Yeast is used in the fermentation process to convert simple sugars in ethanol. This process creates excess CO2 which is often thought of as a waste product to brewers. Team Y.A.Y. B.E.E.R. sees an opportunity to recapture CO2 to be used later in the brewing process to carbonate beer or flush tanks for sterilization. Typically, breweries have to get pressurized CO2 tanks delivered, but team Y.A.Y. B.E.E.R. will create a system where the output gases will be recycled instead of being expelled into the atmosphere. Team Y.A.Y. B.E.E.R. decided that in order to provide a quality piece of equipment that is suitable for breweries to accomplish CO2 recycling, certain design specifications must be met. The device must be compatible with various fermenter designs, be easily movable, and fit down corridors less than two feet wide. The device must be economical for breweries making as little as one barrel of beer per brew (~250 gallons) but making as much as 10 barrels (~2500 gallons). It must be easy to clean and be able to withstand boiling temperatures and high pressures. It must conform to the Federal Trade Commission’s definition for “sustainable recycling of materials.”
Proof of Concept
Team Y.A.Y.B.E.E.R.’s proof of concept is a test brew to find out as much as possible about yeast and the brewing process. The goal is to figure out how much CO2 is produced per gram of sugar, how yeast reacts to high pressures, and an average temperature of fermentation. The team will construct an average homebrewer setup for one gallon and set it up in a member’s ventilated garage. The fermentor will have a rubber grommet attached to the top will have some tubing connecting it to a holding tank. The holding tank will have a pressure gauge mounted to it and a vent valve to release excess pressure. The team will start by adding a gallon of store bought cider to the fermentor, along with 500 grams of sugar. An ale yeast will be pitched and the original gravity of the must (cider/yeast/sugar slurry) will be calculated. Every four hours during the day the pressure and temperature of the must will be recorded. The vent valve will be opened to relieve excess pressure and then closed again to be checked later. After the last check of the day the vent valve will remain open until the first check of the next day. After three consecutive pressure readings, the final gravity will be recorded to see if the brew has completed fermentation. The process from pitching the yeast to recording the final gravity will be timed and recorded.
The purpose of the project is to recycle carbon dioxide from the fermentation process of brewing beer and use it for the bottling process. Small breweries and homebrewers release their carbon dioxide into the atmosphere which is harmful to the environment and forces them to truck in CO2 adding additional costs to the brewing process. The application of the device will save small brewers money while also helping to preserve the environment.
A main feature of the device is that it is modular to allow for use by multiple consumers. This is because each brewer has their own brewing setup. Quick connect/disconnect fittings are used to allow for minimal downtime and fast cleaning/repairs. The device is built on a small, rolling cart to allow for easy movement around the brewing station. This allows a person the ability to move the device without the need of assistance as the entire device is large. Multiple ball valves are attached to the compressor to allow for simultaneous filling of the carbon dioxide tanks. Ball valves also allow the user to attach/detach more tanks without having to halt the brewing process. Pressure gauges are placed at various points on the device so that the user is able to determine the amount of CO2 flowing through each stage of the device and if there is a leak. One way flow valves placed after the inline filter prevents the clean CO2 from mixing with the dirty CO2 coming from the fermenter. A regulator provides manual release of the CO2 and has a safety relief valve so that the pressure in the holding tank does not cause it to fail. Food grade tubing and holding tanks are used so that the compressed CO2 is safe for consumption. All materials used withstands high temperatures and pressures from brewing.
The B.R.E.W.C.O.O.L. uses standard parts and no machining was required on the device. The compressor needed to be disassembled and the hose from the holding tank to the compressor needed to be added to the piston assembly. After the hose was inserted, all other holes and gaps were sealed with high pressure, food grade silicone. A hole was made for the inlet hose to pass through in the compressor case. The compressor case was then reassembled and reattached to the compressor tank. The inline filter had quick release connectors added at both ends, and then was attached to hose at both ends. The hose at the holding tank was inserted and sealed with silicon. A rubber gasket was added on top of the holding tank and a threaded to quick release connector was added on top. The holding tank outlet was then connected to the compressor inlet. Tubing with a quick release was installed after the compressor tank, which was connected to a ball valve that was bought to fill the CO2 pressurized tank. All fittings were either PTFE taped (on the threaded fittings) or sealed with silicon (on the barbed ends).
Figure 1: Materials used in construction
Figure 2: Completed fabrication of a B.R.E.W.C.O.O.L.
Testing and Results
The B.R.E.W.C.O.O.L. was tested using a 1 gallon cider brew. After the product had been assembled according to the drawing assembly, testing of the product began. The trials followed the same order as the user manual specified. These are as follows:
- Ensure all fittings, tube, and connectors are secured properly, free of any obstruction, and clean.
- Attach inlet tubing to fermenter, making sure connection is securely in place. Allow holding tank to accumulate carbon dioxide for a minimum of 4 hours and a maximum time of 24 hours.
