the relatively fast reaction rate by making the feed material more susceptible to reaction with additional steam to produce hydrogen than in the case of hydrocarbon material containing little or no oxygen. I have found that it is particularly preferable in the process of the present invention to produce a synthesis gas from organic feed material containing at least 20 weight percent oxygen and still more preferably, between about 35 and 70 weight percent oxygen.

I have also found that organic feed material containing the oxygen substantially in the form of polyhydroxylated compounds is particularly advantageous from the standpoint of high reaction rates with steam to form synthesis gas. Feeds containing oxygen in the form of polyhydroxylated compounds are meant to include carbohydrates such as cellulose and sugars.

The oxygen and the hydrogen content in the organic feed material are to be understood as chemically combined oxygen and hydrogen, i.e., oxygen and hydrogen which are connected through one or more chemical bonds to the carbon present in the organic feed material. Solid waste material which is largely cellulosic, as for example agricultural waste such as corn husks or solid municipal waste such as common garbage containing a large amount of paper, are particularly preferred feedstocks to the process of the present invention. Usually and preferably, the oxygen in the solid waste feedstock to the process of the present invention is oxygen which is directly chemically bonded to carbon in the solid waste feedstock.

In general, the term "solid organic waste material" is used herein to connote solid municipal waste or common garbage, sewage, industrial wastes such as sawdust, and agricultural wastes such as corn husks and other discarded cellulosic materials.

An important aspect of the present invention is the bringing together of the two concepts that garbage material or solid municipal waste can be converted to a combustible gas and that the combustible gas can be converted to energy, most preferably electrical energy. In the process of the present invention, the electrical energy is generated by expanding combusted gases obtained from the gasification of solid wastes, such as solid municipal waste in a gas turbine with the gas turbine being used to drive an electricity generator. This type of plant can be employed at various locations to solve the increasing problem of solid municipal waste disposal, particularly the disposal of increasing amounts of municipal garbage.

Another very important aspect of the present invention which cooperates in the over-all process of the present invention to make the process of the present invention more economically feasible is the discovery of the surprising catalytic effect of alkali metals, particularly potassium, to accelerate the reaction of oxygen containing organic material and particularly to accelerate the gasification of solid municipal waste such as garbage to produce a combustible gas which can be burned to supply the driving power for the gas turbine.

It is preferred in the process of the present invention to use an organic oxygen containing feed material which contains less than 5 weight percent sulfur. The sulfur is calculated as the element sulfur, although for those undesired and excluded feedstocks, the sulfur is usually present as a compound as, for example, an organic sulfur compound or an inorganic sulfur compound present in the feed material. Thus, it is to be understood that the organic feed material contacted with steam according to the process of the present invention is preferably free from a high percentage of inorganic or organic sulfur compounds, i.e., that the feed contains less than 5 weight percent sulfur either as sulfur chemically combined with the organic feed material or as inorganic sulfur compounds physically mixed with the organic feed material. Feeds such as Kraft black liquor produced as a waste material in the manufacture of paper pulp are usually not suitable in the process of the present invention because of the relatively high content of sulfur compounds in the Kraft black liquor. It is undesirable to have substantial amounts of sulfur feed to the reaction zone in the process of the present invention because of the increased reactor cost and, more particularly, because of the increased problems in removing sulfur compounds from the synthesis gas produced in the reactor. It is preferred that the sulfur content of the organic feed material be below about 3 weight percent sulfur.

The catalyst used in the process of the present invention is preferably an alkali metal catalyst, as we have found particularly high reaction rates using alkali metal catalysts. Potassium carbonate has been found to be particularly preferable among the alkali metal catalysts. Other catalysts comprising Group VIII metals such as nickel can be used in the process of the present invention, but nickel catalysts have been found to be relatively susceptible to sulfur poisoning even at relatively low sulfur contents for the organic feedstock to the process of the present invention. Nickel catalysts are not soluble in water and thus cannot be readily recovered from the ash product from the reaction zone for reuse as a catalyst such as can be done with the alkali metal catalyst like potassium carbonate. Thus, although we have recently found that nickel catalysts such as nickel acetate i.e., Ni(Ac).sub.2, nickel nitrate i.e., Ni(NO.sub.3).sub.2, result in a very high reaction rate for combustible gas production from oxygen containing organic feedstocks at temperatures between about 1,200.degree.F. and 1,400.degree.F, alkali metal catalysts such as the potassium carbonate catalysts are preferred because of their very low susceptibility to sulfur poisoning and because of their recoverability, for example, by removing them from gasification zone ash by dissolving them in water.

