Natural coal is generally regarded as a non-renewable energy source in part because of the amount of time needed for the formation thereof to occur naturally. For instance, lignite coal requires millions of years, and anthracite coal requires hundreds of millions of years for its respective formation. The burning of natural coal releases toxic agents, such as heavy metals (e.g., mercury, uranium) co-deposited as part of its sedimentary formation process. Other serious toxic by-products resulting from the burning of coal and other fossil fuels such as oil, gasoline, tar and natural gas include: soot, ash, and oxides of nitrogen, sulfur, and carbon. The release of these toxic chemicals into our atmosphere from the burning of these fossil fuels for the production of energy has resulted in air pollution as well as global warming. Additionally, since fossil fuels are a finite resource and the recovery thereof is becoming more costly as the supplies thereof dwindle, continued reliance thereon will at some point become economically as well as environmentally unfeasible. Also, since a significant amount of crude oil used in the United States is imported, a substantial imbalance in the balance of trade with oil-exporting countries has resulted in severe economic damage to US economy due to the outflow over time of trillions of dollars.
A further environmental problem concerns the need for nitrogen fertilizers for agricultural purposes. Currently, nitrogen fertilizers such as ammonium nitrate and urea require ammonia for their manufacture. Ammonia is chiefly manufactured from nitrogen and hydrogen at high temperature and pressure employing the Haber-Bosch process. While nitrogen can be obtained relatively easily from the atmosphere, hydrogen is obtained by a process known as steam reforming from natural gas. Currently, 5% of the world's annual natural gas is utilized for that purpose. Thus, it would be desirable to generate nitrogen fertilizers without reliance on the use of natural gas.
In response to significantly increased crude oil prices and politically and economically uncomfortable dependence on imports of crude oil, ethanol has been utilized as an additive to gasoline since 1980 and has now commonly reached concentrations of 10% by volume, with 20% by volume being legislated to occur in Minnesota in 2013. Several states also currently offer E85 which contains 85% ethanol and 15% gasoline. A primary advantage of synthetic fuels derived from biomass is that the carbon in them that is released as carbon dioxide into the atmosphere when burned is not newly introduced and additive to the carbon dioxide already present therein. Rather, the released carbon dioxide is recaptured and recycled by plants through photosynthesis resulting in no net addition of that global warming gas to the earth's atmosphere.
The prior art process of producing ethanol and which is representative of how 85% of the ethanol produced in the US is made, can be understood by referring to FIG. 3. As seen therein ethanol, a two carbon alcohol and, to a lesser degree, butanol, a four carbon alcohol, are obtained in the United States primarily by the fermentation in large fermentation vats 10 containing a ground fermentable material. Typically, such material is starch as present in corn kernels, potatoes and other like vegetable materials. Water is added to the fermentable material and enzymes, natural and/or added, are used to breakdown the starch into fermentable dextrins and sugars. Of course, it is also well known to simply start with sugars as obtained, for example, from sugarcane or sugar beets. Yeast is also added to the vat 10 and the mixture is heated by a heater 12 to approximately 37 degrees C. to facilitate the fermentation of the dextrins and sugars producing the ethanol and generating carbon dioxide gas. At the end of the fermentation process the fermented material in vat 10 is pumped along line 14 to a “beer well” 16 which also includes a heater 18. Well 16 is a sealable container and a distillation apparatus 20 is fluidly secured thereto by an outlet conduit 22. The fermented material is then heated by operation of heater 18 to a temperature sufficient to boil the ethanol but not the water, i.e. between approximately 78 and 90 degrees C. As is well understood, the ethanol vapor is then cooled and condensed to liquid form by distillation apparatus 20 and directed to a storage container 24. As is well understood, the resultant ethanol product will contain small amounts of water because water and ethanol form an azeotropic mixture that cannot be separated by distillation. As is also well understood, subsequent processes can be applied such as through the use of molecular sieves for the conversion of the distilled ethanol into absolute or 100% ethanol. After the removal of the ethanol from the fermented material, what remains is a fermentation residue. Those of skill will recognize that the fermentation residue is a highly processed material which differs from the original ground fermentable materials in it is depleted of carbon both from the loss of the carbon dioxide gas during the fermentation step and from the ground fermentable material and the fermented residue as it is further depleted of carbon through the loss of the carbon contained in the ethanol or butanol that is removed from the fermented residue by distillation.
