Seth Kane et al (2024) Uncertainty in determining carbon dioxide removal potential of biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More. Environ. Res. Lett. in press https://doi.org/10.1088/1748-9326/ad99e9

Biochar, a byproduct of biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More, has gained attention as a tool for carbon dioxide removal (CDR). However, its actual carbon impact varies significantly depending on production practices. A recent study highlights this variability by analyzing two scenarios: a “best-practice” setup with optimized pyrolysis and energy recovery, and a “poor-practice” scenario reliant on less efficient methods.

Under best practices, where high-temperature pyrolysis and energy-efficient processes are employed, biochar production consistently removes 1.4 kg of CO2 per kilogram of biomass. This scenario captures energy from the process and uses co-products like bio-oil in chemical applications, ensuring a net carbon removal outcome.

Conversely, the poor-practice scenario—marked by lower pyrolysis temperatures and reliance on natural gas for energy—results in a median emission of 0.09 kg CO2 per kilogram of biomass, with a 66% chance of emitting carbon instead of removing it. Key differences stem from how energy is sourced and whether co-products are utilized efficiently or flared.

This variability underscores the importance of refining biochar production methods. The study suggests prioritizing renewable energy inputs, improving thermal efficiency, and optimizing the use of co-products. Policy initiatives and industry standards, such as prohibiting fossil fuel inputs and requiring energy recovery, are critical to ensuring biochar consistently functions as a reliable CDR solution.

As the biochar industry grows, adhering to best practices is essential to maximize its potential in combating climate change.