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According to the Department of Transportation, this March saw Americans driving 11 billion fewer miles than we did in March 2007. This is the first time that estimated travel on public roads has fallen since the energy crisis of 1979 and is the largest drop in one year since the Federal Highway Administration began its "Traffic Volume Trends" reports in 1942.

The highway administration talks about traffic volume as "vehicle miles traveled." The latest year for which statistics are available is 2006; the total miles traveled by American drivers for that year was more than 3 trillion miles.

The bad news is that the Highway Trust Fund, which was created in 1956 to finance the national road system, is losing a lot of money because it depends on the federal gasoline tax. Fewer miles driven mean fewer dollars going to the fund.

The good news is that the federal transportation department is estimating that greenhouse gas emissions are down 9 million metric tons for the first three months of 2008. Fewer miles driven means less emissions.

We can see that the rising cost of oil and gasoline is already having an impact on the amount of traveling people are doing. There is a serious need for sustainable energy sources for transportation and electricity.

Transportation is mostly fueled by oil, whereas electricity is mostly produced by coal. There are enough coal reserves left for hundreds of years, but oil is a different story with the reserves measurable in decades if consumption stays level.

Can consumption stay level? Dr. Robert Jensen of Austin, Texas, pointed out at the recent Building a New World conference in Radford that the current level of consumption of everything, not just oil, is higher than anything that has ever been seen in the history of the world. Consumption of energy, of calories, of goods, it's all at levels that are untenable in the long run.

Jensen also made it clear that he believes that substitutes such as solar power or biofuels will not allow the current levels of consumption to continue -- the alternate energy sources do not have the concentrated power that oil has. He foresees a future that includes a peak, a collapse, a period of resultant chaos and then a stabilization that will feature lower levels of energy usage and probably attendant lower standards of living, at least as measured by consumption.

Since listening to Jensen speak, I have been paying more attention to consumption.

In ways that I used to take totally for granted, I am constantly consuming. Whether it is food, snacks, caffeine, Kleenex, gasoline or electricity, I am always using up something. I sometimes walk to work, but I balance that out by constantly being on a computer, at home and at work.

I read a lot more than I watch TV, but I still use plenty of electricity in the form of lights and appliances. I recycle, but I am always drinking my diet sodas in a somewhat pointless but comforting cycle of consumption.

It all seems so normal until I compare my standard of living to that of someone in another country who subsists on the equivalent of an American dollar a day.

There is no single solution for the current energy crisis, but as oil continues to rise in cost, researchers are getting more serious about alternatives.

My dad tipped me off to Google's project to supply 30 percent of its electricity with solar power. Google is working with two companies, eSolar and BrightSource Energy, to install a solar power plant at its headquarters. Their method uses arrays of flat mirrors, each one small enough for a person to pick up and install. Like a field of phototropic sunflowers, the mirrors are attached to motorized arms that turn them to face the sun. They are positioned to reflect the sun's rays onto central towers that contain water, which is heated to steam, which powers turbines, which create electricity.

There are many other innovations that are being investigated, and they have their good and bad points. Nuclear power can generate immense amounts of electricity with no emissions, but the initial investment to build a plant is very high and risky and there are problems with security and what to do with spent fuel.

Biofuels could be cleaner than fossil fuels, but they take a lot of fossil fuels to actually produce and, depending on the biomass, it might be more efficient to just eat it rather than make ethanol out of it. Hydrogen is a possible source of power, but storage and distribution problems keep it from being viable on any large scale.

As oil continues to skyrocket in price, I expect that we'll continue to see falling "vehicle miles traveled" and rising use of bicycles and feet. Tourism revenue will go down, and money for roads will be reduced. We'll have to continue to find additional ways to reduce consumption. As Leonardo da Vinci put it, "Simplicity is the ultimate sophistication."

Pris Sears grew up in Florida, lives in Blacksburg and works among Virginia Tech's computers.