The Pro Bono Thinking Society

PBTS1: Spent Grains Need Spent

Status: Complete

REPORT (updated September 2nd, 2011)

PBTS Project #1
Title: Spent Grains Need Spent
Start Date: 7/25/11
Report Date: 8/29/11

I. Summary of the problem
Half Acre Brewing, of Chicago IL, produces ~15,000 lbs of spent grain each week as a byproduct of their brewing process. Spent grain, also known as brewer’s spent grain (BSG), consists primarily of grain husks and fragments with a high moisture content. BSG is known to spoil within a day or two of production. The quantity of spent grain produced each day at Half Acre is significant in relation to the size of brewery. The urban setting of the brewery makes large scale solutions unlikely.

All breweries are faced with the problem of how to deal with their spent grain. The larger the brewery, the more sophisticated the options that are available. Based on our research, currently the two most common solutions to dealing with spent grain for a brewery of Half Acre’s size are giving it away to local farmers or sending it off to the landfill. The latter is least desirable due to the costs incurred by the brewery and environment.

II. Initial research
We believe there is value in approaching a problem from a fresh, uninformed, unbiased, and original angle. Our approach for this project was to come up with a broad range of original ideas and then compare our ideas to existing research. This approach allows us to evaluate each alternative on its own merits instead of simply following popular consensus. Our initial research scope included using spent grain for composting, mushroom production, worm farming, biofuel, livestock feed, bird/chicken feed, drying and retail sale, dog bones, soap, and water treatment.

After assembling a critical mass of alternatives, we then turned to current academic articles that summarized potential uses for spent grain, in an attempt to “compare notes”.  We found two works to be particularly helpful in bringing us up to speed on proposed alternative uses for spent grain: “Brewer’s spent grain: A review of its potentials and applications” by Aliyu and Bala of Kaduna State and Kano State (Nigeria) in 2011 and “Business Study of Alternatives Uses for Brewers’ Spent Grain” by multidisciplinary group of students at IIT in Chicago in 2011.

Finally, after taking the current body of research on the subject into consideration, we once again tried to think of original alternatives and analyze all existing alternatives based on the specific parameters for the situation at Half Acre. Our findings are below.

III. Recommended solution
Drying and pelletizing by coalition

Given the resource constraints of Half Acre in terms of size and capital, our research suggests that the best alternative is to continue using spent grains as a feedstock for local farmers, with a few improvements to the process. Our recommendation is to first dry the spent grains and then pelletize for sale as feed or fuel.

There is a wide range of grain drying equipment, including rotary dryers, steam tube dyers, flash-type dryers, steam disc dryers, and belt presses. In addition, capturing waste heat from the brewing process, or from other local industrial businesses with a large amount of waste heat, is an alternative worth researching. An in-depth look at the economics of various dryers can be found by visiting “Energy Costs and Spent Grains Drying” by The Richards Engineering Group.

Drying the spent grain significantly increases their shelf life and removes the time sensitivity of the product. Pelletizing the dried spent grains would allow additional ingredients to be added to meet the demands of the market. Spent grain can be mixed with combustible material to create biomass fuel pellets. In addition, spent grain can be pelletized “as is” or mixed with other feed ingredients to make feed pellets customized for individual farms or livestock. Pelletizing the spent grain for feed or fuel would help standardize the product and make transportation easier.

Our initial research indicates that basic drying and pelletizing equipment can be purchased within a budget of a small brewery, and definitely within the budget of a coalition of small breweries. This coalition would consist of several small brewers that agree to chip in for a site and equipment to handle all local spent grain. Costs savings for each brewery can be achieved by decreasing their dumpster capacity from covering disposal of 100% of their spent grain to 0% of spent grain. A portion of these cost savings would be dedicated to this drying/pelletizing venture. Revenue from sales of pelletized feed to local farmers would offset all costs incurred by each brewery.
Creating a joint venture to handle all local spent grain would benefit Half Acre by ensuring consistent, timely pickup and disposal of their spent grains each day at a cost not much greater than what is currently spent on dumpster capacity.

IV. Other viable alternatives
Peat pots
One idea we think may have legs is pressing spent grain into peat pots to be used for planting. Further tests need to be done to determine viability of this idea, but the properties of spent grain that make it viable for compost should also apply to its use in peat pots. Machinery required for producing peat pots is relatively basic and should fit within space and capital constraints. Peat pots could be branded with the Half Acre logo/name and sold to increase brand awareness and generate additional revenue.

Community pickup times
There are many different community groups that could have a use for Half Acre’s spent grain. Bakers, bird owners, gardeners, restaurants, etc. all have some demand for free spent grain. While each group’s quantity demanded of spent grain is small, the aggregate could be large enough to meet weekly disposal needs. One alternative is to set up weekly “community pickup days” where members of the community are free to visit Half Acre and pick up spent grain free of charge. Benefits to the brewery include increased foot traffic, increased community involvement, and favorable media coverage.

Pickup incentives
One overriding issue with giving spent grain away for free, whether it is to farmers or community groups, is that the recipient has no incentive to be consistent and timely with their pickup. One idea we propose is to create a “free with penalty” model where recipients of free spent grain can “reserve” a certain amount of spent grain weekly or daily. As long as they make their agreed upon pickups, the grain is free. If the recipient’s pledged amount is not picked up, they pay an agreed upon penalty that can be used by Half Acre for alternative disposal of the spent grain. One twist on this idea is to transfer the penalty paid by one recipient to some other recipient who agrees to pick up the others’ slack and share of spent grain. This creates additional incentive for everyone to pick up their spent grain, as it is now possible for some recipients to be “paid” to take spent grain.

