Making Ethanol

The Background of Ethanol

In ethanol production, preprocesses are necessary for the extraction of sugars from cellulose structures due to their exterior shell.  Environmentally hazardous acids have historically provided a means of producing this extra step.  This extra step can be an unwanted cost if the crop source also has to be watered and harvested prior to production.  However, relatively inexpensive cropless organic materials exists in the form of mining the recycled garbage in enough abundance to fuel every vehicle in the nation.  A process known as cellulosic ethanol can derive sugars from the cell tissue of plant stock using hydrolysis, as opposed to methods that extract sugar from the fruit or kernel.  Hydrolysis involves accessing and separating the sugar in the cellulose of the plant using acid or enzymes.  Enzymatic hydrolysis activities have not been successful until For Fuel Freedom’s discovery for the organic breakdown of biomass.

Now, different organics will decay at different rates and thereby yield differing amounts of sugar.  For example, newsprint and branches decay fastest at around 40%, glossy paper and green waste tend to rate in the low 30’s, cardboard 26%, and food scraps 8%, whereas other paper products like envelopes, letters, and ledgers typically have more cotton fiber than other paper products, and therefore a negligible decay rate but a greater percentage of glucose: 62%, 84%, 91% respectively ("The Effect of Lignin on Biodegradability", Tom Richard, Tables; For Fuel Freedom, "Industry Report").  For Fuel Freedom’s discovery consistently produces sufficient fermentable sugars for ethanol production.

Biomass Basics

Conservative estimates say the U.S. produces over 500 million tons of municipal solid organic waste annually in the form of wood, paper, and scraps ("Mash Making 101", pg. 16).  Suitable cellulosic material from biomass fit into two categories: Organics [Construction Composites, Crop Residue, Food Scraps, Green Waste] and Woods: [Branches and Wood, Cardboard and Cardstock, Envelopes, Gloss and Polymers, Ledgers and Books, Letters and Stationary].  Organic biomass has 57.2% organics, 42.8% woods (CA CA Integrated Waste Management Board, www.ciwmb.ca.gov/profiles, Tables).  Combined sources of organic and wood biomass includes approximately 25% lignin, 31% hemicellulose, and 44% cellulose, but the amount of lignin increases and cellulose decreases the older and dryer the material becomes, resulting in an average of 30% lignin and 39% cellulose ("Wood Technology", McGraw-Hill, Tables; "Effect of Lignin on Biodegradability", Tom Richard; CA Integrated Waste Management Board, www.ciwmb.ca.gov/profiles, Tables).  Paper contains about 22.8% cotton fiber, depending on purpose, resulting in 57.7% average fermentable sugar (glucose) content, as compared with most other organics producing only 37% ("Effect of Lignin on Biodegradability", Tom Richard; Wikipedia.org, “Cotton Linters”).  Together, they produce around 45.9% due to the size of their waste streams.  Biomass has the potential of producing 10’s of billions of gallons of bio-fuel, without the present process enhancements, but even more if its lignin can be converted ("Mash Making 101", pg. 16).  The reason the composition of plant cells change with time is the aging process conforms to more lignified molecules as plant geriatrics battle with higher alkalinity, resulting in stronger defense to microbes.

Complex Sugars

Sugar crops are normally complex sugars that need to be broken into glucose.  Proteins that perform the function of a biocatalyst for specific tasks at certain temperatures for a particular pH acidity are called enzymes.  Fungus are commonly parasitical in nature, having the enzymes that digest plant composition, accessing its starches and dextrins and converting them to food in the form of glucose ("Mash Making 101", pg. 2).  Biotechnology studies determined enzymes alone were not powerful enough agents to breakdown lignin in a profitable timeframe (or at all).  The sugar must be extracted from starch indirectly by a conversion or other preprocess.

Starch is a complex sugar, made of multiple links of glucose monomers ("Wood Technology", McGraw-Hilll, Fig. of Wood Cells).  Alpha-type enzymes fragment the links that hold the complex sugar branches together, simplifying the carbohydrate structure into what are called “dextrins” ("Mash Making 101", pg.15).  This process can get expensive, as temperature and time have an inverse relationship when seeking cellulose degradation.  Without a process for growth, penetration, digestion, and increase in biomass, ethanol from this alone would not be economical.

