Heavy-duty vehicles cover a very wide range of applications and typical driving profiles. A one-size-fits-all approach is unlikely to work for reaching zero tailpipe emissions from this sector. Here’s a summary of the application diversity from a US viewpoint.
This is part 1 of 2 technology updates on pathways to meet the low NOx standards for heavy-duty vehicles set by California and being considered by the EPA for nationwide implementation starting model year 2027.
What’s your guess – how much will the battery requirement increase relative to passenger cars if we electrify the heavy-duty sector? Taking the US as an example, we navigate this question.
Starting with Euro 7 regulations in Europe, particles down to 10 nm will be counted and regulated, a change from the current cut-off of 23 nm, reflecting both the increasing awareness of health impact due to ultra-fine particles and also improved measurement capabilities. We give an overview of the issue.
As we enter into the final lap of the SuperTruck 2 program, all teams are confident of meeting the 55% BTE and doubling-of-freight-efficiency targets. Here are the technical solutions being pursued.
If you have not heard of the term “Environmental Justice” or “EJ” as it is abbreviated, then it’s time to read up. Policy makers have to pay close attention to this topic in the quest for a rapid transition to greener energy and mobility.
In-use NOx emissions from heavy-duty trucks and buses Journal Paper Review : Real-world NOx emissions from heavy-duty diesel, natural gas, and diesel hybrid electric vehicles of different vocations on California roadways Science of the Total Environment 784 (2021) 147224 Background This is one of the largest studies in California on measurement of in-use NOx emissions from 50 heavy-duty trucks and buses for various vocations. The fleet included 2 diesel vehicles without SCR (selective catalytic reduction of NOx), 14 diesels with SCR, 2 diesel hybrids, 29 compressed natural gas (CNG) and 3 liquified petroleum gas (LPG) vehicles. Emissions were measured using portable emissions measurement systems (PEMS) and on actual driving routes and applications (e.g. transit buses making stops and refuse trucks making the rounds collecting garbage and delivering to landfills). All vehicles had less than 435,000 miles of prior driving, so that these were within the useful life requirements. This is a good database to identify future potential of advanced powertrain & after-treatment technologies as we move towards the Low NOx regulations starting 2024 – 2027. Key Takeaway (1) Compared to diesel vehicles with SCR technology, CNG vehicles certified to 0.02 g/bhp-h standard emitted 94% lower NOx. LPG vehicles
Let’s put things in perspective first. Brake thermal efficiency was ~ 35% in 1960. In 2020, Weichai announced a 50% BTE commercial engine (more details on Dieselnet). And the US Department of Energy’s SuperTruck 2 program is targeting 55% BTE next year. At least two participants announced this year that they are close to 53%. Navistar, Book chapter in “Alternative Fuels and Advanced Vehicle Technologies for Improved Environmental Performance”, 2014 doi:10.1533/9780857097422.2.225 Here are some enabling technologies that the participants are pursuing to achieve 55% BTE and doubling of freight efficiency. Improvements include those at the engine, transmission and vehicle level. Also included are model based control of the drivetrain and emissions systems. The table below shows some of the options being evaluated by each of the participants at the engine level. Common elements include light thermal barrier coated pistons, high compression ratios, Miller cycle, high efficiency turbochargers, waste heat recovery and close-coupled SCR. The program enters its final year and we will see whether the participants can demonstrate achieving the targets at the DOE Annual Merit Review in 2021. See you there.
