California Demo Produces First Low-Carbon, Whole-Beet Ethanol

by Susanne Retka Schill (Ethanol Producer Magazine) Results from Mendota Bioenergy LLC’s Phase I demonstration plant in Fresno County, California, arrived last week, and were quite favorable, reported project manager, Jim Tischer. “We’ve made the first whole-beet, low-carbon ethanol in the United States,” Tischer said. The developers now need California Energy Commission approval before moving on to Phase II, proving the process in larger reactors and with more complex equipment. Though the demo facility has a 1 MMgy capacity, Tischer said the initial production runs will be smaller, dependent upon the availability of feedstock. The Phase II demonstration is expected to run in mid- to late-summer, when the next crop of energy beets is ready for harvest.

Sugar beets are a familiar ethanol feedstock, particularly in Germany, but until now it has been produced from the standard sugar extraction process using steam. Mendota Bioenergy’s process sizes down the whole beets, warms them up and liquefies using enzymes. “We’re substituting enzymes for the slope diffusers and tower diffusers in the standard process that use a lot of energy,” Tischer said.

Initial carbon intensity scores, calculated for the California Low Carbon Fuel Standard, give whole-beet ethanol a low CI score of 22, Tischer added. Energy beets are showing agronomic promise, as well. A 25-acre field raised under drip irrigation for the demonstration facility this year yielded 52 tons of beets at 17 percent sugar content. That amounts to a 1,200 gallon-per-acre yield, which Tischer said is nearly 25 percent better than Brazilian sugarcane. Mendota Bioenergy energy beets are expected to compete well with forage crops and be a viable rotation crop with high-value vegetable crops such as canning tomatoes.