Landfill Gas as a Source for Renewable Natural Gas

What’s the issue?

According to the EPA, municipal solid waste landfills are the third-largest human-caused source of methane emissions in the United States.

Why does it matter?

As the U.S. seeks to reduce its greenhouse gas emissions, gaining control of these emissions and putting them to productive use will be a critical component of net-zero ghg goals.

What’s our view?

We believe that as pipelines adopt their own net-zero goals, they will begin to not only accept landfill gas but actually seek out projects that have the greatest potential for converting their landfill gas into renewable natural gas (RNG). Landfills with certain characteristics, including being located near the interstate gas system, are the ones that can most economically support projects that capture and use the methane that would otherwise simply be vented or flared. By using available data, pipelines can begin now to locate the landfills that offer the greatest likelihood of a successful RNG project.

 


 

According to the EPA, municipal solid waste landfills are the third-largest human-caused source of methane emissions in the United States. As the U.S. seeks to reduce its greenhouse gas emissions, gaining control of these emissions and putting them to productive use will be a critical component of net-zero ghg goals.

We believe that as pipelines adopt their own net-zero goals, they will begin to not only accept renewable natural gas (RNG) as we discussed last week in New Flavors of Natural Gas (Certified and Renewable) are Showing up in Pipeline Tariffs, but will actually seek out projects that have the greatest potential for converting their landfill gas into RNG. Landfills with certain characteristics, including being located near the interstate gas system, are the ones that can most economically support projects that capture and use the methane that would otherwise simply be vented or flared. By using available data, pipelines can begin now to locate the landfills that offer the greatest likelihood of a successful RNG project.

 

Landfill Gas

The U.S. Environmental Protection Agency (EPA) has an entire program devoted to municipal solid waste (MSW) landfills. The program is voluntary. Through it, the EPA works cooperatively with industry stakeholders and waste officials to reduce or avoid methane emissions from landfills by encouraging the recovery and beneficial use of biogas generated from organic MSW. The EPA notes that the U.S. generated approximately 292 million tons of MSW in 2018. About 50 percent of that was deposited in landfills. One million tons of MSW produces roughly 300 cubic feet per minute of landfill gas (LFG). This LFG will continue to be produced for as many as 20 to 30 years after the MSW has been landfilled. Each standard cubic foot of LFG has a heating value of about 500 British thermal units, which is about half that of geologic natural gas.

 

Landfills

These MSW landfills are located in all fifty states. The amount of LFG that is produced, however, is dependent upon the conditions of the landfill itself and, in particular, the presence of moisture. Some landfills intentionally introduce moisture into the landfill material to speed up the production of LFG, but most just rely on the natural moisture. Thus, the EPA considers a number of factors in determining whether a particular landfill is a good candidate for producing enough methane to support an energy recovery project. These screening criteria include:

Does the landfill contain at least one million tons of MSW?

Does the landfill have a depth of 50 feet or more?

Is the landfill open or recently closed?

Does the site receive at least 25 inches of precipitation annually?

Does the landfill contain enough organic content to generate sufficient LFG?

Does the landfill already have a gas collection system in place?

 

Energy Recovery Projects at Landfills

Currently in the U.S. there are over 700 projects that recover LFG and use it for another purpose. There are currently three main uses of the LFG: direct use to create heat, use of the LFG to create electricity, or sufficiently purifying the LFG to make it into RNG.

 

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As seen above, a project that uses LFG to generate electricity is by far the most common type of project, but with far fewer total projects, the RNG projects are still producing over 80 Bcf of LFG on an annual basis.

 

Environmental Benefits

For each of these projects, the EPA calculates two types of environmental benefits, the direct benefits, which arise from the destruction of methane, and indirect benefits, which is the displacement of fossil fuel use by LFG, which is generally considered to be a renewable energy resource. Looking just at the RNG projects, the EPA estimates that those projects generate over 260 million metric tons of carbon dioxide equivalent benefits. This combination of environmental benefits and the creation of a gas that can be blended into the existing interstate gas system is what we think will make these landfill-based RNG projects attractive to pipeline companies as part of their own net-zero ghg programs.

 

Candidates for RNG Projects

Based on the screening criteria described above, the EPA looks at all landfills across the country and categorizes them as either current candidates for some type of gas recovery program or as landfills that have a future potential for such projects. However, the EPA does note that proximity to an existing gas pipeline is an additional critical element for a project that hopes to generate RNG. By reviewing the list of the landfills that the EPA has identified as likely candidates for future development, we can see which ones are within one mile of an existing interstate natural gas pipeline.

 

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As seen above, we have identified 74 landfills that are located within one mile of an interstate pipeline. All of these landfills are viewed by the EPA as current or future candidates for a viable gas recovery system. The proximity to a pipeline may mean these landfills are also viable candidates for an RNG system. Twenty-eight of these landfills already have an operating gas recovery system, but are typically just flaring all of that gas. The total waste in place in these landfills is over 300 million tons, which, based on the EPA’s estimate that one million tons of MSW can produce about 300 cubic feet per minute of LFG, means that these seventy-two facilities could produce 47 Bcf of LFG annually.

 

If you would like information on the landfills we have identified on the map, please contact us.

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