DOE: Journal issue addresses challenges to bioenergy production

By U.S. Department of Energy | April 04, 2019

Storing chopped, wet corn stover in conditions with reduced oxygen not only reduces microbial loss and risk of fire but also can increase yields during conversion to biofuels.

This finding is one among many in a compendium of new research that explores how grinding, sifting, drying, pelletizing and chemically treating plant material and other forms of biomass before it reaches the biorefinery could help solve big challenges plaguing today’s bioenergy industry.

Bioenergy is a form of renewable energy derived from organic material (biomass), which includes crop wastes, forest residues, purpose-grown grasses, woody energy crops, algae, industrial wastes, sorted municipal solid waste, urban wood waste and food waste.

The collection of 23 journal articles from some of the nation’s leading biomass experts appears as a special issue from the journal Frontiers in Energy Research entitled Advancements in Biomass Feedstock Preprocessing: Conversion Ready Feedstocks.

The special issue comes after years of research and development into biomass preprocessing supported in large part by the U.S. Department of Energy’s Bioenergy Technologies Office (BETO), which is part of DOE’s Office of Energy Efficiency and Renewable Energy.

Researchers from four national laboratories—Idaho National Laboratory, National Renewable Energy Laboratory, Oak Ridge National Laboratory and Lawrence Berkeley National Laboratory—were part of more than 100 authors representing more than 30 research institutions, universities, and private companies who contributed to the special issue.

The interest in conversion-ready feedstocks arose out of biomass supply logistics, handling, and feeding challenges that oftentimes result in U.S. biorefineries operating at less than 50 percent capacity.

For example, these challenges include variability in biomass physical and chemical characteristics—especially moisture content—that have caused feeding and handling problems such as clogged conveyor belts and hoppers at biorefineries. Other types of variability include ash content, which can cause excessive wear on equipment. Later on, biomass variability can interfere with the conversion processes that turn the processed biomass into fuels, chemicals, or power.

The research suggests several solutions to solve variability challenges, including the creation of preprocessed feedstocks that are custom made for a given conversion process.

Other solutions include densification processes such as turning biomass into pellets and reducing ash content via physical or chemical treatments.

Tim Rials is the co-editor of the issue and Associate Dean for research for the Institute of Agriculture at the University of Tennessee. He thinks that, taken as a whole, the conversion-ready feedstock technologies outlined in the Frontiers in Energy Research special issue could significantly reduce feedstock costs and increase reliability for the bioenergy industry. Rials credited DOE and BETO for recognizing the need for advanced preprocessing technologies.

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