Advocates are talking about moving into a "biobased economy" where farms replace oil wells as the primary source of many products and much of our energy.

This sounds like a pretty big change of direction -- and it is -- but it also has a "back to the future" aspect. Up until around 1940, the American economy was mainly biobased.

In the 1920s, dyes, inks, paints, medicines, clothing, and even synthetic fibers and plastics were manufactured from trees, vegetables or crops. And there were people -- Henry Ford among them -- who thought grain alcohol (ethanol) was a better automobile fuel than gasoline.

Cheap oil and new technologies based on oil changed all that. Today we are surrounded with petroleum-based products, and biobased fuels account for less than one percent of our total liquid fuel consumption.

But the new biobased economy -- if it arrives -- won't look much like the past. Its boosters envision high-mileage cars cleanly burning ethanol or ethanol-gasoline mixes; bio-refineries bringing new prosperity to farm regions; a whole new range of textiles, plastics and building materials (many of them biodegradable) made from plants; agricultural countries freeing themselves of their dependence on foreign oil; and tobacco farmers growing their crops for medicines instead of for cigarettes.

The push for change is coming from several directions. The Clinton Administration has strategic reasons -- mainly nervousness about global petroleum supplies running low (or prices running high) in the years ahead. Agricultural economists see the possibility of new income sources for farmers -- currently kept afloat by billions of dollars a year in subsidies. And many industries see the opportunity for many new things to make and sell.

So, wherever farm and energy policy is made or projections of the future are crafted, there are signs of movement in a new direction.

Among the indications:

- The White House has established a President's Council on Bioenergy and Biobased Products to encourage industrial use of plant matter "with specific attention to rural economic interests, energy security and environmental sustainability."

- The National Research Council has called for an increase in the use of biobased fuels and an even greater increase in the use of biobased specialty chemicals -- and wants the U.S. to take a leadership role in "the global transition to biobased products."

- Congress just passed the Biobased Research and Development Act which sets up a board to coordinate federal programs promoting the use of biobased industrial products, and authorizes several millions of dollars over the next five years on research and development.

- The U.S. Department of Energy issued a document, entitled "BioEnergy 2020," encouraging an almost twentyfold increase in the amount of plant matter used for fuels and industrial purposes.

- The National Agricultural Biotechnology Council recently focused its annual meeting on "The Bio-Based Economy of the 21st Century: Agriculture Expanding into Health, Energy, Chemicals and Materials."

Despite this burst of high-level enthusiasm, there are many uncertainties. How will environmentalists react to the heavy involvement with biotechnology? The biobased scenarios envision new biorefineries in which genetically engineered bacteria happily digest wood chips and corn husks to make ethanol, while new bioengineered plants grow in the fields.

The refineries may not be a problem, since genetically engineered bacteria are already being used in fermentation processes to produce drugs and vaccines. But new bioengineered crops could well raise some of the same concerns -- especially about whether the traits might spread to other plants -- that are now part of the GM foods debate.

When and if environmental issues arise, producers are sure to respond that the environmental benefits of the transition -- such as its potential for producing fuels that don't dump huge quantities of greenhouse gases into the atmosphere -- outweigh the problems.

It's impossible to say how far the bio-economy revolution will go, or how fast. It depends on many variables -- including the effectiveness of new technologies, market conditions and the adaptability of farmers. And it's all a matter of percentages anyway, since nobody expects petroleum to go away in the foreseeable future. But the momentum appears to favor the plants over the oil wells, and it may carry us all forward -- or backward -- into a much different world.