Homegrown Fuel Ethanol
Local self-reliance provides feed and fuel
By Richard Freudenberger
BackHome Magazine July/August 2008
Tucked away in Pennsylvania's Tioga County, Painterland Farms is an organic dairy operation that's home to some 300 Holsteins, Jerseys, and Linebacks. It's a family affair, with several generations of kin working the farm along with help from hired hands.
In 2005, John and Lynda Painter and their son, John, looked into developing an enhanced dairy cattle diet that would improve milk production while keeping sources local and costs under control. They ended up with not only feed for the livestock but fuel and heat for the farm too. The Painters, as you've probably guessed, discovered ethanol. The clear, grain-based alcohol, when distilled to high concentrations, makes a clean-burning, high-octane motor fuel, and by-products of the process can be used for livestock feed and other applications.
John Painter and his distillation column
The project got rolling when they met with their Penn State Cooperative Extension agent Craig Williams to develop a USDA Sustainable Agriculture Research and Education grant that would provide a level of practical on-farm research. Williams worked with them to expand their goals to include fuel sustainability as part of the working dairy farm. The primary intent was to explore the practicality of operating a small-scale ethanol facility within a stable farm operation to broaden the scope of value-added products and to supply energy needs through both traditional distillation and new disciplines.
The Painters had hoped that even in complex markets, an established and diversified agricultural operation would be able to provide for many of its own needs, aiming towards sustainability while protecting its ability to maintain operations during periods of market volatility and economic upset. They had to prove the efficacy of an enhanced dairy cattle diet through the feeding of distiller's grains (a coproduct of distillation), and they had to develop a clean, renewable on-site energy source in the form of ethanol A third economic objective was to minimize waste by using salvaged components where possible and recycling water and heat within the system to economize on resources.
Using their records from prior years, the Painters were able to estimate the total volume of distiller's grains they'd need on an annual basis. Then, based upon that figure, they were able to establish the design volume needed for the distillation equipment. Armed with that information, they began a search and eventually located a used distillation tower and some equipment in North Carolina.
After hauling it back to the Keystone State, they set up in an unused dairy barn, which they had to modify by raising a portion of the roof to accommodate the nearly 30-foot tower and by gutting the inside to make room for the mixing equipment, fermenting vats, beer tank, and distiller's grains processing.
The Painterland ethanol operation uses organic corn and barley and, at some point in the future, will use rye as feedstock. The market price of these commodities determines to a great extent which crop will be used. If the price of one rises to the point where it's more valuable on the market than it is as a fuel, another feedstock will replace it for distillation. If the cost of all available feedstocks is prohibitive, ethanol production can be suspended—as it has been more recently—until prices stabilize. This kind of flexibility is possible on a small scale and helps to keep the price of ethanol down. It also keeps the Painters on their toes scrutinizing commodity markets and planning for future crops.
Similarly, the fuel source for the steam boiler is currently rice coal, a fine-grain anthracite common in Pennsylvania. It's readily available, but as a fossil fuel is subject to market fluctuations. The family is now investigating renewable resources and biomass options to supplement, or eventually replace, the coal source that could become a costly component in the future and already is a known contributor to CO2 emissions.
From Feedstock to Fuel Stock
The ethanol-making process begins with ground corn and grain in bin storage. Shredding, grinding, or mashing gives the fine-meal grind needed to initiate the breakdown of starches. A conveyor chute transfers the material to a ration mixer in the distillery, which includes a set of scales to record weight measurements. The grain is then piped to a group of stainless steel vats, where cooking and fermenting processes occur in the same vessel. In the conventional process, after dry grinding, the kernels are slurried in a vat with pH-adjusted water and treated with an alpha amylase enzyme. Then the slurry is cooked at high temperatures to gelatinize, or liquefy, the starch. Following that, the mash mixture is cooled, and a second enzyme, gluco amylase, is added to begin the saccharification that converts the starch to fermentable sugars. Once that's completed, a yeast is added to ferment the sugars, a process that yields ethanol and carbon dioxide gas. The low-grade ethanol is then distilled to bring it to a high-proof strength.
Mash is slurried in a mixer. About 900 gallons of water is added to every 50 bushels of grain feedstock. Once the ethanol is removed, the residual grain is used as cattle feed, and the water used as well.
Using a relatively new raw starch hydrolysis or "cold-cooking" method developed by Genencor International (Stargen™ is their granular starchhydrolyzing enzyme), the Painters are able to complete the enzymatic breakdown of starch into fermentable sugar at near room temperatures—about 90°F—which eliminates two stages of the traditional process and saves considerable energy, giving them a cost-cutting edge.
Typically, the Painters will introduce 900 gallons of water for every 50 bushels (approximately 2,850 pounds) of grain used. Their water source is a spring that was developed for the purpose; municipal water would have to be treated to remove chlorine that would affect the enzymes. The pH level is also checked and adjusted with the use of a dilute acid or a phosphate buffer.
