Patent Publication Number: US-2009235578-A1

Title: Compressed fuel composed of renewable organic residues and/or raw materials and production thereof

Description:
The invention relates to a compressed fuel composed of organic residues and/or raw materials, having at least one additive, to increase its heating value and to reduce the formation of slag, and a method for producing such a material. 
     Fuels composed of compressed renewable organic raw materials, such as straw as a byproduct of grain or rapeseed agriculture, and of other seed plants, but also wood waste, rapeseed cake as a waste product in the production of oil from rapeseed, and similar organic raw materials and residues, are increasingly gaining importance for generating energy, particularly heat energy, both in the industrial and the residential sector. 
     A compressed fuel is known from DE 103 34 645 A1, which consists of a mixture of wood, in shredded form, and other organic byproducts and residues, whereby the wood proportion in shredded form amounts to between 20 and 80%, and the remaining proportion consists of other organic components of renewable raw materials, without binder. This fuel is produced using a method according to which the mixture is adjusted, before being compressed, to an initial and compressing moisture between 5% to 40%, by way of the mixture ratio of wood in shredded form and organic components. However, an initial and compressing moisture adjusted in this manner can lead to great variations in the moisture of the fuel mixture, which can be unimportant for binder-free compression of the mixture itself, but has a negative effect on the density and the complete combustion behavior of the fuel bodies, and thus on the heating value, which is supposed to lie between 4.8 and 5 kWh/kg, and on the smoke development when the fuel is burned. 
     A molded fuel body is known from DE 10 2004 042 659 A1, which is produced, in terms of method, by mixing an agrarian waste material, a first additive to increase the heating value, and a second additive to reduce slag formation, to form a substance mixture, and subsequently molding the substance mixture to produce a molded body. In this connection, the agrarian waste products used are primarily waste products of grain harvesting, and the first additive used is residual products of grain processing, and the second additive used, to reduce slag formation, is lime. 
     This composition of the fuel bodies consists essentially of straw and residual products of grain processing, so that similar to pure straw combustion, the combustion process takes place in four phases, namely: 1. evaporation of the moisture; 2. gasification, in which a combustible gas having a certain content of carbon, hydrogen, methane, and other hydrocarbons is formed; 3. gas combustion; 4. combustion of the coke residues. In this combustion process, a sufficient oxygen supply must be assured at all times, in order to guarantee complete combustion and to prevent a greater proportion of carbon monoxide from forming in place of carbon dioxide, which would then be given off into the atmosphere with the flue gas. It is known that the sufficient oxygen supply is achieved by means of what is called an air excess, which lies above the combustion air required in theory. Consequently, this air excess increases the amount of flue gas that must be passed off into the atmosphere, which contains small ash particles, fine dust, and alkali salts that form during this combustion process, among other things, and imposes an additional burden on the environment. However, the required air excess also leads to the result that these fuels can only be used in firing systems that guarantee an additional air excess. 
     But the heating value is also not significantly improved with these fuel bodies, as compared with comparable fuels, and reportedly lies approximately in the vicinity of wood, in other words at approximately 5.0 kWh/kg. 
     Furthermore, the ash of fuels from agrarian raw materials is not without problems, due to the mineral components, such as, for example, silicates, which are known to have a low melting point. For example, it has been shown that the ash can become tacky at temperatures as low as ≦600° C., and this leads to slag formation and to the fire grates becoming clogged, which is very disadvantageous, particularly for smaller boilers. It is true that slag formation can be reduced by means of the proposed additive, lime, but it cannot be permanently prevented. 
    
