Study finds biochar alone cannot offset carbon emissions in China’s Guangdong province

A new study reveals that while biochar technology can play a meaningful role in reducing greenhouse gas emissions, it cannot by itself achieve carbon neutrality in one of China’s most economically developed regions.

Researchers analyzed the carbon balance of Guangdong province and evaluated the potential of biochar produced from biomass resources to remove carbon dioxide from the atmosphere. Their findings show that even under the most optimistic scenario, biochar could offset only about nine percent of the province’s net carbon emissions. The study highlights the need for broader climate mitigation strategies that combine multiple technologies and policy approaches.

The study was published in Carbon Research, a journal managed by the Biochar Editorial Office.

Guangdong province is one of China’s largest economic centers and a major source of industrial and energy-related emissions. Rapid economic growth has significantly increased greenhouse gas output in recent decades. Understanding the region’s carbon balance and identifying effective mitigation strategies are essential for supporting China’s national goal of achieving carbon neutrality by 2060.

In the new study, scientists compiled a comprehensive inventory of carbon emissions and carbon sinks across five sectors in Guangdong province between 2016 and 2021. These sectors include energy consumption, industrial processes, agriculture, waste management, and forest carbon sinks.

The results show that Guangdong has not yet reached carbon neutrality. Net emissions in 2021 were estimated at approximately 925.63 million tons of carbon dioxide equivalent after accounting for natural carbon sinks such as forests. Energy consumption was the dominant source of emissions, responsible for about 83.8 percent of the total, followed by industrial processes, agriculture, and waste management.

To explore potential mitigation options, the researchers assessed the carbon dioxide removal potential of biochar. Biochar is a carbon-rich material produced when biomass such as crop residues or forestry waste is heated in a low-oxygen environment. When applied to soil, it can store carbon for long periods while improving soil properties.

Using life cycle analysis, the team estimated how much carbon could be removed if biomass from agricultural residues, forestry residues, and bioenergy crops were converted into biochar and applied to soils.

The analysis found that Guangdong province has significant biomass resources, including crop residues, forestry residues, and marginal land suitable for bioenergy crops such as miscanthus and eucalyptus. Under the most ambitious scenario, converting these resources into biochar could remove up to 84.30 million tons of carbon dioxide equivalent per year.

However, this would offset only about 9.11 percent of the province’s current net carbon emissions, indicating that biochar alone cannot close the gap to carbon neutrality.

“Our results show that biochar can contribute to climate mitigation but cannot by itself balance the large carbon emissions from energy and industrial activities,” the authors explain. “A combination of emission reduction and carbon removal strategies will be necessary.”

The researchers emphasize that reducing emissions from energy consumption remains the most critical step. Transitioning to cleaner energy sources, improving energy efficiency, and adopting low-carbon industrial technologies could substantially lower the region’s carbon footprint.

At the same time, increasing carbon sinks through afforestation, bioenergy crops on marginal land, and biomass-based carbon removal technologies such as bioenergy with carbon capture and storage may help further reduce emissions.

The authors also note that Guangdong’s coastal ecosystems and marine environments may offer additional opportunities for carbon sequestration in the future.

By providing a detailed carbon inventory and evaluating the potential of biochar deployment, the study offers valuable guidance for policymakers seeking effective pathways toward regional carbon neutrality.

“Our findings highlight both the promise and the limitations of biochar as a climate solution,” the researchers conclude. “Integrating multiple carbon removal technologies with aggressive emission reductions will be essential for achieving long-term climate goals.”

Wang, F., Zhou, W., Wang, X. et al. Biochar technology cannot offset land carbon emissions in Guangdong province, China. Carbon Res. 3, 55 (2024).

https://doi.org/10.1007/s44246-024-00140-1