In a joint venture formed in December 2017, Novi, Michigan-based Aria Energy and London-based BP worked together to market and distribute low-carbon renewable fuel to US customers through the landfill gas (LFG) to renewable natural gas (RNG) development across the country.

Since the company’s inception, the energy partners have partnered with Republic Services, Phoenix, to develop four RNG projects at the company’s landfills in Canton, Michigan; Millington, TN; Memphis, TN; and Oklahoma City.

Aria, one of the largest LFG infrastructure developers in the county, is tasked with overseeing the projects and processing and purifying biogas from the landfill into RNG. BP then transports the RNG through the interstate gas pipeline system and markets it to renewable energy customers.

Most recently, the companies announced the start-up of a new LFG project at RNG at Republic’s South Shelby landfill in Memphis, Tennessee in August. The project, which supports Republic’s commitment to send 50% more landfill gas to beneficial reuse by 2030, can produce the equivalent of nearly 33,250 gallons of gasoline per day.

“Renewable energy is a key part of Republic Services’ long-term sustainability platform,” Pete Keller, Republic Services vice president of recycling and sustainability, said in a statement. “We are committed to sending 50% more biogas for beneficial reuse over the next 10 years, and projects like South Shelby Landfill will help us achieve this goal.

CONVERT WASTE

Keller says the South Shelby landfill was an ideal site for the RNG project due to its proximity to the pipeline and high gas production.

“From an infrastructure perspective, when you have a landfill that produces a lot of gas, [it has] there’s a lot of life left on the site… and you can integrate it with the existing distribution infrastructure. That’s what makes these projects feasible,” Keller told Waste Today.

“From an infrastructure perspective, when you have a landfill that produces a lot of gas, [it has] there’s a lot of life left on the site… and you can integrate it with the existing distribution infrastructure. That’s what makes these projects feasible,” – Pete Keller, Republic Services Vice President, Recycling and Sustainability

He adds: “We have [actually] had a landfill gas project in South Shelby for a number of years, but before that it was not about producing high Btu gas for the pipeline. We had an average Btu project there for, let’s call it, the last 20 years, and that fuel was used in a nearby industrial boiler as an alternate fuel for heat and power.

The South Shelby RNG project will instead turn landfill gas into low-carbon RNG, an enhanced methane-rich product that can be used to fuel natural gas vehicle fleets. Using this low-carbon fuel results in approximately a 50% reduction in greenhouse gas emissions compared to equivalent gasoline or diesel vehicles.

“Landfill gas is usually about 50% methane and 50% carbon dioxide (CO2), there is also a very small amount of oxygen, some nitrogen and other constituents in landfill gas,” says Keller. “The other projects we have carried out with BP and Aria are substantially identical. So, [we were] seeking to isolate this methane component from landfill gas, clean it up so that it is 99% methane, and inject it into existing gas pipelines.

According to Keller, LFG is collected by drilling vertical wells in the waste and connecting those wellheads to lateral piping, which carries the gas to a collection pipe using a vacuum induction system. Once all the gas is collected in a single pipe, Keller says it goes through a series of different equipment to remove excess moisture, particulates and other impurities.

At South Shelby, this is done through a technology called Pressure Swing Absorption (PSA) which is used to separate specific types of gases from a larger mixture of pressurized gases. The technology, also known as the molecular sieve process, typically uses compression, moisture removal, and hydrogen sulfide removal steps.

“[With PSA,] you would inject gas into a pressure chamber and pressurize that gas to room temperature, but inside that pressure chamber you have certain materials that would absorb CO2 and not [methane]. Then you can vent the methane from the chamber, take the chamber pressure, and then the CO2 is released in a later step,” says Keller.

Once the raw biogas is converted, the next RNG has a methane content of 90% or more. Typically, RNG injected into a pipeline has a methane content of between 96 and 98 percent, according to the US Environmental Protection Agency (EPA).

Photo credit: Courtesy of Aria Energy

A GROWING MARKET

With the role of transporting RNG fuel to renewable energy markets, BP says it is focused first on bringing the fuel to a market that would create both Renewable Identification Numbers (RINS) and Low Carbon Fuel Standards (LCFS) credits.

“We do this through our subsidiary, North American Gas and Power (NAGP), and they effectively act as the physical buyer of the RNG and reseller of the RNG, both for the product sold and then to get the product delivered. . at CNG stations in California or out of state,” said Sean Reavis, senior vice president of global environmental products for BP.

Reavis says BP will deliver most of the RNG produced to Clean Energy Fuels Corp., Newport Beach, Calif., through a margin-sharing agreement where the fuel will be distributed to the company’s network of 550 stations across the country.

“The other place where we take the gas is the voluntary market,” says Reavis. “It’s a market that is really growing for us. The voluntary market is generally [entities] like utilities and manufacturers who want to shift their purchasing practices away from the fuel they currently use. Many of them use natural gas and they want to integrate RNG into this portfolio. »

The EPA says that reducing methane emissions through RNG projects can help achieve short-term global climate change mitigation benefits. For facilities that are not already required to mitigate these emissions, consideration of RNG can help significantly reduce methane emissions.

Helping to reduce emissions was a major incentive for BP, as the company in February announced a new ambition to become net zero by 2050 or earlier. This includes the goal of installing methane measurement at all major BP oil and gas processing sites by 2023 and reducing the methane intensity of its operations by 50%.

“Part of the ambitions we set for ourselves at the start of the year was that we wanted to take others on board with us and show them how they can reduce their carbon footprint. … Starting with landfills is a good place because obviously that’s a place where the methane escapes and allows the [local municipalities] participate in the attempt to clean up the area there,” says Reavis.

Reavis adds: “We are seeing that whether you are a fleet owner or a manufacturer, people are recognizing the carbon reduction that comes from RNG compared to natural gas. So people, whether on a voluntary basis or fleet owners who just decide they’re going [to pursue] fuels other than diesel fuel, are [beginning to] replace their fuel with natural gas due to low carbon intensity. »

This article originally appeared in the November and December issue of Waste Today. The author is the associate editor of Waste Today and can be reached at [email protected]