The alkali metal catalysts include lithium, sodium, potassium, rubidium and cesium. Preferably, the alkali metal is added to the reaction zone by contacting the feed to the reaction zone with a solution of a salt of the alkali metal catalyst. The salts of the alkali metal catalyst include salts such as sulfates and chlorides. Although it is preferred to add the alkali metal catalyst to the reaction zone in the form of a carbonate, it is suitable to add the catalyst in other forms such as hydroxides or acetates, formates, sulfates, chlorides, or other alkali metal salts. It is believed these compounds will tend to be converted to carbonates in the reaction zone.

Preferred amounts of the catalyst as a weight percentage of the organic feed material are from 1 to 50 weight percent and particularly preferred amounts are from 5 to 20 weight percent. When using the particularly preferred potassium carbonate catalyst, about 2 to 15 weight percent potassium carbonate is preferably impregnated into the feed before contacting the feed with steam in the reaction zone.

As indicated previously, the organic feed material to the process present of the invention must contain a minimum amount of oxygen, namely at least 10 weight percent oxygen. Particularly preferred feedstocks contain 20 percent or more combined oxygen. As indicated in my copending application Ser. No. 34,834, the reason for the fast reaction rate for the formation of hydrogen-rich gas in the catalytic reaction according to the process of the present invention is not completely understood, but the oxygen content of the feedstock has been found to be a realted factor to the fast reaction when using the alkali metal catalyst. Furthermore, progressively higher oxygen contents, particularly from 10 to 25 weight percent, have been found to result in progressively faster reaction rates for the formation of hydrogen-rich gas in the process of the present invention.

An important advantage obtained in the process of the present invention compared to coal gasification processes using no alkali metal catalyst, is the essentially complete elimination of chlorides such as hydrogen chloride and many other acid gases excepting hydrogen sulfide by reaction of the added alkali metal catalyst used in accordance with the process of the present invention with acid constituents such as hydrogen chloride formed in the gasification zone.

In the process of the present invention, it is preferred to add an oxygen-containing gas such as air or molecular oxygen to the reaction zone to burn a portion of the organic feed material with steam to form synthesis gas and carbon oxides. The heat for the reaction can also be supplied by heating the steam fed to the reaction zone to a sufficiently high temperature to supply the required amount of heat for the endothermic reaction of steam plus organic material to form synthesis gas.

Although the gasification reaction of the present invention can be carried out at temperatures between about 700.degree. and 2,000.degree.F., it is strongly preferred to use a lower temperature, preferably between 1,000.degree. and 1,400.degree.F., and still more preferaby between 1,100.degree. and 1,300.degree.F. The lower temperature is particularly made feasible in my process because of the relatively fast reaction rate obtained with oxygen-containing waste material using an alkali metal catalyst such as potassium carbonate. Advantages achieved using the lower temperature include greater life for the gasification reactor, better heat efficiency, less tendency to slagging of glass, and less expensive reactor metallurgy requirements. Therefore, the lower temperatures used in the process of the present invention compared to other gasification processes is a very important advantage.

The concept of the present invention also is extendable to generating energy, from high oxygen content solid waste material, in other manners as, for example, by generating a combustible gas from oxygen-containing solid waste material followed by combusting the gas in a steam boiler so as to obtain steam which can be used to drive a turbine, the energy of which turbine can be used to generate electrical power. Also, particularly since the gases obtained according to the process of the present invention are rich in hydrogen (especially at the low temperatures made feasible in the gasification zone of the present invention), the gases can be combusted in a fuel cell to convert the gases to electrical energy.

