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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Bioproducts Research » Research » Research Project #433658

Research Project: Optimizing End-Use Applications of Almond and Walnut Shells by Activating its Carbon

Location: Bioproducts Research

Project Number: 2030-41000-068-005-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Sep 15, 2017
End Date: Sep 14, 2022

Thermally treat almond and walnut shells to create (1) biochar, (2) activated carbon and (3) torrefied biomass. Optimize their environmental and commercial applications by testing them for use in water remediation, as soil amendment and in bioplastic and rubber composites toward commercial scale-up and marketing.

A team of researchers at the USDA, Agricultural Research Service (ARS) and the University of California, Davis (UCD) agree that more commercial outlets are needed for walnut and almond shells to provide broader market applications. In this project, thermal conversion is applied as a means to convert shells into useful commercial products. This ARS-UCD team is applying thermal-treatment of shells at various temperatures, water concentrations, and oxygen levels, and creating, depending on those parameters, (1) activated carbon, (2) torrefied biomass, (3) biochar and (4) hydrothermally carbonized shells. Each of these thermal treatments has their relative advantages, with corresponding differences in costs and process challenges. Research will be carried out to discern the relative merits of each thermal process for developing products that remediate waste water, help regulate nutrient levels, and improve soil health. The unique approach of this research will be that multiple outlet streams will be considered within a total process, thus the total output will be assessed toward commercial optimization. Research questions are to focus on the relevant properties for market application, market size and economic returns of individual output products. The potential commercial end-uses of thermally-treated shells will be tested in the following applications: (1) as activated carbon for filtering systems, used in agricultural processing, (2) as biochar for sequestering carbon in soils and to amend soils for nutrient management and related purposes, (3) as biochar for removing heavy metals through soil amendment, (4) in commodity plastics as a filler/additive, and (5) in tire formulations. Research is needed to optimize outputs and process parameters as an entire process, not as individual outputs, thus targeting scale-up strategies for commercial markets that optimize return on the entire biomass and product supply chain.