Rotary kiln approach to produce biochar from invasive scrub species for soil remediation and carbon sequestration

The loss of productive farmland by the depletion of soil organic carbon and degradation due to inadequate water, nutrient contents, and increased soil acidity is a significant challenge to U.S. food security and cropland diversity. In addition, the U.S. has nearly 3,000,000 acres of reclaimed strip mine lands of limited agricultural value due to poor soil quality, and over 3,000,000 orphaned hard rock mines which can be a source of acid mine drainage, heavy metal, and cyanide contamination. The sites are often overrun by invasive plant species and frequently bordered by poorly managed forests. The production and application of biochar can be an approach to solve these problems by (1) improving soil characteristics, (2) improving soil water retention, (3) reducing bioavailability and mobility of organic and inorganic contaminants, and (4) utilizing invasive scrub species. Biochar can also be employed as a method for fixing atmospheric carbon in the soil. Furthermore, biochar production technology can help the local underserved community by realizing the community’s needs in technology development, addressing the availability of productive agricultural land, and providing economic opportunities. In Phase 1, a feasibility study of a low-cost, mobile, modular, continuous biochar production process, using a rotary kiln reactor will be performed. Lab-scale rotary reactor testing will be conducted to produce biochar from invasive scrub species in Appalachian Region under a range of operating conditions including heating rates and peak temperatures to identify appropriate biochar production conditions. The biochar samples will be characterized to determine surface morphology, surface area, porosity, and cation exchange capacity for soil amendment evaluations and preliminary soil testing will also be performed. Process and multi-phase threedimensional computational fluid dynamic modeling analyses will be performed to guide the determination of the test condition matrix, validate the modeling approach, and finally, perform a preliminary evaluation of full-scale concept implementation. Phase I will conclude with preliminary economic and marketing evaluations. After the feasibility study is completed, the mobile and continuous biochar production system will be scaled-up for pilot-scale testing and full-scale demonstration in Phases II and III. A longterm soil testing demonstration will also be performed. This cost-effective and systematic biochar production system will be transportable to where resources are located such as remote farmland, power plants, or industrial furnaces, and modular for easy capacity increase.