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CRC ACES Phase 2 report finds emissions from modern heavy-duty diesels well below required levels

2010 engines emissions reduction relative to 2010, 2007, and 2004 US emission standards. Source: CRC. Click to enlarge.

A rigorous emissions testing of modern heavy-duty diesel engines in the US has demonstrated a greater than 94% reduction in the levels of nitrogen dioxide (NO2 - an important contributor to ozone smog), and substantial reductions in all other pollutants, even when compared to engines first marketed to meet 2007 standards, according to a study released today by the Coordinating Research Council (CRC).

For a number of the most important pollutants, levels were substantially lower than required by regulations. The study, the Phase 2 Report of the comprehensive Advanced Collaborative Emissions Study (ACES) (earlier post), found that emissions of NO2 and other nitrogen oxides—which can have direct health effects and contribute to the formation of smog—were approximately 61% below the 2010 EPA standard and 99% lower than in 2004 engines. These reductions came while emissions of fine particles were also 92% lower than the 2010 standard 99% lower than 2004 emissions.

Emissions of carbon monoxide and hydrocarbons were also significantly below required 2010 levels: 97% and more than 99.9%, respectively.

The Phase 2 ACES study was conducted by the Southwest Research Institute in San Antonio, Texas, under the oversight of the CRC. Investigators tested heavy-duty diesel engines from the three major manufacturers of these engines (Cummins, Detroit Diesel, and Volvo), and subjected them to well-established federal test procedures, and to a much more rigorous 16-hour operation cycle designed especially for ACES.

All the engines were equipped with after-treatment devices to reduce the emissions of particulate matter as well as oxides of nitrogen. They were tested on multiple repeats of these cycles, and measurements of more than 300 regulated and unregulated air pollutants were made in accordance with the highest laboratory standards.

ACES is a multi-party five year initiative to test the emissions and health effects of new technology diesel engines to document the improvements that have been made and to ensure that there are no unintended emissions from this new technology. The study is being undertaken by the Health Effects Institute (HEI)3 and the CRC with support from a wide range of government and private sector sponsors, including the US Department of Energy, US Environmental Protection Agency, California Air Resources Board, Engine Manufacturers Association, American Petroleum Institute, and manufacturers of emission control equipment.

Overall design and management of ACES—and all laboratory testing of health effects—is being undertaken under the aegis of HEI. All emissions characterization for ACES is being overseen by CRC.

The Health Effects Institute is an independent, non-profit research institute funded jointly by government and industry to provide credible, high quality science on air pollution and health for air quality decisions.

Background. In 2010, EPA’s stringent NOx limit of 0.20 g/hp-hr became fully enforceable; the NOx emissions limit decreased from an average level of 1.2 g/hp-hr between 2007 and 2009 to a level less than or equal to 0.20 g/hp-hr in 2010.

To comply with the 2010 NOX limit, on-highway heavy-duty engine manufacturers utilized a urea-based selective catalytic reduction (SCR) catalyst in engine exhaust placed downstream of a diesel oxidation catalyst (DOC) and a catalyzed diesel particulate filter (DPF) used for particulate matter (PM) emissions control.

The engine manufacturers devoted substantial efforts to calibration of the urea dosing and mixing, SCR catalyst formulation, and engine control to achieve the desired NOx reduction while maintaining a controlled level of ammonia slip using an ammonia oxidation (AMOX) catalyst downstream of the SCR catalyst.

Improvements were also made in PM emissions control, eliminating the need for active regeneration (onboard cleaning via exhaust fuel injection upstream of DOC) of the DPF during ACES Phase 2 testing, compared to the several regeneration occurrences with the 2007 technology engines tested in ACES Phase 1.




This is good news for our children and the health care program but manufacturers had no other choice but to meet the standards. Is it also a very smart way to block imports.

Without strict standards, nothing would have been done to lower emissions; they may have gone up instead, as they did for decades before.


Well, Harvey, this does not help. People are still complaining about diesel exhaust. It is sufficient that one single researcher tests one old engine/vehicle without any aftertreatment system and the low emission level of new engines/vehicles (i.e. everything achieved during the last couple of decades…) will instantly be forgotten. Recall that Cal EPA prefer to base their newest cancer risk estimates on exposure studies from the 1950’s where 2-stroke locomotive engines conceived in 1938 were used. Also WHO has a similar approach for their risk estimates.


Based on 2007 data, diesel exhaust annually create 6% or 12,000 of the incurable lung cancers in USA and UK.

It is probably worst than that in China, India and many EU countries.


