METHOD FOR BIOFUEL PRODUCTION

FIELD OF THE INVENTION

The present invention generally relates to a method for biofuel production. The present invention more particularly relates to a method for biofuel production, which minimizes or eliminates the consumption of fossil fuel in the production.

BACKGROUND OF THE INVENTION

There are generally known methods to produce biofuel such as ethanol, biodiesel and biohydrogen. Such known methods include fermenting carbohydrates to ethanol, which is then distilled and dried; oil extraction requiring solvent distillation; and catalytic dehydrogenation, etc. However, such known methods have several disadvantages including the consumption of fossil fuel, which minimizes the net energy value of biofuel and results in net addition of carbon dioxide to the atmosphere.

Accordingly, there is a need for a more environmentally-friendly method of producing biofuel. There is also a need for a method for biofuel production, which minimizes the consumption of fossil fuel in the production process.

SUMMARY OF THE INVENTION

In one embodiment of the present invention is a method for the production of biofuel that includes the step of providing a renewable, photosynthetically- produced biological material having at least one biofuel precursor and a cell-wall component. The method further includes the steps of fractionating the photosynthetically-produced biological material into at least two fractions, a first fraction enriched in the biofuel precursor and a second fraction enriched in the cell-wall component. The method then includes the steps of processing at least one of the second fraction and a product of its modification to generate thermal energy and processing at least one of said first fraction, a product if its modification, and a component of the first fraction to generate at least one biofuel. In this embodiment, the processing includes at least one energy-consuming

operation that consumes energy resulting from the processing of the second fraction.

In another embodiment of the present invention is a method for the production of biofuel that includes the steps of providing a starch crop comprising starch and fiber, and fractionating the starch crop into at least two fractions, a first fraction enriched in starch and a second fraction enriched in fiber. The method of this embodiment further includes the steps of processing at least one of said second fraction and a product of its modification to generate thermal energy and processing at least one of said first fraction, a product of its modification, and a component thereof to generate biofuel. In this embodiment, the processing includes at least one energy-consuming operation and that consumes energy resulting from the processing of the second fraction.

In yet another embodiment is a method for the production of biofuel that includes the step of providing an algal material having at least one biofuel precursor and a cell-wall component. The method further includes the steps of fractionating said algal material into at least two fractions, a first fraction enriched in the precursor and a second fraction enriched in the cell-wall material and processing at least one of the second fraction and a product thereof to generate thermal energy. In this embodiment the at least one of said first fraction; a component thereof and a product thereof is processed into at least one biofuel such that the processing step includes at least one energy-consuming operation that consumes energy resulting from processing of the second fraction.

DESCRIPTION OF THE DRAWING

FIGURE 1 is a flow diagram of biofuel production according to a preferred embodiment of the present invention.

DETAILED DESCRIPTION

Production of biofuel from renewable resources is an attractive concept of converting solar energy - via photosynthesis in the field or in a bioreactor, and via processing in a "biorefinery" - into transportation fuel. Yet, present processing methods consume relatively large amounts of fossil energy, which decreases the

net energy gain of biofuel production and results in increased CO ₂ emissions. The net energy gain can be defined as the difference between the energy value of the biofuel product (output energy) and the energy needed to produce the product (input energy). In the case of ethanol from corn the input energies are life-cycle energies, including growing the corn (including fertilizer and pesticides production, corn harvesting and transporting) and distilling and drying the ethanol. Many studies were reported, reaching different conclusions, from negative net value (more energy is spent to produce ethanol than is contained in it) to positive gains in the range of 20-35%. A comprehensive report and review of the literature can be found in Shapouri et. al., "The Energy Balance of Corn Ethanol: An Update", USDA, Agricultural Economic Report # 814 (2002), incorporated herein by reference. See www.usda.gov/oce/oepnu/aer-813.pdf. According to a reference in that report, with further improvement in agricultural practice and improvement made to ethanol plants, the net energy gain will increase to 47% in the near future.