EXAMPLES

1. Fifty grams of simulated solid municipal waste composed of 50 weight percent paper, 10 weight percent sawdust, 3 weight percent wool, 2 weight percent plastic, 10 weight percent cotton, 10 weight percent iron, 2 weight percent aluminum, and 13 weight percent food peels such as orange peels, etc. The oxygen content of this particular organic feed material was approximately 50 percent by weight excluding the metallic materials, i.e., iron and aluminum in the reactor charge.

Fifty-three millileters of H.sub.2 O was added to the quartz reactor over a 4-hour period. The internal reaction zone in the reactor was maintained at a temperature of about 1,200.degree.F. to 1,400.degree.F. during most of the reaction time. No catalyst was used in this laboratory run.

Over the four-hour period, the total gas production was approximately 22 liters. The maximum gas production rate during the four-hour run period was about 10 liters per hour. The gas produced contained about 60 volume percent hydrogen with the remainder being mostly CO.sub.2 and CO.

Remaining from the 50 grams charge to the reactor was 11.8 grams of residue. 6.3 grams of this residue was iron and aluminum. The carbon, hydrogen, oxygen elemental analysis of the organic residue was about 85 weight percent C, about 1.4 weight percent H, and about 14 weight percent 0.

The above results illustrate that solid waste material can be converted to substantial amounts of combustible gases with the simultaneous production of a residue which is sanitary because of the high temperature treatment of the solid waste material and the breaking down of the solid waste material into various constituents. The results also illustrate that the combustible gas can be produced at a fairly high rate; the rate of combustible gas production from the garbage was surprisingly found to be considerably higher than the rate of combustible gas production from carbon by reacting carbon with H.sub.2 O under similar temperature conditions.

2. In a subsequent run, 50 grams of simulated solid municipal waste having the same composition as in the preceding example was reacted with steam in the presence of 16.6 weight percent potassium carbonate catalyst based on the 50 grams of solid municipal waste feed. The alkali metal catalyst resulted in a surprising increase in the hydrogen gas production. Compared to 22 liters of gas produced over 4 hours in the preceding example with no catalyst, 54.6 liters of gas were produced in this run using the alkali metal catalyst. Compared to a maximum gas production rate of 10 liters per hour in the preceding example, the gas production rate in this run using an alkali metal catalyst was 24 liters per hour.

The composition of the gas produced was approximately as follows:

C.sub.1 5.2 volume percent C.sub.2 -C.sub.5 2.1 volume percent CO 6.8 volume percent CO.sub.2 21.6 volume percent H.sub.2 64.3 volume percent

The above gas analysis was based on approximately 18.1 liters of gas collected while the reaction zone was raised, by electrical heating of the reactor, from about 800 to 1,200.degree.F. When heating the solid waste feed from 1,200.degree.F. - 1,400.degree.F., 27.6 liters of gas were recovered having the composition shown below:

C.sub.1 0.5 volume percent C.sub.2 -C.sub.5 Nil CO 17.2 volume percent CO.sub.2 18.7 volume percent H.sub.2 63.6 volume percent

The residue recovered after this run was about 12.4 grams composed of 5.6 grams iron and iron oxide, 0.8 grams aluminum and aluminum oxide, 5.0 grams potassium carbonate, and 1.0 grams water-insoluble ash.

3. Another run was carried out using 50 grams of simulated solid municipal waste having the same composition as in the preceding examples, but using 10 weight percent sodium carbonate catalyst. The sodium carbonate catalyst was found to be very effective in increasing the rate of hydrogen production. The maximum rate of combustible gas production during this run was 34 liters per hour compared to only 10 liters per hour in the Example 1 above, wherein no catalyst was used. The total amount of combustible gas produced in this run was 47.1 liters.

The temperature range during this run was essentially the same as that in the preceding examples with the maximum temperature being 1,425.degree.F.

The residue recovered after the run was about 12.2 grams composed of 5.4 grams iron and iron oxide, 0.8 grams aluminum and aluminum oxide, 1.5 grams water insoluble ash, and 3.2 grams sodium carbonate.

