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ICCT can't even stay consistent with their own reports.
VW has several Euro6 diesel vehicles that meet the NOx limit in real-world conditions according to Emissions Analytics "Equa Index." Some even meet the petrol NOx limit. Even the 2017 Porsche Panamera 415 hp diesel meets the petrol limit for NOx emissions in that test. There's no fundamental reason diesels can't achieve NOx emission levels as low as petrol.
@EP According to a report by the National Academy of Sciences (“Reducing the Fuel Consumption and Greenhouse Gas Emissions of Medium- and Heavy-Duty Vehicles, Phase Two”), a particle filter would not be needed with DME as a fuel. No mention of methanol though.
Even diesel-hating California Air Resources Board has confirmed that diesel cars with DPF have particle number emissions that are indistinguishable from HEPA-filtered dilution air (State Of California, California Environmental Protection Agency, Air Resources Board, "California’s Informal Participation in the Particle Measurement Programme (Pmp) Light Duty Inter-Laboratory Correlation Exercise (ILCE_LD) Final Research Report." October 2008, pages 28-30). The VW cheating had to do with NOx emissions, NOT PM. Even in the ICCT/WVU study that discovered the VW cheating in the first place, PM emissions were barely measurable: "…In general, PM emissions are on the order of 0.01mg/km ±0.005mg/km (±1σ), thereby nearly 100% (99.89%) below the US-EPA Tier2-Bin5 standard…." [Page 83 of report]. So in this case, the cars are polluting a tiny fraction of what the manufacturer claimed (certified PM emissions of 2013 Passat TDI were 0.002 g/mile (2 mg/mile)). Even in the case of NOx emissions, all diesel vehicles certified in the U.S. are subject to months of extensive additional testing and have since the NOV was issued to VW in September 2015. The additional testing is conducted to ensure the vehicles' certified emissions are representative in all "driving cycles and conditions that may reasonably be expected to be encountered in normal operation and use."
@Jeffgreen54 This isn't recent, but take a look at this presentation from ORNL , slide #10, to confirm what Peter_XX said. Also see @3:32 - 3:58 of video for a demonstration of the "filtering" capabilities of diesels with DPF.
Based on personal communications with EPA, all diesel vehicles certified in the U.S. undergo months of rigorous extra testing, including real-world testing under a variety of ambient conditions using PEMS. The certification process has become so onerous that some manufacturers have pulled the certification requests. The Equa tests are real-world tests conducted with PEMS. According to ICCT: "...Recent actions by California’s Air Resources Board and US EPA indicate that future LD diesel NOx emissions will be much closer to regulatory emissions limits. These actions include ARB’s newly-developed defeat device screening methods, which notably include the use of “special driving cycles and conditions that may reasonably be expected to be encountered in normal operation and use”. As a result, average NOx emission factors for future vehicles certified to Tier 3 standards are estimated to be within 30% of the certification limit, equivalent to 14 mg/km...." Anenberg et al. "Impacts and mitigation of excess diesel-related NOx emissions in 11 major vehicle markets." Nature 545, 467–471 (25 May 2017), page S7
Four out of four diesel cars tested by Equa in the U.S. have received an air quality rating of "A", which corresponds to meeting California's SULEV limit for NOx (<0.02 g/mile). Europe is implementing RDE testing, which should preclude any diesel vehicle that exceeds the Euro6 NOx limit from being certified.
According to ANL's GREET model (GREET_2017), bioDME has the greatest GHG reductions of any transportation fuel pathway available in GREET. BioDME has net GHG emissions of -206 grams/CO2e/MJ (WTW) when configured to co-generate electricity according to GREET1_2017.
It should be noted that a previous study by CMU showed that increasing the ambient NMOG:NOx ratio increased SOA production non-linearly; increasing NMOG:NOx ratio from 4:1 to 10:1 increased SOA yield by a factor of 8. Thus, decreasing NMOG emissions while leaving NOx emissions as is would decrease the NMOG:NOx ratio and result in much lower SOA production.