    
     It is therefore the task of the present invention to improve the fuels named initially, composed of renewable organic residues and/or raw materials, in that the fuel can be used in any kind of firing system, demonstrates an improved complete combustion behavior and a higher heating value at lower smoke formation, and which is almost soot-free and emission-free during combustion, and has an ash softening point that permanently prevents slag formation and thus clogging of the fire grates, as well as to propose a method for production that reduces energy consumption, when managed continuously, and guarantees a uniform quality of the fuel. 
     This task is accomplished, according to the invention, with a compressed fuel composed of renewable organic residues and/or raw materials, in which the fuel mixture consists of
         72 to 83 wt.- % combustible organic residues and/or raw materials, having a moisture of 8 to 20%,
           15 to 25 wt.- % natural organic oils and/or fats,   to increase the heating value, and   2 to 3 wt.- % sodium perborate to increase the ash melting point and as an oxygen supplier.   
               

     It has surprisingly been shown that with this fuel composition, a compressed fuel composed of organic substances can be produced, which, at a significantly improved complete combustion behavior, has a heating value of approximately 6.8 kWh/kg, which is significantly greater than the heating value of fuels composed of compressed straw; wood; wood/straw, and can even be situated approximately in the range of the heating value of liquid gas. 
     With the proportion of natural oils and/or fats, which are known to have good adhesion behavior, it was possible to do without additives of native or modified starches, and to prevent dust formation during combustion, so that the flue gases to be conducted away are almost free of fine dust. 
     By means of the proportion of sodium perborate, which continuously gives off its oxygen component (approximately 9.9%), as is generally known, the combustion process is also constantly supported, even without an additional air excess, and with a sufficient oxygen component, up to complete combustion of the fuel bodies. Consequently, these fuels are suitable for all firing installations in which an additional air excess cannot be guaranteed. Moreover, because of the continuous and sufficient oxygen component that is given off as the sodium perborate is heated, smoldering fires, whose flue gas can be charged with increased carbon monoxide, are completely avoided. 
     Furthermore, the sodium perborate is converted to oxoborate when heated, and is free of water, so that the ash softening point can be increased to approximately 815° C. to 1098° C. At this ash softening point, the ash no longer becomes tacky, so that slag formation and caking of same onto the fire grate can be excluded. 
     It is advantageous if this mixture contains 0.4 to 0.6% hexamethylene tetramine, with reference to the total mass. Hexamethylene tetramine supports ignition of the fuel, and significantly promotes burn-off acceleration of the fuel and soot reduction. 
     It is also advantageous if this mixture contains 1.0 to 1.5% lignine, with reference to the total mass. Lignine promotes solidification of the compressed fuel, and leaves almost no or only insignificant pollutants in the flue gas and/or in the ash after combustion. 
     In order to further increase the ash softening point, the mixture can contain up to 3%, with reference to the total mass of the fuel mixture, of another powdered additive or an additive dissolved in water, having a pH≧7, to increase the ash softening point. 
     These additives are preferably borax or sodium metasilicate or trisodium octaborate or zinc borate or trisodium phosphate or ammonium sulfate or similar chemical substances that are suitable for raising the ash softening point. 
     The organic residues and/or raw materials used are preferably grain straw of all kinds, sugar cane, bamboo, cotton bushes, jute, sisal, hemp, ramie, rice straw, rice shells, Chinese silver grass, elephant grass, flax, coconut, kenaf, or alfa grass. With these types of residues and raw materials, it was possible to achieve approximately the same heating values in connection with the proposed composition of the compressed fuel, but it was also possible to produce dense and compressed fuels having good metering ability. 
