Good morning, Mr. Chairman, Senator Chafee, and other distinguished Members of the Committee. I am pleased to have this opportunity to appear before the Subcommittee this morning.
My name is Jake Garn. I am appearing on behalf of the Huntsman Corporation, headquartered in Salt Lake City, Utah. I am vice-chairman of the Board of Directors of Huntsman. Huntsman is the largest privately owned chemical company in the United States. Huntsman is the one of the largest domestic manufacturer of MTBE for the merchant market and is a member of the Oxygenated Fuels Association which represents manufacturers of oxygenates used in fuels. Huntsman's decision to make additives that clean our air is consistent with this Corporation's longstanding commitment to socially responsible actions designed to improve the lives of all Americans. The Huntsman family has contributed over $150 million to state-of-the-art cancer research facilities, home to over 300 of the world's top researchers. Our belief in protection of human health and the environment is no mere slogan; it is a promise we have made to our community.
On behalf of the Huntsman Corporation, I want to commend the Chairman Inhofe and Chairman Chafee for convening the Subcommittee to examine the findings and recommendations of the Blue Ribbon Panel. As the manufacturer of a significant amount of MTBE, we have an obvious interest in the BRP's findings and recommendations and, perhaps more importantly, in the actions Congress may take based on those recommendations.
We agree with much of what the Blue Ribbon Panel concluded. For example, we agree that more research and monitoring is necessary concerning the health effects of not only MTBE, but also other constituents of gasoline. However, we have strong concerns with several of the BRP's conclusions. Most importantly, we disagree strongly that there is sufficient justification to recommend a substantial reduction in the use of MTBE. As described in greater detail below, we believe that the BRP left many important questions unanswered. Unfortunately, the BRP is gone and the responsibility to answer these questions falls to the Congress, and to this Subcommittee in particular. Until those questions are answered, we believe it is inappropriate to move forward with any effort to amend the Clean Air Act to modify the reformulated gasoline program. We appreciate this opportunity to contribute our thoughts on how Congress should endeavor to answer these remaining important questions.
II. Huntsman and MTBE
Huntsman Corporation is one of the largest producers of MTBE in the United States. It has been producing MTBE since early 1998 when it acquired Texaco's MTBE-producing facility in Beaumont, Texas. The company sells its MTBE product to refiners who, in turn, use it to meet the requirements of the Clean Air Act.
III. The Blue Ribbon Panel Recommendations
As you know, in 1998 EPA Administrator Browner appointed a Blue Ribbon Panel (BRP) to investigate the air quality benefits and water quality concerns associated with oxygenates in gasoline, and to provide independent advice and recommendations on ways to maintain air quality while protecting water quality. The BRP met on several occasions and issued its final report in July 1999. Mr. Greenbaum, the chairman of the BRP, is better qualified to describe the work of the Panel and to summarize its findings and recommendations. I would like to take this opportunity to explain why Huntsman agrees with some -- but not all -- of those findings and recommendations.
A. Points of Agreement
The BRP made a number of findings and recommendations with which Huntsman Corporation agrees. They are, in significant part, the following:
-- that MTBE has been detected in a number of water supplies nationwide, primarily causing consumer odor and taste concerns that have led water suppliers to reduce use of those supplies. The Panel further found that incidents of MTBE in drinking water supplies at levels well above EPA and State guidelines have occurred, but are rare;
-- that MTBE is currently an integral component of the U.S. gasoline supply both in terms of volume and octane, and as such, changes in its use, with the attendant capital construction and infrastructure modifications, must be implemented with sufficient time, certainty, and flexibility to maintain the stability of both the complex U.S. fuel supply system and gasoline prices;
-- that the BRP's recommendations were intended to "simultaneously" maintain air quality benefits while enhancing water quality protection and assuring a stable supply at reasonable cost;
-- that EPA should take actions to enhance significantly the Federal and State Underground Storage Tank programs;
-- that EPA should work with its State and local water supply partners to enhance implementation of the Federal and State Safe Drinking Water Act programs;
-- that EPA should work with States and localities to enhance their efforts to promote lakes and reservoirs that serve as drinking water supplies by restricting use of recreational water craft, particularly those with older motors;
-- that EPA should work with other Federal agencies, the States, and private sector partners to implement expanded programs to protect private well users;
-- that we should expand public education programs at the Federal, state, and local levels on the proper handling and disposal of gasoline;
-- that we should develop and implement an integral field research program into the groundwater behavior of gasoline and oxygenates;
-- that EPA should work with Congress to expand resources available for the up-front funding of the treatment of drinking water supplies contaminated with MTBE and other gasoline components to ensure that affected supplies can be rapidly treated and returned to service, or that an alternative water supply can be provided;
-- that States should reexamine and enhance State and Federal "triage" procedures for prioritizing remediation efforts at UST sites based on their proximity to drinking water supplies;
-- that we should accelerate laboratory and field research, and pilot projects, for the development and implementation of cost-effective water supply treatment and remediation technology, and harmonize these efforts with other public/private efforts underway; and
-- that we should identify and begin to collect additional data necessary to adequately assess the current and potential future state of contamination.
