NREL Report Counters Big Oil’s False E15 Claim

The concept of the blend wall is based on a controversial study that has been called into question, most recently by a National Renewable Energy Laboratory analysis that identified a series of serious flaws.
By Bob Dinneen | November 22, 2013

There are legal and economical ways for refiners to meet their renewable fuel blending obligations. Instead, Big Oil is using all its energy and power to push the U.S. EPA to decrease the renewable fuels portion of the renewable fuel standard (RFS) to protect its monopoly. The petroleum industry claims its hitting a “blend wall” and is unable to blend higher levels of ethanol. They base this assertion on a controversial study by the Coordinating Research Council falsely concluding that E15 will damage vehicle engines. The National Renewable Energy Laboratory delved deeper and unveiled the many inconsistencies and problems with the CRC study, ultimately disputing any evidence that E15 caused engine damage. Therefore, no such change is needed to the RFS blending levels because the easiest and most sensible way around the blend wall is to blend more ethanol, specifically E15, which has been tested and approved by the EPA for vehicles 2001 and newer. 

NREL carefully reviewed 43 studies on the effects of E15 on engine durability, emissions and other factors and issued a report finding that the available literature “did not show meaningful differences between E15 and E10 in any performance category.” In specifically evaluating the CRC’s controversial engine durability study, NREL found “the conclusion that engines will experience mechanical engine failure when operating on E15 is not supported by the data.” 

The NREL report identified numerous flaws with the CRC engine durability study, including:

Failure to use E10 as a control fuel. Engines that “failed” on E20 or E15 were subsequently tested on E0, but not on E10 (despite the fact that E10 is the predominant in-use fuel today). This approach presumes that failures were related to ethanol content, rather than any number of other factors that could have caused the failure.

One of the engines that “failed” on E15 also failed the test on E0. Quite obviously, ethanol content had nothing to do with the failure for this engine. Yet, CRC discarded the data from this vehicle for the study’s statistical analysis. 

Cherry-picked engine sample. Despite the fact that most modern engines employ technologies that improve valve and valve set performance, CRC chose engines that do not use these technologies and, thus, were “most likely to have valve problems.” According to NREL, the vehicles chosen “included several engines already known to have durability issues, including one that was subject to a recall involving valve problems when running on E0 and E10.”

Lack of transparency in test cycle schematic. According to NREL, “the durability test cycle schematic published in CRC’s report does not contain enough detail to allow it to be independently reproduced.”

Test cycle’s maximum speed limit increased likelihood of valve damage. The CRC test cycle enforced a low maximum engine speed, which “had the effect of increasing the likelihood of valve damage, because low speed operation may decrease valve rotation rates.”

Faulty leakdown failure criteria. Most of the “failures” on E15 and E20 were related to engines that did not pass an arbitrary cylinder “leakdown” test. While other tests in the CRC study used established standards from OEMs and EPA, the leakdown test utilized arbitrary criteria with no scientific basis. According to NREL, “CRC selected a 10 percent leakdown failure limit, more restrictive (50 percent below) than that of the lowest value specified by OEMs for engines in the study.”

Incorrect use of leakage tester tool. The manufacturer of the leakage tester used states that “no cylinder will maintain 0 percent leakage” and that “this tool is best used to compare a suspect cylinder to a known good cylinder on the same engine.” However, the CRC test used the tool to measure leakage compared to an arbitrary failure criterion of 10 percent. 

Inappropriate statistical analysis. The CRC study used assumed values, i.e., dummy data, for vehicles that were not actually tested. These dummy values demonstrated consistent bias in relation to the question that the analysis was intended to determine. 

The one leg Big Oil tried to stand on regarding E15 has now been knocked out from under it. The NREL study is the next step in expanding the use of E15. It’s time for Big Oil to get out of the way so we can get back on track to continue making America a truly energy independent nation.  

Author: Bob Dinneen
President and CEO,Renewable Fuels Association