Cellulose

Understandably, for yeast to digest sugars deep in the cell tissue, the cellulose must be broken down.  Hydrolysis treatment then, breaks up the structure of cellulose.  However, the interior of the plant cell wall, the exoskeleton in most solid waste organics, varies in makeup.  This variation depends on the plant and its age.  This variation is the relationship created by cellulose, hemicellulose, and lignin.  Cellulose strands are held together by certain molecules in the sugars and are surrounded by the hemicellulose and encased by lignin.  These form microfibrils, the tiny reeds that make the cell wall ("Wood Technology", McGraw-Hilll, Fig. of Wood Cells).

Acid Preprocess

One important factor in finding the solution to access sugars that ferment has been identifying what processes are capable of eating away at the exteriors of cellulose.  Chemical acid has been the common method of breaking down cellulose.  Most cellulosic tissue breakdown has been traditionally achieved by some combination of heat, water, and acid.  For the level of heat required alone to breakdown outer tissue, 400° F, the cellulose and its sugars end up destroyed because the breaking down of cellulose occurs at lower heat.  So, acid hydrolysis is used.

Acid hydrolysis is the process of mixing acid with the biomass in an starchy mix, so that exposed tissue will break apart.  Different types of hydrolysis may reduce the time needed for enzymatic breakdown.  Normally, a caustic solution of 1% would treat the biomass at 140° F for three hours ("Mash Making 101", pg.19).  When alkalinity levels contain too much acid, powdered limestone or ammonium hydroxide will neutralize it ("Mash Making 101", pg.13).  Cellulosic material, once it has a pH imbalance, can be recovered with filtration and shocked with hydrochloric acid to restore alkalinity.  Since For Fuel Freedom does not use conventional acid, the pH level is not extreme.  Whatever the method, alkalinity must be stabilized following hydrolysis for later fermentation.

Challenges

Acid processes are both economically and environmentally challenging, leaving the invention of an organic option preferred.  Acid poses a threat to water and livestock.  If ammonium hydroxide (ammonia) is used, its composition is regarded as a hazardous material and lung toxin (Wikipedia.org, “ammonia”).  If the acid is neutralized by limestone, by-products will be gypsum wallboard, limiting profits to U.S. construction cycles.  An environmental solution would break down the exoskeleton and lignin without destroying the sugars in order to maximize ethanol production.  This makes the activity more economical in coastal cities where extreme costs are associated with environmental clean-up.

Ethanol Distilling

The major components of our process are: degradation of exoskeleton, capture of carbon dioxide, conversion of cellulose to cellobiose, use of separated sugars, recycling of undigested cellulose, and reuse of remaining pulp.

Grinding

For grinding, the biomass must be chopped or ground into a course constituency as known in the art.  The more refined the biomass, the more surface area will come in contact with the yeast culture in the fermentation process and thereby making digestion more effective.  The faster the rate of fermentation, and more profitable the production of ethanol.  However, degradation can reduce ethanol production, so less abrasive means of breakdown are used after grinding.  Otherwise, the size of the fragmented material can be between half a centimeter and 2 inches, as long as the material can be suspended with sufficient water to be pumped and filtered.

Hydrolysis

Hydrolysis is the pre-boil process of mashing where the biomass is suspended in a watery solution and heated, to allow the glucose molecules to expand and gel.  Hydrolysis of the slurry softens the lignin, so the breakdown process can prevail.  This complex process includes consideration for the type of installation, relative operating conditions, and maximum capacity.  Variables to factor in calculations are: tonnage of biomass, rate the biomass will be introduced into the slurry, heated at what temperature for how long, when and how to stop activity, and run-off filtration of by-product that varies with method used.

Stopping the pH

The temperature in acid hydrolysis is higher and resulting pH is lower, so the acid must be neutralized and its pH restored prior to fermentation, in addition to using glucoamylase or other enzyme as claimed to convert the remaining dextrins.  At a pH below 7, certain biotechnologies do not ferment.  pH can be corrected with a combination of heat plus either limestone, ammonium hydroxide, and alkalinity can be increased with citrus lime.  Increasing the pH will also cause a chemical reaction that accelerates lignification.  Agitation is used to stop remaining activity and to sort out plastics and metal shards.

