Posted on 05/11/2006 11:27:04 AM PDT by B Knotts
The U.S. Environmental Protection Agency (EPA) will be allowed to implement potentially counterproductive smog-prevention regulations after the U.S. Supreme Court on November 14 let stand a lower court decision that a legal technicality prevented the National Alternative Fuels Association (NAFA) from challenging the regulations.
Complex Interactions
EPA says regulations it implemented in 2000 will reduce the formation of ground-level ozone, a key smog component. Ozone forms when nitrous oxides (NOx) react with volatile organic compounds (VOC) on hot, sunny days. Accordingly, "smog season" in the U.S. tends to run from approximately April 1 through September 30.
A cursory look at the components of ozone formation would lead one to believe cutting either NOx or VOC concentrations would reduce ozone and, hence, smog. However, computer models and real-world observations indicate the equation is not so simple.
Ozone formation is not dependent only on the mere presence of NOx and VOC. "Ozone formation depends on the ratio of VOC to NOx, and different ratios of VOC/NOx lead to very different outcomes," explained Joel Schwartz, a visiting fellow at the American Enterprise Institute.
According to computer models, "when the VOC/NOx ratio is high--greater than about 10 to one--ozone formation is limited by the availability of NOx, and VOC reductions have no effect on ozone levels. But when the VOC/NOx ratio falls below 10 to one, VOC reductions begin to reduce ozone," Schwartz observed.
Paradoxically, when the VOC/NOx ration is below 10 to one, "reducing NOx actually increases ozone." Urban areas currently tend to have the lowest VOC/NOx ratios and are therefore most prone to this paradox.
According to the computer models, NOx reductions in urban areas will actually increase ozone and, thus, smog.
"Smog in many urban areas increases when NOx concentrations are further reduced, while declines generally occur in less heavily populated areas," noted Dr. Kay Jones of the Competitive Enterprise Institute.
Real-World Observations
The computer models, moreover, have been verified by real-world observations. "A disproportionate number of exceedances of the ozone standard are occurring on weekends, when emissions of ozone-forming chemicals--especially NOx--are down anywhere from 10 to 40 percent," Schwartz reports.
"At some monitoring locations in the Los Angeles area," Schwartz noted, "weekend exceedances account for nearly 80 percent of total exceedances. And these ozone increases are occurring in spite of large declines in NOx. Although the 'weekend effect' is most pronounced in California, it is becoming increasingly prevalent in other cities across the nation, including Denver, Chicago, Philadelphia, and New York."
"EPA failed to consider compelling science that its NOx reducing regulation would actually severely worsen the nation's air quality," observed a summary of the issue prepared by NAFA.
"Ozone is not very likely to improve much in the future," explained Doug Lawson, a researcher with the National Renewable Energy Laboratory. "In fact, it's very likely to get worse, given that all the regulations in place for the next decade or so have larger NOx reductions built in to them than VOC reductions, which is exactly what takes place now on weekends relative to weekdays."
Negative Consequences
The negative effects of this policy are twofold. The first negative effect is apparent: Increases in urban smog result in greater discomfort and greater alleged health impairments associated with smog.
Second, a short-term rise in ground-level ozone and resulting smog is likely to be paraded by activist groups as "proof" that EPA's mandated NOx reductions are not stringent enough. More stringent, and more costly, reductions would then be advocated on the false premise that more stringent NOx reductions would further reduce ground-level ozone.
"EPA ignored other viable less costly solutions, which could have easily resolved the stated ozone problem," observed the NAFA summary.
A solution, agreed Schwartz, lies in targeting more front-loaded VOC reductions rather than front-loaded NOx reductions.
"What makes this strategy appealing is that VOC reductions will reduce ozone in most places, especially places where most people live," Schwartz noted.
"After substantial near-term VOC reductions, later NOx reductions would achieve the EPA's ozone standard on the same schedule as currently planned, but with less harm in the interim," Schwartz said. "In addition, this change would give each non-attainment area flexibility to tailor its ozone reduction strategy based on the specifics of local emissions and air chemistry."
If we could get these NOx regulations relaxed, we could get more diesel cars and small trucks on the market in short order, and start saving a lot of fuel, as well as expanding the market for biodiesel.
But this is one of those instances where science and common sense part ways. There is a complex equillibrium between all the components involved. In order to reduce the ozone level, which is unhealthy at ground level, requires a thorough understanding of the all the different chemical pathways involved and their respective equillibrium constants. The algebra can get complicated fast, but it needs to be done in order to get a workable solution.
Based on the article, it seems like the best approach is to reduce VOC's at least as much as the NOx's. Unfortunately, diesel, I believe, is a very potent source of VOC's compared to gasoline.
So the bottom line is that the new, tighter NOx regulations will have the opposite effect than intended. Smog will increase.
I think you have that backwards. Emissions-wise, I think there isn't a whole lot of difference, based on figures I've seen.
Transfer of fuel (e.g., refueling) is an entirely different story. Fueling a gasoline vehicle, even with reasonable precautions releases more than 100 times the amount of VOCs as fueling a vehicle with diesel fuel.
That's why overall, a compact diesel car is probably responsible for half the VOCs that a Prius is responsible for, once you factor in refueling.
I should add that the reason for the VOC difference is that gasoline, as you know, evaporates rapidly, while diesel fuel does not.
And, yes, while diesel fuel VOC emissions are already quite low, biodiesel's are even lower.
Based on the article, it seems like the best approach is to reduce VOC's at least as much as the NOx's.
The problem here is that to reduce NOx formation, the flame front temperature in the diesel combustion process must be lowered. Below a certain temperature NOx formation does not occur.
But lowering the flame front temp has two undesirable effects: VOC are not readily destroyed, and the engine operates at a much lower efficiency than it could be.
So to reduce NOx formation by this method you increase VOC's and significantly reduce mileage.
The current approach, is to use NOx catalytic converters and EGR to (hopefully) completely combust VOC's.
But as you point out "there ain't no such thing as a free lunch" We should look to Europes automobiles for the right way to "do Diesels".
By the way, The Great Smoky Mountains got that name because of all the smog formed by pine trees releasing VOC's. They are terrible polluters!
Cut down all the pine trees to save the Earth!
The problem gets more complex because we simply cannot reduce the primary source of volatile organic compounds in the American South without greatly offending environmentalists (and impeding the forest industry). In hot, humid environments and warm, wet mountains, especially across the South, trees and other plants produce the overwhelming majority of volatile organic compounds (isoprene and pinenes). Because these compounds lead to tropospheric ozone formation in the presence of sunlight (abundant in the South), early settlers labeled the mountains "Great Smoky" and "Blue Ridge." Some species of trees produce more and different types of volatile organic compounds than other species. Drought and heat stress can cause certain trees to vary their emissions. So we don't have any easy answers here.
True. But easing up on the NOx regulations seemingly could help.
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