4.4. Barriers and limitations to biochar systems
A market for carbon credits in which land managers can engage in deploying biochar does not exist. In general, there also remains a lack of knowledge and awareness of bioenergy and carbon markets, how to access these markets, and particularly a way to accurately evaluate costs and benefits associated with the use of biochar in soil. Crucially, as well as being multiple, the relevant markets are interdependent, extending to the supply of feedstock for pyrolysis. However, no framework exists within which the carbon sequestered in biochar can be certified as a tradable commodity, and this extends beyond trading under the CDM to the voluntary carbon markets. To date the methodology required to recognize the stabilization of degradable organic matter as an avoided CO2 emission has not been presented.
There are significant organizational and institutional obstacles to the use of biochar in soil. Since biochar could be used on a large scale and cannot be removed from soil once applied, there is a need to carefully assess the potentially negative impacts on occupational health, environmental pollution, water quality, and food safety. This requires a concerted effort to evaluate potential products, and ideally define product standards. Support for the use of biochar in meeting policy objectives will draw upon life-cycle analysis with full greenhouse accounting, backed by a body of experimental data. Where biochar is designated as a regulated waste material, pending defined standards land users in many countries may be subject to a complex and expensive approval process.
The lack of mechanistic understanding as to the function of biochar, and its interaction with already complex soil processes, means predicting the return to an investment in biochar between locations in terms of extent, predictability, and durability of benefits does not yet exist. Providing a measure of certainty to the many possible benefits is a key challenge to be addressed by further research.