Cradle-to-gate emissions associated with asphalt mix production in the United States represented approximately 0.3 percent of total U.S. greenhouse gas (GHG) emissions in 2019. By comparison, U.S. Environmental Protection Agency data indicate that transportation emissions from fossil fuel combustion represented 27.8 percent of total emissions in 2019, while industrial emissions represented 25.3 percent.
That's according to a new report from the National Asphalt Pavement Association (NAPA), authored by its director of Sustainable Pavements, Joseph Shacat; vice president of Engineering, Research, & Technology, J. Richard Willis; and TriSight LLC partner Ben Ciavola.
The report, GHG Emissions Inventory for Asphalt Mix Production in the United States (SIP 106), is the first national cradle-to-gate assessment of GHG emissions associated with the production of asphalt pavement mixtures that uses a life cycle assessment-based methodology.
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 to 2019.
"Publishing this report puts NAPA and the asphalt pavement industry at the forefront of transparency among carbon emitters," said NAPA President and CEO Audrey Copeland. "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."
"To our knowledge, this is one of the first cradle-to-gate GHG emissions inventories for any major U.S. industry," added Shacat. "While there are several studies that show cradle-to-gate emissions intensities for various industries, we're not aware of any publicly available reports that add up all of the emissions for a given industry nationwide."
Jim Mertes, director of Environmental Affairs at Construction Resources Management Inc., A Walbec Group Company, 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."
What's more, said Mertes, "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) CO2e emissions — equivalent to the annual emissions from approximately 630,000 passenger vehicles.
The authors 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 kg 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 (EPD) and should not be used as a benchmark for project-level decision making during procurement or project delivery."
Nonetheless, the report "will be a valuable tool as discussions with government, agencies, and owners accelerate in the coming years," said Ron Sines, vice president, Performance — Asphalt, CRH Americas Materials Inc.
"Additionally, it provides clear direction on what the industry should be doing today, as well as what the industry could do in the future, if the identified obstacles can be overcome," added Sines, who chaired NAPA's Climate Stewardship Task Force, which created The Road Forward, the industry's 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."
The industry, along with its suppliers, partners and customers, must invest in emission reduction strategies related to materials, transportation, and mix production. Examples include carbon capture, utilization and storage (CCUS); use of carbon sequestering bio-based materials; use of local recycled materials and alternative fuels for trucking; and technologies that reduce burner fuel consumption.
Raven Adams, vice chair of NAPA's Sustainability Committee and Granite Construction's sustainability manager, remarked, "NAPA's publication of this document will empower our industry to advocate for the funding, research, and support needed to allow us to respond to climate change."
For more information, visit www.asphaltpavement.org.
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