E85 and Global Warming

Source: St. Louis Post Dispatch
[May 12, 2006]

Your life is pumping an enormous amount of CO2 into Earth's atmosphere. Every mile you drive, your car releases about a pound of CO2 into the air. The natural gas that heats your home and the electricity that lights it are generated mostly by the burning of fossil fuels, which also produces CO2.

And 300 million other Americans are making similar contributions. In 2005, the United States released six billion metric tons of carbon dioxide into Earth's atmosphere from the burning of fossil fuels.

Carbon dioxide has the chemical property of absorbing sunlight and remitting it at a lower wavelength as heat, much as the glass windows of a greenhouse do. As CO2 has been added to the atmosphere, the earth has been getting warmer. A lot warmer. Global warming, once a controversial hypothesis, is now a clearly established scientific observation.

Although hydrogen might be a future alternative for powering our cars, for now they will continue to run on chemical fuels. That means that the best way to reduce our contributions to global warming would be to switch to a different carbon-rich chemical that doesn't increase the atmosphere's load of CO2.

Ethanol, the same alcohol found in beer and wine, is such a chemical. Burning fossil fuels such as gasoline releases into the atmosphere stores of carbon dioxide that have been trapped for eons within oil buried deep inside the earth. Burning ethanol also releases carbon dioxide into the atmosphere, but the carbon dioxide released by ethanol is carbon dioxide that had recently been removed from the atmosphere by photosynthesis. Thus, there is no net increase in the amount of atmospheric CO2.

If ethanol is to replace gasoline in our cars, we'll need lots of it. Brazil powers most of its automobiles with ethanol fermented from sugar cane by yeasts, much as beer is made. Here in the United States, commercial ethanol fuel traditionally has been produced by fermenting sugars from the starch stored in corn kernels.

Last year, the United States produced nearly 4 billion gallons of ethanol from corn. The ethanol is typically added to gasoline, rather than burned by itself. New cars called Flexible Fuel Vehicles have redesigned engines that can burn a blended fuel called E-85, which is 85 percent ethanol and 15 percent gasoline. This is sensational news for combatting global warming.

Right now, less than half the biomass of a corn plant goes into the production of the ethanol in E-85 fuel. The stalk, leaves and cob of the plant typically are left in the field to decay. This unused biomass represents an enormous opportunity for future ethanol production.

Fully 80 percent of the stems and leaves of a corn plant is cellulose (the material from which this newspaper is also made), and hemicellulose, a close chemical relative. Cellulose consists of linked chains of glucose sugars. Why aren't the sugars in cellulose used to make ethanol? Because there is a subtle but very important chemical difference between starch and cellulose.

Each glucose sugar molecule in cellulose has six carbon atoms arranged in a ring, as does starch. But in cellulose, the rings are turned inside out, and yeast enzymes don't break down the links between these kinds of sugars.

In order to use cellulose to produce ethanol, bioengineers had to find a way to make yeasts break these links. They succeeded, and in Spain today, a factory is making commercial ethanol from biomass cellulose. Other such factories are planned for Canada.

Using the sort of plant genetic engineering technology for which St. Louis is becoming famous, researchers might add to the yeast some DNA taken from plant-digesting bacteria found in the gut of termites, DNA that contains the genes these bacteria use to break down cellulose into free sugars.

Corn, meanwhile, is far from the only plant that could be grown to produce cellulose biomass for ethanol. Other fast-growing plants such as switch grass or hybrid poplar and willow trees could be used to produce fuel. Cellulose reclaimed from sawdust and paper pulp also could be used to make ethanol, as could the leaves, yard waste, paper and cardboard now filling our municipal dumps.

Developing strains of ethanol-producing yeasts that can ferment cellulose would be an extremely attractive long-term investment for our country's future. President Bush was wise to restore funds his administration had cut from the budget for ENREL, the federal laboratory that carries out such research. Now he should increase this funding substantially.

With a serious national commitment to the development of biomass-to-ethanol technology, we could be filling up our tanks with farm-grown fuels, rather than with fossil fuels. It would be to the world's great benefit.