     The mixture proportion of the organic residues and/or raw materials can also consist of 50-58 wt.- % organic residues and/or raw materials and 22-25 wt.- % rapeseed cake. This mixture proportion has an advantageous influence on economical production of the proposed fuel, whereby at the same time, the heating value can be further increased, in cost-advantageous manner, by the remaining energy-rich residual oil content in the rapeseed cake, which can have different values, as a function of the method used to recover the oil from the rapeseed. Furthermore, at the same time, economical and environmentally friendly disposal of the rapeseed cake takes place, if it cannot be utilized as animal feed, because of its high protein content. 
     However, in this fuel, the mixture proportion of natural organic oils and/or fats can also consist of 13-21 wt.- % natural organic oils and/or fats and 2-4 wt.- % fusel oil. 
     It is advantageous, in this case, if the fusel oils are homologs of ethyl alcohol or higher alcohols, such as amyl alcohol. Since it is known that fusel oils reduce the viscosity of oils and fats, the penetration of organic raw materials can be promoted with a mixture of oil and/or fat/fusel oil. Consequently, the costs of the fuel can be structured to be more advantageous for the consumer, as a result of the more cost-advantageous fusel oils, without impairing the combustion process or the heating value of the fuel, or additionally burdening the flue gas with pollutants. 
     A fuel in general, particularly fuels that are used in open hearths, such as fireplaces, the mixture for compressing the fuel can also contain 1.5 to 3 wt.- % of an odor improving agent, with reference to the oil amount. 
     The odor improving agent is preferably an ether oil that is soluble in oil, such as pine needle oil, clove oil, or citrus oil or forest fragrance oil. These odor improving agents are miscible in oil and demonstrated no negative influence on the combustion of the fuels and the waste gas to be conducted away, at a proportion of 1.5-3 wt.- %, with reference to the oil amount. 
     It is also advantageous if the mixture contains 1.5 to 3 wt.- % of an air pore forming agent, with reference to the mass of the total mixture. 
     Preferably, this air pore forming agent is a powdered sodium lauryl sulfate or sodium dodecyl sulfate, or a sodium lauryl sulfate or sodium dodecyl sulfate dissolved in water, having a pH≧7. 
     Air pore forming agents having a pH≧7 are not toxic, but rather biodegradable, and, on the one hand, additionally increase the oxygen content in the fuel, which advantageously promotes combustion, and, on the other hand, they contain disguised surfactants, which improve the penetration of the organic residues and/or raw materials. 
     Preferably, the organic residues and/or raw materials used are naturally aged new raw materials or used raw materials, such as gray straw, for example, which have been stored appropriately for their use. 
     In the case of these raw materials, the chemical substances, some of them aggressive, such as silicate, chlorine, potassium, and others, which are contained in the organic residues and/or raw materials and which have a corrosive effect on the boiler system and flue gas pipes, or impair the combustion process or the ash, have been partially decomposed as the result of weathering. 
     The organic residues and/or raw materials used can also be residues and/or raw materials that are artificially aged, for decomposition of the chemical substances, some of them aggressive, in a manner appropriate for their use. 
     For artificial aging, 0.1 to 3.0 wt.- %, with reference to the mass of the organic residue and/or raw material component, of a UV absorber having a preferred pH≧7 or a UV additive that promotes aging, having a preferred pH≧7, is added to the organic residue and/or raw material, or the organic residues and/or raw materials are alternatively pretreated with UV rays. Thus, the duration of the aging process can be limited to a very short time, and it is possible to do without storage areas for long-term aging as the result of weathering, and the production process of the fuels can be carried out more efficiently. 
