Fueling Our Fleet
Critical to our natural gas strategy is an infrastructure of Waste Management-owned and -operated fueling stations. As of the end of 2017, we operated 107 natural gas fueling stations across North America, with 9 of these also open to the public. Waste Management finances and constructs the stations, as well as purchasing the fuel.
Our landfill-gas-to-fuel plants convert landfill gas into renewable natural gas (RNG), a pipeline-quality gas that is fully interchangeable with conventional natural gas and thus can be used in our vehicles in the form of CNG or liquefied natural gas (LNG). This lowers fuel costs and reduces GHG emissions more than 80 percent compared to vehicles powered by diesel.
Offsetting Fossil Fuel With RNG
RNG is biogas, the gaseous product of the decomposition of organic matter, that has been processed to purity standards. Like conventional natural gas, RNG can be used as a transportation fuel in the form of CNG. Biogas is produced from various biomass sources through a biochemical process, such as anaerobic digestion. With minor cleanup, biogas can be used to generate electricity and heat. To fuel vehicles, biogas must be processed to a higher purity standard. This process is called conditioning or upgrading, and involves the removal of water, carbon dioxide, hydrogen sulfide and other trace elements. The resulting RNG, or biomethane, has a higher content of methane than raw biogas, which makes it comparable to conventional natural gas and thus a suitable energy source in applications that require pipeline-quality gas.
Offsetting natural gas is comparable to the process of yielding renewable electricity from our landfills. In the case of renewable electricity, energy is added to the electrical grid at one of our landfills, and that same amount of energy is “credited” as renewable electricity by a user at another site within the same electric grid. Key to this process is that the amount of electricity delivered into the grid equals the amount of electricity taken off the same grid. Waste Management has been offsetting electricity with renewable energy for decades using this process.
Renewable fuel works in exactly the same way. Biogas is processed and cleaned before the clean biomethane is put into the pipeline at our (or another company’s) landfill — and an equal amount is used as fuel within the same pipeline system. As with electricity, the gas input and outflow must be on the same gas pipeline system and must be carefully recorded to ensure that they are the same. The process is carefully tracked and verified as renewable fuel by the U.S. EPA when the cycle is complete and only qualifies as RNG after the gas has been used in natural gas vehicles. This certification system is in place at each of our qualified landfills and fueling facilities. Each gas project is reviewed and qualified by the U.S. EPA using engineers who verify that the RNG entering the gas pipeline equals the volume of gas extracted from that same pipeline, and is actually used for vehicle fuel.
Closing the Loop: Converting Landfill Gas to RNG
Waste Management has the largest fleet of natural gas vehicles in our industry, with 6,536 natural gas collection trucks operating in North America. We support this fleet with our 107 natural gas fueling facilities. Waste Management is unique in that we are both a source of, and an end user of, renewable fuel. We currently fuel over a third of our natural gas fleet with RNG produced from landfill biogas at three of our own facilities plus third-party producers. Our long-term and ongoing investments in RNG production facilities, coupled with a natural gas fleet that can operate on RNG, are moving us closer to a near-zero emissions collection fleet.
In 2017, Waste Management’s fleet consumed 6,670,000 MMBtu of natural gas in 6,536 natural gas vehicles (NGVs). Of that total usage, we are managing approximately 2,010,000 MMBtu/year, or 30 percent, of biogas that offsets our total fleet needs. This includes internal and external biogas sources. 100 percent of our natural gas fleet in California, Oregon and Washington runs on RNG, which reduces GHG emissions by 70 percent compared to diesel.