Role of biochar toward carbon neutrality

Abstract

Carbon neutrality by the mid-twenty-first century is a grand challenge requiring technological innovations. Biochar, a traditional soil amendment which has been used for fertility improvement and contaminant remediation, has revealed new vitality in this context. In this review we highlight the huge potential of biochar application in different fields to mitigate as high as 2.56 × 109 t CO2e total greenhouse gas (GHG) emissions per year, accounting for 5.0% of the global GHG emissions. Soil applications of biochar as either a controlled-release fertilizer or an immobilization agent offer improved soil health while simultaneously suppressing the emissions of CH4 and N2O. Non-soil applications of biochar also contribute to carbon neutrality in unique ways. Firstly, biochar application as a ruminant feed decreases CH4 emissions via physical sorption and enhanced activities of methanotrophs. Secondly, biochar can be used as a green catalyst for biorefinery. Besides, biochar as an additive to Portland cement and low impact development (LID) infrastructure lowers the carbon footprint and builds resilience to climate change. Furthermore, biochar can be used as novel batteries and supercapacitors for energy storage purposes. Finally, the high CO2 adsorption capacity makes it possible for biochar being used as a sorbent for carbon capture, utilization, and storage (CCUS). We advocate that future research should further explore the effectiveness of biochar systems for climate change mitigation in large scale applications, and assess the economic and social viability of local biochar systems to combat climate change. Graphical Abstract

Sustainable remediation and redevelopment of brownfield sites

“…As a waste-derived biosorbent, it immobilizes a wide range of pollutants, both organic and inorganic, via its porous structure, large surface area and abundant functional groups 59 . Biochar is also carbon-negative as its carbon content can be highly stable, with reported half-lives (t 1/2 ) of >1,000 years, potentially promoting in-ground carbon sequestration 60 (Fig. 4a).…”

Carbon Sequestration Strategies in Soil Using Biochar: Advances, Challenges, and Opportunities

“…Their dynamics predominantly affect GHG emissions and C sequestration in soil environments. Although converting biomass into biochar can reduce GHG emissions that would otherwise have arisen from the decomposition or combustion of biomass, high amounts of harmful GHGs or their precursors, including CO, CH 4 , and NO x , as well as PAHs, are emitted with the decomposition of labile C and N during thermochemical treatment and subsequent land application processes. , The emissions of CO 2 and CH 4 induced by biochar production and soil application have been thoroughly summarized (e.g., refs , , , , and ). However, quantitative information on the N-containing GHG emissions associated with biochar, especially during its production, is frequently overlooked and thus lacking.…”

“…Biochar, as a stabilized form of C derived from biomass wastes, can persistently exist in soil environments for decades or longer and significantly decrease/delay C emissions from biomass. , Biochar can also mitigate GHG emissions from soil and facilitate vegetation C (including plant litter and root exudates) sequestration via improving soil structure and microbial communities. − Thus, biochar is proposed to be a promising material and solution toward C sequestration and C neutrality in soil. − Over 6.5 Gt C of biomass is harvested and available for biochar production annually in the world, which provides a bright prospect for C sequestration via biochar. , It is estimated that if all available biomass is converted into pyrochar in China, the total CH 4 and N 2 O emissions from China’s croplands can be fully offset . Although biochar has splendid prospects for C sequestration, a previous focus was predominately paid to the function of biochar for improving soil quality and remediating contaminated environments due to its clear agronomic and environmental benefits. , For instance, about 31988 journal publications were obtained in the field of biochar up to March 31, 2023, based on the search results from the Web of Science core collection.…”

Soil health and ecosystem services

“…Soil amendments such as biochar and compost have been widely used to improve soil health (Gao et al, 2022; Thakur et al, 2023; Zhang, Liu, et al, 2022). In recent years, biochar has attract attention because it offers a wide variety of soil health benefits (Abel et al, 2013), such as supplying slow‐release nutrients, mitigating climate change by carbon sequestration and reducing soil contaminant leaching and bioavailability (Hou et al, 2023; Wang, Deng, et al, 2023). However, the effect of biochar on soil health depends on its feedstock and production conditions (Li et al, 2023).…”