Reformulated Gasoline in Metro-Atlanta

An analysis of E10 Reformulation

CEE/EAS 6792

Burcak Kaynak &

Grant T. Michalski

Why Is This Issue Important?

• “Court Orders New Fuel Mix” – AJC 10/8/04– Result of Atlanta’s problems with ground-level ozone

concentrations.• 1999-2002 168 recorded violations of 0.085 ppm 8-hour

ozone standard.

– Federally-mandated reformulated gasoline (RFG) would contain 10% ethanol to act as an oxygenate and octane enhancer.

• 13 Metro-Atlanta counties required to switch to a federally designed fuel by mid-January.

Why Is This an Issue?

• Clean Air Act, 1990 Amendments– Title II, Section 211 (k) (1) – “the [EPA] Administrator

shall promulgate regulations under this section establishing requirements for reformulated gasoline to be used in gasoline fueled vehicles in specified nonattainment areas.”

– Atlanta recently designated as being in “Severe Nonattainment” for ozone.

– As of 1999, 29 areas in 18 states used reformulated gasoline.

Why Is This an Issue?

• State of Georgia claims the new gasoline will cost more, and increase air pollution.– Estimates predict reformulation could increase

gasoline costs by 5 cents per gallon.– Studies show that new gasoline would increase certain

emissions while decreasing others.

• April 1999, California requests exemption for RFG– EPA denies request in June of 2001

1990 Clean Air Act Amendments

• Objectives– Enhance octane rating– Reduce air pollution

• Smog in summer months• CO in winter months• Air toxics year-round

– Enhance energy security by extending the gasoline supply through the use of oxygenates.

– Encourage the use of domestically-produced, renewable energy sources.

1990 Clean Air Act Amendments

• Requirements for reformulated gasoline– Must contain 2% (by weight) oxygen.

• Ethanol not specifically required.

– Limits benzene to 1% by volume.• Non-RFG can contain as much as 5% benzene.

– Limits total aromatics to 25% by volume.• Aromatics include benzene, ethylbenzene, toluene, xylene• Non-RFG can contain as much as 50% aromatics.

– Limits NOx emissions to non-reformulated levels.

1990 Clean Air Act Amendments

• Options for meeting CAA requirements:– Addition of 11% (by volume) of methyl tert-butyl ether

(MTBE)– Addition of 5.7% (by volume) ethanol.

1990 Clean Air Act Amendments

• Separated into 2 phases– Phase 1 (January 1995)

• Reduce VOCs and Air Toxics by 15%

– Phase 2 (January 2000)• Reduce VOC and Air Toxic emissions by an additional 5-10%

(to be determined by the EPA Adminstrator)

Benefits of E10

• Enhanced Octane Rating– Reduces “knocking”

• Reduces emissions of certain air pollutants by providing for more complete combustion.

• Reduced levels of harmful aromatics in gasoline.• Reduce amount of crude oil needed for a gallon of

gasoline.• Provide additional use for domestically-grown corn

in the production of ethanol.

Benefits of E10

• Equivalence Ratio = (amount of fuel)/(amount of oxygen)

Benefits of E10

• PM2.5 from automobiles is primarily soot.

• Soot and Carbon Monoxide (CO) are both products of incomplete combustion.

• Adding oxygen (through the use of oxygenates) improves combustion efficiency.

• Hydrocarbon (HC) emissions are also reduced, largely due to the increased combustion efficiency.

Benefits of E10

• Reduced Greenhouse Gas (GHG) emissions– RFGs are more fuel efficient than non-reformulated

options. Less GHSs are produced.

• Reduction of benzene emissions– Dilution effect– Reduced incidence of cancer due to benzene

Issues with E10

• NOx

– Typically, engines operate at an equivalence ratio of Φ=1 (stoichiometric amount of oxygen fed with fuel)

– Adding oxygenates decreases the equivalence ratio.

– NOx peaks at equivalence ratios just less than 1.

– Mixed data on effect on NOx emissions, though one study shows that with RFG, emissions from pre-1986 cars dropped 0.5%, while increasing 5% with post-1986 cars.

Issues with E10

• Ethanol– Increased permeation through polymer materials.– Increased soil and groundwater contamination.

• Ethanol increases corrosion steel underground storage tanks.

– Increased risk of leakage to surrounding soil.

– Material incompatibility with several components of fueling systems.

– Inhibits bioremediation and natural attenuation of NAPL by affecting NAPL/water interface.

Issues with E10

• Ethanol (continued)– Toxicity of ethanol.– Low (occasionally negative) Net Energy Value (NEV)

• Ethanol production occasionally requires more energy to produce than is released in its combustion.

• Energy used to produce ethanol typically comes from power plants, resulting in a relocation of combustion emissions.

Issues with E10

• Evaporative losses– Above 16° C (61° F), E10 exhibits a higher Reid Vapor

Pressure (RVP) than standard gasoline (E0)– Higher vapor pressure implies greater volatility, more

evaporation.– Evaporation causes release of additional air toxics, as

well as VOCs.

Issues with E10

• Ozone (O3)

– VOCs + NOx + sunlight = O3

ROG (ppm C)

NOx

(ppm)

O3

ROG/NOx = 5

A

B

0.5 1.25

0.25

0.10

Issues with E10

• Acetaldehyde– RFG increases acetaldehyde emissions by 100-200%– Chemically similar to ethanol

• Ethanol (C2H5OH) vs Acetaldehyde (C2H4O)

– Precursor to Peroxy Acetyl Nitrate (PAN)• Important chemical in long-range transport of NOx

– Probable carcinogen

Issues with E10

• Acetaldehyde (continued)– Cost-benefit analysis from 2000 compared decrease in

incidence of cancer from benzene emissions to increase in cancer from acetaldehyde due to use of RFG

– Analysis predicted savings from reduction of benzene-related cancer of $2.4-65 million per year.

– Same analysis predicted annual cost due to acetaldehyde-related cancer to be $2.7-200 million per year.

Alternatives to E10

• Methyl Tertiary-Butyl Ether– Provides better results for air quality, but has been

found in groundwater since its use as an oxygenate.– Generally discounted as an option

• Alkylates– Highly-branched alkanes with low aromatic content– Meet many of the objectives of RFG– Do not contain oxygen

• Do not meet CAA requirements for RFG

Conclusions

• E10 can be shown to reduce emissions of carbon monoxide (CO), hydrocarbons (HC), and particulates.

• Emissions of NOx are largely unaffected, with research suggesting a slight tendency towards increased NOx emissions.

• E10 use results in increased emissions of ethanol and acetaldhyde

• E10 causes an increased risk of soil and groundwater contamination.

Conclusions

• Greatest issue appears in emissions of air toxics, where increased incidence of cancer could cost as much as $135 million per year.

• Conclusion – The minor gains in CO, HC, and particulate emissions do not outweigh the costs associated with the numerous risks of E10 use, particularly the increased incidence of cancer due to increased acetaldehyde emissions.