Thermochemical biomass conversion systems have the potential to produce heat, power, fuels and other products from forest biomass at distributed scales that meet the needs of some forest industry facilities. However, many of these systems have not been deployed in this sector and the products they produce from forest biomass have not been adequately described or characterized with regards to chemical properties, possible uses, and markets. This paper characterizes the producer gas, biochar, and activated carbon of a 700 kg h⁻¹ prototype gasification system and a 225 kg h⁻¹ pyrolysis system used to process coniferous sawmill and forest residues. Producer gas from sawmill residues processed with the gasifier had higher energy content than gas from forest residues, with averages of 12.4 MJ m⁻³ and 9.8 MJ m⁻³, respectively. Gases from the pyrolysis system averaged 1.3 MJ m⁻³ for mill residues and 2.5 MJ m⁻³ for forest residues. Biochars produced have similar particle size distributions and bulk density, but vary in pH and carbon content. Biochars from both systems were successfully activated using steam activation, with resulting BET surface area in the range of commercial activated carbon. Results are discussed in the context of co-locating these systems with forest industry operations.

There are thousands of abandoned mine land (AML) sites in the U.S. that need to be restored to reduce wind and water erosion, provide wildlife forage, shade streams, and improve productivity. Biochar created from woody biomass that would normally be burned in slash piles can be applied to soil to improve soil properties and is one method to restore AML soil productive capacity. Using this ‘waste’ biomass for biochar and reclamation activities will reduce wildfire risk, air pollution from burning, and particulates released from burning wood. Biochar has the potential to improve water quality, bind heavy metals, or decrease toxic chemical concentrations, while improving soil health to establish sustainable plant cover, thereby preventing soil erosion, leaching, or other unintended, negative environmental consequences. Using forest residues to create biochar also helps reduce woody biomass and improves forest health and resilience. We address concerns surrounding organic and inorganic contaminants on the biochar and how this might affect its’ efficacy and provide valuable information to increase restoration activities on AMLs using biochar alone or in combination with other organic amendments. Several examples of AML biochar restoration sites initiated to evaluate short- and long-term above- and belowground ecosystem responses are presented.

We replaced a control peat medium with up to 75% biochar on a volumetric basis in three different forms (powder, BC; pyrolyzed softwood pellets, PP; composite wood-biochar pellets, WP), and under two supplies of nitrogen fertilizer (20 or 80 mg N) subsequently grew seedlings with a comparable morphology to the control. Using gravimetric methods to determine irrigation frequency and exponential fertilization to ensure all treatments received the same amount of N at a given point in the growing cycle, we successfully replaced peat with 25% BC and up to 50% PP. Increasing the proportion of biochar in the media significantly increased pH and bulk density and reduced effective cation exchange capacity and air-filled porosity, although none of these variables was consistent with resultant seedling growth. Adherence to gravimetric values for irrigation at an 80% water mass threshold in the container revealed that the addition of BC and WP, but not PP, required adjustments to the irrigation schedule. For future studies, we encourage researchers to provide more details about bulk density, porosity, and irrigation regime to improve the potential inference provided by this line of biochar and growing media work.