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Renewable Natural Gas 101

Renewable Natural Gas (RNG) is an innovative, carbon negative energy source that’s changing the way we create energy. Plus, it works the same way as conventional natural gas in homes and businesses. 

RNG is added into existing gas distribution systems and provided to customers, being used in everyday appliances while reducing the amount of conventional natural gas used. 

How RNG is Made

RNG is made using organic waste like compost or cow manure. When this waste decomposes, it releases biogas into the atmosphere, which can then be captured and purified to create RNG. 

We are open to exploring all biogas sources, but biogas is most often captured from wastewater treatment plants, agricultural waste, landfill waste, wood waste, and residential or commercial organic waste (e.g. from municipal curbside pickup).

How Biogas is Produced From Livestock Operations

Livestock operations can use recovery systems to produce RNG. First, the animal manure is collected and sent to an anaerobic digester, which stabilizes and optimizes methane production. Then, the biogas that is created is processed into RNG, which can be used to generate electricity or fuel natural gas homes or vehicles.

Either way, the basic process for creating biogas is the same:

  1. Anaerobic digestion
  • Organic waste is delivered to an oxygen-free, temperature-controlled environment. (e.g. a digester tank)
  • Naturally occurring bacteria break down the organic waste, creating raw biogas as a byproduct

Did you know? Biogas is primarily composed of methane, but it also contains 25-50% carbon dioxide and small quantities of other gases.

2. Purification

  • First, contaminant gases are removed through a careful gas cleaning process that leaves only methane and carbon dioxide.
  • Next, the carbon dioxide, which lowers the heating value of the gas, can be removed. 
  • Last, after the gas is cleaned, it only contains methane and a small amount of nitrogen. This means it is nearly impossible to tell the difference between it and conventional natural gas. This purified biogas is called biomethane, or renewable natural gas.

What are the benefits of RNG?

  • RNG is a carbon negative energy source that essentially recycles carbon that is already circulating in the environment. Unlike the burning of fossil fuels, which is the release of new carbon emissions that were previously sequestered in the earth, RNG is derived from captured methane that otherwise would be released into the atmosphere.
  • RNG is distributed through the existing infrastructure.
  • RNG production at dairy farms creates useful, environmentally-friendly byproducts.
  • RNG, when used in the transportation sector, yields up to an 85% reduction in lifecycle GHG emissions in comparison to conventional diesel.