Biogas

What Does Biogas Mean?

Biogas is a type of fuel derived from organic matter like food, plant, and animal waste. It is produced through anaerobic digestion, where microorganisms break down the organic matter in an environment that contains no oxygen.

Biogas is a renewable energy source, since it is derived from matter that grows or is produced cyclically. It can be used to generate electricity, heat homes, and fuel some types of vehicles.

Biogas is also commonly known as biomethane, though it has a number of other names, such as marsh gas, sewer gas, and compost gas.

Safeopedia Explains Biogas

The anaerobic digestion that produces biogas occurs naturally in places like landfills and livestock manure management systems. However, the process can be optimized and the resulting biogas captured by using an anaerobic digester, which are tanks that create an ideal oxygen-free environment. They can have vastly different designs and range from small containers to industrial digesters the size of buildings.

Source: Environmental and Energy Study Institute

Components of Biogas

The main constituents of biogas are carbon dioxide (CO₂) and methane (CH₄). It also contains small amounts of hydrogen sulfide (H₂S), siloxanes (Si-O-Si), and moisture. The exact composition depends on the type of feedstock and the production technology.

Biogas is mainly produced using three types of technology:

• Landfill gas recovery systems – The municipal solid waste piled into landfills creates an anaerobic environment where they will decompose. The resulting biogas can be trapped using pipes and extraction wells.
• Wastewater treatment plants – Sewage sludge produced at wastewater treatment plants consists of solids, organic matter, and nutrients like nitrogen and phosphorus. These materials can be recovered and further treated and in anaerobic digesters to produce biogas.
• Biodigesters – Airtight containers or tanks where organic matter is stored, diluted in water, and broken down by naturally occurring microorganisms.

Uses of Biogas

Agricultural operations can use the biogas produced by their organic waste to power their equipment and buildings, thereby decreasing their operational costs. Fair Oaks Dairy in Indiana, for instance, produces 1.2 million cubic feet of biogas per day using manure from about 9,000 dairy cows. Some of this biogas is upgraded to compressed natural gas (CNG) and used to power trailers that deliver milk to processing plants, reducing the use of diesel fuel by 1.5 million gallons per year.

Biogas can be used for various purposes, depending on the level of processing:

• Raw biogas – Unprocessed or minimally processed biogas can be burned on site to power boilers or heat buildings, or used for combined heat and power (CHP) operations.
• Renewable natural gas (RNG) – Also known as biomethane, this is refined biogas that has been cleaned of carbon dioxide, water vapor, and trace gasses to meet industry standards. It can be used interchangeably with natural gas.
• Compressed natural gas (CNG) and liquefied natural gas (LNG) – Renewable natural gas that has been converted into these forms can be used to power vehicles.