Coincidentally, 2007 was when on-road diesel trucks (actually, all on-road diesel vehicles) were effectively required to use DPF to meet the 2007 emission regulations.

Another Phase of ACES (Phase 3) looked at health effects from almost continuous exposure to concentrated exhaust from a 2007-compliant diesel truck engine (http://pubs.healtheffects.org/getfile.php?u=708). Only a few health effects were observed through 12 months, and preliminarily through the lifetime of the laboratory animals (http://www4.eere.energy.gov/vehiclesandfuels/resources/merit-review/sites/default/files/ace044_greenbaum_2013_o.pdf - slide #19).

Based on the Phase 2 ACES, emissions from 2010-compliant diesel engines are significantly lower than even the 2007-compliant engines (in virtually all regulated and unregulated emissions). Emissions from these engines are getting so close to zero as to make no practical difference.


The current war on diesel as I would like to call it has placed many in harms way. Case in point with MY2011 and newer light duty pickup trucks the use of EGR, SCR/UREA, DOC, and a DPF the combined package is a mess. The use of UREA in a diesel engine with ULSD 15ppm is a dangerous combo it produces ammonia gas before it reaches the DOC(diesel oxidizing catalyst)if you have a leak or some other imperfection in the exhaust or turbo system it is not good. I had a bad encounter with this not to long ago ending with a trip to the er no damage was done.

Besides the inherent chemical dangers the cost of maintenance and repair is skyrocketing ten fold. I currently own a MY2013 F-350 King Ranch CCSB diesel 4x4 the best millage I have seen is 14 highway empty in the summer, while towing 11-12 at the best winter is 10-12 average. Overall the performance is great but the economy is poor at best the truck has 18,000 miles mostly hwy it will not pass emissions via the tailpipe after 5,0000 miles the emissions systems are virtually a hassle and waste a lot of fuel. During the regen cycle it causes the truck to lack power waste fuel(7-9 MPG) on a good day. burnt one turbo already seals went.
Most of these happenings are from my personal vehicle over the past two years customers trucks are a horror show of basket cases. I've seen everything from blown turbos pouring oil into the cylinders burning that as fuel. In the process burning motor oil the whole emissions system is trashed and turbo system turning the engine into scrape metal. It cost the customer 15k+ to repair his truck plus down time it was determined that the extensive heat from the EGR, DPF and normal work combined caused this major failure.

What I am getting at is the path they are taking is crazy four years to redesign a entire engine, create technology to conform to regulations and release in 5 years. overall as a taxpaying citizen I truly disagree with the measures and lack of proof to enforce such radical policies. In the end it cost more to have food on your table and clothes because of these policies.

the chart below was a test done by myself on a
-2013 powerstroke 71/68/.96 CEA CHRA turbo billet cast wheels 39mm wastegate custom tuning
30% injectors ported fuel internals 10mm stroker cp4 built engine cam swap and built tranny dynos at 640hp 1200tq no smoke
lifted 37's 4:10 gears spool rear 23.85 mpg hwy empty via OBDII datalogging 17.75 city same access route.

-2013 mustang boss 302 5.0 coyote DOHC 10.5:1 aftermarket intake manifold radiator shorty headers no cats 2.5" mandrel bent T-304 tubing hi flow mufflers custom tuning and double carbon disk clutch 5-speed 4:11 gears spool. best hwy 17.55 best city 13.65 on 93 marine gas no ethanol.

results follow first column is gas job mustang second column is 13 powerstroke with tuning set to street performance 85hp #1 200ppm sulfar diesel cetane of 48 here they are in real world test on private logging roads.
all values are in parts per million/6hr run time/ 14 day average. all variables have been factored in

N2 71 67
CO2 14 13
H2O 12 11
O2 0 10

trace elements <0.5 +/- 0.3
NOx < 0.25 < 0.015
CO 1 - 2 < 0.045
PM < 0.045
CxHy < 0.25 < 0.03
SO2 possible traces < 0.03

The test concludes that with new technology we do not need the EGR, DOC, SCR, UREA and DPF systems they are a waste. the truck tested was a fully built race truck and is that are near compliance when built for optimum performance and reliability. It proves they do not have a clue to what they are doing at all it makes my job harder everyday as a diesel tech and people who own these trucks as work vehicles. It just goes to show when the people with the knowledge are not the ones writing the regulations more so just making technology to combat them.


In 2007, there were no MY 2010 Engines on the road. I hope this conclusion is clear enough.

Why not concentrate on the pollution that causes the remaining 94% of cancer cases.

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