Many corporate leaders committed to supply chain sustainability are waiting for a full range of electric vehicles to hit the market to achieve zero emissions from their heavy-duty truck fleets. But there’s no need to wait: With a new model natural gas engine now in commercial production, fleets can meet their heaviest-duty needs using carbon-negative renewable natural gas (RNG) in near-zero-emission natural gas trucks.
Early-adopter fleet operators such as UPS and Waste Management have already embraced RNG, but others could be forgiven for not having it on their radar. The conversation about achieving zero emissions from transportation has focused almost exclusively on electric vehicles. But policies that look only at tailpipe emissions are leaving out a vital part of the transport supply chain: fuel production. It’s there that RNG shines.
A climate twofer
RNG is a climate twofer, reducing greenhouse gas emissions through its production and use. It’s the lowest-carbon fuel available on a full fuel-cycle basis (production to end use), according to California Air Resources Board analyses for the state’s Low-Carbon Fuel Standard. It’s produced by capturing methane — a potent short-lived climate pollutant — that would otherwise flow into the air from landfills, wastewater treatment plants, food waste, and dairies and other large agricultural operations. The process is a compelling realization of circular economy principles: byproducts and waste that turn pollution into a valuable new product.
When made from food waste, RNG powering a heavy-duty truck has a carbon intensity of negative 25.5. RNG from other sources has carbon intensity scores ranging from 8.6 to 26.2 when used in heavy trucks (compared with 38.9 for a battery electric truck running off California’s average electrical grid mix). Those scores are even lower when RNG is used in trucks with near-zero natural gas engines, which cut tailpipe methane emissions as much as 70 percent. And with Cummins Westport’s new ISX12N near-zero engine going into production in February, there’s now an RNG-capable truck for even the most challenging heavy-duty transportation needs.
The near-zero engines also produce almost no nitrogen oxides (NOx), a primary component of smog. These engines running on RNG have NOx emissions more than 90 percent lower than the current federal standard, according to Air Resources Board testing. They also provide relief from black carbon, a major component of diesel exhaust that’s both toxic and a short-lived climate pollutant.
A step toward environmental justice
In addition to cutting climate-changing emissions, rapid conversion to RNG-powered fleets would solve an urgent environmental justice problem: People who live around ports and major trucking routes are literally dying from air pollution. Even in California, with the strictest emissions standards, upwards of 95 percent of trucks run on diesel. These and other heavy-duty vehicles produce a disproportionate share of emissions — 20 percent of transportation-related greenhouse gases in the U.S., about 50 percent of smog-forming emissions, and more than two-thirds of toxic diesel particulate pollution.
Putting RNG-fueled, near-zero heavy-duty trucks to use at scale would immediately benefit the low-income, predominantly minority communities that are suffering the most from exposure to diesel exhaust. The health effects these communities face are severe: premature death; hospitalizations and emergency department visits for aggravated chronic heart and lung conditions, including asthma; increased respiratory symptoms; and decreased lung function in children.
Running the numbers
Fleets are waking up to the RNG opportunity. Another early adopter, the Los Angeles County Metropolitan Transportation Authority (LA Metro), is upgrading its natural gas bus fleet to near-zero buses and transitioning them to RNG. The agency commissioned an analysis from M.J. Bradley & Associates and Ramboll Environ that found over the next 40 years, “the use of RNG and transition to [low-]NOx buses will be more effective at reducing PM, total CO2, total GHGs, and total NOx from the LACMTA fleet than transition to either electric or fuel cell buses,” at by far the lowest cost. That’s in large part because LA Metro can put hundreds of RNG-powered buses on the road immediately.
Fuel availability should not be a problem. Nationally, members of the Coalition for Renewable Natural Gas are on track to produce more than 622 million gallon-equivalents of RNG in 2018, including more than 541 million for transportation. That’s enough RNG to replace more than 15 percent of diesel consumption in California. The UC Davis Institute of Transportation Studies forecasts that California alone could produce 750 million gallon-equivalents of RNG annually.
For example, CR&R Environmental Services has opened one of the world’s largest anaerobic digesters in Perris, a town in Riverside County, where it employs 1,500 people. The facility turns food waste and landscaping and other green waste into RNG without emitting any pollutants. When fully built out, the digester will convert 335,000 tons of waste annually into 4 million gallons of RNG and 260,000 tons of soil amendment.
So, what’s holding us back?
Despite all its benefits, RNG’s potential is largely unsung outside the vanguard fleets. One factor is that RNG requires specialized fuel dispensers — but so does electricity, and fleets already using natural gas vehicles can switch seamlessly to RNG. Another is that some advocates are pushing to end support for any clean transportation solution other than battery electric vehicles, creating an impression that they are the only truly clean option. That is not the case, and waiting for a full spectrum of EVs to come to market means delaying reductions in climate-changing emissions and condemning millions to harmful air in the near term.
Transportation accounts for 27 percent of U.S. greenhouse gas emissions (and 39 percent of California’s). We can do better, and we don’t have to wait. RNG offers a carbon-negative path to lower emissions from high-fuel-use heavy-duty fleets that’s open right now.