B. Points of Disagreement
However, there is one important recommendation of the BRP with which we emphatically do not agree. The BRP recommended that "in order to minimize current and future threats to drinking water, the use of MTBE should be reduced substantially." The BRP also recommended that the current Clean Air Act mandate requiring 2 percent oxygen, by weight, in RFG must be removed in order to provide flexibility to blend adequate fuel supplies in a cost-effective manner while quickly reducing usage of MTBE and maintaining air quality benefits. As a member of the Oxygenated Fuels Association, Huntsman Corporation has supported refiner flexibility through removal of the oxygen standard as long as adequate assurances of no air quality backsliding are provided. Concurrently, we have encouraged EPA to review its authority under existing law to provide such flexibility. However, we must object strongly to the suggestion that there is a sufficient basis of knowledge upon which to base a recommendation to limit the amount of use of MTBE, an effective tool to reduce air pollution.
C. Comments on the BRP's Recommendation to Reduce Substantially the Use of MTBE
We believe several comments are in order concerning the BRP's recommendation to reduce substantially the use of MTBE. I hope what is evident from the following discussion is that Huntsman Corporation does not challenge the mandate of the BRP or the great majority of its findings and recommendations. Instead, Huntsman believes that for a variety of reasons, the BRP was unable to finish the job, and it now falls to Congress to answer the remaining questions, including both questions of fact and questions of policy.
1. The BRP Made No Finding Concerning Health Effects of Exposure to MTBE
It is important to note that the BRP did not make any finding concerning the health effects of exposure to MTBE. The Panel acknowledged that was not constituted to perform an independent comprehensive health assessment. Of course, it could not perform such an assessment and report to EPA in the limited time available to it. Instead, the Panel chose to rely on "recent reports by a number of state, national, and international health agencies."
We now understand that there is negligible risk associated with exposure to levels of MTBE being reported in drinking water supplies. It is instructive to review the status of reports by state, national and international health agencies.
There is currently no regulated standard for MTBE in drinking water under the Federal Safe Drinking Water Act. EPA has published an Advisory document on MTBE which recommends that keeping levels of contamination in the range 20 to 40 micrograms per liter or below "to protect consumer acceptance of the water resource would also provide a large margin of exposure (safety) from toxic effects." By its authority under the Federal Safe Drinking Water Act, EPA recently issued a regulation requiring most public water systems to monitor levels of a number of unregulated contaminants, including MTBE. EPA will use this information, together with the results of research on the human health effects of MTBE, to determine whether it should regulate the amount of MTBE permissible in drinking water.
For over a decade, scientists have studied MTBE to identify its toxic properties and to determine whether they might be manifest in people exposed to small concentrations in air and water. MTBE, like all other chemicals, has the ability to cause some injury at sufficiently high dosages. Extensive research has indicated that the MTBE doses required to produce illness in laboratory animals are thousands of times greater than those humans could conceivably be exposed to. Furthermore, MTBE has been shown to be incapable of impairing fertility, or of damaging the developing fetus. Also, based on numerous tests, MTBE is incapable of damaging the genetic structure of cells, greatly reducing the chance that it might affect numerous bodily processes controlled by a person's DNA.
