Those of us committed to Green causes often respond more strongly to symbolic values than to careful analysis. Recycling offers a clear example. The environmental value of recycling depends on time- and place-specific circumstances. It almost always makes both ecological and economic sense to recycle aluminum and other metals. Often this holds for paper, only occasionally for plastic and glass. Recycling plastic and glass often consumes more resources than it saves.

Does this mean we should criticize those who strive to recycle nearly everything? Of course not. But we can best understand much recycling as a religious act of contrition. Employing narrow efficiency criteria to criticize folks who compulsively recycle is as silly as evaluating holy communion by nutritional standards. To do so betrays a paucity of empathy and sensitivity.

The move to embrace ethanol as a substitute for gasoline shares many of the same cultural and behavioral characteristics as recycling. Whatever the good intentions, ethanol also involves political forces driven by self-interest. And the consequences of mandating the displacement of gasoline by ethanol are far more serious than any waste of resources produced by inefficient recycling.

The cover story of the October Consumer Reports is “The Ethanol Myth.” This popular magazine is published by Consumers Union (CU), an “independent, nonprofit testing and information organization serving only consumers. We are a comprehensive source for unbiased advice about products and services, personal finance, health and nutrition, and other consumer concerns. Since 1936, our mission has been to test products, inform the public, and protect consumers.” Many of us consult its magazine when we are considering what vacuum cleaner or lawn mower to buy.

CU is hardly a right-wing organization. Former Wall Street Journal deputy features editor Max Boot criticized Consumers Union as “Guardian of the Lawyers’ Honey Pot.” Others have called it “the handmaiden of the nanny state.” Hence, when it criticizes a movement favored by many “progressives” and sincere Greens, as well as politicians, I pay heed.

Here’s CU’s evaluation of ethanol. First, the energy content of ethanol is low when compared with gasoline or diesel. While diesel contains around 140,000 Btu per gallon, and gasoline 115,000 Btu, denatured ethanol contains only 78,000 Btu per gallon. We can’t cheat physics. These numbers translate into low fuel mileage.

CU tested a new Chevy Tahoe. “In highway driving (on 85 percent ethanol), gas mileage decreased from 21 to 15 mpg; in city driving, it dropped from 9 to 7.” In marked contrast, we have two old diesel ranch trucks that weigh a ton more than the new Tahoe and each gets 20+ mpg on the highway at 65 mph.

We can grow the feed-stocks for ethanol -- but I’d feel a bit guilty for using it. And not only for the subsidies built into its production.

Let’s consider one among many egregious ethanol subsidies. Flexible fuel vehicles (FFVs) are designed to run on either gasoline or a blend of 85 percent ethanol and 15 percent gas, E85. Automotive manufacturers receive generous fuel-economy credits for each FFV built -- even if it never runs on E85. This credit enables them to build more large SUVs that burn more gas than ethanol replaces. This is a perverse but predictable outcome of political forces.

The cellulosic ethanol touted by both Greens and President Bush may be a worse one for Third World ecosystems. What could be wrong with using carbohydrates to replace hydrocarbons? Here are some unintended consequences foretold by Peter Huber, an MIT engineering Ph.D.: “To improve on wood-burning fires, or grass-eating cows, perfect the cellulose-splitting enzyme. Then watch what 7 billion people will do to your forests and your grasslands.”

Essentially, he fears if the process for producing cellulosic ethanol becomes cheap and easy in poor countries, it would hasten the conversion of forestlands and other wilderness into a fuel source. Huber concluded: “History has already taught us what a carbohydrate energy economy does to a rich, green landscape -- it levels it.”

When evaluating ethanol mandates, responsible citizens ask: “What are the probable consequences of the policy, however well intended?” Surely, ethanol is not a pure Green elixir, but rather can be an intoxicating political potion.