The method for the production of biofuel according to the present invention includes the steps of: (a) providing a renewable, photosynthetically-produced biological material having at least one biofuel precursor and a cell-wall component; (b) fractionating said biological material into at least two fractions, a first fraction enriched in the precursor and a second fraction enriched in the cell- wall material, which fractionation is optionally energy consuming; (c) processing at least one of the second fraction and a product thereof to generate thermal energy; and (d) processing at least one of said first fraction, a component thereof and a product thereof to generate at least one biofuel, wherein processing comprises at least one energy-consuming operation and wherein said operation consumes energy resulting from processing in step (c).

According to a preferred embodiment of the present invention, energy production in step (c) is sufficient to supply the energy need in step (d). According to a particularly preferred embodiment energy produced in step (c) is sufficient to supply the energy needs of both (d) and (b), so that no fossil energy is consumed

for those steps. Use of co-products of step (c), (d) or both as nutrients in step (a) also decreases fossil energy consumption in that step (e.g. fertilizer production).

According to a preferred embodiment of the present invention, the net energy gain is greater than 50%, preferably greater than 100%, more preferably greater than 150%, most preferably greater than 200%.

Fermenting corn to ethanol is a well-known method for converting a renewable material to biofuel, but not the only one. According to alternative preferred embodiments, various other methods of conversion are suitable for the conversion of renewable precursors into biofuel in operation (50) as described hereinafter with reference to Figure 1. According to alternative preferred embodiments, those methods are selected from a group consisting of fermenting, esterification, trans-esterification, pyrolysis gasification, reforming and various combinations thereof. Conversion may use a catalyst selected from the group consisting of chemical catalysts, biological catalysts and combinations thereof. According to a preferred embodiment of the method, the conversion in operation (50) consumes energy, e.g. has an energy consuming step, and said energy is supplied from operation (40) also described hereinafter with reference to Figure 1. Such energy-consuming step may involve heating, distilling, concentrating, separating, drying and various combinations of those, according to alternative preferred embodiments. Preferred conversion methods depend on the nature of the renewable raw material and on the desired biofuel. Those also determine the energy-consuming step. Several examples are briefly described in the following sections. Some of those are described later in more detail.

According to a preferred embodiment, the biofuel precursor is glucose and/or starch and the biofuel is ethanol. Conversion in that embodiment involves fermenting the glucose and/or starch with a microorganism (e.g. yeast) into ethanol and CO2. The ethanol is formed in a relatively dilute fermentation liquor, which is then concentrated by distillation. The concentrated ethanol is then dried to form fuel ethanol. The conversion in that preferred embodiment involves fermentation, distillation and drying. Both distillation and drying consume energy.

Further preferred embodiments of producing fuel ethanol from a starchy material are described in more details in the following.

According to a preferred embodiment, ethanol formed is dehydrogenated to form biohydrogen and other products, such as ethyl acetate. The reaction is preferably catalyzed with a copper or silica catalyst, as described in US Patent 6,809,217, incorporated herein by reference. Alternatively, biohydrogen is formed by steam reforming. In those processes, both reaction and related separation processes are energy consumers.

According to another preferred embodiment, the biofuel is a biodiesel, e.g. fatty acid methyl ester (FAME), and the precursor-enriched fraction ((32) in Figure 1) is dehulled oilseed. The conversion step in that preferred embodiment involves several operations. The dehulled oilseed is tempered, flaked and extracted with hexane to form defatted soybean flakes and oil-containing hexane solution (miscella). The defatted soybean is desolventized by distillation and optionally toasted to form a feed or food ingredient. The oil is recovered from the miscella by distilling the hexane (optionally further treated), and reacted with methanol in a trans-esterification reaction to form FAME and glycerol. The reaction mixture is treated to separate non-reacted methanol, FAME and glycerol. The energy- consuming operations in that process scheme include the distillation steps and the separation.

According to alternative preferred embodiments, suitable precursor- enriched fractions could be converted to liquid transportation fuel by processes such as pyrolysis and gasification, which are energy consumers.