     In order to achieve improved penetration of the organic residues and/or raw materials, it is advantageous if the mixture of organic residues and/or raw materials, with the oil and/or fat component that has been metered in, or the finished, mixed fuel mixture, are subjected to vacuum impregnation. In this manner, the embedded gas (air) is drawn out of the pores of the organic residues and/or raw materials, and thus the absorption capacity of the residues and/or raw materials for the oil and/or fat is significantly increased. Consequently, the compressing process and the combustion process are significantly promoted, and the compressed fuels are given a greater density and stability. 
     In order to improve the penetration, however, it has proven to be particularly advantageous if the fuel mixture contains an additive of 1-5 wt.- %, with reference to the oil and/or fat component, of surfactants having a pH≧7. 
     It is advantageous if the surfactants mixed in are from the group of ampholytic or amphoteric surfactants, whereby ampholytic or amphoteric surfactants that have a fatty acid composed of coconut oil or palm oil or jatropha oil are preferably used. 
     It has surprisingly been shown that the surface tension of the residues and/or raw materials can be so greatly reduced, using surfactants, that organic residues can be penetrated to a high degree, so that when surfactants are added, it is possible to do without additional vacuum impregnation of the raw material/oil mixture or the fuel mixture. Consequently, the production process of the fuel can be configured in significantly more efficient manner. 
     Furthermore, surfactants having a pH≧7 lie in the alkaline range, and are therefore not hazardous goods, whereby ampholytic or amphoteric surfactants that contain a fatty acid of coconut oil, palm oil, or jatropha oil, in particular, are easily and quickly biodegradable, and promote combustion of the fuels, and do not impair the waste gases. 
     However, combustion tests have also shown that a heating value of approximately 6.8 kWh/kg and higher can also be achieved with a fuel mixture that contains surfactants, whereby the fuels demonstrated good, dust-free complete combustion behavior and smoke-free combustion, in the same manner. Furthermore, test measurements actually showed that hardly any measurable pollutants could be detected in the waste gas during combustion of these fuels. 
     It is furthermore advantageous if the fuel is preferably compressed into molded bodies at a compressing pressure between 200 and 250 bar. At this compressing pressure, a high metering ability of the substances as well as a high density and stability were achieved. 
     It is furthermore also advantageous if the additives used lie in the alkaline range (pH≧7), and are not toxic, but rather biodegradable. In this way, it is guaranteed that the fuel does not contain any corrosive components that can lead to corrosion during combustion, and the ash of the fuel can easily be disposed of, in environmentally friendly manner. 
     According to the invention, the compressed fuel composed of organic residues and/or raw material is produced using a method according to which
         the organic residues and/or raw materials, by themselves or in a mixture, having a moisture of 8- to 20%, are cleaned of foreign bodies, dust, and waste, and are shredded,   the shredded residues and/or raw materials are freed of dust by way of an exhaust air filter, and metered into the components of the other substances to be mixed in, at a previously determined percentage ratio, in a mixing and metering device,   the oil and/or fat component is metered into the component of the residues and/or raw materials metered into the mixing and metering device, at a temperature of ≧60°, and the liquid components of the air pore forming agents and/or fusel oils and/or substances that raise the ash melting point, in aqueous solution, are metered in, by themselves or mixed with the oil and/or fat component, and   subsequently, the powdered and/or granulate components of the sodium perborate and/or hexamethylene tetramine and/or lignine and/or substances that raise the ash melting point and/or air pore forming agents are metered in, in powder form, by themselves or in a premixed batch, and   afterwards, the fuel components are mixed in the mixing and metering device, to form a homogeneous fuel mixture, and the homogeneous fuel mixture is passed to a pelleting press, in metered form, where it is compressed into fuel bodies, preferably at a compressing pressure of 200 to 250 bar.       

