Biochar can be used for renewable heat and power generation or a soil amendment and carbon sequestration agent.
Biochar is the solid, black product from the Avello®FRAC process. The properties of biochar may vary widely depending on biomass type, processing technology and operating conditions; but all exhibit a high carbon content that typically ranges between 50 and 85%+. The highly aromatic structure of biochar make it chemically and biologically more stable than the biomass from which it was made.
Anecdotal evidence of the benefits of biochar can be traced to Amazonian Indians who produced a form of biochar to create Terra Preta (“Black Earth”) soils that remain in the Amazon Basin today. These Terra Preta soils, which are a mixture of charcoal, organic matter, nutrients and pottery shards, exhibit higher fertility and lower nutrient leaching compared to surrounding low nutrient soil. Terra Preta soils were created by pre-Columbian Indians between 450 BC and AD 950.
Biochar can be produced from forestry and agricultural residues and purpose-grown energy grasses or trees. Fast pyrolysis and slow pyrolysis produce significant quantities of biochar with high carbon and mineral content. Gasification converts biomass mainly to syngas, with lower biochar yields with high ash and mineral content.
Biochar Uses. Biochar can be utilized as a soil amendment, fuel for heat and power and as a carbon sequestration agent. Fuel uses of biochar include combustion in furnaces and boilers and co-firing with coal as a renewable fuel in existing power plants to offset carbon emissions.
The benefits of adding Biochar to the soil include:
- Replacement of Plant Nutrients. Biochar retains most plant nutrients found in the initial biomass. Incorporation of Biochar into the soil may make these nutrients available for plant use.
- Nutrient Efficiency Increase. Incorporating Biochar in the soil limits nutrient leaching; including nitrogen. Other nutrients are readily made available to plants because of the high cation exchange capacity of Biochar. This could reduce fertilizer requirements.
- Crop Yield Increase. Application of Biochar on poor soils has increased yields. Biochar's porous structure may increase water and nutrient retention in soils, particularly in poor, sandy soils.
- Carbon Sequestration. The half-life of Biochar carbon is estimated to be hundreds of years, significantly longer than the half-life of plant matter carbon which is only 6 to 12 months. Production of Biochar may be a mechanism to collect and concentrate atmospheric carbon into a stable and solid form. Burying Biochar in soils may be an alternative and safe method for carbon sequestration.