Scooters should scoot. Take motorcycles with them. --------- Forwarded message ---------- http://www.gristmagazine.com/ask/ask052803.asp?source=daily
The Wheel Deal Sage advice on minivans, motorcycles, and more by Umbra Fisk 28 May 2003 Dear Umbra, I recently read a claim that "motorcycles produce far more pollution per mile than your typical car, truck, or SUV." Is that true? I've got a friend who's currently making her (bad-ass) way across country on a Harley -- 60 mpg, baby -- and we are both curious about the environmental impacts compared with a car. Billy Brooklyn, N.Y. Dearest Billy, Bad news for your friend and her bad behind. If she's getting 60 miles per gallon, that's about three times better than the average car these days, and certainly far better than the 1984 Nissan Rustbucket that I drove across country when I made my pilgrimage to Gristonia years ago. (Appalling, I know, but I was young, and the car was free.) However, and this is the word from California -- where they actually care about car exhaust, post signs in garages warning that carcinogens are present, and have an entire government department devoted to breathing -- anyway, the word from California is that the cleanest 2004 motorcycle is eight to nine times dirtier than the dirtiest 2004 car. Put differently, the best allowable California motorcycle is many times worse than the worst allowable California car. This "worst" is in terms of pollutants, not greenhouse gases. The U.S. EPA says the motorcycle hydrocarbon burden is 90 times higher than that of the typical passenger car, and a motorcycle releases 20 times more total pollution per mile than a new car. Why is such a high-mileage engine so dirty? Well, I'm glad you asked, because it means: Time to talk about the internal combustion engine! Our car engines are powered by endlessly repeating small explosions. Gas is forced into a small space and then ignited, resulting in a powerful explosion: Think aerosol cans in a campfire. The energy from the explosion is used to move other parts of the engine, such as pistons, cranks, rods, reels, hooks, etc. Excitingly comprehensible diagrams of this process can be found at HowStuffWorks.com. If an engine were perfectly efficient, the only combustion byproducts would be carbon dioxide and water. Instead, we get other byproducts, such as carbon monoxide, hydrocarbons, particulate matter, and nitrous oxides, which are poisonous/smog-forming/depressing. That's what's following after your pal's bad behind. Car engines have become cleaner over time through innovations (such as fuel injection) that allow fuel to burn more efficiently. Catalytic converters also clean up car exhaust by converting harmful compounds as they pass through a catalyst. (Go figure.) Motorcycle manufacturers have been slow to add efficiency and catalytic converters to their engines but are working with regulators to clean up their acts. Trouble is, anything that adds weight to the engine can impede its bad-ass performance. Motorcycle regulations are steadily improving, and the feds are following California's guidelines. Still, to date, motorcycles are bad, bad, bad. Cautiously, Umbra Dear Umbra, I was thinking of buying a scooter with the idea that (in addition to being fun) I would be using a more fuel-efficient means of transportation on days when the weather was good. Then I got the edition of the Daily Grist telling me how dirty motorcycles are. Now I'm worried: Are scooters the same? I'm talking about a Vespa-type thing. Please tell me that's not as polluting as a Harley! Thanks (even if the answer isn't what I want to hear!), Patricia Audubon, Penn. Dearest Patricia, The answer is not what you want to hear. To continue our exploration of the coarser points of engine mechanics and travel safety, which I'm sure is making the experts out there cringe, we will now discuss the two-stroke vs. four-stroke engine. The best way to understand this distinction is to look at the two-stroke diagram and four-stroke diagram on HowStuffWorks.com, so go there right now if you wish to skip my crude explanations, or at least understand them. In a four-stroke engine, the explosion that powers your car has four steps, called strokes because of the piston movements: The gas is injected, the gas is compressed, the gas is ignited, and the explosion leaves the chamber. In general, four-stroke engines are found in larger mobile transit sources, like Nissan Rustbuckets, and, increasingly, in motorcycles. Two-stroke engines combust in, surprise, two steps: The fuel and oil are mixed and compressed in a separate chamber, then brought into the piston area, where ignition and exhaust happen in two strokes. Compared with four-stroke engines, two-stroke engines are powerful for their size, lighter, shorter lived, and filthy dirty. They are found in scooters, chain saws, lawn mowers, jet skis, and so forth. There is a moment in the two-strokers' combustion process when the intake and exhaust valves are open simultaneously, allowing some gas/oil mixture to escape into the outside world in the form of liquid (the oil sheen around motorboats), gases (the poisonous/smog-forming/depressing compounds mentioned in the motorcycle question), and asthma-causing particulate matter. As much as 30 percent of the fuel may escape, depending on the engine. Cheap, powerful, fun scooters and their exhaust are a huge health concern in crowded Asian cities, where they are often the most significant mobile source of pollution. So far, scooters are not as big a concern in U.S. cities, where we are wed to larger vehicles and our sprawling cities are built with cars in mind. But just think about the snowmobiles in Yellowstone and you'll know what kinds of problems two-stroke engines pose in rural areas. Here are the sobering comparisons you're looking for: Scooters are more polluting than Harleys. They have equivalent particulate-matter emissions to large diesel trucks, and three times the carbon monoxide and hydrocarbon emissions of those trucks. On the bright side, their low fuel use means they contribute fewer global-warming gases such as carbon dioxide and nitrogen oxides (NOx). In short, from an environmental standpoint, four-stroke motorcycles with catalytic converters are a far better two-wheeled choice than scooters. The engine is more efficient, fuel economy is comparable or better (meaning less greenhouse gas emissions), the engine will last longer (reducing the manufacturing burden), and exhaust pollutants are lower. If you're totally wedded to owning a scooter, there are electric models that you could look into. Otherwise, I have one word for you: bicycle. Vroom, Umbra Hi Umbra, I'm wondering if you have any numbers comparing the fuel efficiency of flying versus driving the average car for the same distance. Also, how does carbon dioxide production compare for the same trip? Steve Loomis, Calif. Dearest Steve, Here's what I can find so far, courtesy of the Rocky Mountain Institute in beautiful Snowmass, Colo. Single-occupancy automobiles produce 0.91 pounds of carbon dioxide per mile. (You can do the long division to figure out the per-person impact if more people are traveling.) Commercial aircrafts, meanwhile, produce 0.57 pounds of CO2 per person per mile. However, planes emit gobs of other pollutants at high altitudes, particularly our smoggy friends the nitrogen oxides, which may almost triple the climate impact of plane travel. Little is known about the effects of atmospheric releases of NOx. As you know, the pollution impact of every plane trip includes your travel to and from the airport, all the little golf carts zipping around on the tarmac, and the thousands of airline employees who go to work to get you on the plane. These other "mobile sources" must be factored into the per-mile pollution burden of air travel, and RMI appears to be working on it. Flightily, Umbra ________________________________________________________________ The best thing to hit the internet in years - Juno SpeedBand! Surf the web up to FIVE TIMES FASTER! Only $14.95/ month - visit www.juno.com to sign up today! _______________________________________________ Bikies mailing list [EMAIL PROTECTED] http://www.danenet.org/mailman/listinfo/bikies
