What is Renewable Natural Gas (or RNG)?
Renewable Natural Gas (RNG), also known as Sustainable Natural Gas or biomethane, is a biogas which has been upgraded to a quality similar to fossil natural gas and having a methane concentration of 90% or greater.
A biogas is a gaseous form of methane obtained from biomass.
Traditionally, pipeline natural gas comes from deep underground wells and is often associated with petroleum production.
RNG, on the other hand, is natural gas derived from organic waste material found in daily life such as food waste, garden and lawn clippings, and animal and plant-based material. It can also be derived from degradable carbon sources like paper, cardboard and wood. The abundance of these materials allows for production of substantial quantities of biogas. A study conducted by UC Davis estimates that more than 20% of California’s current residential natural gas use can be provided by RNG derived from California's existing organic waste alone.
In the transportation sector, that’s enough to replace around 20% of the fuel used by heavy-duty trucks in the state. This can help reduce the need for other fossil-based fuels while boosting our supplies with a locally sourced renewable fuel. Looking outside California, the opportunity to produce RNG is vast. According to estimates, the United States could produce up to 10 trillion cubic feet of RNG annually by 2030 — that’s more than five times California’s projected natural gas consumption.
Green Energy Around-the-Clock
RNG can be an important renewable energy tool because it is available when consumers need it. Wind and solar are intermittent energy sources – meaning the energy isn’t available when the sun isn’t shining and the wind isn’t blowing. RNG is available 24 hours per day, seven days a week and can be deployed when and where it is needed through the pipeline network.
Where Does Renewable Natural Gas Come From?
Natural gas consists largely of methane. Since methane comes from the decomposition of organic matter, there are ways to generate natural gas other than extracting it from the ground. Biogas is produced from existing waste streams and a variety of renewable and sustainable biomass sources, including animal waste, crop residuals and food waste. Organic waste from dairies and farms can be repurposed into biogas. The most common source of biogas is the naturally-occurring biological breakdown of organic waste at facilities such as wastewater treatment plants and landfills.
How is Renewable Natural Gas Produced?
Biogas typically consists of methane and carbon dioxide, with traces of other elements. Biogas is cleaned and conditioned to remove or reduce non-methane elements in order to produce RNG. The RNG is processed so it’s interchangeable with traditional pipeline-quality natural gas to ensure the safe and reliable operation of the pipeline network and customer equipment. This RNG is extremely versatile, and can be delivered by the nation’s extensive pipeline infrastructure.
Negative Carbon Impact for Greenhouse Gas Reductions
Reducing carbon dioxide and other greenhouse gas levels is important to help reduce global warming. RNG is considered a carbon-neutral fuel because it comes from organic sources that once absorbed carbon dioxide from the atmosphere during photosynthesis. RNG has even greater benefits when it’s produced from organic waste that would otherwise decay and create methane emissions. By capturing more greenhouses gases than it emits, this RNG is actually considered carbon-negative!
Up to 400% Reduction in Greenhouse Gas Emissions
When RNG is used to fuel vehicles, it can provide major reductions in greenhouse gas emissions – in addition to clean air benefits. According to the California Air Resources Board, RNG sourced from landfill-diverted food and green waste can provide a 125% reduction in greenhouse gas emissions, and RNG from dairy manure can result in a 400% reduction in greenhouse gas emissions when replacing traditional vehicle fuels.
More than half of all natural gas dispensed in California for transportation utilize RNG, powering buses, refuse trucks and heavy-duty trucks.
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