The method of the present invention drastically decreases the consumption of fossil energy for processing of renewable material into biofuel according to a preferred embodiment, and according to a more preferred embodiment totally eliminates it, with practically no compromise on biofuel production yield. According to a particularly preferred embodiment, the amount of energy produced

in operation (40) as described hereinafter with reference to Figure 1 , is in excess of the need for the processing and supports other processes or is available for sale. In addition to increasing the net energy gain (and thereby decreasing the consumption of energy from non-renewable sources), the method of the present invention decreases the emission of greenhouse gas CO2 to the atmosphere. Another important aspect is the use of co-products, such as ashes generated in operation (40) and/or organic matter as nutrient or nutrient precursors, reducing thereby energy consumption in fertilizer production and further increasing the net energy gain.

According to another preferred embodiment, the method of the present invention generates additional products of commercial value. Examples for such commercial products are oil and refined oil (e.g. that of corn and oilseeds), glycerol, fatty acids, unsaturated fatty acids, Omega 3 fatty acids, arachidonic acid, xanthophylls, carotenoids, β carotene, Co-enzyme Q-10 and astaxanthin. Such additional products are formed in at least one of the fractionating step (b), processing step (c) and converting step (d) (operations 30, 40 and 50 respectively as described hereinafter with reference to Figure 1 ,) according to a preferred embodiment, and/or in an additional operation (not shown in Figure 1) according to an alternative embodiment.

According to the method of the present invention, a biofuel is produced from a renewable, photosynthetically-produced biological material. As used here, biofuel is any fluid material from a renewable biological source that could be oxidized and thereby generate energy. According to a preferred embodiment, the produced biofuel could be used for transportation, e.g. via combustion. Examples of suitable biofuel products are ethanol, biodiesel such as fatty-acid methyl esters, other esters, products of plant material pyrolysis, hydrogen generated from biological material, etc.

According to the present invention, biofuel is produced from a photosynthetically-produced, renewable biological material comprising cell-wall material and biofuel precursor. Both whole plants and fractions of whole plant

comprising those components are suitable starting materials. Also suitable are algae, micro-algae and other microorganisms. Any combination of the above is suitable too. According to a preferred embodiment, the precursor content of the renewable biological material is greater than about 10%, more preferably greater than 30%, most preferably greater than 50%.

According to a preferred embodiment, biofuel precursors include carbon- rich compounds, e.g. carbohydrates such as glucose and sucrose; oligosaccharides and polysaccharides, such as starch; fatty materials such as triglycerides and phospholipids, products of their hydrolysis, proteins, various combinations of those, etc. According to a preferred embodiment, biofuel precursors include compounds used for energy storage in plants and organisms. Such precursors are found in various parts of plants such as grains, seeds and beans and in microorganisms.

Suitable cell-wall material includes cellulose, hemicellulose, lignin and similar compounds. Such compounds are present in various parts of plants such as wheat straw, corn fiber, soybean hull, sugar cane, algae, etc.

Typically, suitable renewable biological material also contain inorganic compounds, organic complexes of inorganic compounds and biological compounds having a heteroatom, such as phosphorous (e.g. phytic acid and phospholipids) and sulfur (e.g. cysteine, and methionine). On burning such renewable biological material, such compounds form ashes.

According to the method of the present invention biofuel is generated from a renewable biological material comprising at least one biofuel precursor and a cell-wall component. The renewable material is fractionated into at least two fractions, a first fraction enriched in the precursor and a second fraction enriched in the cell-wall material. The term enriched, as used here, means having higher proportion than in the renewable material on the same basis, e.g. on dry-weight basis. The second fraction, and/or a product of its modification, is processed to generate thermal energy. The first fraction, a component thereof and/or a product of its modification is converted into at least one biofuel in a process that consumes

W 2

energy. The thermal energy generated by processing the first section is used for the production of biofuel.

While the invention will now be described with reference to the accompanying figure so that aspects thereof may be more fully understood and appreciated, it is not intended to limit the invention to these particular embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the scope of the invention as defined by the appended claims.

