Whichever way you “slice” it, the future of the 150-year-old internal combustion engine is moving steadily into the hands of global emissions-policy regulators. New ICE programs are dwindling amid the electrification juggernaut. Fuels chemists and combustion scientists are fighting a rear-guard action to keep the “heat engine” viable in the face of ever-tighter tailpipe standards for both light-duty vehicles and commercial trucks and equipment. For many emission-control system suppliers, the sunset is already beginning. The key question is, how quickly will it arrive?

“The continued development of ICEs must support de-carbonization,” asserted Jim Szybist, senior research staff scientist at Oak Ridge National Laboratory, who kicked off the 2022 SLICE (Sustainable Low-Impact Combustion Engine) Symposium, held during the first day of SAE International’s annual WCX World Congress in Detroit. Reducing greenhouse-gas (GHG) emissions is now the dominant driver in ongoing ICE planning and fuels/technology development, Szybist noted, particularly for the light-duty vehicle sector responsible for 57% of transport-generated GHGs.

The sharpened focus on GHG emissions, amid industry’s shift to EV development, prompted SAE advanced-powertrain committees to pivot their annual High-Efficiency IC Engines meeting toward one incorporating sustainable/renewable-fuels research discussions. Hence the creation of SLICE. The symposium’s main audience – fuels experts, commercial-diesel engineers, combustion- and aftertreatment-systems engineers, and scientists from research universities and the U.S. national laboratories – was reflected in the packed meeting room on April 4.

Life-cycle analysis (LCA) is playing a significant role in both product and policy planning, explained Dr. Michael Geller, deputy director of the Manufacturers of Emission Controls Association (MECA). His SLICE keynote presentation, “Integrated Approach to Mobile-Source GHG Reductions,” highlighted the industry’s collective progress toward meeting the Biden administration’s GHG reduction goals for 2030 (50-52% lower than in 2005). “We’re almost there,” he observed.

Geller also clearly noted the challenges and uncertainties facing the industry, including the significant impact of grid-CO2 intensity on upstream GHG emissions, the pace of renewable-energy power and EV battery development, and cost. While bullish on the influence of increased penetration of hybrids and EVs on overall GHG reduction, Geller, an environmental engineer and former EPA official with deep experience in GHG and particulate emissions, stressed the challenge of electrifying transport sectors beyond LDVs, particularly aircraft. Biofuels from renewables, he said, “are at the forefront” of GHG mitigation in aviation.

Subsequent presenters at the 2022 SLICE detailed developments in hydrogen, methanol, ammonia, synthetics and other potential fuel solutions for large-displacement commercial ICEs, as the drive to promote a lower carbon footprint and lower emissions across all transportation sectors gains steam.