Waste Management (WM) is no stranger to landfill gas capture. The Houston-based company was one of the first waste services companies to experiment with converting renewable landfill gas to electricity when it built its processing plant at its Altamont Landfill in Livermore, California, in 1987. In 2008, the company partnered with Bridgewater, New Jersey-based Linde North America to build a facility at the Altamont Landfill that is the largest landfill gas-to-liquefied natural gas (LNG) plant in the world. This facility produced 6,300 gallons per day of LNG (about 3,750 diesel gallon equivalents per day) last year, enough to fuel about 170 of the company’s natural gas collection trucks.

In 2014, the company commissioned its first “pipeline-quality” renewable natural gas (RNG) facility at its Milam Landfill in East St. Louis, Illinois. Then, in June, the company made news with the opening of its $30 million Outer Loop Recycling and Disposal Facility in Louisville, Kentucky, where methane produced by its Outer Loop Landfill is converted into pipeline-quality RNG.

RNG, or biomethane, is interchangeable with conventional natural gas. This means RNG can be used as a replacement fuel in natural gas vehicles. RNG is the byproduct of decomposing organic matter captured from landfill. Once captured, the gas is processed to meet purity standards. Like compressed natural gas (CNG), RNG can be used as a transportation fuel in the form of CNG or LNG.

The new facility is able to process up to 5,000 standard cubic feet per minute (SCFM) of incoming landfill gas, which equates to approximately 18,000 diesel gallon equivalents per day of fuel. The facility’s daily output is enough to fuel about 800 of the company’s CNG collection trucks.

Although WM already operates RNG facilities at its Milam Landfill and American Landfill in Waynesburg, Ohio, the Outer Loop Recycling and Disposal Facility was designed to improve upon the operations of its predecessors.

“Louisville employs the latest technologies as well as the lessons learned and best practices from our East St. Louis facility. East St. Louis was our first pipeline-quality facility. The Waynesburg, Ohio, facility produces a high Btu (British thermal unit) product, but requires blending assistance from the local gas utility, Dominion, to meet pipeline specifications,” Randy Beck, senior director of renewable energy at WM, says. “We typically produce about 850 Btu, where the pipeline typically requires 970 (or higher depending on the utility) to enter the transmission line, so we send our gas to a Dominion blending plant, where they blend out any remaining nitrogen, oxygen and CO2 (carbon dioxide) and convert the gas to the higher Btu for the pipeline.”

The Outer Loop facility doesn’t need blending assistance from outside utilities, which cuts out a step in the conversion process for WM.

The gas operations team works to capture the gas using a series of wells and pipes connected to a vacuum source that pulls the gas into the facility. WM has three full-time employees at its new RNG facility, and five additional team members work remotely to provide support.

While the process is a familiar one, the Outer Loop Landfill needed to be initially vetted to determine its ability to produce ample gas for RNG conversion. According to Beck, a number of front-end considerations need to be taken into account when deciding on a suitable landfill candidate worthy of capture.

“As every landfill is different based on the waste composition, the major challenge and consideration is making sure that any candidate landfill is producing gas flow and quality that can sustain a long-term capital investment,” Beck says. “The second major consideration is whether we can get to a pipeline in a cost-effective manner. A final consideration is whether local permitting challenges exist that would preclude us from building a facility.”

Beck says the Outer Loop facility checked all the boxes in what the company was looking for from its latest RNG plant. This new facility will be instrumental for the company as it continues to push its operations to be more sustainable.

“It is an excellent beneficial use project as it has very little air emissions yet has the ability to process more gas than most of our power plants,” Beck says. “These projects continue to assist us in developing more efficient technologies, and ultimately, lowering our carbon footprint.”

According to Marty Tufte, corporate fleet director at WM, converting the company’s fleet from diesel to CNG will also allow WM to reduce its truck emissions and better meet its sustainability initiatives.

“In 2007, as part of our corporate sustainability goals, we committed to reduce our total carbon dioxide fleet emissions by 15 percent below 2007 levels by 2020. We achieved this carbon dioxide fleet emissions goal several years ahead of schedule, reducing fleet carbon dioxide emissions by 20 percent below 2007 levels in 2011,” Tufte says. “Achieving this goal yielded significant benefits in 2011, including eliminating nearly 20 million gallons of diesel fuel consumption and reducing carbon dioxide emissions by 350,000 metric tons that year. As we increase the number of natural gas trucks in our fleet each year, the benefits continue to grow.”

Building up infrastructure

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To meet the fueling needs of its new trucks, the company has invested in infrastructure to support the push for RNG-enabled fleets.

“Waste Management has the largest fleet of natural gas vehicles in our industry,” Tufte says. “We support this fleet with fueling capabilities at 112 of our sites, as well as 25 public fueling stations. Our long-term and ongoing investments in our natural gas fleet support our efforts to create a near-zero emissions collection fleet. At the end of Q2 2018, Waste Management’s fleet included 6,895 natural gas trucks, the largest heavy-duty natural gas truck fleet of its kind in North America.”

The company says that it is seeing a measurable impact from every diesel truck it takes off the road.

“For every diesel truck we replace with natural gas, we reduce our use of diesel fuel by an average of 8,000 gallons per year along with a reduction of 14 metric tons of greenhouse gas emissions per year (the equivalent of a 15 percent emissions reduction per truck),” Tufte says. “Our vehicles powered by CNG emit nearly zero particulate emissions, cut greenhouse gas emissions by 15 percent and are quieter than diesel trucks.”

In total, 16 million diesel equivalent gallons of renewable natural gas are produced by harnessing the methane at the company’s landfills through its RNG facilities. The access to this gas helps lower fuel costs and reduce greenhouse gas emissions more than 80 percent compared to those powered by diesel.

Currently, WM’s fleet of 6,895 natural gas trucks represents 30 percent of the company’s overall fleet. By year’s end, Tufte says that 50 percent of the company’s routed trucks will be fueled by CNG. Moving forward, roughly 80 percent of the company’s fleet purchases will be of the CNG variety. To meet its needs, the company uses trucks manufactured by multiple original equipment manufacturers (OEMs) that feature the Columbus, Indiana-based Cummins natural gas engine lineup.

While the conversion to CNG fleets is capital intensive and requires a learning curve for employees, WM has training programs in place for operators and maintenance technicians to get them up to speed on the new technologies.

According to the company, the Outer Loop facility is just the tip of the iceberg, as it will serve as a model for the planned rollout of additional CNG facilities in the coming years as Waste Management continues to phase out its diesel trucks.

The author is the editor for Waste Today and can be contacted at aredling@gie.net.