As explained earlier in this testimony, Huntsman agrees that there should be more research on the health effects of exposure to the all constituents of gasoline, including MTBE. Indeed, wherever MTBE is detected, there are likely to be other, potentially more harmful constituents of gasoline present. However, there is not yet sufficient evidence of harmful health effects from MTBE. The BRP accurately reflects this absence of such evidence. Without such evidence, and in light of the overwhelming evidence of benefits from the use of MTBE in gasoline, it is not appropriate to recommend that the use of MTBE be reduced substantially.
The latest scientific evidence concerning the health effects of MTBE must be considered together with the most recent information concerning the scope of MTBE contamination in drinking water. There is evidence to indicate that MTBE contamination of drinking water sources is limited to geographic pockets within the United States, and that the number of gasoline effected wells that exceed national guidelines and state primary and secondary drinking water standards is small. The Water Contamination Issue Summary shows primary and secondary drinking water standards and action levels for States that have them. The average secondary standard (aesthetically based) is over 20 ppb and the average primary standard (health based) is over 50 ppb. Yet, Table 1 of the same report shows that only 1% - 2% of all wells tested so far exceed 5 ppb of MTBE. Therefore, the number of wells that exceed State standards is small enough to be manageable.
2. The BRP Underestimated the Air Quality Benefits of Oxygenates
Huntsman Corporation is also concerned that the BRP underestimated the air quality benefits of oxygenates. The BRP recommendations are predicated on the regulatory requirements established in EPA's existing RFG rules. They fail to recognize that the RFG program (with MTBE as the oxygenate of choice in 80 percent of the market) has exceeded by nearly double the requirements of EPA's regulations. By underestimating such benefits, it is easier for the BRP to assume that other fuel formulations can achieve the same, or better, air quality benefits.
According to EPA's May 24, 1999 RFG Fact Sheet, oxygenates such as MTBE substantially reduce toxics such as benzene and other aromatics. Oxygenates also dilute or displace other fuel components like sulfur, which in turn reduce emissions of the smog precursors VOC and NOx. They also provide additional reductions in the distillation temperatures of gasoline. These improvements are important in reducing vehicle exhaust emission, particularly during the first few minutes of cold engine operation when the catalytic converter is not fully operational.
Unfortunately, the BRP underestimated the real-world air quality benefits of MTBE (and oxygenates, in general) in its narrow application of emission prediction models. Air quality predictions using these models ignore many of the remaining benefits that were identified during the Panel's meetings and presented in the Air Quality Issue Summary.
Throughout the recent debate, it has been convenient to ignore a large portion of oxygenate air quality benefits, to ascribe them to other fuel parameters, or to discount them altogether in favor of automotive technology advances. Real world impacts, such as the contribution of oxygenates to improved combustion before a vehicle's catalytic converter achieves normal operating efficiency, have been largely ignored. Similarly, the "leaning-out" benefits of off-road gasoline engines without catalytic converters have remained unaccounted for even though their percent share of the total emissions picture continues to rise. The benefits of lower combustion deposit formation and associated decrease in particulate emissions are also not quantified. Indirect oxygenate dilution benefits of undesirables such as olefins, sulfur and aromatics are typically discounted by the suggestion that refiners will find some other way to achieve them. The same is true for positive drivability impacts associated with improved oxygenated fuel midrange volatility. In their eagerness to obtain oxygenate flexibility, refiners have clearly misrepresented the degree of difficulty involved in replacing MTBE.
The risk of backsliding on the air quality gains of the last decade looms large in the horizon. This fact is demonstrated by recent claims by California refiners that they face great difficulty in achieving the actual air quality benefits of that state's clean burning gasoline (CBG) without MTBE, according to an August 20, 1999 "Inside CalEPA" article. Regulators are not clear on how to preserve the air quality benefits of CBG without MTBE.
Several years ago, EPA asked the National Research Council (NRC) to (1) assess whether the existing scientific information allows a comparison of the ozone forming potential of automotive emissions obtained with different reformulated gasolines, and (2) evaluate the impact of applying the "ozone forming potential" approach to air quality on the overall assessment of oxygenate benefits within the RFG program.