Fermentation occurs in the same six 1,250-gallon stainless steel vats so the batches can work in a six-day rotation. It takes about three and a half days for each fermentation cycle to be completed. Efficient fermentation depends on the correct dosage
Six 1,250-gallon stainless steel vats allow fermentation to occur in a sixday rotation. Once the enzymes have broken down the feedstock's starches and complex sugars into simple fermentable sugars, yeast consumes some of it in growth, and converts the rest to ethanol and carbon dioxide
of yeast, based on the sugar content of the mash. Yeast is mixed and agitated briefly in a smaller vessel, then is added to the mash and left to work in the sealed vat. Temperatures are held below 80°F, and anaerobic conditions are maintained through the use of a simple fermentation vapor lock to encourage the production of ethanol and CO2 . After fermentation is complete, the mixture is pumped to a separator, where the liquid beer is sent to a tank prior to the distillation column, and the wet solids, or distiller's grains, are collected in another container. The 12-inch distillation column, or tower, rises into the roof cupola and contains a series of perforated plates. The distillation process functions through the difference in boiling points between alcohol and water. Because of the higher vapor pressure of alcohol, ethanol evaporates faster than water when the mixture is boiled. As a result, the vapors contain a disproportionately large share of ethanol. The perforated plates in the column stage a series of evaporations as beer is added to the column. At each stage, vapors flow through the perforations in the plates and are cooled by water flowing across the plates. The ethanol rises, as vapor, and the water falls through down tubes staggered at the edge of each plate. At each level, the proportion of alcohol to water becomes a bit greater, as the process works its way to the uppermost reaches of the column.
At the top of the column, the distilled and condensed ethanol vapors are collected and piped to a storage tank. The descended water is collected at the bottom of the tower and fed warm to the cattle as sweet water. To comply with federal regulations, the 190-proof (95 percent pure) ethanol is denatured with 2 percent unleaded gasoline to make it nonpotable. It takes some attention to detail to squeeze a high-proof product out of the still, and the operators concentrated on tweaking the condensing process at the peak of the tower. The best result, according to the senior Painter, came about when they simply placed a ventilating fan at the top of the column to spot-cool it. The product they get is about the highest obtainable without utilizing special equipment and has reached 192 proof on occasions.
That equipment is available in the form of a molecular sieve, which is a dehydration device used industrially to remove the final 5 percent water from the mix. The sieve is made of an aluminum-silica material containing microscopic pores that only allow water and carbon dioxide to be adsorbed, leaving pure ethanol behind. This kind of high-tech investment is well beyond the farm's budget, but the Painters are confident that they may eventually be able to locate a suitable device as surplus or through an industrial auction.
Alcohol yield comes to between 110 and 120 gallons of fuel-grade ethanol per ton of grain at maximum proof. It's stored in metal and polyethylene containers and pumped off as needed. Absolutely pure ethanol is required only for the manufacture of gasohol (10 percent ethanol) and E-85 (85 percent ethanol) blends. The 190-proof fuel made on the farm is perfectly usable straight-up in gasoline engines, as the small amount of water at that concentration remains miscible and does not separate out. The Painters use the fuel in various farm engines on the premises as well as in farm vehicles, without blending or additional drying. The federal Alcohol Fuel Producer's permit allows for use on the farm or for travel between farm operations exclusive of a fuel excise tax.
The farm's diesel equipment is not yet on the table for ethanol use. Technicians have advised that the fuel's lack of lubricity could be problematic, even in a blend, and the working equipment is too much of an investment to risk. John Painter still plans on acquiring an older tractor or loader to proceed with some testing of his own, however.
Lower-proof fuel is regularly used in the farm's heating equipment and in the family's home furnace. It also provides space heating for cold corners of the barns and outbuildings.
For the dairy farm, the value of the by-product was a key element. Besides an immediate and significant milk production increase, the nutrient value of the soy and distiller's grain–blended feed supplement increased markedly. The distiller's by-product consistently runs close to 26 percent protein, an 18 percent increase over corn alone, and a big advantage over having to buy supplemental organic soybean meal at $700 per ton.
An analysis of milk production indicated a 4 percent decrease concurrent with a decrease in the feeding of distiller's grain over a several-month period. One percent coincided with the removal of soy residue, and the remaining 3 percent drop was attributed to the final removal of corn distiller's grain from the ration.
Carbon dioxide is also a coproduct of ethanol production and in especially larger operations has marketable value. The Painters have not implemented CO2 recovery in their operation as of yet.
A Managed Economic Cycle
The organic feature of the farm has obliged the Painters to conduct their business in a more broad and traditional manner than do some operations. They do things the old-fashioned way, from breeding and raising the cattle on-site to raising hay and cultivating the corn and organic soybeans themselves. The elder Painter says that despite the higher cost of producing alcohol from organic feedstocks, the gains from the protein-rich distiller's grains, plus the sale of feeder steers, organic hay, and high-value dairy all contribute to bringing the bottom line into balance.
Good record keeping is critical to data analysis and in estimating cost and profitability. The circumstances and results of each batch run were dutifully recorded, indicating date and time, temperatures, water volume, weight and cost (if any) of feedstock, enzyme type and cost, acid volume and cost, distiller's grain volume, and amount of ethanol and proof-strength produced.
The improvements have moved Painterland closer to sustainability and self-sufficiency. Very little goes to waste in a system where recycling is crucial to making a profit. By-products are just as important as the fuel itself, and the Painters are constantly seeking to develop markets for anything with value, a strategy that can make the difference between red ink and black.
Richard Freudenberger is the author of Alcohol Fuel: Making and Using Ethanol as a Renewable Fuel, due to be released in February by New Society Publishers.