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California ARB releases draft assessment of heavy-duty truck efficiency technologies

15 June 2015

The California Air Resources Board (ARB) has published a Draft Technology Assessment: Engine/Powerplant and Drivetrain Optimization And Vehicle Efficiency that evaluates a range of technologies to increase fuel efficiency and reduce CO2 emissions from heavy-duty trucks. The release of the report coincides with the US EPA proposal for Phase 2 (post-2018) greenhouse gas (GHG) regulations that is expected to be released this week. In April, the California ARB published a related assessment of heavy-duty emission and fuel technologies.

Engine/powerplant and drivetrain optimization technologies evaluated in the report included:

In addition, a number of vehicle efficiency technologies have been evaluated:

The assessment found that the evaluated technologies can produce significant reductions in fuel consumption. Table 1 summarizes the potential additional fuel consumption reduction (FCR) beyond Phase 1 GHG standards (i.e., model year 2018) compliant vehicle that incorporates all of the applicable technologies.

Table 1: Potential additional fuel consumption reduction (FCR) beyond Phase 1 GHG standards
Vehicle CategoryFCR Potential, %
Heavy-Duty Tractor-Trailer (Class 7-8) Long Haul8 - 36
Heavy-Duty Tractor-Trailer (Class 7-8) Short Haul8 - 33
Heavy-Duty Vocational (Class 3-8)10 - 28
Heavy-Duty Diesel Pick-ups and Vans (2b/3)3 - 23
Heavy-Duty Gasoline Pick-ups and Vans (2b/3)10 - 27

The percent FCRs shown in the table correspond directly to potential reductions in CO2 emissions, and can be used to help inform the Phase 2 GHG standard setting process, said ARB in the report.

California air quality targets also require significant further reductions in emissions of criteria pollutants, particularly NOx emissions. In the past, many NOx reduction technologies (such as exhaust gas recirculation and retarded ignition timing) have resulted in increased fuel consumption and reduced fuel efficiency. However, the introduction of urea SCR technology in 2010 allowed for increased fuel efficiency (and reduced GHG emissions) while achieving low tailpipe NOx emissions, noted the report.

The California ARB will further discuss NOx control technologies for heavy-duty engines (both diesel and natural gas) as part of three separate upcoming technology assessment documents expected to be released later this year: (1) Lower NOx Heavy-Duty Diesel Engines, (2) Heavy-Duty Hybrid Vehicles, and (3) Low Emission Natural Gas and Other Alternative Heavy-Duty Fuel Engines.

Source: California ARB