The NRC's recent report on Ozone-Forming Potential of Reformulated Gasoline raises serious questions regarding the contribution of cleaner burning facts to the nation's air quality program in general, and the specific contribution of oxygenates in cleaner burning gasoline formulation. The NRC report correctly captures the impact of the substantial advances in automotive emissions controls over the past decades. However, it diminishes the value of fuel controls by ignoring real-world impacts and focusing exclusively on direct oxygenate impacts on ozone. A more detailed discussion of the NRC report was prepared by the Oxygenated Fuels Association, of which Huntsman is a member, and is attached as Appendix A.
3. The BRP Did Not Have the Most Up-to-date Information on the Underground Storage Tank Program
The BRP presented detailed recommendations aimed at making the Underground Storage Tank (UST) program more effective. Huntsman Corporation agrees with those recommendations. Unfortunately, when the BRP made its recommendations, it did not have the most up-to-date information on the effectiveness of the UST program. Had the BRP had this information, its recommendation would still have been appropriate, but it would have had even less basis upon which to recommend a substantial reduction in the use of MTBE.
Most MTBE detections in groundwater were found prior to the UST regulation implementation deadline (December 1998). The MTBE contamination data presented by the USGS and reviewed by the BRP was collected between 1988 and 1998 when underground storage tanks were only 25% to 50% in compliance with EPA's regulations. Data presented by the Association of State and Territorial Solid Waste Management Officials (ASTSWMO) show that less than 50 percent of all USTs were in compliance prior to 1998 and that as recently as 1996 only 30 percent were in compliance.
There is also evidence that the risk of drinking water contamination by MTBE and other gasoline constituents has been greatly reduced with the onset of UST regulation compliance. The University of California at Davis study, part of which was presented to the BRP March 25 & 26, 1999, showed that tank failure rates decrease by over 95 percent (from 2.6 percent failures per year for non-upgraded tanks to 0.07 percent per year for upgraded tanks) once tanks were upgraded to the current UST regulations. Also, with the required installation of early leak detection monitors, the time between when a leak occurs and when it is detected should be significantly reduced. As a result, the amount of gasoline released from a site before it has been remediated is minimized. Both of these effects combined should lead to substantial reductions in the amount of MTBE and other gasoline components that escape undetected.
4. The BRP Failed to Adequately Assess Alternatives to MTBE
One of the most disturbing shortcomings of the BRP's report is its failure to provide an analysis of the alternatives to MTBE. The BRP's recommendation to reduce the use of MTBE is of little use to policymakers if there is no credible alternative. It is our view that potential alternatives should be evaluated according to the same criteria by which MTBE is judged, to wit:
-- whether the alternative yields the same real air quality benefits as MTBE;
-- whether the alternative presents no significant risk to human health and the environment; and
-- whether the alternative is preferable from the standpoint of cost and availability.
Huntsman Corporation agrees with the BRP recommendation to more fully investigate any major new additives to gasoline prior to their introduction. We would expect that this process should apply to the alternatives already identified by the panel, namely ethanol, alkylates, and aromatics. We should be hesitant to accept expanded use of these alternatives without more rigorous analyses of their respective impacts on human health, air and water quality, as well as gasoline supply and price.
It is especially disturbing that the most often suggested alternative to MTBE ethanol has not been subjected to a more rigorous analysis under the criteria set out above. For example, there are serious questions as to whether ethanol yields the same real/air quality benefits as reformulated gasoline using MTBE. Ethanol has a higher volatility; it evaporates more readily, creating more air pollution. EPA has acknowledged that the increased use of ethanol will result in increased emissions of nitrous oxides (NOx). And in addition to contributing to ozone exceedences, emissions of NOx contribute to elevated ambient levels of nitrogen dioxide and fine particulate matter, both of which are criteria pollutants for which EPA has established national ambient air quality standards.
Even assuming that there are some air quality benefits from the use of ethanol, those benefits as likely to be outweighed by the environmental costs of growing more corn and other ethanol feedstocks. The production of corn in the United States involves substantial applications of fertilizers, herbicides and pesticides. It would be interesting to compare the current incidence of MTBE contamination in drinking water supplies with the incidence of drinking water supplies contaminated with atrazine and other farm chemicals if corn production were to expand to the level necessary to produce enough ethanol to replace MTBE as an oxygenate in reformulated gasoline.