     By means of this method, it is made possible for the fuel to be produced from a fuel mixture, in a continuous process, which mixture has a uniform composition of the fuel substances and a controlled, constant moisture, and is free of non-combustible components. 
     With the oil and/or fat component that is metered in, at a temperature of ≧60° C., the oil and/or fat component has a viscosity that guarantees good adhesion to the organic residues and/or raw materials. Even more, by compressing the fuel mixture at a preferred compressing pressure of 200 to 250 bar, the fuel is compressed at a very high density and stability, which contributes, among other things, to keeping the complete combustion behavior uniform, up to complete combustion of the fuel bodies. 
     The liquid substances and those dissolved in water can optionally be already premixed, both by themselves and with one another, but the powdered or granulate substances can also optionally be metered into the residue and/or raw material component in premixed form, by themselves or with one another. The only deciding factor is that the liquid substances or those dissolved in water are metered in first, then the powdered or granulate substances. 
     According to an advantageous embodiment of the method, the residues and/or raw materials that have been shredded and freed of dust are put into intermediate storage in a metering silo, and passed to the mixing and metering unit in metered form. In this way, the method can be operated without interruptions for an extended period of time, even if problems occur in the treatment of the residues and/or raw materials or during air transport of the shredded raw materials to the exhaust air filter, or during raw material delivery, which cannot be precluded. 
     It is also advantageous if naturally aged organic residues and/or raw materials are used to implement the method, such as gray wheat straw, for example. As already mentioned, these residues and/or raw materials contain only slight components of chemical substances, some of them aggressive, such as, for example, silicate, chlorine, potassium, and others, so that the corrosive effect on the combustion system and negative effects on the combustion process and the flue gas development resulting from these chemical substances is significantly reduced. 
     According to a particularly preferred embodiment of the method, the shredded organic residues and/or raw materials are treated with UV radiation after the dust has been removed, and then stay in a silo for the aging period, or alternatively, that the shredded organic residues and/or raw materials are mixed with a UV additive that promotes aging, or a UV absorber, at 0.1-0.3 wt.- % with reference to the mass of the residue and/or raw material, after the dust has been removed, and then stay in a silo for the aging period. In this way, the possibility is created for the residues and/or raw materials to age artificially, in a very short period of time, so that long-term aging by means of weathering can be eliminated, and thus no additional storage area for weathering of the organic residues and/or raw materials is required. In this way, however, it is also guaranteed that a uniformly aged raw material is always available for production of the fuel mixture, without any additional inspection of the aging condition. Consequently, quality variations of the fuel can be excluded. 
     Preferably, the metering silo provided in the course of the process for the artificial aging period is used for the residues and/or raw materials, in that the metering silo is designed to have a storage capacity that allows continuous implementation of the process, when adhering to the aging period. 
     According to another, particularly advantageous embodiment of the method, the oil and/or fat component is passed to the mixing and metering device with the component of 1-5 wt.- % surfactants, with reference to the oil and/or fat component, mixed in. 
     In this manner, the surface tension of the organic residues and/or raw materials is reduced, and the ability of the residues and/or raw materials to be penetrated is significantly improved, and already starts with metering of the oil and/or fat component into the residues and/or raw materials. Testing of the compressed fuel bodies has shown that after the fuel mixture was compressed, the oil and/or fat component was completely homogeneously bound in the fuel mixture. As a result of the homogeneous distribution of the substances in the fuel mixture, uniform complete combustion of the compressed fuels can be guaranteed. 
     However, a similar effect is also achieved if, in place of the surfactants, the shredded residues and/or raw materials are vacuum-impregnated with the oil and/or fat component that is metered in, or the homogeneously mixed fuel mixture is vacuum-impregnated before pelleting. 
     It is also advantageous if, during implementation of the method, the air transport of the shredded residue and/or raw material to the exhaust air filter is carried out with heated air, for moisture equalization. In this way, it is guaranteed that the shredded organic residues and/or raw materials metered into the mixing and metering unit always have approximately the same moisture. 
     According to another advantageous embodiment of the method, in order to maintain the percentage composition of the fuel mixtures, the amount units of the oils and/or fats, of the liquid and powdered or granulate substances metered into the mixing and metering unit, are regulated volumetrically or gravimetrically, as a function of the mass of the residues and/or raw materials metered into the mixing and metering device. In this way, it is assured that in case of varying metering masses of the residues and/or raw materials, the predetermined percentage proportions of the substances for the fuel mixture are always guaranteed. 
     In the following, some possible compositions of the fuel mixture for production of a compressed fuel according to the invention, in accordance with the method, are presented. 
     Fuel mixture (1) consists of a formulation of 
     
