Mr. Chairman, I appreciate the honor of providing testimony to you and your distinguished Subcommittee on the environmental benefits of using oxygenates, particularly ethanol, under the Clean Air Act. In addition to my testimony brief, I have provided the committee with Technical Supporting Material that I would like included in the record.
I will use the brief time I have today to summarize the results of my analysis. In my analysis I look at the effects of removing oxygen from reformulated gasoline on emissions of ozone-forming volatile organic compounds, carbon monoxide, toxic air pollutants, and particulate matter. The following environmental and public health benefits result from the use of oxygenates in comparison to gasoline produced without oxygenates.
Effect of oxygenates on Toxic Emissions:
Based upon the 1998 EPA Reformulated Gasoline (RFG) compliance survey, I have estimated how refiners will produce phase 2 reformulated gasolines (RFG2) with ethanol and without oxygen and compared the resulting potency weighted toxic emissions to those from RFG2 containing MTBE. Because the various air toxics pose different cancer risks, potency weighting allows us to compare one toxic compound with another. Using these potency weightings, we can add all the toxic emissions together and compare the relative toxicity of one fuel formulation with another. Potency weighting uses benzene as the reference giving it a value of 1 and weighing other compounds against benzene. For example, if a compound has been shown to be twice as toxic as benzene, its potency weighting is 2.
Figure 1 shows how I expect refiners to produce RFG2 fuels if they were to also satisfy the 28.1% reduction in average mass toxic emission from RFG1 surveyed in 1998. Based upon public statements by refiners, I expect new alkylate production to replace most of the lost gasoline volume resulting from the removal of MTBE with aromatics being used to balance octane.
Figure 1 shows that oxygenated fuels with ethanol provide a greater reduction in potency weighted toxic emissions compared to the MTBE fuel where benzene is used as the reference weight. The non-oxygenated fuel in figure 1 has increased aromatic content. Increased aromatics are necessary to meet octane requirements. In this case, the only way for the refiner to also produce the same benzene-equivalent potency weighted toxic emissions is if olefins are reduced but there is no economic incentive for such a reduction. Therefore, we can reasonable expect refiners to increase aromatics when oxygenates are removed from the gasoline pool.
If refiners make non-oxygenated RFG with the same mass toxics reduction as oxygenated gasoline there will be a negative impact on public health because potency weighted toxic emissions will increase. These increases will be due to increases in aromatics that will be used to meet octane and other performance requirements of the fuel when oxygenates are removed.
Impact of Removing Oxygen on Summer Ozone:
I recently examined the impact of removing oxygen from RFG in a typical RFG area, Philadelphia-Wilmington-Trenton using EPA inventories and modeling tools. Removing oxygen will increase exhaust emissions of carbon monoxide (CO) from light duty vehicles. In the case of off-road engines, volatile organic compounds (VOC) and CO will both increase as a result of removing oxygen.
Both VOC and CO has been proven to be ozone-forming agents. Figure 2 shows my estimate of how removing 2% oxygen from RFG will impact the VOC and CO inventory. Figure 2 shows that ozone-forming emissions may increase by almost 3% when oxygenates are removed from RFG. Figure 3 relates the increases to the total combined VOC and CO emissions benefit for the on-road fleet when RFG2 replaced RFG1 on January 1, 2000.
The impact of removing oxygen from RFG2, either as ethanol or as MTBE, is to lose as much as 35% of the additional ozone benefits attributable to RFG2 compared to RFG1.
Impact of Oxygen on Fine Particulate Emissions:
I am also investigating the impact of oxygenates, especially ethanol, on reducing fine particulate emissions, commonly called PM 2.5. I would like to share some of my preliminary observations. PM2.5 has been identified as a public health hazard, and EPA is currently attempting to regulate PM2.5. Fine particulate from light duty vehicles is a major contributor to PM2.5 in metropolitan areas and will be so for the foreseeable future. Studies show that ethanol reduces PM2.5 emissions and heavy carcinogenic aromatics emitted from cars and trucks by 30% for clean, normal emitting cars, and 60% for dirty, high emitting cars.
Scientists have also identified aromatics as significant contributors to the formation of fine mists (aerosols) during the ozone forming process. One recent analysis estimates that aromatics are responsible for 20% to 30% of the yearly average PM2.5 in the California South Coast Air Basin. Removing oxygenates, MTBE or ethanol from gasoline, as we have already said, is likely to raise the use of aromatics in gasoline and lead to more PM2.5 pollution.
Removing oxygen from RFG is likely to result in an increase in direct emissions of particulate matter from automobile tailpipes, and the subsequent formation PM2.5 in the atmosphere through a complex series of chemical reactions, potentially harming public health.
I believe that the use of oxygen in gasoline has important environmental and public health benefits that must be maintained in any changes in the Clean Air Act. I hope that this discussion will be of value to you in your legislative actions. Thank you for your attention. I will now be happy to answer any questions you may have.