The BRP also failed to consider important issues related to the cost and availability of alternatives to MTBE, especially ethanol. First, ethanol production results in a net negative energy yield; it has been proven that it takes more energy to make a gallon of ethanol than you get from that gallon of ethanol. According to the Department of Agriculture, it takes 75,000 to 95,000 Btu's for a gallon of ethanol, and yet the gallon of ethanol yields only 76,000 Btu's.
Second, each gallon of ethanol receives a tax subsidy of 54 cents. In a March 1997 letter report, the U.S. General Accounting Office estimated that the subsidy for alcohol fuels reduced motor fuels excise tax revenues by about $7.1 billion from fiscal years 1979 to 1995. Congressman Bill Archer, Chairman of the House Ways and Means Committee, has estimated that the ethanol tax credit will cost American taxpayers approximately $2.4 billion between 1997 and 2000.
In addition, expanded ethanol production will increase the cost of gasoline at the pump, and will add to consumers' grocery bills. The cost of gasoline at the pump will increase because there will be less competition among fuel additives. The cost of food products will increase because as the demand for corn increases, the cost of corn used as animal feed will increase. Thus, the price of pork, beef and chicken in the supermarket will increase.
Finally, there is no guarantee that ethanol can replace MTBE as the oxygenate of choice without creating serious supply disruptions and, as a result, price increases. Because of its physical characteristics, ethanol cannot be blended with gasoline at the refinery and shipped by pipeline or barge to the marketplace. It must be transported separately and blended with gasoline near the location where it is to be sold to consumers. This limitation on the ability to transport gasoline with ethanol presents additional risks of supply disruptions and price dislocations. Right now, ethanol is being supplied to metropolitan areas in the vicinity of the ethanol producing facility with reasonable reliability. It remains to be seen whether ethanol could be transported nationally in a reliable and cost-effective fashion.
Ultimately, the net impact of whatever decision is taken will be reflected in the economics of the marketplace. There can be no doubt that the mandated use of oxygenates, primarily achieved by MTBE use, extends the nation's fuel supply. This helps keeps prices in check and helps overcome localized spot shortages when they do occur. The recent California experience of increased MTBE use during gasoline shortages brought about by refinery hardware problems serves as a clear reminder of that fact. California Energy Commission studies showed a cost of 3-7 cents per gallon to remove MTBE from California's gasoline, assuming essentially unlimited and reasonably priced supplies of clean burning replacement blendstocks of ethanol and alkylate.
The true economic impact of a national phase down (or phase-out) of MTBE is likely to be dramatically higher, depending on the specifics of the action taken. MTBE makes up 10 to 15 percent of gasoline volume in RFG markets. With refinery capacity utilization currently running at 98 to 99 percent in the U.S., it is not difficult to see that drastic action could have catastrophic consequences. Members of Congress should insist on fully defining this price and supply risk to the American motoring public before it considers modification of the Clean Air Act.
IV. Conclusion
Again, on behalf of the Huntsman Corporation, I would like to thank the Subcommittee for this opportunity to present our views on this important issue. We respect the work that the Blue Ribbon Panel has conducted and agree with many of its recommendations. At the same time, we feel strongly that the Blue Ribbon Panel's report is only the first albeit important step toward addressing the problem of contamination of drinking water supplies. We hope we have identified some of the important questions that the BRP has highlighted and which remain to be fully answered. Until those questions are answered, we believe there is no sound basis upon which to limit the use of a chemical -- MTBE -- which has helped to achieve important air quality goals.
Appendix A
Comments on: National Research Council Report
An Analysis of the National Research Council's Report on Ozone-Forming Potential of Reformulated Gasoline
Oxygenated Fuels Association, Inc. Arlington, Virginia May, 1999
SUMMARY
The recently issued report by the NRC's Committee on Ozone-Forming Potential of Reformulated Gasoline, raises serious questions regarding the contribution of cleaner burning fuels to the nation's air quality improvement programs. The study questions the effectiveness of the reformulated gasoline program in general, and the specific contribution of oxygenates (such as MTBE and ethanol) in cleaner burning gasoline formulations. Several of the study's conclusions appear to contradict real-world air quality monitoring results and are inconsistent with previously held beliefs that the use of RFG significantly improves air quality.