The amount of H.sub.2 O added during this run was about 16 milliliters per hour, compared to 14 milliliters per hour for the previous example wherein the potassium carbonate catalyst was used.

4. Fifty grams of dried Milwaukee sewage, commonly referred to as Milorganite, was impregnated with about 10 weight percent sodium carbonate and then reacted with steam at a temperature within the range of about 1,200.degree.F. - 1,440.degree.F. The reaction was carried out over a period of about 6 hours and 39 liters of gas were produced. The gas contained about 63 volume percent hydrogen and about 11 percent CO. 12.3 grams of residue remained. About 2.5 grams of the residue was soluble in water and could be processed to recover a large amount of the sodium carbonate catalyst for re-use in the catalytic reaction. 5. If the gas produced in Example 2 were converted to kilowatt hours, a theoretical field of approximately 0.13 KWH can be produced from 50 gr. of organic feed. This is equal to 1,000 KWH/ton of organic feed, assuming a turbine efficiency of 42 percent.

Although various embodiments of the invention have been described, it is to be understood that they are meant to be illustrative only and not limiting. Certain features may be changed without departing from the spirit or scope of the invention. It is apparent that the present invention has broad application to gasification of solid waste containing at least 10 weight percent chemically combined oxygen to obtain a combustible gas, followed by combusting the combustible gas and expanding the combusted gas through a gas turbine in order to obtain energy. The invention is not to be construed as limited to the specific embodiments or examples discussed but only as defined in the appended claims or substantial equivalents thereto.

Claims

I claim:

1. The process for gasifying waste material and producing energy which comprises:

1. forming a combustible synthesis gas by contacting a mixture of solid organic waste material and 1 to 50 weight percent, based on the weight of solid organic waste material, of an alkali metal carbonate catalyst, with steam at an elevated temperature;

2. combusting at least a portion of said gas; and

3. rotating a turbine by expanding said combusted gas through the turbine; and said organic waste material containing at least 10 weight percent chemically bonded oxygen and containing less than 5 weight percent sulfur.

2. The process in accordance with claim 1 wherein the turbine is used to drive an electricity generator.

3. The process in accordance with claim 1 wherein the alkali metal catalyst is potassium carbonate or sodium carbonate.

4. The process in accordance with claim 1 wherein the alkali metal catalyst is potassium carbonate.

5. The process in accordance with claim 1 wherein the temperature in the reaction zone is maintained between 700.degree.F. and 2,000.degree.F.

6. The process in accordance with claim 1 wherein the temperature in the reaction zone is maintained between 1,000.degree.F. and 1,400.degree.F.

7. The process in accordance with claim 1 wherein a gas comprising oxygen is fed to the reaction zone and a portion of the solid organic waste feed material to the reaction zone is burned with the oxygen to provide at least a portion of the endothermic heat of reaction for the conversion of the organic feed material plus steam to combustible synthesis gas.

8. The process in accordance with claim 1 wherein the oxygen content of the solid organic waste feed material is at least 20 weight percent.

9. The process in accordance with claim 1 wherein the oxygen content in the organic feed material is between 35 and 70 weight percent.

10. The process for gasifying waste material and producing energy which comprises forming a combustible synthesis gas by contacting a mixture of solid organic waste material containing at least 10 weight percent chemically combined oxygen and containing less than 5 weight percent sulfur, and 1 to 50 weight percent of a potassium carbonate catalyst with steam at a temperature between 1,000.degree.F, and 1,400.degree.F., combusting at least a portion of the combusting gas to obtain combusted gases, and expanding the combusted gases through a turbine.

11. The process in accordance with claim 10 wherein the turbine is used to drive an electrical generator to produce electrical power.

12. The process in accordance with claim 10 wherein the organic feed material is solid waste material selected from the group consisting of solid municipal waste, industrial waste, or agricultural waste.

13. The process in accordance with claim 1 wherein the solid organic waste material feedstock is selected from the group consisting of municipal solid wastes, agricultural wastes and dried sewage.

14. The process in accordance with claim 1 wherein the solid organic waste material feedstock is a cellulosic material.