       
         
           
               
               
             
               
                   
               
             
            
               
                   75% 
                 wheat straw having a moisture of approximately 12%, 
               
               
                   
                 which is pretreated with UV radiation for artificial 
               
               
                   
                 aging, 
               
               
                 20.5% 
                 palm oil, 
               
               
                   3% 
                 sodium perporate 
               
               
                  1.5% 
                 surfactants from the group of ampholytic or amphoteric 
               
               
                   
                 surfactants having a pH ≧ 7. 
               
               
                   
               
            
           
         
       
     
     For the production of this fuel mixture, a shredded UV-irradiated wheat straw is used, which was therefore artificially aged. After aging, the palm oil component, heated to ≧60° C., with the surfactants mixed in, is metered in, along with the sodium perborate component. 
     Fuel mixture (2) consists of a formulation of 
     
       
         
           
               
               
             
               
                   
               
             
            
               
                 77.8%  
                 bagasse, i.e. extracted sugar cane, 
               
               
                 17.4%  
                 soybean oil, 
               
               
                   2% 
                 sodium perborate, 
               
               
                 0.5% 
                 hexamethylene tetramine as an ignition aid 
               
               
                 2.1% 
                 surfactants from the group of ampholytic or amphoteric 
               
               
                   
                 surfactants having a pH ≧ 7, and 
               
               
                 0.2% 
                 of a UV additive that promotes aging, having a pH ≧ 7, 
               
               
                   
                 or of a UV absorber having a pH ≧ 7. 
               
               
                   
               
            
           
         
       
     
     For the production of this fuel mixture, shredded bagasse is used, which is mixed with the component of the UV additive that promotes aging or of the UV absorber, and is therefore artificially aged. After aging, the soybean oil component, heated to ≧60° C., with the surfactant component mixed in, is metered into the bagasse, along with the sodium perborate component. 
     Fuel mixture (3) consists of a formulation of 
     
       
         
           
               
               
             
               
                   
               
             
            
               
                 49.75%  
                 hemp fibers, 
               
               
                  25% 
                 rapeseed cake after oil extraction, 
               
               
                 20.9%  
                 sunflower oil, 
               
               
                   2% 
                 sodium perborate, 
               
               
                 1.2% 
                 lignine in powder form, 
               
               
                 1.0% 
                 surfactants from the group of ampholytic or amphoteric 
               
               
                   
                 surfactants having a pH ≧ 7, and 
               
               
                 0.15%  
                 of a UV additive that promotes aging, having a pH ≧ 7, 
               
               
                   
                 or of a UV absorber having a pH ≧ 7. 
               
               
                   
               
            
           
         
       
     
     For the production of this fuel mixture, shredded hemp fibers are used, which are mixed with the component of the UV additive that promotes aging or of the UV absorber, and is therefore artificially aged. After aging, the sunflower oil component, heated to ≧60° C., with the surfactant component mixed in, is metered into the hemp fibers, along with the sodium perborate component, and subsequently, the lignine component is metered in, in powder form. 
     Fuel mixture (4) consists of a formulation of 
     
       
         
           
               
               
             
               
                   
               
             
            
               
                 75.75%  
                 rice straw, 
               
               
                 12.9%  
                 canola oil and/or tall oil, 
               
               
                   2% 
                 sodium perborate, 
               
               
                   4% 
                 fusel oil, 
               
               
                 1.8% 
                 zinc borate, 
               
               
                 3.3% 
                 surfactants from the group of ampholytic or amphoteric 
               
               
                   
                 surfactants having a pH ≧ 7, and 
               
               
                 0.25%  
                 of a UV additive that promotes aging, having a pH ≧ 7, 
               
               
                   
                 or of a UV absorber having a pH ≧ 7. 
               
               
                   
               
            
           
         
       
     
     For the production of this fuel mixture, shredded rice straw is used, which is mixed with the component of the UV additive that promotes aging or of the UV absorber, and is therefore artificially aged. After aging, the canola oil component, heated to ≧60° C., with the surfactant component mixed in, and the fusel oil component, are metered in, along with the sodium perborate component, and the zinc borate component. 
     Fuel mixture (5) consists of a formulation of 
     
       
         
           
               
               
             
               
                   
               
             
            
               
                 71.6% 
                 Chinese silver grass, 
               
               
                 20.9% 
                 olive oil, 
               
               
                   3% 
                 sodium perborate with an additive of trisodium 
               
               
                   
                 octaborate (polybor), 
               
               
                  4.2% 
                 surfactants from the group of ampholytic or amphoteric 
               
               
                   
                 surfactants having a pH ≧ 7, and 
               
               
                  0.3% 
                 of a UV additive that promotes aging, having a pH ≧ 7, 
               
               
                   
                 or of a UV absorber having a pH ≧ 7. 
               