Referring to Figure 1 , a renewable biological material (22) is fractionated in operation (30) into at least two fractions. A fraction enriched in the cell-wall material, e.g. cellulose or hemicelluiose, (34) is processed in operation (40) to form thermal energy (42). A fraction enriched in biofuel precursor (32) is converted in operation (50) to biofuel (52) in a process consuming energy (42) generated in operation (40).

Suitable renewable biological materials include material resulting from sources such as plants, algae, microorganisms and other photosynthesis products. Suitable renewable materials are both direct products of photosynthesis or indirect products, e.g. products of fermenting a photosynthetic product, such as starch and its hydrolyzates. Those sources could be fully utilized, e.g. a whole plants. In other cases, only part of the plant is used. Particularly suitable plants are starch crops, such as com, wheat, rice and sorghum, oilseeds, such as soybean, canola and sunflower, sugar cane and sugar beet. Referring to Figure 1 , the renewable biological material (22) results from a photosynthetic process, operation (20). The photosynthetic process utilizes solar energy and/or suitable irradiation from another source (12) and consumes CO2 (16). Typically it also requires nutrient such as inorganic material (14), e.g. in the form of fertilizer. According to a preferred embodiment, inorganic matter is formed in operation (40), e.g. ashes, metal oxides, metal hydroxides and inorganic salts, and is used as a source of inorganic matter (44) for the generation of the renewable matter. According to still another preferred embodiment, coproducts of biofuel generation,

e.g. inorganic salts, ashes, organic matter, proteinous matter, organic and inorganic phosphorous compounds, organic and inorganic nitrogen compounds and combinations thereof are used to provide nutrients for the generation of the renewable material (58). According to another preferred embodiment, CO2 is generated in operation (40) and is used to partially or practically completely supply the CO2 (46) needs of generating the renewable material. According to still another preferred embodiment, CO2 is generated in operation (50) and is used to supply the CO2 (56) needs of generating the renewable material. If required, a fraction of the thermal energy generated in operation (40) is used (42b) for the generation of the renewable material.

In the fractionation step (30), the renewable biological material is fractionated into at least two fractions, a first fraction, which is enriched in the biofuel precursor (32) and a second fraction enriched in the cell-wall material (34). The concentration of the biofuel precursor in the first fraction is greater than its concentration on the same basis (e.g. on dry matter basis) in the renewable material. According to a preferred embodiment, the concentration is greater by at least about 10%, more preferably at least about 20%, most preferably at least about 30%. According to a preferred embodiment, fractionation - in addition to enrichment - facilitates the processing of the enriched fraction to biofuel by making the precursor more available for processing. That is for example the case of dehulling or debranning corn or wheat, which makes the starch more available to processing into fermentables and eventually to ethanol. The concentration of the cell-wall material (e.g. cellulose and hemicellulose) in the second fraction is greater than its concentration, on the same basis (e.g. on dry matter basis), in the renewable material. According to a preferred embodiment, the concentration is greater by at least about 30%, more preferably at least about 50%, most preferably at least about 100%. According to a preferred embodiment, the fraction that is enriched in the precursor is further fractionated prior to the conversion in operation (50). According to another preferred embodiment, the fraction that is enriched in the cell-wall material is further fractionated prior to the processing in operation (40). According to still another preferred embodiment, fractionation

generates additional fractions, which could be used as such, added to either of the other fractions, used as ingredients in animal feed and/or other products, etc.

According to a preferred embodiment, the fractionation operation (30) uses a method selected from a group consisting of dehulling, debranning, decorticating, abrasion, extraction, dissolution, enzymatic degradation, fermentation, steam explosion and various combinations of those. The fractionation means could be optimized for each of the renewable material. Specifically preferred embodiments are described in the following. According to a preferred embodiment, if energy is consumed in the fractionation operation (30), it results from the thermal energy (42a) generated in operation (40).

