NAPA report analyzes emissions from asphalt mix production

The National Asphalt Pavement Association (NAPA) has released a first-of-its-kind cradle-to-gate assessment of greenhouse gas (GHG) emissions associated with the production of asphalt pavement mixtures.

Using a life cycle assessment-based methodology, the report found that carbon emissions from asphalt mix production in the U.S. represented approximately 0.3 percent of total U.S. GHG emissions in 2019. The emissions inventory includes upstream raw materials inputs, transportation of those materials to the production site and plant emissions (including upstream energy processes) for the years 2009-2019.

By comparison, data from the U.S. Environmental Protection Agency indicates that transportation emissions from fossil fuel combustion represented 27.8 percent of total emissions in 2019, while industrial emissions represented 25.3 percent.

“Publishing this report puts NAPA and the asphalt pavement industry at the forefront of transparency among carbon emitters,” says NAPA President & CEO Audrey Copeland of the report. “We’re demonstrating our commitment to doing better—as prescribed in ‘The Road Forward’ initiative we announced in January—by taking stock of where we are and identifying proven as well as innovative strategies to reduce carbon emissions.”

Jim Mertes, director of environmental affairs at Construction Resources Management Inc. and chair of NAPA’s Sustainability Committee, described the report as “a comprehensive industry benchmark, which can be used to measure future industry improvements in carbon reduction.”

He adds, “It identifies what we can achieve using existing strategies and technologies and demonstrates the unprecedented technological challenge ahead to get to net-zero.”

By identifying “avoided emissions,” the report demonstrates how existing environmentally preferable technologies like reclaimed asphalt pavements (RAP), reduced-temperature asphalt mix production (called warm-mix asphalt, or WMA) and switching to alternative fuels for plant operations have already had an industry-wide impact on limiting emissions.

In 2019 alone, the industry avoided 2.9 million metric tons (MMT) of carbon dioxide equivalent (CO2e) emissions—which is comparable to the annual emissions from approximately 630,000 passenger vehicles.

The authors—which include NAPA Director of Sustainable Pavements Joseph Shacat; NAPA Vice President of Engineering, Research and Technology J. Richard Willis; and TriSight LLC Partner Ben Ciavola—note that increased implementation of such measures could further reduce emissions by up to 24 percent relative to 2019. In fact, each ton of RAP used in new asphalt mixtures reduced 2019 GHG emissions by approximately 27 kilograms of CO2e.

However, they caution, “Although the report provides an estimate for the national average GHG emissions associated with asphalt mix production, it is not an industry average Environmental Product Declaration and should not be used as a benchmark for project-level decision making during procurement or project delivery.”

Nonetheless, NAPA members say the report will serve as a valuable tool “as discussions with government, agencies and owners accelerate in the coming years.” The report also is aimed toward providing clear direction on ways the industry can achieve goals set by NAPA’s Climate Stewardship Task Force, which created The Road Forward—a goal to reach net-zero carbon emissions by 2050.

To advance that goal, the report states, “New technologies and additional innovative practices will need to be developed and implemented to achieve more significant GHG emission reductions.”