Research Supports Idea that Mid-level Ethanol Blends Are the Best Near-Term Fuel

Source: By Jessie Stolark, EESI • Posted: Sunday, September 14, 2014

The EPA recently released its Urban Air Toxics report to Congress, which documents the tremendous success that federal regulations in the last 20 years have had in decreasing air toxics that are “known or suspected of causing cancer and can damage the immune, respiratory, neurological, reproductive, and developmental systems.”  And while Americans are driving less overall, and using more fuel-efficient vehicles to do so, gasoline tailpipe emissions may be getting worse.  High octane gasoline –needed by newer engine technologies – can cause an increase in the emissions of ultrafine particulates (UFPs).  These particulates act as vectors for polycyclic aromatic hydrocarbons (PAHs), carrying them into the soft body tissues and bloodstreams which larger particulates can’t reach.   A significant source of PAHs is the incomplete combustion of gasoline aromatics – the very source of octane in gasoline. These aromatics are often referred to as the BTEX complex (benzene, toluene, ethyl benzene, xylene), and represent more than 20 percent of the volume of gasoline.  Because these aromatics boost the octane value of gasoline, oil companies are reluctant to dispense with them.Ethanol is a known octane enhancer, and may be used to replace the BTEX complex.  But, questions of overall health benefits of ethanol have been raised by public health researchers and the policy community.   While ethanol may decrease the volume of the BTEX complex, does it significantly raise aldehydes, or evaporative emissions, which are also health concerns?  Life Cycle Associates LLC., an environmental consulting firm specializing in life cycle analysis of fuel production pathways, recently conducted a meta-analysis of research on this topic.  Using research from the Department of Energy, the National Renewable Energy Laboratory, the California Air Resources Board, the Coordinating Research Council, Oak Ridge National Laboratory, Argonne National Laboratory and the University of Illinois at Chicago, they examined what the effects of a switch from E10 to E15 would mean.  Life Cycle Associates’ review focused specifically on emissions of carbon monoxide, particulate matter, hydrocarbons, and ozone forming chemicals – all significant contributors to negative health impacts.  Through their review of peer-reviewed research, they found:

    • E15 use displaces more cancer causing emissions (such as benzene and 1,3 butadiene) from gasoline 6.6 percent, relative to E10.
    • Smog forming potential is lowered further by the use of E15 versus E10.
    • E15 reduces greenhouse gas emissions 1.5 percent, relative to E10.
    • Although ethanol increases the emissions of formaldehyde and acetaldehyde, benzene and 1-3 butadiene make up 29 percent and 68 percent of the cancer risk in an E5.7 blend, while acetaldehyde makes up only 3 percent of the cancer risk of an E5.7 blend.
    • A reduction in toxic evaporative emissions – although the vapor pressure of ethanol is lower than that of gasoline – the evaporative emissions it releases are significantly less toxic than those in gasoline.

While E15 use was approved by the EPA in 2009, its adoption by fuel retailers has been slow.  On September 5, the Renewable Fuels Association (RFA) requested that the EPA revisit this issue, particularly the issue of summer blend waivers.   Fuels are blended differently depending on the season, since in the hotter summer months; evaporative emissions from fuels are higher.   Although ethanol has higher evaporative emissions relative to gasoline, EPA has acknowledged the lower resulting tailpipe emissions from E15.  According to RFA, the waiver provided to E10 recognizes that “evaporative emissions resulting from the increased volatility of E10 were more than offset by the fuels reduced carbon monoxide and exhaust hydrocarbon emissions.”  Now RFA is asking the EPA to extend the same waiver to E15, since currently, the fuel doesn’t meet summer blending requirements, despite overall lower tailpipe emissions relative to E10.  According to RFA – the fact that E15 does not meet summer blending requirements is a significant roadblock into its further integration in the fuel supply, since retailers don’t have the ability to toggle between fuel blends in a given year.

As EESI has pointed out before – mid-level blends, including E15 and E30, continue to be ignored as a potential Renewable Fuels Standard (RFS) compliance strategy.  Not only would mid-level blends help surpass the often quoted E10 ‘blend wall’, mid-level blends have multiple benefits, including lowering theoverall toxic amount of tailpipe emissions.  Already, the EPA has certified the use of E15 in make and model year cars 2001 and newer – representing about 80 percent of the cars on the road today.  These fuels have also been found to be safe for use with existing infrastructure, including gas station pumping equipment.  Just imagine – ethanol-blended fuel could even be co-deployed with both hybrid and plug-in electric vehicle technology, which could provide a fuel efficiency rating of up to 500 miles per gallon of conventional gasoline! But in order to run, you must walk first. Therefore, it should be a no-brainer to remove barriers for further E15 use.  Mid-level ethanol blends represent the best immediate solution to reducing dependence on petroleum, as well as providing an improvement for public health.

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