State agencies administering millions of dollars in VW grants are using a tool, the Diesel Emission Quantifier (DEQ), that grossly under-estimates NOx emissions of newer diesel engines and is off target on assessments of some alternative fuels. The inaccuracies likely would lead to less overall positive health impacts of the VW funding program resulting from skewed cost-benefit analyses of projects. Specifically, NOx emissions reductions from alternative fuel and zero emissions options would be understated while diesel-to-diesel impacts would be overvalued. Alternative methodologies such as the Heavy-Duty Vehicle Emissions Calculator (HDVEC) from Argonne National Laboratory would produce fairer comparisons. New Jersey is one state that allows use of HDVEC, as noted on page 14 of the State of New Jersey Mitigation Plan for the Volkswagen Mitigation Trust.
History of the DEQ
State agencies administering millions of dollars in VW grants are using a tool, the Diesel Emission Quantifier (DEQ), that grossly under-estimates NOx emissions of newer diesel engines and is off target on assessments of some alternative fuels.
The U.S. Environmental Protection Agency (EPA) developed the DEQ shortly after the EPA created the National Clean Diesel program, following passage of the Diesel Emission Reduction Act (DERA) by Congress in 2005. The DEQ always has lived up to its billing as user friendly for non-technical users. Fleet applicants could use it to estimate reductions in emissions from diesel cleanup projects. The DEQ draws its data from the Motor Vehicle Emission Simulator (MOVES), a sophisticated tool used by modelers to estimate contributions to regional air pollution from a variety of mobile sources. Data sources pulled by MOVES are largely to blame for the DEQ’s underlying deficiencies.
Originally, the DEQ didn’t provide the ability to assess the relative emissions reduction benefits for alternatives such as natural gas or propane because engines using these fuels were not part of MOBILE, a forerunner to MOVES. Propane was not on the menu of options; selecting natural gas rendered output values of zero. USEPA has made some changes to how the DEQ handles alternative fuels, but problems with assessing comparative impacts from alternative fuels vs. diesels remain.
New Diesels Can Emit NOx Well Above the Standard
While the current inaccurate treatment of alternative fuels remains a concern, an even larger problem has more recently come to light. According to a report co-authored by Andy Burnham from Argonne National Laboratory, the USEPA’s MOVES does not include “in-use test data” (i.e. “real-world” operating emissions data) to model heavy-duty emissions. Recent studies demonstrate that diesel vehicles using the latest NOx controls conforming to the 2010 NOx standard can emit several times the amount of NOx than allowed by the standard. This problem is worse with new diesels operating on an urban drive cycle. One study found that new diesels operating at “near dock” (7 mph average) drive cycle emitted NOx at 9 times the federal NOx standard. Those operating at a “local” (9 mph average) drive cycle were 6 times above the standard. Those at a regional (22 mph average) emitted at twice the standard. By contrast, new natural gas (NG) engines were under the NOx standard at all drive cycles, with the “near zero” NG engines were well below it. Obviously, electric and hydrogen vehicles produce zero NOx. Because the DEQ currently doesn’t draw from this in-use data but engine dyno data (and a simulated version at that), it can’t render a true picture of NOx emissions.
Recent studies demonstrate that diesel vehicles using NOx controls conforming to the 2010 NOx standard can emit several times the amount of NOx than allowed by the standard.
Diesel Pollution Impacts Urban Communities
This is problematic for two reasons. One, it significantly disadvantages any technology that is not diesel (electric, hydrogen, natural gas, propane), since cost-benefit calculations are based on inaccurate emissions estimates. Two and more importantly, for any state agency that relies on the DEQ, this undermines the very health basis of the VW program, which is to reduce NOx emissions from existing heavy diesels. The fact that urban drive cycle NOx emissions are most significantly under-estimated is especially concerning because diesel pollution impacts urban communities most.
In response to an email, USEPA indicated that fixes to the problem of severe under-estimation of NOx emissions from new diesels will have to wait until MOVES is updated. No timeframe for these updates was given and it’s unlikely that these fixes will occur before states begin evaluation and scoring for awarding VW funding.
VW Funding Projects Should Use HDVEC as Calculator
This is a big deal to states like Ohio in the Midwest. Ohio’s VW allocation is about $75 million, less the $12 million segmented for an electric vehicle charging infrastructure deployment program. We’re not accustomed to this level of funding, so it’s important that every dollar have as much impact as possible. To their credit, Ohio EPA has kept the VW funding process moving. They issued an initial solicitation last summer and are preparing for another one within the next few months. Ohio’s stated goal is to award projects that maximize the cost-effectiveness of NOx emission reductions in order to generate the most beneficial health impacts. Unfortunately, this worthy goal will be undermined if the chosen analytical method incorrectly calculates cost-effectiveness – significantly over-estimating the benefits of new diesels and under-estimating the dollar-for-dollar impacts of alternative technologies.
Ohio’s stated goal is to award projects that maximize the cost-effectiveness of NOx emission reductions in order to generate the most beneficial health impacts.
The longer-term solution is to fix MOVES, which provides the underlying data for DEQ analyses. In the meantime, state agencies should use alternative methodologies that don’t simply rely upon this single tool. Fortunately, Argonne’s Heavy-Duty Vehicle Emissions Calculator (HDVEC) draws from both USEPA’s MOVES and Argonne’s own GREET calculator. HDVEC includes an “in-use multiplier” that causes the tool to render results that much more closely resemble actual emissions levels from real-world vehicle operations. Fleets that are considering options and preparing to submit proposals to state agencies for VW funding should encourage state agencies to take this approach. While there is no perfect tool, especially today, agencies can and should use methods that provide the basis for more accurate cost-benefit analysis of the proposals they receive.
