Two Crumbler Modules in a Tower Arrangement

Techno-Economic Analysis of Forest Concepts, LLC Crumbler® Operated at Proton Power to Process Crumbles® from Hardwood Chips


Developing cost-effective methods for processing biomass into an economic biofuel product is critical to the success for the bioenergy industry in the United States. Size reduction and drying of the material, where used, are two of the most costly and energy-intensive operations that are undertaken during preprocessing. Reducing the energy required during these two phases will lower the cost of processing and ultimately reduce the overall cost to the final user. 

In an effort to lower the cost for size reduction, Forest Concepts, LLC has developed a rotary shear for the comminution of biomass feedstocks. Forest Concepts has called this rotary shear the Crumbler®, which uses intermeshed rotating disks that shear the material rather than using impact to reduce the particle size of the materials. Forest Concepts, LLC has teamed with Proton Power, Inc., located in Lenoir City, Tennessee, to set up a pilot plant that uses the Crumbler® to produce roughly 1/4-inch crumbles that ultimately feed a renewable diesel plant in Rockwood, Tennessee. Idaho National Laboratory (INL) was contracted to test Crumbler® performance and provide a techno-economic analysis of the process. 

This demonstration used chipped (roughly 2-inch) hardwood trees, harvested locally near the Rockwood facility. Following the chipping process, a two-stage Crumbler® process was used to size-reduce chips to approximately 1/4-inch particles. The material produced from the Crumbler® (“Crumbles“) is normally dried prior to feeding a bank of “CHyP” engines operated at Proton Power to make renewable diesel. 

For this techno-economic analysis, INL compared two methods of processing. First, INL measured the energy required to dry processed Crumbles to less than 10% moisture content. Second, INL measured the energy used to dry raw chips prior to hammer milling. This analysis compares the energy and cost implications for biorefineries of both methods.  

About the Publication 

Yancey, N.A., D.S. Hartley, D.N, Lanning and J.H. Dooley, J. H. (2019). Idaho National Laboratory, Idaho Falls, ID.

This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Energy Efficiency & Renewable Energy, and Bioenergy Technologies Office Small Business Innovation Research Program under Award Number DE-SC-0010122.

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