- Plug in compressor to wall outlet, be careful of electrical shock.
- After carbon dioxide has accumulated, turn 1 way valve to the open position. Turn on compressor. Allow compressor to run for at least 10 minutes(~40 psi in air compressor). Turn off compressor.
- Attach pressurized cylinder to compressor tank. Change regulator settings to 100% flow.
- After cylinder is attached to compressor tank, open ball valve for cylinder. Depress red handle on compressor outlet. Begin filling cylinder.
- Fill cylinder to 90% of weight. Close ball valve when done filling. Cylinder may be removed from compressor outlet at this time.
- Continue process until fermentation has stopped. Remove inlet tubing from fermenter.
There were a couple of differences from the user manual for the test runs. The compressor was run until there was about 30 psi in it, and the connection between the compressor and the pressurized cylinder was left open for increasing amount of times (not to 90% weight). The first trial run used atmospheric air as the working gas. The filter was left open to the atmosphere, the ball valve was opened and then the compressor turned on. It was pressurized to 30 psi and then turned off. The pressurized cylinder was then connected to the compressor tank and filled for 5 seconds. The cylinder pressure was 15 psi. The air was then released from the compressor and pressurized cylinder and the next trial was then setup with carbon dioxide. The filter was attached to the fermentor using the quick disconnect fitting. The test proceeded but only to a compressor pressure of 10 psi. The pressurized cylinder was again left open for 5 seconds and the carbon dioxide recovered was 4 psi. The carbon dioxide in the compressor and pressurized cylinder was then released in a well ventilated area to set up for the next trials. The next two trials occurred 4 and 12 hours later (to let the carbon dioxide build up again in the holding tank). The testing procedure remained the same, except the compressor was pressurized to 30 psi in the next two trials, and the pressurized cylinder was left open for increasing amount of time. Trial 4 was recorded and can be seen in this video.
|Test Run||Gas used||Compressor pressure||Cylinder Pressure|
The product is considered a success. Carbon dioxide was recycled from a brewing process, in accordance with the original purpose the team set out. If scaled up, it could dramatically decrease the amount of carbon dioxide breweries would need to ship in, while also reducing their carbon dioxide footprint.
Meet the Team
Jacob T Smith is a mechanical engineering student graduating the Spring of 2017. He plans to continue his education with a Master’s in Business Administration that same fall. He hopes to enter the Renewable Energy field and eventually own his own business. He is currently a bartender and enjoys spending his free time rock climbing, snowboarding, teaching acroyoga and laying on the beach in Tahoe. He was born in Pahrump, Nevada on a rainy Saturday in 1993.
Alton is a senior Mechanical Engineering student at UNR. He was born in Los Angeles, California but raised in Gardnerville, Nevada. In his free time, he enjoys drawing, painting, and reading. In the Spring of 2017, he is expected to graduate with a Bachelor’s of Science in Mechanical Engineering. After graduation, Alton is planning to find a job in the engineering field.
Matthew is a senior Mechanical Engineering student at UNR. He is from Granite Bay, California and plans on graduating in Spring of 2017. He enjoys listening to music and reading. After graduation, Matthew plans on finding a job in engineering.
Kyle Donnelly is a senior studying Mechanical engineering at the University of Nevada, Reno. He excels academically and has been interested in mechanical engineering since his freshman year of high school. Kyle is originally from Las Vegas but has come to enjoy northern Nevada since coming to college. He is most interested in being an automotive or control systems engineer. Kyle has, however, previously held an internship in HVAC and is open minded to learning about anything new and exciting. In his free time, Kyle enjoys reading, going to concerts, and watching cartoons. After graduating in May 2017, Kyle plans to relocate to Indianapolis to pursue a career in engineering.
Michael Wordelman is currently a senior Mechanical Engineering and math minor student at the University of Nevada, Reno. He was born in Foresthill, California and moved to Reno to attend school. Michael enjoys spending time outdoors, especially snowboarding and biking. Michael is also a member of the SAE Wolfpack Racing, and wishes to use the knowledge he is gaining to get a job in the automotive field. With an expected graduation date of May 2017, he plans on moving to the greater Sacramento area to be nearer his family.
We are appreciative for all of the help we have received while working on this project. We would not have the success we have had so far without this help. Thank you Alex Jankovic, our mentor, for being one step ahead at all times and always keeping us on track. Thank you to Michael J. Lewis, Professor Emeritus of Brewing Science at U.C. Davis for technical advice and guidance. Thank you to Brandon Wright at The Depot and Matt Johnson at Imbib for the tours and insight into the needs of local breweries. Lastly, thank you to professors Sudeep Ingole and Nich Maus and to the class T.A.’s Pedram Safaei, Jake Mestre, Patrick Stampfli and Nick Zerbel for the help, support, and necessary criticism needed to make this project successful.