What Is It Made Of?
Biogas is made from organic matter. It is produced by the natural fermentation process. Some of the materials that are used are farm waste (manure), plant matter, sewage, and biomass.
How Is It Made?
This gas is made in large containers called digesters. There are several types of digesters, but one thing they have in common is that they are anaerobic, or without oxygen. It is the action of anaerobic bacteria that produces the biogas. The three main types of digesters are:
* Fixed dome – These digesters begin underground. The organic matter (also called slurry) is displaced into a “compensation tank” as the gas forms. The gas is collected in a brick structure that sits above ground, right over the rotting matter.
* Floating drum – This type of digester also begins underground. A metal drum floats above the slurry, either in a water jacket or directly on the slurry. The drum floats higher and higher as it is filled with gas.
* Balloon – This kind of digester is basically a big bag. The bottom of the bag contains the material, and the top of the bag contains the gas. It expands as the gas is produced.
All digesters need a regular supply of water to function properly.
The technology itself is divided into two types:
# Batch digesters, which are used in large-scale production. They can accommodate a large amount of organic matter at one time.
# Continuous flow digesters are better for smaller-scale production, such as for individual households and small businesses. These digesters are designed to add and remove organic matter as often as every day.
How Is It Used?
This gas can be used to:
* Light homes and buildings
* Cook (as with propane)
* Run generators and make electricity
* Power combustion engines
Production of this gas is a very good use of waste matter, and can improve sanitation and make energy available in underdeveloped countries. Here in the United States, farmers are looking into biogas as a way to make use of the copious plant and animal waste that is generated on a farm. A farm in Vermont is run entirely on biogas generated by cow manure, and there is such a significant surplus that the farmers sell the extra electricity to their neighbors.