The NRC Committee searches for certainty in the complex field of fuel contributions to atmospheric impacts, where few simple, direct cause-and-effect answers exist. The NRC report correctly captures the impact of the substantial advances in automotive emissions controls over the past decades. However, it improperly diminishes the value of fuel controls by ignoring real-world impacts and focusing exclusively on direct oxygenate impacts on ozone. More specifically, the report suffers from several fundamental drawbacks:
-- It ignores real world air quality shifts associated with cleaner burning oxygenated fuels. EPA data based on actual RFG air quality surveys clearly indicate that, since 1995, the reformulated gasoline program has delivered emissions benefits substantially exceeding the minimum anticipated requirements. While vehicle technology advances have contributed the lion's share of the ambient air quality gains recorded since the 1960s, it is difficult to see how vehicle controls have changed substantially since the introduction of RFG. Furthermore, although the NRC report briefly alludes to real-world conditions when the vehicle emissions controls may not be active (i.e., cold start) or are not operational (high emitters), it largely bases its conclusions on laboratory controlled engine testing on low emitters (newer, well-maintained vehicles) under equilibrium conditions, where fuel contributions are appreciably diminished.
-- It attempts to identify an exclusive, direct oxygen contribution to ozone abatement, similar to the one seen for carbon monoxide. Such an impact can not be supported on newer vehicles featuring advanced emission controls. However, understanding the indirect pathways by which oxygenates impact ozone, is essential to the overall assessment of oxygenate benefits. The report does not credit oxygenates for indirect impacts on other key fuel parameters that do, in turn, impact VOC and NOx emissions. By diluting gasoline sulfur, olefins, aromatics and benzene, and lowering gasoline mid-range volatility, oxygenates substantially (albeit indirectly) impact ozone precursor formation. Furthermore, oxygenates allow refiners octane flexibility to implement operating changes that reduce gasoline benzene and aromatics content. When these indirect VOC and NOx ozone precursor reductions are considered along with Carbon Monoxide reductions, NRC's focus solely on direct ozone impacts appears oversimplified and misleading.
-- The Committee clearly exceeded its primary task (i.e., assess RFG ozone impacts) to evaluate impacts on other pollutants such as carbon monoxide, air toxics, etc. A comprehensive review of RFG and oxygenate benefits is ordinarily welcomed; however, the NRC report is largely superficial in presenting oxygenate impacts on these other key pollutants. The report does grant that "the most significant advantage of oxygenates in RFG appears to be a displacement of some toxics (e.g., benzene) from the RFG blend, which results in a decrease in toxic emissions." This substantially understates the facts: according to EPA, oxygenates are responsible for approximately two thirds of the large overcompliance reported in air toxics since the introduction of the RFG program. Similarly, oxygenates are directly responsible for a 10-15% reduction in CO. As a result of focusing only on direct ozone impacts and the inadequate treatment of non-ozone pollutants, the NRC report leads to the improper conclusion that oxygenates have no air quality benefits.
-- Lastly, the report leads to the erroneous conclusion that fuel controls may not play a key role in future air quality strategies. A key premise of the current RFG program is that reformulated fuel and vehicle controls contribute to emissions reductions in a mutually complementary way, i.e., they have been designed to function as a closely interactive system. In very simple terms, poorly performing vehicles are likely to pollute more and the fuel's role in optimizing vehicle performance is critical. The need for lower sulfur, improved distillation index controls and reduced combustion chamber deposits (CCD) are all testaments of the close coupling between fuel controls and vehicle technologies. Furthermore, in dismissing fuel contributions as potentially "small," the report ignores the regulatory dilemma of identifying additional and/or alternative air quality controls in the face of ever increasing vehicle miles traveled and continued pressure to improve ambient air quality. Ozone control strategies often depend on small incremental reductions in VOC or NOx emissions, which should be evaluated in terms of their magnitude and cost effectiveness versus remaining candidate controls, and not already implemented strategies.
