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Improved life cycle assessments of natural gas systems can help in the short-term energy transition | News

The new open-source SLiNG-GHG model provides a better understanding of the natural gas supply chain


Photo of two liquefied natural gas storage tanks.
There are two liquefied natural gas storage tanks on the premises. Photo from Getty Images

The natural gas industry is one of the largest emitters of greenhouse gases (GHG) in the United States, and significant amounts of natural gas are used for electricity generation, heating, and industrial and chemical processes. Strategies such as electrification of process equipment can reduce greenhouse gas emissions in natural gas systems and accelerate the transition of today’s energy system to 100% clean electricity by 2035.

“When talking about the energy transition, it is important to understand the existing energy system, especially in terms of its greenhouse gas benefits,” said Garvin Heath, an analyst at the National Renewable Energy Laboratory (NREL). “To evolve, you have to understand the current system you’re leaving.”

Heath is one of the authors of the new report, Charting the Course: Reducing Greenhouse Gas Emissions from the U.S. Natural Gas Supply Chainconducted by the National Petroleum Council in response to a request from the Secretary of the U.S. Department of Energy (DOE).

The report presents recommendations on how to reduce methane emissions based on a new, open life cycle assessment model that examines natural gas and liquefied natural gas: Streamlined Life Cycle Assessment of Natural Gas – Greenhouse Gases (SLiNG-GHG).

Improved data for natural gas life cycle assessment

To get a full picture of the potential environmental impact of a technology or service at every stage of its life, researchers use what is known as life cycle assessment (LCA).

“One of the things that life cycle assessments do really well is gathering knowledge about each individual step in the process and calculating the environmental costs each step may incur versus the benefits it may provide,” Heath said.

Natural gas supply chain LCAs examine the carbon footprint associated with raw material sourcing, production, product use, and disposal. This analysis requires enormous amounts of information from hundreds of inputs.

The SLiNG-GHG model breaks this information down into just a few dozen parameters, giving users the ability to generate their own initial estimates of greenhouse gas emissions from the life cycles of natural gas and liquefied natural gas. Heath and researchers from McGill University (Montreal, Canada) co-led a small team of LCA experts from the National Petroleum Council study to develop a streamlined model by meta-analysis, or harmonizing, LCA studies from the past decade, making it customizable so anyone can use it.

NREL researcher Garvin Heath standing in front of a screen showing life cycle assessment data.
Garvin Heath works on life cycle assessment data for a greenhouse gas emissions study at NREL’s Center for Strategic Energy Analysis. Photo: Dennis Schroeder, NREL

“The idea is that the model can make tailored estimates for a specific supply chain, a specific company or a specific region because they vary significantly,” Heath said.

As an open-source model, SLiNG-GHG is available to anyone and can help stakeholders at all stages of the natural gas supply chain understand their greenhouse gas emissions. SLiNG-GHG can be valuable to government officials, investors, natural gas and liquefied gas producers and purchasers, and regulators outside the federal government, to name a few.

Because streamlined LCA data is available for every step of the natural gas supply chain, stakeholders can more easily prioritize where they would like to focus decarbonization efforts.

“When you look at the entire system in detail, you can understand where you need to focus,” Heath said. “You can look at all of them and say, ‘This is the biggest one that we want to target with our decarbonization efforts,’ or, ‘We have great technology to decarbonize this section.’”

Informed decision making: next steps

Ultimately, the goal of the SLiNG-GHG model is to encourage stakeholders at all levels of the supply chain to increase the integration of natural gas LCA data into planning and policy.

To this end, the National Petroleum Council study made several planning and policy recommendations based on its findings, many of which are directly related to the team’s work and the chapter in which Heath was involved.

“Several recommendations address the potential future and expanded applications of the SLiNG-GHG model, which could be of great benefit not only to policymakers and the Department of Energy, but also to every user in the natural gas supply chain when it comes to determining the potential impacts of greenhouse gases in the future.” Heath said.

Recommendations include:

  1. Stakeholders should use LCA models such as SLiNG-GHG to determine the impact and potential reductions in greenhouse gas emissions at all points in the supply chain.
  2. Stakeholders should expand the use of the SLiNG-GHG model for initial screening tests to estimate the carbon footprint of natural gas.
  3. DOE should support models like SLiNG-GHG in its measurement, monitoring, reporting, and verification efforts.
  4. Users should review the harmonization process when evaluating LCA data from other studies, and DOE should create best practice guidelines for natural gas LCA.
  5. DOE should sponsor research and development of LCA tools designed to test the greenhouse gas intensity of various supply chains and pathways.
  6. DOE should sponsor the establishment of an expert stakeholder advisory group to develop further recommendations for the integration of greenhouse gas measurement data.
  7. DOE should sponsor the development of LCA models consistent with existing frameworks supporting the analysis of greenhouse gas impacts on the future use of natural gas compared to other energy sources.

Read more about natural gas life cycle assessment, and learn more about NREL energy analysis research.