A Different Route to Corn-Based Fuel

Jack Huttner, the executive vice president of Gevo, a five-year old company in Englewood, Colo., would like to take over an ethanol plant and, using the same base ingredients that go into corn-based ethanol – corn and natural gas for fuel – manufacture a different molecule: isobutanol.

The company is arguing that current ethanol plants are like old cellphones or laptops, in that they may still work, but newer equipment can do a better job. Ethanol works, by that logic, but most cars can only take gasoline/ethanol blends up to 10 percent, and some places in the corn belt are producing so much ethanol that the motor fuel market is glutted.

Ethanol, also, has a nasty tendency to evaporate before it is burned, which adds to ingredients of smog in the atmosphere; isobutanol does not. (Gasoline used in blends with ethanol can be refined to compensate for ethanol’s evaporation.)

Isobutanol is something many car drivers have never heard of, but it is familiar to refineries that make gasoline, and they can turn it into ingredients that make up as much as 16 percent of the gallon. And while ethanol has only about two-thirds as much energy per gallon as unleaded regular gas, isobutanol is almost equal to gasoline in miles per gallon, Mr. Huttner said.

And isobutanol can substitute for petroleum in other ways; it can also be used in solvents, coatings, paints and chemicals used in plastics.

But the real potential lies in discoveries that are not quite commercialized. One is that the yeast used for ethanol only likes the sugars that come from corn, which are known as six-carbon sugars. (That is also the kind that comes in packets for coffee.)

Six carbon sugars come from food crops. But researchers around the world are trying to unlock the sugars in cellulose, including the nonfood parts of crops, like corn cobs, as well as wood chips and even paper garbage. Some of that sugar is five-carbon sugar, which Mr. Huttner said his yeast will eat and convert. A key part of the company’s technology is patented genes in the yeast.

Isobutanol also has a carbon footprint about one third smaller than ethanol’s, he said, and that can probably be brought down further. That makes it a good ingredient for one market ethanol cannot now enter: jet fuel. The airlines are interested because the the European Union is preparing to tax them for their carbon emissions.

source: nytimes