BIODIGESTION: YOU CAN COOK FOOD ON POOP AND FOOD WASTE
Each season, one Science, Technology, Engineering, and Mathematics (STEM) subject is the featured theme of the VEX IQ STEM Research Project Challenge. In this 2015-16 season, the STEM Research Project Challenge theme is Science.
Our team is doing our STEM project on biodigestion.
Question
Can you create cooking fuel out of poop and kitchen/household waste?
After researching different methods of creating biofuel, we determined that a biodigestor would be the most clean, efficient and cost-effective way to create biogas.
Research
Part of our reserach included watching and learning from this Ted Talk done by Janice Kelsey and Jody Spangler, from Solar Cities.
Our research inlcuded part of our team visiting Mrs. Kelsey's house to see the different biodigesters she has set up on her property. She also showed us slides of an inground biodigester that was installed at Mrs. Spangler's house nearby. Mrs. Kelsey is in the process of experimenting with different methods of warming the biodigestor so it will work in colder climates, such as in the colder areas in the US as well as places such as the Syrian refugee camps.
Here the digesters are painted black to keep the digester warm.
Pictured top: Janice Kelsey, Dave Leuter
Pictured Bottom: Clayton Young, Jody Spangler
Mirrors and CD's were added to reflect the day's sunlight to the digester.
Foam insulation was added to keep the warmth inside and windows were added to allow the sun's heat in during the day.
Mrs. Kelsey and Clayton in front of the model biodigestor. It's a baby girl dragon!
Making hot chocolate on a biogas stove using methane fuel from the biodigester. Mmmmmm!
A family can use their waste materials to supplement or replace some of their energy needs.
Hypothesis
Resources/Research:
Websites:
1. Green Learning: http://www.re-energy.ca/docs/biomass-energy-bg.pdf
http://www.re-energy.ca/docs/biogas-generator-cp.pdf
2. Solar Cities: http://www.solarcities.eu
3. Merriam-Webster: http://www.merriam-webster.com
4. Science Daily: https://www.sciencedaily.com/terms/fossil_fuel.htm
5. Environmental Defense Fund: https://www.edf.org/methane-other-important-greenhouse-gas
6. Wikipedia: https://en.wikipedia.org/wiki/Methane
https://en.wikipedia.org/wiki/Organic_matter
7. Science Buddies: http://www.sciencebuddies.org/science-fair-projects/project_scientific_method.shtml
Books:
1. Biofuels: http://tinyurl.com/zm7vf7h
2. Mythbusters: Confirm or Bust! Science Fair Book #2: http://tinyurl.com/hb4btgt
3. Methane Energy (Innovative Technologies): http://tinyurl.com/zc6jvyu
Procedure/Method
1. Make a small scale digester model with a scale of 55:1.
2. Determine how much cooking time a family needs per day.
3 meals/day x 1 hr cooking time/meal = 3 hours/day needed
3. Compute results of small scale x 55 to determine if the
output meets the family’s needs of 3 hours/day.
Data
STEM DATA
BUDGET
Analyze
As we analyzed the data through out the experiment, we discovered a few problems:
1. There was no gas production because our digester was outside and it was too cold to produce gas.
2. Once we brought the digester inside, we knew we were producing gas, but it was not being collected. This was due to a problem with the mylar balloon we were using.
3. Even after bringing the digester inside, gas production was steady, but slow. This was because it was still too cold for efficient gas production.
Once we fixed the balloon problem, we could then address the temperature issue. We first installed an Arduino Temperature System to monitor the digester's temperature. The initial temperature was 66 deg. F. We then brainstormed ways to heat the digester and decided to put a heated seed mat under the bucket and also to wrap the bucket in fiberglass insulation. The digester's temperature is now an average 84 deg. F.
THE RESULTS ARE IN:
Burn times for the three different gas storage systems:
1. Mylar Balloon = 48 seconds
2. Small 17 1/2” x 22 1/2” bag = 12 min. 28 sec.
3. Large 21” x 33” = 25 min. 39 sec.
Conclusion
We were able to get about 40 minutes of cooking gas
between the three different balloons/bags.
The bulk of the gas we used for cooking was collected from
April 2, 2016 through April 13, 2016, a total of 11 days.
40 minutes / 11 days = 3.6 minutes per day
3.6 minutes per day * 55 (the ratio of bucket : full size IBC) = 198 min.
198 minutes = 3 hours 18 minutes per day on a larger scale.
In addition to the numbers, we also noticed a direct relationship between the temperature and gas production. The lower the temperature, the less gas produced. The higher the temperature, the greater the gas production. We found a temperature above 80 degrees F to be a productive temperature.
Our conclusion is YES, a family can use their waste to supplement or replace some of their energy needs by using biogas. However, certain conditions, such as temperature, need to be met in order to produce a sufficient amount of methane gas.
Summary
Here is a summary of a presentation I did at the Christian Homeschool Association of Pennsylvania.