Richard – The Scoop on Poop!
Though many people think that carbon dioxide is the biggest contributor to the greenhouse effect (trapping heat in the atmosphere), methane is even stronger than carbon dioxide. One way methane is produced is by the decomposition of poop.

That’s right. Poop.

All animals poop, and cows do it a lot. That’s why many dairy farmers are starting to find ways to block the gas from being trapped in the atmosphere. When methane is burned as a fuel, it is not as harmful, so farmers have found away to use the gas as a source of electricity. They’re using a tool called an Anaerobic Digester (AD) to break down manure into the biogases like methane. “How does an AD work?” you might ask.
Well, we’re here to tell you.

• Manure is flushed by water into a separator where liquids and solids are separated. On a typical farm, the solids would sit in a lagoon, decompose naturally, and let methane into the air, but not in an AD.

• There are three kinds of digesters:
1) The first is called a Covered Anaerobic Lagoon and on it is a plastic cover. This helps keep the oxygen down, lets the bacteria break down the manure into biogases, and has a system to collect the gas. These can only really be used in hot climates because the bacteria need to be kept very warm.

2) The second kind of AD is called a Complete Mix digester. Instead of a lagoon, the manure is held in a large steel or concrete tank that is heated.

3) The third kind is called a Plug Flow digester. The manure is slowly pushed down the length of a rectangular tank that has heated pipes in it. The manure slowly decomposes and at the end is flushed into another lagoon.

• An important part of the process is that it is anaerobic. This means there is very little oxygen. The lagoons or tanks are always very tightly covered. This allows only the kinds of bacteria that produce methane to work and cuts down on smell and harmful bacteria that might pollute groundwater. Also, the solids left over from the process are full of nutrients and can be used later as fertilizer.

• The gas that is captured from each of these AD’s can either be used to run the generator for the heating elements, burned as fuel in a biogas generator, or be stored to be used as a source of electricity at other sites. The Smits family that Richard visited provides 86 homes in their area with methane-generated electricity. Generating their own electricity and selling it to others really helps farmers save money.

• A single digester on an average dairy farm will save about 500 coal cars a year at a power plant that is producing electricity.

Poop’s a pretty powerful thing, isn’t it?