Biomass Transformations

Call us lucky or good, with the timing of this issue focused on biomass feedstocks. At press time in early September, a grand opening was held for Project Liberty, Poet-DSM’s high-profile cellulosic ethanol plant in Iowa. Our team was there and we’ve got photos. In addition, the National Advanced Biofuels Conference & Expo is taking place in Minneapolis, Minnesota, Oct. 13-15, and our theme complements the agenda by design. And finally, October marks the earliest stages of America’s corn harvest, and with it another round of stover collection campaigns—trial runs no more.

While corn fiber and stover are, respectively, the favorite feedstocks of today’s advanced and cellulosic ethanol runs, we can’t ignore the promise of dedicated energy crops. So we begin this month with a vital energy crop roundup. In “Boosting Biomass for Bioenergy,” EPM Staff Writer Katie Fletcher summarizes the energy crop research supported by the DOE-USDA Plant Feedstock Genomics program, which aims to accelerate the rise of super bioenergy plants. These resilient future crops, like energy sorghum, switchgrass, poplar and miscanthus, are being designed for superior agronomic performance. They’ll make fabulous ethanol feedstocks, say scientists, because they have the latent potential to grow fast with low inputs and big yields. Time will tell.

Until those megaplants get here, producers of next-generation ethanol will make do with the nonstarch components of corn, mostly stover. Transporting and storing all those stalks and leaves is cumbersome, though, and that makes densification strategies attractive. In “Stover Pellets Pack in the Pounds,” we learn that pelletizing corn stover improves the material’s bulk density four-fold, and also renders its sugars more accessible during enzymatic conversion. Stover pelletizes easily, reports EPM Senior Editor Susanne Retka Schill, but bringing a densified feedstock to an ethanol plant’s door brings its own set of challenges.

For broader perspective, we report on another alternative to dry biomass storage. In “Ahead of His Time,” EPM Managing Editor Holly Jessen profiles Jim Hettenhaus of CEA Inc., who has been a purveyor and champion of biomass wet storage for years. And if you think pelletization of corn stover offers strong benefits, consider the upside of wet storage. Hettenhaus tells us that wet biomass takes up 10 times less space than dry biomass and loses less of its volume during storage. And that’s not all. Wet storage, not surprisingly, allows biomass to be collected wet, doing away with dry-time scheduling. Hettenhaus says a wet approach also results in improved feedstock quality and process performance. Ultimately, he says, producers are wasting time, energy and money drying biomass only to get it wet again during the fermentation process.