Often, farm owners get confused over whether biogas produced at farms should be considered a renewable or a non-renewable source of energy.
So, for them, and everyone at the back:
Biogas produced at farms through anaerobic digestion is considered to be a renewable source of energy because it’s production and use-cycle is continuous, and it generates no-net carbon dioxide.
This biogas roughly contains 60% methane and 29% carbon dioxide. The rest of it is made of trace elements of hydrogen sulphide and other gases.
The presence of hydrogen sulphide in biogas makes it largely unsuitable for use as a fuel gas other than for burning gas stoves.
This is because hydrogen sulphide is corrosive in nature and can damage the internals of engines, machinery and other equipment.
To overcome this problem, biogas is purified or “upgraded”.
Traditionally, anaerobic digestion plants used pressure swing adsorption, water washing, amine gas treating or adsorption to upgrade impure biogas. Nowadays, they use membrane separation technology to perform this function to achieve the goals of producing methane quality. Similar to natural gas and meet Utility standards for gas fed to the pipeline as RNG.
The membrane separation purification technology is based on the principle that gases diffuse through membranes at different speeds. The aim is to achieve the highest possible permeability with high selectivity to purify a given mixture of gases (in this case biogas).
Biogas and Solid Waste Management
After biogas has been purified, it is then be used by farms as transport or energy fuel. Some of the purified biogas is also injected into national natural gas grids, allowing farm owners to generate additional income.
This purified or upgraded biogas is called biomethane or renewable natural gas (RNG).
RNG when used as truck fuel carry tax benefits, especially here in the U.S. It serves as an additional incentive for farm owners to install anaerobic digesters at their farms. And use anaerobic digestion to produce biogas and biomethane.
Do you own a diary farm in New York State? Would you like your NY dairy farm to benefit from anaerobic digestion and digesters?