Reducing China's Fertilizer Emissions: A Path to Cleaner Air and Lower Carbon Output

What is it about?

The research quantified lifecycle CO₂-equivalent (CO₂-eq) and ammonia (NH3) emissions associated with China's synthetic nitrogen (N) fertilizer system, focusing on carbon and nitrogen flows from mining through production, application, and export. In 2020, the total emissions from this system were 496.04 Tg of CO₂-eq and 3.74 Tg of NH3, with ammonia production and fertilizer application contributing significantly to these emissions. The analysis included both direct and indirect emissions from coal and natural gas mining, fuel combustion, and energy consumption during production. A bottom-up data set was developed using China's Environmental Statistics and Emission Permit System, alongside comparisons with official statistics, achieving consistency within a 5-10% margin for key measures. The research identified the potential for significant emission reductions by improving N fertilizer utilization efficiency and employing nitrification inhibitors, which could reduce CO₂-eq emissions by 20% and NH3 emissions by 75%. Additionally, transitioning to energy sources like green electricity or hydrogen in ammonia production was highlighted as a major step towards further decarbonization of the N fertilizer system.

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Photo by Ling Tang on Unsplash

Photo by Ling Tang on Unsplash

Why is it important?

This study is important as it addresses the significant environmental challenges posed by China's synthetic nitrogen (N) fertilizer industry, which is the largest in the world. By quantifying the lifecycle CO₂-equivalent (CO₂-eq) and ammonia (NH₃) emissions, the research highlights the substantial contributions of N fertilizer production and application to greenhouse gas emissions and air pollution. The findings are crucial for informing policies aimed at achieving China's carbon-neutral goals by 2060 and improving air quality by reducing PM2.5 concentrations, which are exacerbated by ammonia emissions. This research provides actionable insights for enhancing sustainability in agricultural practices through technological innovations and strategic energy transformations. Key Takeaways: 1. Emission Contributions: The study reveals that in 2020, China's N fertilizer system was responsible for emitting 496.04 Tg of CO₂-eq and 3.74 Tg of NH₃, with ammonia production and N fertilizer application accounting for the majority of these emissions. 2. Comparative Emissions: The research shows that each ton of N fertilizer produced and used in China results in significantly higher emissions compared to Europe, with 16 t of CO₂-eq and 0.18 t of NH₃ emitted in China versus 9.7 t of CO₂-eq and 0.13 t of NH₃ in Europe. 3. Mitigation Strategies: By adopting available technologies and improving fertilizer efficiency, China could reduce CO₂-eq emissions by 20% and NH₃ emissions by 75%. Energy transformation efforts, including the use of green electricity or hydrogen for ammonia production, could further cut CO₂-eq emissions by 59%.