Nice to see Tom Friedman on the energy tax bandwagon. As he wrote in his Dec. 27 New York Times column, “I’ve wracked my brain trying to think of ways to retool America around clean-power technologies without a price signal—i.e., a tax—and there are no effective ones.”

Friedman needs to give his cranium a holiday break. Policymakers have been searching for this magic bullet for years, without success. They’ve tried government-mandated (CAFE) auto mileage standards, tax credits for the use of everything from hybrid cars to low-E windows, massive government subsidies for production of alternative fuels and sincere pep-talks from sweater-clad Presidents. Nothing has worked. Take a look at this chart from the Energy Information Agency:

[[{"type":"media","view_mode":"default","fid":"149441","attributes":{"class":"media-image","typeof":"foaf:Image","style":""}}]]

As it shows, the only break in the steady growth of fossil energy use over the past half-century came with the oil price shocks of the 1970s and 80s. Friedman has discovered a pretty basic rule of economics: If you want people to buy less of something, raise the price.

For another example, take a look at some charts Diane Rogers over at Economistmom.com put together that show what happens, at least in the short run, when gasoline prices change dramatically. We’ve run a nice little natural experiment and the results are fascinating. When gasoline prices exploded last summer, demand plunged. You might say that $4-a-barrel gasoline focused the mind. Then, as prices plummeted over the past few months, consumption again rebounded, even with the economy in the tank.

It is a bit more evidence that consumers of energy will change behavior in response to price. Most economists think it takes a while for people to react, but react they do. CBO figures a sustained price increase of 10 percent will eventually cut consumption by about 4 percent. Others think the long-run response may be even stronger.

Sooner or later, however, if you use a tax to push up the price of energy, people will buy more fuel-efficient cars, appliances, and even homes. They may even think twice about buying that oversized mini-mansion 40 miles from work.

So far, Barack Obama’s transition team has been troublingly mum about raising energy taxes, even though he embraced a tax-like cap and trade program for fossil fuels during the campaign. Aides have dropped broad hints about a new round of big new government subsidies to develop alternative fuels and using a chunk of stimulus money to pay for mass transit. And, of course, Washington has made $25 billion available to automakers for energy R&D and pressed them to make new fuel-efficient cars in return for the additional bailout money they just got.

Giving away money to encourage green behavior is the easy stuff. But it will take more than that. I know, we are in a recession and can’t raise taxes right away. But with gas prices again south of $2.00 a gallon, it is folly to think many consumers will eschew a gasoline-powered $20,000 car for a $40,000 electric ride. Consumers are not dumb, and forcing automakers to build those cars in the absence of demand is madness. So is talking about energy independence without raising the price of fossil fuel.