Project Update

My project has advanced in numerous ways since my first inception of the project. My original plan was to build a very small digester (Gatorade bottle size) in order to experiment with materials that I could use for digestion. The next order of business on my plan of attack was to build a “medium-scale” digester that would be able to produce a small flame. I built both of these digesters and researched the use of anaerobic digestion – which would have completed my original project – in about half of the time I allotted for myself. Since then, I have expanded my project in three ways that are all very closely linked.

1. I have been in contact with Paul Harris of the University of Adelaide in South Australia and Brad Frazee of Intrepid Technology & Resources, Inc. I have tried to get a hold of the Idaho National Laboratory but I have had no success yet. Paul Harris has helped me a ton with ratios of organic matter introduced into digester systems and gas produced. Every kilogram of volatile solids consumed in the digester produces about 0.5 cubic meters of methane. (17.6 cubic feet.) And about 70% of the volatile solids in the system will be destroyed. Brad Frazee gave me a lot of information on the Whitesides Dairy in Rupert, Idaho. The digester system at the Whitesides Dairy produces about 30 million cubic feet of methane per year. This information has helped me a lot in determining whether or not a digester large enough could be built for our school. Brad told me that in order to produce about 160,000 cubic meters of methane that we need for the school we would need 800 cows. These cows would produce 13,000 gallons of manure per day.
2. With the above information I have decided to go forward with my designs for an industrial-sized digester for The Community School. I have acquired the information about the annual natural gas usage at The Community School, which has helped out a lot with my project in determining how much methane needs to be produced.
3. Once I talk to Brad Frazee again I will have the information that I need for designing and building a digestion system at The Community School. I will know if digester systems are scalable and how big the housing building will have to be. The only problem with the digester system at school would be the number of cows that we need. I plan on contacting the architect that built the two new buildings at school in order to design another building at school.

I am very excited about the progress that I have made on my project, because when I think back on it, my original ideas would have left me well short of what I wanted to accomplish. The development of the design for a digester at The Community School is a great way to exercise my interest in mechanical and architectural engineering. Although the available land at school may pose a problem to ever designing a system that significantly decreases the annual natural gas cost at the school, this project is very possible. I know this because the Whitesides Dairy plant produces more than five times the amount of methane that the school uses annually.

School Digester

I have been in contact with Brad Frazee of Intrepid Technology & Resources, Inc. about the Whitesides Dairy biogas facility in Rupert, Idaho. The Whitesides plant produces about 30 million cubic feet of methane per year (~850,000 cubic meters.) In order to produce the 160,000 cubic meters of methane per year for the school Brad said that we would need approximately 800 cows, which would produce a total of 13,000 gallons of manure per day.

A facility this size would be very possible to build but the capital cost per cubic foot of methane would be high. The cost of the equipment does not scale down to our required size very well.

I have found that natural gas produces 1,000 Btus per cubic foot of natural gas. The methane produced from biogas produces about 600 Btus per cubic foot of biogas. This may sound like the biogas does not help much at all, but this methane would otherwise be released into the atmosphere. The school requires approximately 3.3489 billion Btus per year. The gym/theater building is the most inneficient building at school; using approximately 40% (1,376,500,000 Btus per year) of the natural gas that is routed to the school uses.

Project Changing

My anaerobic digester project has changed direction. I still have two digesters in operation at my house but my main goal is now to figure out how big of a building can be built on our current campus to reduce the cost and amount of natural gas that the school uses per year. I am essentially just trying to figure out the pure logistics of an anaerobic digester at school. This may simple include blue prints or it might be more advanced. For example I might have the opputunity to talk with the architects in Seattle who designed our two new buildings. A huge step would be to speak with Intrepid Technology & Resources about coming to look at our campus. The typical cost of this is generally between $5,000 and $20,000.

Intrepid Technology & Resources, Inc.

Intrepid Technology & Resources, Inc. is a company in Idaho Falls, Idaho. They are responsible for the construction of biogas generators in Rupert, Idaho and Wendell, Idaho. (Intrepid Technology & Resources, Inc. uses the term biogas generator instead of anaerobic digester.)
I am determining the questions I want to ask them about a possible generator at school. My main goal here is to see if it is even possible to fit a generator on campus and whether or not the waste from the Horseman's Center will work for a generator.

Link to ITR, Inc.:
http://www.intrepid21.com/index.htm

Loading the Digester

Gas Production

My medium-scale digester is now in progress. I added about 3 liters of cow manure into the digester container the other day to let the process begin. My digester has not created any methane as of now because the bacteria must consume all of the available oxygen first. I am hoping to see methane production begin later this week.

The design and construction plans that I used worked very well and the system is very manageable. I don't have to worry about any of it spilling or leaking in my house. The last time I exchanged email between an employee of the Pembina Institute, he said that a copper pipe that has the end of it crushed to form a small hole will work just fine for the gas jet that I will use in place of a Bunsen burner. (The original plans had the outlet hose connect directly to a Bunsen burner).

New Digester

My medium-scale digester is now complete and I have put the cow manure into the container. The cow manure was not hard to work with but when it was right up in my face combined with the smell, it made stuffing the manure into the container a little strange. The digester is now in one of the warmer areas of my garage so that it begins to work as quickly as possible. I will have to wait for a few days for the bacteria to consume the oxygen. Once the oxygen is consumed the bacteria will begin producing methane.

