Achieving net-zero emissions in agriculture: a review

Abstract

Agriculture accounts for 12% of global annual greenhouse gas (GHG) emissions (7.1 Gt CO2 equivalent), primarily through non-CO2 emissions, namely methane (54%), nitrous oxide (28%), and carbon dioxide (18%). Thus, agriculture contributes significantly to climate change and is significantly impacted by its consequences. Here, we present a review of technologies and innovations for reducing GHG emissions in agriculture. These include decarbonizing on-farm energy use, adopting nitrogen fertilizers management technologies, alternative rice cultivation methods, and feeding and breeding technologies for reducing enteric methane. Combined, all these measures can reduce agricultural GHG emissions by up to 45%. However, residual emissions of 3.8 Gt CO2 equivalent per year will require offsets from carbon dioxide removal technologies to make agriculture net-zero. Bioenergy with carbon capture and storage and enhanced rock weathering are particularly promising techniques, as they can be implemented within agriculture and result in permanent carbon sequestration. While net-zero technologies are technically available, they come with a price premium over the status quo and have limited adoption. Further research and development are needed to make such technologies more affordable and scalable and understand their synergies and wider socio-environmental impacts. With support and incentives, agriculture can transition from a significant emitter to a carbon sink. This study may serve as a blueprint to identify areas where further research and investments are needed to support and accelerate a transition to net-zero emissions agriculture.

Global biomethane and carbon dioxide removal potential through anaerobic digestion of waste biomass

“…Multiple benefits can be achieved by the BECCS supply chain envisioned in this study. Agricultural production accounts for 12% of global total GHG emissions excluding forestry and land use (7.1 Gt CO 2 equivalent per year) [49]. We estimate that BECCS supply chains that use waste biomass and residues have the potential to reduce 21% of GHG emissions from agricultural production.…”

“…In addition, the utilization of waste biomass and residues can avert numerous disposal problems, such as water pollution [144][145][146], air pollution, and GHG emission from crop residues, biomass burning, and manure management [147][148][149]. For example, if waste biomass were not deployed for BECCS, wastewater would contribute to 0.65 Gt CO 2 equivalent, the burning and decomposition of agriculture residues and livestock manure would generate 1.6 Gt CO 2 equivalent [49], and the decomposition of organic matter in municipal solid waste results in CH 4 emission [150,151], which would contribute to 0.8 Gt CO 2 equivalent [152]. Replacing fossil fuel with biomethane can avoid 1.1 Gt CO2 equivalent per year [133].…”

“…Food systems account for about 30% of the global annual GHG emissions [47][48][49]. Within food systems, waste biomass, including manure, crop residue, and food waste, contribute to 16% of GHG emissions the food sector emits, predominantly releasing nitrous oxide and methane [49].…”

“…Food systems account for about 30% of the global annual GHG emissions [47][48][49]. Within food systems, waste biomass, including manure, crop residue, and food waste, contribute to 16% of GHG emissions the food sector emits, predominantly releasing nitrous oxide and methane [49]. Utilizing this waste biomass and producing biogas during anaerobic digestion leads to a reduction in nitrous oxide and methane emission [49], which will significantly enhance agricultural sustainability and contribute to a circular economy towards net-zero agriculture.…”

“…Within food systems, waste biomass, including manure, crop residue, and food waste, contribute to 16% of GHG emissions the food sector emits, predominantly releasing nitrous oxide and methane [49]. Utilizing this waste biomass and producing biogas during anaerobic digestion leads to a reduction in nitrous oxide and methane emission [49], which will significantly enhance agricultural sustainability and contribute to a circular economy towards net-zero agriculture. In addition, waste biomass is a limited resource [20] and there is growing consensus that the social value of deploying biomass for CDR via BECCS may exceed its value for bioenergy production only [50][51][52].…”