The various reports of air quality in Europe is so conflicting that it is impossible to really tell what's going on there. For example, this IMechE report states: "...It has become evident that London has a particularly bad NO2 problem, with levels similar to such cities as Shanghai and Beijing. This puts it among the worst cities globally in terms of overall air quality...." (Page 07) However, the latest official report by the European Environmental Agency - "Air quality in Europe — 2017 report; EEA Report, No 13/2017" - states that <10% of Europe's population lives in an area that exceeds Europe's ambient air quality standard for NO2, and that's mostly because Europe has adopted the extremely restrictive (overly restrictive?) WHO guidelines for ambient NO2 of 40 µg/m3. EU has NOT adopted the WHO guidelines for any of the other criteria pollutants. If it had, PM10, PM2.5, ozone, SO2, and benzo(a)pyrene would all be far more of a concern that NO2. Based on Figure 6.1 (page 42) of the EEA report, there would NOT be any monitor (of the thousands monitoring for NO2) that would exceed the U.S. ambient air quality standards (NAAQS) for NO2. The U.S. NAAQS for NO2 is 53 ppb or about 100 µg/m3, i.e., about 2.5 times higher than the European standard for NO2. USEPA JUST reviewed the adequacy of its NAAQS for NO2 and concluded the 53 ppb (100 µg/m3) was adequate as is ( Hard to believe there is such a crisis when there would not be any monitors in London or anywhere else in Europe that would violate the U.S. NAAQS for NO2.
"...I wonder about their ability to meet emission standards when VW and many others have failed." It will have to or it won't be certified. Every light-duty diesel vehicle line certified in the U.S. is subject to months of extensive additional testing and has since the NOV was issued to VW in September 2015. The additional testing is conducted to ensure the vehicles' certified emissions are representative in all "driving cycles and conditions that may reasonably be expected to be encountered in normal operation and use."
Those are ambient levels to which all sources of PM2.5 and NO2 contribute.
According to EPA, ambient PM2.5 levels have dropped by an average of 42% and ambient NO2 levels 47% between 2000, shortly before the end of the study period (2004), and 2016. That should mean that air pollution-related cancers should be dropping like a rock, shouldn't it?
@kalendjay, just to be clear, N2O (nitrous oxide) is the powerful greenhouse gas to which you're referring and is not considered "NOx". NOx = NO (nitric oxide) + NO2 (nitrogen dioxide). Neither NO or NO2 are considered greenhouse gases; atmospheric lifetimes are much too short.
I agree this is a highly biased study. Even diesel-hating CARB has lower upstream GHG emissions for ULSD than gasoline (per MJ) in its "Low Carbon Fuel Standard" regulation, and biodiesel/renewable diesel from crop oils has lower upstream GHG emissions than ULSD, even with the controversial indirect land use change included.
In the first place, that study was done in India. Not relevant to U.S./Canada. In the second place, gassers have been shown to have much high PM and PM precursor emissions than diesels. I'll take a little higher NOx emissions over those any day. Thirdly, Tier 3 diesels in the U.S. have been shown to have NOx emissions near SULEV levels in "driving cycles and conditions that may reasonably be expected to be encountered in normal operation and use." This has been confirmed by the ICCT itself: ("USA" - "Tier 3") Fourthly, even in this study, CO emissions from the I20 gasoline are 74 times higher than the CO emissions from the I20 diesel in the "independent" real driving tests. Why are high NOx emissions any worse than high CO emissions?
The study was funded by U.S. National Science Foundation. Grant Number: 0967353 and Norwegian Research Council. Grant Number: 190940, according to the paper.
There was a study conducted in 2013 that analyzed the full life-cycle impacts of electric and diesel transit buses ( In only 8 states were the electric buses superior to the diesel buses, and that was with regular petroleum-based diesel fuel. B20 clearly would be better still. Since OTR trucks cross many states, there are probably no scenario in which electric trucks overall would be superior to diesel trucks running B20 with respect to GHG emissions or damages to public health and the environment.
@mahonj, DEF (urea solution) usage will likely increase in these circumstances. It's also probably at least one reason why manufacturers cut corners in the first place - to allow a tank of DEF to last through a full service interval without placing a huge DEF tank in the vehicle. BMW is using a combination of a LNT (called a "passive NOx adsorber" - "PNA") and SCR for their diesel cars in the U.S. The PNA adsorbs NOx during engine start-up or periods where the SCR isn't sufficiently warm to convert the NOx to N2. The NOx is desorbed from the PNA when the SCR is sufficiently warm. The U.S. BMW diesel cars/SUVs have been shown to have extremely low NOx emissions.