BACKGROUND
At the request of Congress, the U.S. Environmental Protection Agency (EPA) asked the National Research Council (NRC) to:
-- Assess whether the existing scientific information allows a comparison of the ozone forming potential of automotive emissions obtained with different reformulated gasolines,
-- Evaluate the impact of applying the "ozone forming potential" approach to air quality on the overall assessment of oxygenate (i.e., methyl tertiary-butyl ether and ethanol) benefits within the RFG program.
The NRC report's conclusions were unexpected. While the study concedes that ground level ozone has declined by more than 10% since 1995, it claims that it is not possible to attribute a significant portion of these benefits to the introduction of reformulated gasoline during this period. Instead, the NRC study concludes that overall emissions of ozone precursors have substantially decreased in recent decades, largely as a result of better emissions control systems on vehicles. Furthermore, given the declining contribution of fuel formulations to air quality, the study concludes that, the direct contribution of oxygenates to ozone reduction is very small. Lastly, the NRC finds that evaluating fuel formulations based on their ozone reactivity potential (rather than strictly comparing mass emissions) does not alter the study's conclusions, even though it acknowledges that the ozone forming potential of carbon monoxide in exhaust emissions is large and has not been comprehended in existing fuel evaluation tools.
DISCUSSION
Real World Emissions Performance
The NRC study acknowledged that ambient monitoring data demonstrate RFG successfully helps reduce ozone levels, and lowers overall ambient air toxics levels. According to EPA data, Phase I RFG areas have performed better than planned:
-- VOC reductions average 36% in the south and 17% in the north (goal is 15%); -- Air toxics reductions average 22% (goal is 16.5% when averaging) -- NOx reductions average 3% (goal is 1.5% when averaging); -- Ambient benzene levels have decreased by 43%.
EPA's RFG Survey Group has estimated the average vehicle emission reductions by using fuel surveys for each of the cities in the Federal RFG Phase I program:
-- Reductions in toxics from vehicles for all RFG cities far exceed the Performance Standard and that the average reduction is about double the requirement. More specifically, reductions in cities with RFG/MTBE blends exceed 35 percent in most cases while the average reduction for the four cities using RFG/ethanol blends is only about 27 percent. It would appear that the 2% oxygen standard and the benzene standard in RFG combine to provide a reduction in toxic emissions that is much greater than the Phase I Performance Standard as well as the Phase 2 Performance Standard for the year 2000 (22% minimum average reduction). Without the oxygen requirement, the toxic reductions with RFG would be expected to decrease to near the performance standard.
-- NOx reductions with RFG are more than double (in many cases more than triple) the Performance Standard required by CAA regulations (1.5% reduction). In most cases, the NOx reductions with the MTBE/RFG blends are a few percentage points greater than that observed with the cities using ethanol blends. Low RVP fuels actually increase NOx emissions and are, thus, ineffective program for reducing peak ozone.
-- VOC reductions for RFG cities generally exceed the corresponding performance standard by 1.5 to 8 percent. The performance standard for VOC reduction is more severe for southern cities as compared to northern cities. The cities using RFG with ethanol are all located in the north while low RVP cities (Atlanta, St. Louis, Phoenix, etc) are mostly located in the south. There is little difference between RFG made with ethanol and MTBE in reducing VOC emissions. However, low RVP gasoline only provides about two-thirds of the VOC reduction as that observed for southern RFG cities.
Based on ambient monitoring data, RFG areas have performed better than conventional gasoline areas (including lower vapor pressure areas) in lowering the frequency of ozone exceedances as shown in Figure 1. By focusing on percent change, the effects of fleet turnover, weather, economic activity and related factors cancel out in the comparison. The control data set used was conventional gasoline areas because fuel standards did not change in those areas.
Figure 2 shows that MTBE is less likely to form ozone than most gasoline components. Only benzene, which is reduced in RFG, has a lower potential. Limited Auto/Oil results comparing "matched" oxygenated and a non-oxygenated reformulated gasoline blends showed that the oxygenated fuel had a 5-7% lower ozone forming tendency. It is noted that the results of that study likely underpredict the ozone reactivity impact, since despite efforts to control the experimentaldesign, the oxygenated fuel had an octane value of 2.4 numbers above that of the non-oxygenated fuel. If the fuels had been octane balanced, the differences in emissions would have been even greater in favor of the cleaner burning oxygenated gasoline.
