Achieving Ultra-Low NO<sub>x</sub> and Meeting Full Useful Life Requirement for CARB 2027 NO<sub>x</sub> and GHG 2027 Phase 2 CO<sub>2</sub> Regulation w/Opposed Piston 2-Stroke Engine and a Conventional ATS

<div class="section abstract"><div class="htmlview paragraph">Internal combustion engines are expected to continue to play an important on-going role in the future of transportation, particularly in long haul transit and off-road applications. Substantially reducing criteria emissions of heavy-duty (HD) commercial vehicle engines while also reducing fuel consumption is the quickest way to achieve more sustainable transportation. The opposed-piston (OP) engine developed by Achates Power has demonstrated the ability to meet the most stringent ultralow NO<sub>x</sub> emissions requirements using only a conventional, underfloor aftertreatment system, offering reduced cost, complexity and compliance risk compared to other diesel engines. This paper is focused on the measurement results of Achates Power heavy-duty engine achieving CARB proposed ultralow NO<sub>x</sub> emission for 2027 and 2031+ full useful life requirements while also meeting the EPA Greenhouse Gas (GHG) Phase 2 limits with a conventional aftertreatment system (ATS), which was aged to 435k, 600k and 800k equivalent miles. The paper will describe EPA cycle results at each aging step and highlight the challenge of simultaneously meeting both criteria and CO<sub>2</sub> emissions.</div></div>