The movement for a blanket "diesel ban" is off-the-chart foolishness. Most likely, diesel will be replaced by gasoline, mostly GDI at that. GDI has been shown to have higher CO, NMVOC, and PM/PN than current Euro 6 diesels, not to mention unregulated air toxics and higher emissions to refine gasoline compared to diesel fuel. Even if GDI generally has lower NOx emissions, there's a trade-off even with that which doesn't seem to be taking into account. Ambient NO2 and PM nitrate (nitrate aerosols) may be reduced, but ozone and organic PM (SOA) may increase in urban locations. According to the European Environmental Agency, ambient NO2 levels have been steadily declining anyway. If Europe is really having as much trouble with ambient NO2 levels as has been reported, it needs to adopt new certification test procedures to include driving cycles and conditions that may reasonably be expected to be encountered in normal operation and use. The RDE test cycle may be a significant step in this direction.
Looking at it another way, regulators should be/should have been focusing on VOC emission reductions more than NOx emission reductions instead of the other way around.
Another aspect that's generally not considered with volatile fuels like gasoline and ethanol is the waste through simple evaporation of the fuel. According to EIA (, 385 million gallons/day of motor gasoline are consumed in the U.S. That's about 140,500,000,000 gallons of gasoline consumed by the U.S. vehicle fleet per year. According to EPA, 49.7 grams of VOCs are produced per million BTU of gasoline (~5.7 g/gal); 7.9 g VOCs are produced per million BTU of diesel (0.95 g/gal) (EPA, "Draft Joint Technical Support Document: Proposed Rulemaking for 2017-2025 Light-Duty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy Standards." (Table 4-12, page 4-42 [366 of 479])). 140,500,000,000 gallons X 5.70 g/gal = 882,770 tons of VOC WTP per year from the fuel gasoline. Hypothetically switching the light-duty vehicles in the U.S. to diesel could reduce WTP VOC emissions to (140,500,000,000 gallons X 0.95 g/gal) = 147,129 tons/year. 882,770 tons - 147,129 tons = 735,640 tons/year or almost 237,300,000 gallons/year of gasoline not evaporated as VOC. This does not take into account the demonstrably higher VOC emissions of gasoline vehicles during vehicle refueling, diurnal + hot soak, and running loss. That's almost three supertanker ships full. Not only is this a colossal waste of a valuable resource, VOCs contribute to ground-level ozone production and secondary PM2.5 (secondary organic aerosols).
It would be nice to know what emission rates of other criteria pollutants were. Another recent report extolling the virtues of CNG trucks in Southern California (Johnson et al. "Ultra-Low NOx Natural Gas Vehicle Evaluation ISL G NZ") showed very low emissions of NOx emissions relative to diesel trucks with SCR, but higher emissions of all other tested pollutants (CO, NMHC, PN, NH3). The trade-off of lower NOx emissions for higher emissions of all other pollutants is questionable.
@mahonj, Thank you for your response. I assumed that the EEA report was valid, but it's so inconsistent with what I've been hearing about air quality in urban locations in Europe, something has to be hyped, one way or the other. It almost sounds in some articles like the air is barely breathable in many city, almost as bad as Beijing, China! Again, if those EEA data are representative of the current air quality in Europe, they are actually much cleaner than most U.S. cities, especially with respect to ground-level ozone (an especially perplexing air quality problem in the U.S.) I don't disagree about start/stop systems which are consistent with some degree of hybridization. It should be noted though that petrol engines have high PN emissions at each start-up, cold or hot.
@mahonj, According to European Environmental Agency's air quality assessment report (Air quality in Europe — 2016 report, EEA Report No 28/2016), Ireland has very CLEAN air generally, really the cleanest in Europe based on overall criteria pollutant monitoring data. It appears that there are only two monitors in Ireland in that monitoring system, but one of them appears to be in Dublin. According to that report, ambient levels of all criteria pollutants, including NO2 and PM10/PM2.5 are all far below EU's ambient air quality standards, and even well below WHO air quality guidelines. I can tell you as as air pollution meteorologist that most metropolitan areas in the U.S. would be ecstatic with those air quality data! Is EEA embellishing its accomplishments with respect to air quality there?