Renewable natural gas use across multiple sectors could play a material role in curbing greenhouse gas emissions, according to a recent study the American Gas Foundation released.
Broader use of renewable natural gas, or RNG, could reduce greenhouse gas emissions by between 101 million and 235 million tonnes by 2040, according to ICF International, which conducted the study on behalf of the American Gas Foundation. RNG is pipeline-quality gas that has not been extracted as a fossil fuel and can include methane that has been processed from organic materials such as food, agriculture and waste.
The consulting firm estimated that in a so-called high resource potential scenario, about 3,780 trillion Btu of RNG could be produced yearly for pipeline injection by 2040 at a price of between $7/MMBtu and $20/MMBtu and representing a cost of $55/ton to $300/ton of greenhouse emissions reduced. The estimated costs were based on several factors, including feedstock costs and expected revenue from byproducts, among things, and ICF noted that the costs could go down over time with economies of scale.
ICF also said the estimated RNG production in the high-resource case could even be greater than projected since the researchers looked only at more traditional feedstock uses for the gas.
The firm considered a "low resource potential" case as well, in which about 1,660 trillion Btu of RNG could be produced, although ICF said that another 1,910 trillion Btu per year could be added to that scenario if a certain component of municipal solid waste is included in the calculation.
The reported RNG resource potential estimates that ICF reported are 90% and 180% above comparable resource potential scenarios from a 2011 American Gas Foundation study, the Dec. 18 report said.
ICF also explored the power-to-gas system, in which electricity is used to split water into hydrogen and oxygen, noting that this method could contribute to RNG production. Specifically, the firm said power-to-gas systems could run on curtailed electricity from renewable sources and could play "an important transitional role in helping to deploy the technology and achieve the long-term price reductions" that could make this method a sustainable part of RNG production. However, the firm cautioned that the exact role power-to-gas might play in the energy sector merits further study.
Utility company National Grid USA welcomed the study in a Dec. 19 news release, noting that its gas utility in New York is partnering with New York City to develop a project to convert a wastewater treatment plant into a possible energy source that can produce RNG.
"As we work to hit economy-wide emissions reduction targets, we can't afford to leave any solution off the table, and this study further evidences that the gas network can play an integral role in delivering a low carbon future, alongside the electric network," COO Cordi O'Hara said in the release.