My research has shown me somewhat of an outline of how anaerobic digesters work.

1) Bacterial hydrolysis (chemical breakdown of a compound due to reaction with water) of materials --> breaks down insoluable organic polymers (carbohydrates.)

2) Acidogenic bacteria convert sugars and amino acids to carbon dioxide, hydrogen, ammonia and organic acids.

3) Acetogenic bacteria convert these organic acids into acetic acid and more ammonia, hydrogen and carbon dioxide.

4) Methanogenic bacteria convert ammonia and hydrogen to methane and carbon dioxide.
(http://www.nationmaster.com/encyclopedia/Anaerobic-digestion)

Medium-scale Digester is Complete

My medium-scale anaerobic digester is now complete. The construction was very simple compared to finding the required materials. I will put the cow manure into the digester container this afternoon to let the system begin to develop the bacteria that will digest the cow manure. The construction plans that I found on (http://www.re-energy.ca/t-i_biomassbuild-2.shtml) proved to be very helpful. I sent this group an email and they replied very quickly with very helpful answers and even diagrams to help me build part of my digester.

New Materials for Digester

How hard can it be to find the following materials for a medium-scale anaerobic digester?

-Used 18L clear plastic water bottle
-Large Mylar helium balloon
-Plastic water bottle cap (with the "no-spill" insert-see photo)
-Copper tubing (40 cm long, 6.5mm (1/4") inside diameter)
-T-connector for plastic tubing (barbed, 6mm or ¼" long)
-1 cork (tapered, 23mm long)
-Clear vinyl tubing (1.5 m long, 4mm or ¼-inch inside diameter)
-2 barb fittings (¼" x ¼")
-Ball valve (1/4")
-6-8L manure pellets (goat, sheep, llama, rabbit, or other ruminant)
-Rubber gloves
-Large plastic funnel (can be made from a 4L plastic milk jug with bottom removed)
-Wooden dowelling or stick (30 to 50 cm long, 2-3 cm thick)

Evidently pretty hard. I went all over town today to try to find the above materials. Some of which were easily found but the ball valve, copper tubing, T-connector and 2 barb fittings proved to be the most difficult to find. I have found everything aside from the T-connector, the mylar helium balloon and the 6-8 liters of cow manure.

Materials for Medium-scale Digester

I have found materials and construction plans for a medium-scale digester thanks to http://www.re-energy.ca/t-i_biomassbuild-2.shtml. This site has proved to be one of the best resources for this medium-scale digester because of the relatively detailed construction plans and the materials and tools required.

New Material for Digester

I have just recently received another email from Paul Harris of The University of Adelaide in Roseworthy, South Australia on the topic of what is best for an anaerobic digester. His reply to my email message writes:
"Pig or cow manure is best for bacteria (I have used pig manure). Or you may
be able to get some sludge from a sewerage treatment works or an operating
digester if there is one nearby.

You should burn the gas if possible, as methane is 23 times worse as a
greenhouse gas than carbon dioxide (not that you are making a huge amount!).
I have found that a 12mm (1/2") tube (metal!) makes a good burner for small
scale by using a 1mm (1/16") diameter gas jet and low pressure supply -
about 25mm (1") water pressure (there is a sketch on the web page http://www.adelaide.edu.au/biogas/fair/). All I do is run a tube from my
digester to the burner."

My next goal is to find a pretty local ranch or farm that I can get some cow manure from. I believe that this should be relatively easy to accomplish.

After that, my main problem is determining what type of gas is actually being produce and whether or not it is safe to burn. I do not want to have a flame any where near my project if it turns out that the gas will explode rather than burn.

New Ideas

I am currently working on finding new organic waste to put into the digester that will yield more methane gas. The waste that I have used as of now has not created the methane levels that I am looking for in order to produce a flame.

Now that I have done more research I am learning that methane is actually a pretty dangerous gas. It is about 20 times as worse a green house gas as carbon dioxide. Because of this, it is very important that any methane that is produced is burned.

Small-scale Digester Plan

Once I determine how to attach a hose to the methane container, I will fill the digester with the organic matter that I have collected. The gas that is produced immediately is primarily oxygen. Once the oxygen is removed the digester will begin to produce methane and carbon dioxide – the two gasses that can be burned.
My plan for this small-scale digester is to produce as much methane and carbon dioxide as possible. Once I have collected these gases I will use a six-inch metal pipe that will have two openings. One opening will be approximately 1/16 of an inch in diameter and the other opening will be approximately ½ inch diameter. This pipe will allow the gas to exit the containment jar with higher pressure – allowing me to burn the gas. This pipe will essentially serve as a very small butane burner.

Small-scale Digester Complete

My small-scale anaerobic digester is now complete. I let the the first batch of organic matter sit in a saran wrapped bowl in a very warm room of my house. I thought that this would let the organic matter begin breaking down and digesting before I put it into the digester. The organic matter that I have used is left-over salad, onions and carrots.
I am currently stalled in the process of digestion because I need to find a way to let the methane gas out of the container. This should be an easy process. I just need to attach another section of hose to the containment jar with a removable plug.

First Blog - Project Update

I have started working on my project blog. I have put the basic information about my project on the blog and I am now trying to customize my blog site.