Hey Mr. Green,
I always chuckle when I see articles like "Two-Wheeled Wonder" (March/April) make claims of bikes having "no emissions." A bicycle produces no greenhouse-gas emissions the same way my home heating and cooling system does: No emissions are produced on-site. But to claim that a bicycle is emission-free fails to take into account the emissions produced by making the bike and fueling its engine. Specifically, what powers my bicycle? Human muscle. It takes corn, beef, and a variety of other food fuels, most of which require the use of carbon-based energy for production. One might even make the claim that bicycling is less efficient than using an automobile given the resources needed to support my engine. --Philip
We've been through this sort of question before, with folks who wrongly think it takes more energy to make a hybrid car than it'll save. These ideas come from "life cycle" analysis, which calculates the cradle-to-grave environmental impacts of products. Such analysis is useful, but really it's making lots of you think way too hard for your own good.
Of course it takes some energy to make and propel a bike, but nowhere near what's required to make and propel cars that weigh 70 or 80 times as much and demand vastly greater energy for maintenance, from oil changes to tires to new fenders and grilles when they get banged up.
Some time ago in Sierra, I noted that the calories in a gallon of orange juice are sufficient to propel a bike rider approximately 48 miles. (Being a sexist wretch, I based the calculation on the caloric needs of an adult male.) Obviously, the energy required to create orange juice has to be included in its cost. So we can first test your theory with a cost comparison. Since propelling the average car 48 miles requires at least two gallons of gas (the average mpg for the U.S. auto fleet is around 23), the cost of the gasoline for the 48-mile trip by car would be around $7. Or about the price of a gallon of orange juice. If the energy alone required to make orange juice was really that pricey, nobody would produce orange juice. If you've got oranges, make orange juice.
Now orange juice is a high-end, high-water product. I only picked it because it comes in the same volume as gasoline and makes a cute comparison. If your cyclist settled for a humbler fuel, like cornmeal, he'd need about 1.25 pounds of it to propel him 48 miles, or less than a dollar's worth, even at trendy health-food stores and even with the escalating price of corn brought on by the ethanol scam. It takes a gallon or so of fossil fuel to produce 50 pounds of corn, so the amount of fossil-fuel energy needed to grow enough corn for the 48-mile ride is a meager .025 gallons. (Milling and transportation are excluded here, but I've also excluded the considerable energy needed to extract, refine, and transport petroleum.)
Even with pricier commodities like beef, the biker rides cheaper than the driver. A pound and a half of cheap, greasy hamburger, sans bun, could power the cruise in question, at a lower cost than gasoline.
The ethanol "alternative"? Well, not really. Instead of burning ethanol in engines, from a transportation standpoint we're far better off ingesting the stuff. Driving 48 miles takes more than two gallons of ethanol, whereas only eight ounces of liquor, a mere half-pint of vodka, can fuel a cyclist for the same distance. Happy trails! [Editor's Note: As pointed out in the comments below, Mr. Green gets more out of his tipple than is mathematically demonstrable. In fact, his vodka-fueled half-century would require 29.5 ounces--that is, a fifth plus four shots. Good luck staying upright after that.]