Direct Performance Benefits of Oxygenates
The NRC study examined the direct impacts of oxygen on VOC and NOx. The Committee did not attempt to identify the significant indirect benefits of oxygenate blending to RFG. The Table below provides a simplified roadmap to understanding the relative direct and indirect contributions of oxygenate blending to reduced gasoline emissions.
FIGURE
The NRC's main focus was on the direct impact of oxygenates on VOC and NOx. As shown on the table above, this is correctly judged to be a rather insignificant impact. The primary fuel impacts on VOC are vapor pressure (RVP), midrange distillation (T50) and sulfur content. For NOx, the primary impact variables are olefin content and sulfur. The assumed oxygen level in this Table is 2 weight percent; at this level the NOx impact is negligible. However, as the NRC report points out, at 3.5 weight percent oxygen (i.e., maximum ethanol) can lead to increased NOx emissions.
The problem with the NRC analysis is that it fails to recognize the large indirect impacts that oxygenate addition would have on a typical conventional fuel:
-- 10-15% dilution impact in sulfur, olefins, aromatics and benzene
-- 15-20 degree Fahrenheit depression in T50
-- 4-7 degree Fahrenheit reduction in T90
-- 6-8 volume percent reduction in aromatics content
-- 0.2-0.3 volume percent reduction in benzene
Oxygenates do not contain sulfur, olefins aromatics or benzene; they dilute their presence in the RFG blend. Dilution is very important to allow refiners to achieve the RFG air standards while maintaining fuel quality. High oxygenate octane values contributes to aromatics reduction by permitting lower severity in the key catalytic reforming step. Without oxygenate blending, most refiners would find it extremely difficult to produce satisfactory RFG in the premium grade, and probably in the mid-range grade. Such blending advantages for MTBE were unaccounted for in the NRC study.
It should be noted that of the four pollutants listed above, only CO is directly impacted in a very large way by oxygenates. However, this diminish our view of the value of oxygenates in generating overall pollution reduction benefits:
While there is no direct impact on VOC, the indirect effects of lowering midrange distillation, diluting and replacing aromatics, and reducing sulfur combine for to yield a sizeable VOC reduction benefit, estimated at approximately 10-15% of the total RFG VOC reduction.
Similarly, the combined impact of indirect aromatics and benzene reductions resulting from dilution and refinery operating adjustments is equally large at approximately 20% of the overall RFG air toxics benefit.
The large direct contribution of oxygenates to CO reduction is amplified by indirect benefits accruing as a result of the reduction in sulfur and T50. As a result, the portion of RFG's CO reduction benefits attributable to oxygenate use exceeds 30%.
Of the four pollutants listed, only oxygenate contributions to NOx could be described as "small." This is because the oxygenate benefits are primarily accruing as a result of the 10-15 dilution expected in sulfur and olefins content via dilution.
The discussion above is not aimed at fully comprehending all the indirect benefits of oxygenates. For example, reduction in fuel aromatics content should result in lower fuel combustion chamber deposit forming tendency, which will, in turn, result in additional air quality benefits. Furthermore, while the NRC acknowledges that "as VOC emissions from mobile sources continue to decrease in the future, CO will become proportionately an even greater contributor to ozone formation," it fails to credit the large direct contribution of oxygenates in this area.
In conclusion, it would appear that the assessment of oxygenates in cleaner burning gasolines is largely dependent on the reviewer's definition of the action pathways or mechanisms included in the accounting of air quality impacts. While there can be little doubt that oxygenates have a substantial favorable impact on the remaining fuel properties, the NRC study (like the University of California study before it) does not credit oxygenates with any of the emissions shifts associated with these secondary fuel impacts. While it can be argued that such oxygenate benefits can be replaced and thus should not be credited entirely to oxygenate use, there exists no basis to completely discount indirect oxygenate impacts. Moreover, by failing to focus on real world performance results, reviewers such as the NRC have tended to underestimate the fuel's contribution to the air quality gains of the recent past. This, in turn, risks projecting the erroneous view that there is limited value in the fuel component of what has heretofore been a very successful partnership between reformulated gasoline and vehicle emissions controls.