There seems to be more mention of Renewable Natural Gas (“RNG”) lately; from the PA PUC recently approving a pilot program to allow UGI Utilities to purchase it to flow it though its system, 1 to discussions on how the current price could make it untenable as a natural gas substitute, except for ESG purposes. 2 The purpose here is to explain what RNG is and is not, and how it may become part of a renewables driven future.
RNG is gas produced from anerobic decay of organic matter or biomass, the primary sources of this gas are landfills and/or animal waste. RNG is often referred-to as carbon neutral because it eliminates methane that otherwise would have become a powerful greenhouse gas if allowed to enter the atmosphere. The gas produced by landfills or waste digesters contains only 40-60% methane, while pipeline quality natural gas is 95% methane, or more. To turn landfill gas into pipeline quality gas requires processing to remove water, CO 2 , nitrogen, oxygen and other contaminants, making RNG as much as five to ten times more expensive than pipeline gas. There are quite a few landfills that are sequestering the methane produced by the decomposition of the millions of tons of trash produced in the US each day, and keeping that methane out of the atmosphere is an important factor in goals for greenhouse gas emission reduction. Likewise, the methane that is trapped and stored in animal waste digesters pursues the same greenhouse gas reduction result. Additionally, other sources of landfill gas, including wastewater treatment plant facilities, produce similar levels of available landfill gas, but at a smaller and more localized scale than large landfills or agricultural operations, which could lead to innovative and localized options for future, small scale generation.
Today, much of this gas is used “as-is” and is burned at or near the production site to generate electricity and/or heat. This gas can also be compressed and used as vehicle fuel. Both landfill gas and RNG have environmental attributes associated with the generation of electricity. Until recently, the need to transport landfill gas offsite to fuel electricity generation has been a primary driver of the investment to process it into RNG, so it can travel through interstate and local distribution pipelines. There are encouraging signs however, that RNG may become a new means for socially conscious businesses to achieve climate change-oriented goals, and perhaps for ordinary consumers to do the same. At least one natural gas supplier in Pennsylvania, Verde Energy, is advertising 100% renewable gas for sale to retail customers, and several mid-stream pipeline operators have recently cited to RNG as a significant component of their Environmental Social and Governance (“ESG”) efforts. These include Williams and Kinder Morgan. Coupled with natural gas distribution companies, like UGI, including some portion of RNG into their supply portfolios for default service customers, it appears that the natural gas industry is beginning to look ahead to a net zero world.
RNG as an alternative to allowing biologically produced methane to escape into the atmosphere is a positive in terms of climate change, because methane is a particularly potent greenhouse gas. However, it does not erase the fact that the combustion of methane produces greenhouse gases, albeit less potent ones. It is clear that the current administration is promoting a long-term approach to climate change, the end-state of which does not include burning any fossil fuels. Until we get there however, there appears to be room for RNG in the resource mix. There is substantial infrastructure in place that can safely transport it, and there is the potential that as an interim step, customers may desire to use it rather than ordinary methane. As RNG becomes more popular as an alternative, demand should rise, and production costs should decrease. It will take more public awareness – led by environmentally conscious organizations willing to pay more for sustainability, utilities willing to encourage production by adding RNG to their mix of supplies, and ordinary customers willing to insist, through the power of their purchases, that clean energy alternatives be made available.