Pyrolytic biochar stability assessed by chemical accelerating aging method

Abstract: Now that the EU and Sweden have adopted a new climate policy framework to regulate net carbon emission. A new concept, negative CO2 emission, has been considered to neutralize the CO2 generated from necessary consumption of fossil fuel. Biochar, as a pyrolytic product from biomass, can store carbon in a relatively stable way. Therefore, it is one of the most promising and outstanding tools for carbon sink. Biochar stability, defined as the ratio of remaining carbon in biochar after 100 years, is the most crucial factor when using biochar for carbon storage. So far, various approaches have been proposed to measure and predict biochar stability, such as elemental analysis, proximate analysis, accelerating aging methods. Each method has its pros and cons. The reliability of these methods still needs to be verified. In this project, the chemical accelerating aging method has been selected for assessing biochar stability, because this method captures both chemical and physical properties of biochar. Besides, the gas, liquid, and solid products generalized during the chemical treatment are collected and analyzed separately in order to study the oxidation mechanism. Biochar in this project is produced from miscanthus and seaweed at various pyrolysis temperature. It is found that biochar stability can be increased by enhancing pyrolysis temperature, and miscanthus biochar is more sensitive to pyrolysis temperature within the pyrolysis temperature range of 350-600℃. The highest biochar stability (73%) has been achieved with miscanthus-derived biochar produced at 550 ℃, which demonstrates high potential as carbon sequestration tool.