Newspaper article The Christian Science Monitor

Air Quality Better but Water Suffers Fuel Additive's Value Questioned as Cars Pollute Less

Newspaper article The Christian Science Monitor

Air Quality Better but Water Suffers Fuel Additive's Value Questioned as Cars Pollute Less

Article excerpt

A decade ago, MTBE was the silver bullet that would make cars run cleaner. Today, the silver looks tarnished.

Researchers don't agree how useful the gasoline additive really is. Worse, it's starting to show up in drinking wells and public lakes. The controversy serves as a cautionary tale about the dangers of mandating technologies without fully understanding their long-term impact.

''Politically, once you put {the additive} in, there's inertia for people to change,'' says Phillip Myers, emeritus research professor at the University of Wisconsin, Madison.

Since the Clean Air Act of 1990, some 17 states and Washington, D.C., have turned to methyl tertiary butyl ether (MTBE) to help them stay within clean-air standards. When blended with gasoline, it adds oxygen to the fuel. About a third of the gasoline in the United States is reformulated with some kind of oxygenate. MTBE accounts for three-quarters of the total, edging out competing substances, such as ethanol.

The problem is that using oxygenates may not help cut auto emissions anymore, several researchers say. That's because American cars run a lot cleaner than they used to. More than a decade ago, cars used carburetors to mix air and fuel. As the cars aged, they tended to mix more fuel and less oxygen, so the extra oxygen from MTBE-blended fuels helped reduce emissions.

But today's models use catalytic converters, which automatically adjust the fuel-air mixture. So an MTBE-blend simply forces the system to squirt in more fuel. As older cars head for the junkyard, the fuel's overall impact lessens.

Worse, all consumers are paying to correct a problem mostly caused by a small minority of people who drive out-of-tune clunkers, says Douglas Lawson, an air-pollution researcher at Colorado State University. ''You get hit by a double-whammy. Not only do you get hit with decreased fuel economy, you pay more at the pump. …

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