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Renewable natural gas (RNG) provides a clean, easily controlled source of renewable energy from organic waste materials, replacing fossil natural gas with a sustainable carbon neutral fuel option.
Biogas is generated when bacteria degrade biological material in the absence of oxygen, in a process known as anaerobic digestion. Biogas is a renewable fuel, primarily a mixture of methane and carbon dioxide (CO2).
Landfill gas is biogas produced by organic waste decomposing under anaerobic conditions. The waste is covered and compressed mechanically by the weight of the material that is deposited from above. This material prevents oxygen from accessing the waste and anaerobic microbes thrive. This gas builds up and is slowly released into the atmosphere if the landfill site has not been engineered to capture the gas.
Biogas is normally rich in methane (about 65%) and impurities of hydrogen sulfide (H2S), CO2 and water. Technology is commercially available to remove H2S, CO2 and water contaminants present in the biogas and landfill gas through processing to produce high-purity natural gas (RNG or biomethane) suitable for vehicles
Renewable natural gas (RNG) is pipeline quality gas that is interchangeable with fossil natural gas but is produced from biogas and biomass feedstock sources. It can be used as a 100% substitute for, or blended with conventional gas streams for use in vehicle engines.
With an estimated resource potential of 4.8 trillion cubic feet in the United States alone, or 20% of total US natural gas consumption, RNG is a valuable complement to the diversity and security of the natural gas fuel supply.
RNG can be produced from a variety of sources, including:
There are two technological pathways for the production of RNG:
Transportation faces impediments to incorporating renewable and lower carbon energy into the fuel mix. Recent progress in generating lower-carbon sources of electricity have not been matched in the transportation sector.
RNG technology offers a pathway to diversity and decarbonize the transport sector:
One of the largest RNG for transportation projects to date is the Altamont Landfill operated by Waste Management in Livermore, California.
Using the waste that comes into their landfill, Altamont is able to produce 13,000 gallons of liquefied natural gas each day. That’s enough to fuel 400 of their refuse hauler trucks, powered by Cummins Westport ISL G engines, and eliminate 30 000 tons of CO2 emissions annually.
In Europe, there is a greater availability of pure RNG and RNG/CNG blends. The Volvo bi-fuel V70 with “bio-CNG” is a choice available today to a growing number of drivers in Germany, Sweden, and the Netherlands. Germany has 900 natural gas filling stations, of which 100 have been converted to 100% biomethane.
Renewable natural gas can go by a variety of names. Typically, the raw product is called "Biogas", and the upgraded product is referred to as RNG or Biomethane. Occasionally it is called bio-CNG or bio-LNG depending on what form it is stored as.