California Truck Emission Update

Towards Zero-emission Trucks

California has released its proposal to reduce tailpipe NOx emission limits from Diesel trucks by 90% over the next decade. Here is a graphical summary of the sweeping changes proposed (lower limits, inclusion of low load emissions, reduced PM limits, change in emission analysis method and extended durability !)

Also released a few days back is California's advanced clean trucks rule, which requires significant zero tailpipe emitting trucks starting 2024. 

Both regulations are ultimately extremely challenging and will result in lower emissions, so the competing technologies will result in a net benefit for cleaner air. Shown below is also the comparison of NOx from tailpipe and from electricity generation. Note that there have been tremendous reductions in NOx from both sources over the past 3 decades, and that Diesel emission limits have been lower than stack emissions since the 2010 rule. In-use compliance has been an issue for trucks, however, and the latest rule aims to address that. Also electricity is getting cleaner rapidly with renewable share, so expect those numbers to reduce further as well.  

Note that it is practically impossible to see the 0.02 g/bhp-h limit in 2027 on that scale .. we are truly approaching near-zero emissions !