The thermal energy generation operation (40) processes the cell-wall- enriched material (34) into thermal energy. According to a preferred embodiment, it processes to thermal energy other suitable material resulting from the fractionated material or others, for example lignocellulosic material, co-products of biofuel generation (54), such as stillage from ethanol distillation, other product of the fractionating steps, such as oil, etc, according to alternative preferred embodiments. Processing to thermal energy involves oxidation, such as in burning, combustion, enzymatically-catalyzed oxidation, chemically-catalyzed oxidation and various combinations of those, according to alternative preferred embodiments. According to a preferred embodiment, oxygen produced in the photosynthetic process (20), e.g. in the case where operation (20) involves growing biomass such as algae, is used for that purpose (24). The processing typically produces in addition to thermal energy ashes (44) and CO2 (46), either of which or both could be used in the step of generating the renewable material as sources of nutrient and carbon.

The thermal energy formed in operation (40) could be obtained in various useful forms, such as direct and indirect heating, steam generation, etc.

According to a preferred embodiment, the thermal energy is converted into other forms, e.g. mechanical energy or electrical energy. At least part of the thermal energy formed in operation (40) is used (42) as such, after conversion, or both for

the generation of biofuel in operation (50). According to a preferred embodiment, thermal energy and/or products of its conversion is used, if needed, in renewable- material generation and/or fractionation (s) (operations (20) and/or (30), respectively). According to a particularly preferred embodiment, the amount of energy produced in operation (40) and/or resulting from it is more than needed for the total operation of the method and excess energy is available for sale and/or for use in other processes.

An example is a preferred embodiment of the method where corn kernel is provided as the renewable material (22) and com oil is the commercial product. Fractionation in the preferred embodiment is conducted so that the second fraction (the fraction enriched in cell-wall material, (34)), or a third fraction (not shown in Figure 1) contains corn oil. An operation is added wherein said oil is extracted and optionally refined. Various extractants could be used for that oil extraction, including hexane and ethanol. According to a preferred embodiment, ethanol is produced in operation (50) and ethanol is used to extract corn oil. According to an additional preferred embodiment, the first fraction (32) is further fractionated to convert part of the starch contained in it to glucose and that glucose is converted to commercial products. Such glucose conversion may use chemical catalysis, biological catalysis or a combination of those. Examples for chemically catalyzed conversion are hydrogenation to sorbitol and hydrogenolysis to glycols. Examples for biologically catalyzed conversion are fermentations to various products such as carboxylic and amino acids.

Another example for the production of additional product of commercial value (feed and/or food ingredients and glycerol) is a preferred embodiment of the method where soybean is provided as the renewable material (22). Fractionation in the preferred embodiment generates hulls (cell-wall enriched fraction) and dehulled soybean (precursor enriched fraction). The dehulled soybean is tempered, flaked and extracted with hexane to form defatted soybean flakes and oil-containing hexane solution (miscella). The defatted soybean is desolventized and toasted to form a feed ingredient, according to a preferred embodiment. Desolventized soybean is purified via extraction to form a food grade soy protein

isolate, according to another preferred embodiment. The oil is recovered from the miscella and reacted with methanol in a trans-esterification reaction to form FAME and glycerol. The reaction mixture is treated to separate non-reacted methanol, FAME and glycerol. Glycerol is a co-product used in various applications according to a preferred embodiment. According to a particularly preferred embodiment, glycerol is dehydrogenated to form biohydrogen and optionally also other products of commercial value. According to still another preferred embodiment, glycerol is hydrogenolyzed to form ethylene glycol and propylene glycol.

Another example for the production of additional product of commercial value is a preferred embodiment of the method where algae are the renewable material (22). Fractionation in the preferred embodiment generates an extract containing lipophilic material out of which a commercial product such as Omega 3 fatty acids, arachidonic acid, xanthophylls, carotenoids, β carotene, Co-enzyme Q-10 and astaxanthin is separated according to alternative preferred embodiments.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative examples and that the present invention may be embodied in other specific forms without departing from the essential attributes thereof, and it is therefore desired that the present embodiments and examples be considered in all respects as illustrative and not restrictive, reference being made to the appended claims, rather than to the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.