A long-term goal of policymakers in the U.S. has been to reduce our reliance on imported oil for our gasoline needs. Producing ethanol from corn has been a partial solution, but in the long run it will not provide enough energy meet our needs. Furthermore, using farmland to produce fuel rather than food increases the price of food. But what if we could produce energy efficiently from waste biomass material, such as wood chips, corn stalks, or grass? There’s plenty of energy there; the technical problem has been to find an efficient way to unlock the sugars from cellulose, the main structural component of plant cells.
Researchers at a company called Renmatrix believe they have found the answer; treating waste biomass with supercritical water. Apparently when water is heated to over 374 degrees centigrade and pressurized to 217 atmospheres (about 3,200 pounds per square inch), it enters a “supercritical” state that is neither gas nor liquid, but something in between. Supercritical water has a density of only about 30% of that of liquid water, for example. When treated with supercritical water, the five- and six-carbon sugars in waste biomass material are broken off from cellulose and harvested for further conversion to motor fuels. The energy required to fuel the process comes from burning lignin, a material leftover from the process itself.