How Is Gasoline Blended?  Two Groups Ask EPA to Consider This Important Detail

Source: By Jessie Stolark, EESI • Posted: Monday, October 27, 2014

On October 20, the Energy Future Coalition (EFC), an initiative of the UN Foundation, and the Urban Air Initiative (UAI), sent a letter to EPA Administrator Gina McCarthy urging the agency to reconsider the analysis that underpins EPA air toxic modeling for vehicle fuels, arguing that the modeling approach is flawed.  The letter was prompted by EPA’s release of 2014 updates to the Motor Vehicle Emissions Simulator (MOVES) on October 7. EPA had concluded that an increase in ethanol volume in fuels causes an increase in toxic emissions, both in the running and starting of the engine.  Yet, neat ethanol is a non-toxic additive to gasoline, while gasoline, particularly the aromatic portion of each gallon, is toxic, carcinogenic and mutagenic.  Following this logic, shouldn’t adding ethanol to gasoline lower its overall toxicity?

History often repeats itself.  Gasoline was originally oxygenated with lead. Despite evidence of lead’s toxicity stretching back more than a century, it remained in our gasoline supply until the passage of the Clean Air Act Amendments of 1990, which mandated that it be fully removed by 1995.  When lead was finally removed from gasoline, the oil industry insisted on a petroleum product as a replacement, MTBE. MTBE was also eventually replaced due to groundwater and soil contamination concerns, by the BTEX complex (benzene, toluene, ethyl-benzene and xylene). Yes, BTEX, particularly benzene was also known to be toxic when it was added to gasoline.  Today, millions live in close proximity to clogged roadways where the toxic BTEX complex is burned by gasoline vehicles.  Children and fetal development is especially sensitive to vehicle pollution but no one is immune to its effects. The health, societal, and economic impacts of this silent epidemic are staggering. Just as we ‘got the lead out’, it is now well past time to remove this toxic brew – the BTEX complex — from our gasoline.

At the heart of this particular debate is the difference between two methods of fuel blending and their use, or misuse, in the EPA’s research on gasoline emissions.  The difference between “splash blending” and “match blending” of gasoline makes or breaks ethanol from a toxicity standpoint.  Splash blending is how most gasoline in the United States is formulated, and is done by simply adding 10 percent by volume ethanol to finished gasoline.  Several studies have shown that the use of splash blending reduces air toxics and pollution overall; since the addition of a cleaner burning compound lowers the volume of toxics in the gasoline.

Match blending is when the gasoline is adjusted to meet a specific boiling point, generally by adding more aromatics to gasoline (the BTEX complex).  The problem with match blending is it raises the total volume of aromatics, the most toxic portion of each gallon of gasoline, because it uses a dirtier gasoline blendstock is used from the get-go.  Therefore, if you ran emissions tests with match blended fuels, you would expect the toxics to be higher than if you ran the same test with splash blended fuels.  A paper, to be published this November in the journal of the Society for Automotive Engineers (SAE), supports this idea. It will have engineers from Ford, General Motors and AVL Powertrain Engineering Inc. weighing in on the topic.  According to the abstract, not only does the use of match blending cause the emissions profile to be worse than in splash blending, but these results are “primarily due to the added hydrocarbons, but has often been incorrectly attributed to the ethanol.”

When the 2005 Energy Policy Act was passed, the EPA was given authority to predict air toxins through modeling, in order to prevent ‘backsliding’ – i.e., inadvertently making air quality worse by changing fuel properties.  The 2014 updates to MOVES are based on studies conducted for EPA by the non-profit Coordinating Research Council (a group also supported by the American Petroleum Institute).  It is known as the EPAct E-89 study, or EPAct.  The problem with EPAct, according to EFC and UAI, is that it “used an inappropriate fuel sample methodology designed in part by a Chevron consultant.”

The bottom line is that the EPAct study used 27 different match-blended fuels as part of their methodology, which cleverly made the use of ethanol appear to be worse for air quality.  EPA itself admits that if “other fuel parameters” are considered, such as aromatics, lower emissions profiles may be possible.  In EPA’s Tier 3 rulemaking, EPA makes a huge caveat to their finding that the use of ethanol raises air toxics. EPA states that they “do not imply that the model suggests that ‘oxygenates increase PM in gasoline vehicles’ … Changes in the other fuel parameters that result from addition of ethanol also have to be taken into consideration when assessing the potential impacts on PM.” Given this, one is left with the question, why EPA then would insist on incorporating these findings into air quality models?

In their letter, EFC and UAI ask EPA to include the Department of Energy labs in their peer-reviewed fuel testing process, and for now, to exclude the MOVES model from state assessments of air quality impacts from ethanol.  According to the authors of the SAE paper, “studies to evaluate the effects of ethanol should be conducted by adjusting the blendstock only as necessary to satisfy ASTM requirements.”  Not only is match-blending an unnecessary testing method for fuel testing, it allows the oil industry to obscure the real toxins here – the BTEX complex.  This is especially troubling when one knows that in common practice, the fuel is splash blended, not match blended.



EFC & UAI Letter to EPA, Urban Air Initiative

Urban Air Initiative Calls New EPA Emission Models Flawed, PR Newswire

Issues with T50 and T90 as Match Criteria for Ethanol-Gasoline Blends, SAE

Federal Register, October 7, 2014