After the removal of the ethanol, the remaining fermentation residue in well 16, referred to as whole stillage (WS), having a dry solids content of about 10-15%, in the dry-grind corn ethanol production industry, is then sent to a centrifuge 26 where it is separated into a solid portion referred to as Wet Distillers Grains (WDG), having a dry solids content of about 35%, and a liquid portion called Thin Stillage (TS), having a dry solids content of 5-10%. TS can be further processed by the evaporation of the water therefrom in evaporator 28 to produce a thick syrup-like portion referred to as Condensed Distillers Solubles (CDS), having a dry solids content of 30-50%. WDG can be sent along a conduit depicted by dashed line 32 directly to a dryer 30 and dried into a shelf-stable animal feed product called Dried Distillers Grains (DDG) by operation of a heater 34 thereof. Alternatively, a shelf-stable animal feed product referred to as Dried Distillers Grains with Solubles (DDGS) can be manufactured. DDGS is typically what is made in the ethanol industry and is obtained by the combining of WDG and CDS, to form a mixed grains material followed by extensive drying of that combination in dryer 30 until the DDGS has a moisture content of less than 10% dry weight and is used as a shelf-stable animal feed product. Although DDG is an acceptable, high quality shelf stable animal feed as well, the DDGS includes additional nutrients present in the CDS. Typically, a bushel of corn can provide 2.8 gallons of ethanol, 18 pounds of DDGS, and 16 pounds of carbon dioxide.
The WDG fermentation residue is comprised of residual fermentable dextrins, yeast, non-fermentable dextrins, protein, fat, low concentrations of metal salts, and water. Often the protein content can be quite high, ca. 30%, and the material is utilized as a high-grade feed especially for ruminants such as cattle, with small amounts able to be employed in feeds for mono-gastric animals such as swine and poultry. WDG can be transported directly to farm sites but only within a relatively small radius, e.g., 30 miles, of the manufacturing site. The limited shipping radius of 30 miles is due to the amount of water present in the WDG which leads to microbial growth that quickly renders it unsuitable for animal consumption.
Unfortunately, and in either case, the physics of the removal of water by heating in dryer 30 requires the input of substantial amounts of energy which adds considerable cost to the production of either DDG or DDGS feed. It is estimated that the intensive drying operations performed on these by-products accounts for 40-45% of the thermal energy and 30-40% of the electrical energy required in the dry-grind ethanol process. In addition, there is also a significant energy cost associated with evaporating the TS and producing CDS. To complicate matters, ethanol manufacturers are often in the situation of having a large surplus of WDG that must be dried at the manufacturing site as there often exists insufficient need for it within the 30 mile radius of their plants. Other fermentation residue stillages that can have similar negative economic and/or waste disposal issues include Brewer's Grains from the production of beer and whiskey, E.-Coli residues from production of antibiotics, and residues from other bacterial, fungal and yeast fermentation processes. As a result, there has been a long felt need for decades to find an economical, energy-efficient and environmentally sustainable solution for obviating the need to dry fermentation residues such as TS and WDG.
This need is particularly pressing for the production of biofuels because it is has been difficult, if not impossible, for the alternative fuel industry to compete on a dollar per gallon basis with the petroleum industry. And specifically, the ethanol industry has been criticized for not being energy efficient, that is, the energy represented by the ethanol being barely greater or even less than the energy needed to produce it, especially when the drying of the TS and WDG are taken into account. However, despite the tremendous pressure to find solutions that would create an economically viable and sustainable alternative fuel industry, results have not been forthcoming.
There also exists a need in the energy resource field for improved synthetic coal products that possess a commercially viable high British Thermal Unit (BTU) per pound content. There further exists a need for nutritive media that can be utilized as plant fertilizers and reduce the consumption of natural gas required in the manufacture of nitrogen fertilizers.
Additionally, there exists a need for innovative processes utilizing natural biological materials as carbon neutral energy resources, thereby not increasing the net amount of carbon dioxide in the atmosphere that utilizing fossil fuels causes.