Energy, economic, and environmental impacts of sustainable biochar systems in rural China

Biochar production from biomass is a promising solution to tackle the energy and environmental challenges of rural China such as air pollution, soil contamination and degradation, sustainable agricultural waste management, and climate change. Small- and medium-scale (a few kW to 3 MW) gasification systems consisting of a gasification reactor and a gas engine had an energy efficiency of 15–20% and large-scale (>5 MW) systems via an integrated gasification combined cycle had an electrical efficiency of 26–30%. Low system efficiencies and high costs incurred by collection, transport, and pretreatment are some of the major barriers to the economic feasibility of biochar production systems in China. Mobile systems or distributed biochar production systems serve as promising solutions to reduce the biomass cost by utilizing locally generated waste biomass and catering for the bioenergy and biochar demands of local rural communities. From an energy application perspective, biochar production systems can generate heat and electricity, and biochar can serve as an energy storage material in supercapacitors and rechargeable batteries systems and can be used in anaerobic digestion to enhance overall energy recovery. Biochar can be used to achieve carbon sequestration and remediation of soil, and odor control in livestock farms. Systems converting locally generated biomass into energy and biochar that are used by local villages wait to be tested to clarify the intricacies of their viability and large-scale environmental and energy impacts in rural China.