               
                   
               
            
           
         
       
     
     For the production of this fuel mixture, shredded Chinese silver grass is used, which is mixed with the component of the UV additive that promotes aging or of the UV absorber, and is therefore artificially aged. After aging, the olive oil component, heated to ≧60° C., with the surfactant component mixed in, is metered in, along with the sodium perborate component. 
     Fuel mixture (6) consists of a formulation of 
     
       
         
           
               
               
             
               
                   
               
             
            
               
                 80.4%  
                 gray rye straw, 
               
               
                  11% 
                 linseed oil, 
               
               
                 2.5% 
                 sodium perborate with an additive of 2%, with reference 
               
               
                   
                 to the total mass, of a mixture that consists of 
               
               
                   
                 approximately 0.6% borax, approximately 0.6% trisodium 
               
               
                   
                 phosphate, and 0.8% ammonium sulfate, 
               
               
                 2.8% 
                 surfactants from the group of ampholytic or amphoteric 
               
               
                   
                 surfactants having a pH ≧ 7, 
               
               
                 1.2% 
                 odor improving agent, and 
               
               
                 2.1% 
                 air pore forming agent. 
               
               
                   
               
            
           
         
       
     
     For the production of this fuel mixture, naturally aged and shredded gray rye straw is used, into which the linseed oil component, heated to ≧60° C., with the surfactant component mixed in, is metered, along with the sodium perborate component with the mixture of borax, trisodium phosphate, and the component of the odor improving agent. 
     The addition of odor improving agent and/or air pore forming agent can, of course, be included in every fuel mixture designed according to the teaching according to the invention, and is not tied to the use of naturally aged residues and/or raw materials. 
     It should be noted that when adding an odor improving agent, at a percentage proportion between 1.5% to 3%, the oil and/or fat component in the fuel mixture, in each instance, is reduced, in terms of percentage, by the amount of odor improving agent that is added, whereas in the case of an air pore forming agent, at a percentage proportion between 1.5% to 3%, the proportion of organic residues and/or raw materials, in each instance, is reduced, in terms of percentage, by the amount of air pore forming agent that is added. 
     Also, each listed fuel mixture 2 to 6, but also other selected fuel mixtures, can be produced using a technological method in which the organic residues and/or raw materials were aged by means of UV radiation, such as that carried out for fuel mixture 1, for example. 
     In these cases, it is possible to do without the use of UV additives that promote aging, or UV absorbers, and the percentage proportion of the organic residues and/or raw materials is increased by the percentage proportion of the UV additives that promote aging, or the UV absorber. 
     Of course, in the example of fuel 1, a UV additive that promotes aging, having a pH≧7, or a UV absorber having a pH≧7, can also be used in place of the wheat straw pretreated with UV radiation; in this case, the wheat straw proportion is decreased by the percentage proportion of the UV additive or UV absorber. 
     The use of a UV additive that promotes aging or of a UV absorber is dependent on the geographic location of the production facilities of the fuels, and on the basic materials used, respectively, and must be decided on a case-by-case basis, when production of the fuels is started. 
     In place of the artificial aging by means of UV radiation or by means of UV additives that promote aging, or UV absorbers, residues and/or raw materials naturally aged by means of weathering can also be used. In these cases, the residue and/or raw material component is increased by the proportion of the UV additive or UV absorber. 
     The compositions of the fuel mixtures presented above are compositions presented as examples, and can therefore be changed, within the limits of the percentage proportions, as a function of the special nature of the organic residues and/or raw materials. The percentage composition of the fuel mixture and the selection of the additives or their combination, with the exception of the odor improving agents, is dependent on the type and composition of the organic residues and/or raw materials, and possibly on the properties of organic residues that have already been treated, which are supposed to be added as a waste product from other methods.