Biogas is a type of gas that is produced when waste materials such as manure, plant material or sewage are allowed to decompose in an anaerobic environment. Biogas plants collect this natural gas and use it as a source of fuel. Biogas is a sustainable and "green" fuel that can be used to heat homes, power engines, generate electricity and for any other purpose for which more conventional, combustible fuels can be used. Does this Spark an idea?
Floating-Dome and Fixed-Dome Plants
In a floating-dome plant, a mixture of organic waste and water called a slurry is pumped into an underground well with a steel cap on top of it. The material decomposes in the well, generating gas which accumulates in the steel cap, which floats on top of the slurry. The steel dome has an outlet valve through which the pressurized gas can be released. The slurry is pumped from a primary chamber to a secondary chamber inside the well and then, to an overflow tank after it has been allowed to decompose sufficiently. The overflow material can then be used for fertilizer, treated at a sewage-processing plant or disposed of in a landfill. A fixed-dome plant works just like a floating-dome plant except the dome that collects the gas is fixed in place and is not free-floating.
Water Jacket Plant
A water jacket plant is a special type of floating-dome plant. Rather than sitting directly on top of the slurry, the dome floats on a track filled with water. It can still move up and down in response to pressure, but is more sanitary and easier to maintain. Water jacket plants are also less prone to corrosion than standard floating-dome plants.
Balloon Plants
Balloon plants are an alternative to floating- and fixed-dome plants. Rather than being stored inside of a solid dome that must be maintained, the gas is stored in a flexible PVC balloon. The balloon expands as gas accumulates. The pressurized gas can then be pumped out of the balloon through a release nozzle. Balloon plants are cheap and easy to build, but have shorter life expectancies than other types of plants, since the balloon can wear out or be accidentally damaged.
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