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AIR QUALITY AND ETHANOL

AIR QUALITY AND ETHANOL. Gary Z. Whitten. INTRODUCTION. Ethanol impacts both positive and negative Ethanol similar to but not MTBE Trade-off’s can be complex Not readily acceptable due to Regulations Agencies Oil companies And sometimes environmental groups.

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AIR QUALITY AND ETHANOL

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  1. AIR QUALITY AND ETHANOL Gary Z. Whitten

  2. INTRODUCTION • Ethanol impacts both positive and negative • Ethanol similar to but not MTBE • Trade-off’s can be complex • Not readily acceptable due to • Regulations • Agencies • Oil companies • And sometimes environmental groups

  3. Carbon Monoxide, Ozone, Toxics, and PM • CO makes ozone • Toxics are closely regulated and adjusted in RFG • PM needs more recognition

  4. Carbon monoxide makes ozone • 1974 paper “just CO and NOx might exceed ozone standard.” • 1988 testimony “1 pound waiver mainly due to CO reduction by ethanol.” • 1998 NRC study “credit for CO reduction should be in RFG.”

  5. Toxics are closely regulated in RFG • Ethanol can reduce benzene by 30 percent • Dilution • Octane substitute for aromatics • Cleaner burning • Refiners often can adjust benzene for RFG • Acetaldehyde increased by ethanol, but several studies show this is not a problem

  6. PM needs more recognition • Science of PM rapidly emerging • PM can be primary or secondary • Ethanol significantly reduces both • Secondary (man-made)may be essentially all from aromatics • Ethanol impact similar to benzene

  7. Ozone Trade-offs • CO reduction equal to at least 3% of VOC • This is for RFG going from 2% to 3.5% oxygen • For non-oxy the full credit could be 7% • Aggressive driving, high emitters, old cars, and off-road engines also show VOC benefits • Unfortunately, regulations based mainly on data from low-emitting vehicles show much VOC benefit

  8. Trade-offs (Cont.) • Recent data (1999) show 63% of CO and 47% of VOC coming from 10% of vehicles • ARB tests show aggressive driving (REP05) • Ethanol (vs MTBE) showed 3% benefit in normal driving (FTP) but 10% when REP05 data included. • Complex Model for RFG and ARB model both all based on FTP (no REP05 data)

  9. Trade-offs (cont.) • EPA tests on 36 vehicle fleet (half higher emitters) show 6% CO reduction and 4% VOC reduction with ethanol (vs, MTBE), but all the benefits came from the higher emitters. • Note only FTP data here (no REP05) • Grid model tests show • CO major (33% of ozone) impact • Exhaust VOC more important than evaps.

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