Can Portable Pyrolysis Units Make Biomass Utilization Affordable While Using Bio-Char to Enhance Soil Productivity and Sequester Carbon?

We describe a portable pyrolysis system for bioenergy production from forest biomass that minimizes long-distance transport costs and provides for nutrient return and long-term soil carbon storage. The cost for transporting biomass to conversion facilities is a major impediment to utilizing forest biomass. If forest biomass could be converted into bio-oil in the field, it may be more profitable to utilize forest biomass for bioenergy. Bio-oil can substitute for fuel oil, or be used as a crude oil and further refined into additional products. Transporting energy-dense bio-oil is more cost effective than transporting bulky, low-value biomass. In-woods pyrolysis can also address concerns over removing nutrients and carbon from forest sites through reapplication of bio-char, a pyrolysis byproduct, which is equivalent to the charcoal found in all fire ecosystems. Bio-char is 70-80 percent carbon and retains most nutrients contained in biomass. It can be used as a soil amendment to enhance soil productivity through a liming effect, which improves cation exchange capacity and base saturation, increasing anion availability, improving water holding capacity and decreasing bulk density. Charcoal is known to remain stable in soils for hundreds to thousands of years. Long charcoal residence times provide a way to quickly sequester atmospheric carbon by assimilating it into a recalcitrant form that can be applied to soils. In total the portable pyrolysis approach has the potential to improve the economic efficiency of biomass removal from overstocked forests through the in-woods conversion of biomass to bio-oil that avoids the costs and emissions of transportation to central facilities. Biochar can be returned to the forest economically if pyrolysis occurs at or near the site of biomass removal. Reapplication of bio-char will sequester carbon in soil and may enhance site productivity