Liquefaction

Before the ethanol sugars can be separated from those that do not ferment, the mash is heated and a small amount of glucoamylase enzyme is added after alkalinity is adjusted.  This process, called liquefaction, aids in the conversion of glucose using a set of enzymes that breakdown cellulosic complexes called cellulases.  For one method to convert the remaining dextrins, the cellulosic mash must be cooked at 140° F for four hours in 1% cellulase, but only if no sugar separation process used.  However, the amount of enzymes needed is less and temperature of the heat is more when employing a preferred process for separating non-fermenting sugars.  For liquefaction then, the mash is heated to the same temperature as in a steam cooker: 176-212° F (80-100° C) for about an hour and a half.  Boiling will then stop the enzymatic growth.

Sugar Separation

Xylitol and similar sugars are siphoned off primarily because they prevent fermentation but can be salvaged for by-products using a chromatography apparatus, by either osmosis, preservative, or resin, preferably DOWEX-like Strong Base Anion Resin.  This is based on Einstein’s discovery of Capillary Action, how the properties of molecule structures in liquid will tend to bind to certain surfaces.  This filtration occurs before the glucoses in the mash to cool down to 90° F for fermentation.

Cooling Transition

At this point, the cellulosic matter is ready for fermentation.  After boiling to kill the proteins and introduce a chemical base to expose the remaining starches, the enzyme is reintroduced.  For Mash Cooling, the temperature is set to 118.4-154.4° F (48-68° C) for half an hour.  The mash is then cooled down to 90° F, and Beta enzymes eat away to breakdown recently exposed sugars in the sections remaining.

Fermentation

Fermentation of any sort is strictly regulated by the Alcohol Tabacco and Firearm federal government agency and requires special permits to operate any equipment.  Fermentation is a process that can utilize either batch or continuous flow automation depending on system needs, in this case continuous is preferred.  Fermentation occurs best when the cellulose is placed in a slurry tank and carefully agitated.  Following about 10 minutes of agitation, oxygen-starved yeast then stops multiplying and starts feeding on the glucose to produce alcohol and carbon dioxide ("Mash Making 101", pg.15-16).  The bacteria is removed by vacuum or filtration.  At intervals, samples are extracted to determine tolerance.  Determining when ethanol production reaches its tolerance tends to vary with production quality and sugar content.  Fermentation stage includes cellulase with the yeast, so that the substance can be infested by the yeast.  The yeast then proceeds to produce ethanol while consuming the cellobiose.  Yeast cultures produce sufficient quantity to reuse in subsequent fermentation cycles.  Undigested cellulose is removed by filtering when the cellulose-liquid is drained.  Afterwards, the yeast will tend to coagulate in the slurry and can be harvested.

Nutrients

Yeast requires nutrients to grow.  In the fermentation process, an aqueous mineral medium containing an assortment of minerals and electrolytes, plus an iron-oxide inhibitor: including calcium, magnesium, nitrogen, phosphorus, potassium, sodium, and sulfur, as well as trace quantities of elements such as copper, iodine, iron, manganese, molybdenum, and zinc, and preferably contains vitamins such as biotin and thiamine.  The fermentation concentrate should have just sufficient nutrients for both yeast and enzymes to grow in life-generating conditions.  Fibrous cellulosic material gets exposed in this broth will produce at least a significant amount of ethanol.  When the tolerance of the bacteria reaches ethanol equilibrium (about 6-10%), pressure valves release the ethanol at such temperature in vapor form.

Operating Temperature

A low temperature should be maintained during the fermentation to not destroy the yeast.  For example, 82-90° F (27.2-31.6° C) for 24-60 hours, or 36-40 hours with flash fermentation processes.  While fermentation is taking place over the course of two ½ to four days, other processes can be running.  The flow of materials and the flow which the other processes occur is vital to the economics of a Super-cellulosic^SM Hybrid Ethanol and Bio-diesel^SM bio-refinery, and For Fuel Freedom’s proprietary and patented system is engineered for maximum efficiency.

Distilling

Distillation of any sort is strictly regulated by the Alcohol Tabacco and Firearm federal government agency and requires special permits to operate any equipment.  When fermentation is carried out at atmospheric pressure, the contents of the fermentor are then treated to separate and recover its ethanol component through distilling off the ethanol.  Distillation keeps the temperature between 173-212° F (75-100° C) for about 1 hour.  Remains from distillation are separated out through filtration using molecular sieves, and the pulp is typically discarded or used as a by-product, however, the undigested portions can be recycled using For Fuel Freedom’s proprietary and patented system so the entire operation in effect reprocesses the otherwise unusable tissue into ethanol.