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UAI and EFC call EPA MOVES2014 emissions model treatment of ethanol “seriously flawed”; call for peer review

Two organizations, the Urban Air Initiative (UAI) and the Energy Future Coalition (EFC), are asserting that the latest version of the US Environmental Protection Agency’s (EPA) MOtor Vehicle Emission Simulator (MOVES) modeling system for estimating emissions from mobile sources is “seriously flawed” with respect to its treatment of higher ethanol blends.

EPA’s Office of Transportation and Air Quality (OTAQ) developed MOVES; the emission modeling system estimates emissions for mobile sources at the national, county, and project level for criteria pollutants, greenhouse gases, and air toxics. MOVES2014 is the latest version of MOVES and includes the effects of the Tier 3 rule as well the impacts of other EPA rulemakings promulgated since the last MOVES release in 2010; new emissions data; and new features that users have requested.

MOVES2014 will be used to estimate air pollution emissions from cars, trucks, motorcycles, and buses in official State Implementation Plan (SIP) submissions to EPA, the organizations note. MOVES is EPA’s approved model for estimating volatile organic compounds (VOCs), nitrogen oxides (NOx), carbon monoxide (CO), direct particulate matter (PM10 and PM2.5) and other pollutants and precursors from cars, trucks, motorcycles, and buses. EPA has advised states to use MOVES2014 in SIP development as expeditiously as possible.

In a letter to EPA Administrator Gina McCarthy, UAI and EFC are requesting the immediate suspension of the use of the MOVES model with respect to ethanol blends until the EPAct study that underpins it can be peer-reviewed by transportation fuels experts at DOE’s Oak Ridge National Laboratory (ORNL) and National Renewable Energy Laboratory (NREL), and until that analysis can be evaluated for the purpose of maximizing the accuracy of the models.

The two organizations also say that EPA should also refrain from using the EPAct study with regard to an anti-backsliding study required by Congress.

The organizations assert that inaccurate results could block access to the market for higher ethanol blends, denying states what the UAI says could be a valuable tool in protecting public health.

The new elements in MOVES2014 pertaining to ethanol reflect the findings of a study conducted for EPA by the Coordinating Research Council (CRC), a non-profit organization supported by the American Petroleum Institute and a group of auto manufacturers (Chrysler, Daimler, Ford, General Motors, Honda, Mitsubishi, Nissan, Toyota, and Volkswagen). The study … used an inappropriate fuel sample methodology designed in part by a Chevron consultant.

—Letter to EPA

The organization explain that ethanol blends can be created in two ways: by adding more ethanol to a product approved for commercial use, such as E10 (“splash blending”); or by adjusting the gasoline blendstock first to match certain selected parameters (“match blending”).

While many tests of splash-blended ethanol have shown that it reduces pollution, the study behind MOVES2014 used match-blended ethanol instead. Nearly all US gasoline is produced by splash-blending 10% ethanol.

The EPAct study compared the emissions of 27 fuel blends at different boiling points designed to fit a desired distillation profile. Because ethanol’s distillation characteristics are unlike those of hydrocarbons, and because it evaporates at a temperature below two of the specified boiling points, the tests added more “high boiling point” components of gasoline to achieve a “match.” However, these high boiling point components are typically aromatic compounds—the worst-polluting components of gasoline. Emissions increased because of the changes in the base fuel, not the ethanol. Thus, ethanol was unfairly and incorrectly blamed for emissions caused by aromatic hydrocarbons.

The study concluded that “other factors being equal, increasing ethanol is associated with an increase in emissions”—but it later acknowledged: “However, if typical collateral fuel changes (lower T50 and aromatics) are accounted for, we might project that blending ethanol would tend to reduce THC, NMHC and NMOG emissions (highlighting the important sensitivities to these other fuel parameters).”

… Independent investigations by automakers and other fuel experts confirm that the use of match blending in the EPAct study mistakenly attributed increased emission levels to ethanol rather than to the addition of aromatics and other high boiling point hydrocarbons, thereby significantly distorting the model’s emissions results. A peer-reviewed analysis that will be published shortly found that “the degradation of emissions which can result is primarily due to the added hydrocarbons, but has often been incorrectly attributed to the ethanol.” Confirmation or refutation of these findings is critical to an objective analysis of the most effective way to ensure that the composition of gasoline minimizes harmful exhaust emissions.

—Letter to EPA


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