Name: Kevin Lane
Essay Theme: Alternative Fuel Research
State: New Mexico
School: G.V. Koogler Middle School
Manure for a Renewable Future
The U.S. Environmental Protection Agency and farmers have been looking at ways to use biogases (mainly methane) from cow manure to create electricity. In order to make electricity using manure, I need to find out several things: how much methane can be made from a given amount of manure, what helps create the most methane, and what is the most efficient way to convert methane into electricity. I am conducting science fair experiments that help to answer these questions. Last year I completed an experiment to determine if there is an optimum moisture content that creates the most gas from cow manure. I discovered I needed better test equipment, and my assumptions about the bacteria were incorrect.
At the beginning of my research last year, I thought gas was created from aerobic (uses oxygen) bacteria that live in the manure. In addition to oxygen, a bacterium would need water and enough organic matter to make cells, grow, and reproduce. The gas is the waste made by the bacteria.
I thought that different amounts of water would affect the amount of gas created. Not enough water would limit the amount of bacteria that could grow and in turn make gas. Too much water would drown the bacteria and no air would be available for the bacteria to breathe.
I interviewed a man who operates a large ranch and is a local electrical engineer. He suggested using canning jars for test chambers and balloons to measure pressure. Using the same amount of dry manure, I added different amounts of water to the test chambers. During the first 10 days, the balloons on the jars with water inflated. I measured the circumferences of the balloons daily. After 12 days, the balloons started to deflate or stay the same.
I put the results into an Excel spreadsheet and plotted the balloon size for each jar by date measured. The balloons from the jars with moisture contents of 91 % to 203% grew the largest and seemed to stay filled the longest. But it appeared the balloons did not give me an accurate measurement of the gas pressures. I think the balloons leaked, because the molecules of methane may be smaller than the pores of the balloons.
From last year's experiment, I concluded that water is needed to create gas from manure, and dry manure will make little or no gas. An optimum moisture content >91 % weight is needed. Further research indicates that the bacteria are actually anaerobic (without oxygen) and the manure should be water saturated.
This year I am testing different animal manures including cow, sheep, chicken, and pig. I am using stainless steel pressure bombs with pressure gauges. So far, the chicken manure has created the most gas in the shortest period of time. Once everything stabilizes, I will analyze the gas in a lab to determine the amount of methane each sample produces.
I believe that by conducting these experiments, I will learn what it takes to create methane and make electricity from it using manure, which can be a renewable resource.
References:
Bolack, T. 2001. [Rancher, conservationist, and electrical engineer.] Personal communication.
Durban, R. L. 2002. [Laboratory director for Gas Analysis Services, Inc.] Personal communication.
Lane, G. S. 2002. [Researcher, chemical engineer with bp-Amoco.] Personal communication.
Lane, M. K. 2001, 2002. [Professional petroleum/environmental engineer with On Site Technologies and Williams Energy Services.] Personal communication.
"Senate energy tax plan has rewards for efficiency, fuel alternatives." Albuquerque Journal, 2002.
Turner, A. 2001. "Researchers find energy in trash, manure: Procedure produces usable methane gas." The Daily Times.
U.S. Environmental Protection Agency. 2001. AgStar Program. Homepage, 20 June, <http://www.epa.gov/agstar/>
This essay was part of a 2003 essay contest sponsored by Council for Agricultural Science & Technology. Click here to see how essays were selected.