Farmers’ market dropoffs
While most spent grain is given away to farmers for free, picking up the grain involves costs for the recipient. One idea proposed is to lower the costs associated with picking up spent grain by taking spent grain to one distribution point that is easily accessible to farmers and other interested groups. Farmers’ markets have been identified as good focal points for execution of this idea. At a farmers’ market you have farmers, gardeners, and other interested parties traveling to a point within close proximity to Half Acre. At the end of the day these parties leave the city with far emptier loads, loads that can be filled with spent grain. This significantly decreases the costs and effort involved with obtaining and transporting Half Acre’s spent grain.

V. Alternatives to be dismissed
Paper production
One option pursued was using the grain as an ingredient in pulp slurry to make paper. To help us flush out this idea, we meet with Erik Hinkel at French Paper Company with some questions and a sample of the spent grain. After talking with others at the plant Erik got back to us with the disappointing news that using this specific type of grain as a substitute for an ingredient in the standard paper making process isn’t feasible. Pulp slurry is made of a combination of hardwood (Beech, Oak, Maple), softwood (Evergreen, Spruce, Pine) and recycled material. The only place spent grains could be swapped into the process is recycled material, and most places have way more of this than they can handle already.

Erik did offer up the idea of using it as an additive to add texture/color to a sheet. This featured could then be used to market the paper. The downside of this idea is that, even at a full production run, they would maybe use 15,000lbs a month.

Another option pursued was using spent grain as a feedstock for biofuel production. Given their low starch and sugar contents, spent grains are not suitable for producing ethanol. Likewise, given their low oil content, they are unsuitable for producing biodeisel. However, alternative biofuels, such as fast pyrolysis oil may provide a pathway for use. To investigate this idea further, we spoke with Anthony Pollard, co-founder of Avello Bioenergy, a company that specializes in the production of fuels and produces a rapid thermal process called fast pyrolysis. Anthony noted that the lignocelluosic content in the spent grains can certainly be converted to fuel through the fast pyroylsis processes employed by Avello, but the grains would need to be significanly dried before processing. Given the uncertain market value of fast pyrolysis oil and the costs associated with drying and processing, this may not be the most economically viable use of the spent grains.

VI. Off the Wall Alternatives
Chicago River treatment
Aliyu and Bala (2011) summarize promising findings for the use of spent grains for the removal of heavy metals from wastewater:
“Plant wastes, agricultural and industrial by-products have been utilized as the cheapest and unconventional adsorbents for heavy metals from aqueous solutions (Li et al., 2009). BSG was studied by Lu and Gibb (2008) for the removal of Cu(II) ions from aqueous solutions and they found its maximum adsorption capacity to be 10.47 mg g-1 dry weight at pH 4.2. Based on this, BSG being a process by- product, has a significant potential as a bioadsorbent for application in the remediation of metal contaminated wastewater streams.”

“There is need for cheap and efficient carrier with advantageous properties such as high cell loading capacity, low mass transfer limitations, stability, rigidity, reusability, availability, non toxic and food grade. Taking into account these requirements and trying to meet the low price target, BSG, a brewing by-product with considerable cellulose content, was suggested to be a potential carrier for yeast immobilization (Brányik et al., 2001; Almeida et al., 2003).”

We haven’t done much research on what ails the Chicago River, but we do know it is ailing. If Half Acre brewing could use their spent grain to clean up the Chicago River, they would be heralded as saviors and loved by all Chicagoans.

VII. Suggestions for further action/research
-poll IL/WI/IN farmers to gauge interest in pelltized dryed grain
-poll local breweries to gauge interest in a joint venture to deal with spent grain
-obtain specific numbers on drying and pelletizing equipment
-search for viable sites to house drying/pelletizing operation
-seek municipal assistance or environmental grants to help offset costs

VIII. Sources


O’brien, C. (2007, April 15). Grains of possibility: ways to use spent brewing grains. Retrieved from
Mshigeni, K, & Pauli, G. (n.d.). Brewing a future. Retrieved from

Drying & Pelletizing

Christiansen, R. (n.d.). The art of biomass pelletizing. Retrieved from
Brewhouse innovation. (n.d.). Retrieved from
Richards, E.A. (n.d.). Fuel energy from process waste biomass. Retrieved from


Paper from wheat, not wood. (2008, August 28). Retrieved from


A biomass fuelled future. (2009, October 5). Retrieved from
Biograte combustion. (n.d.). Retrieved from


Wahlberg, M. (2009, May 1). Alternative feeds for beef cattle. Retrieved from

Water Treatment

Brányik T, Vicente AA, Machado-Cruz JM, Teixeira JA (2001). Spent grains- a new support for brewing yeast immobilization. Biotechnol.Lett. 23: 1073-1078.
Almeida C, Branyik T, Moradas-ferreira P, Teixeira J (2003). Continuous Production of Pectinase by Immobilized Yeast Cells on Spent Grains. J. Biosci. Bioeng. 60(6): 513-518.
Li Q, Chai L, Yang Z, Wang Q (2009). Kinetics and thermodynamics of Pb(II) adsorption onto modified spent grain from aqueous solutions. Appl. Surface Sci. 255: 4298-4303.
Lu S, Gibb SW (2008). Copper removal from wastewater using spent grain as biosorbent. Bioresour. Technol. 99: 1509-1517.


Erik Hinkel of French Paper
Anthony Pollard of Avello Bioenergy
Curtis Holmes of Alaskan Brewing

BRIEFING (updated July 25th, 2011)

On July 22nd, 2011 Half Acre Brewing Company tweeted the following:

Want to design a business around 15,000lbs of spent grain a week? We have it – for free. Put your head to it and get a hold of us. Stat.

Unfortunately that is all we will get in terms of a briefing but mass amounts of organic material could be used in thousands of different ways.

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