Synthetic ammonia carbon reduction path

I.Because the production process is similar and the emission reduction grips overlap, we will take synthetic ammonia as an example to further clarify each carbon reduction grips in this article.

Demand-side management: The main downstream use of synthetic ammonia is nitrogen fertilizer production, and about 90% of synthetic ammonia is processed into nitrogen fertilizer. Nitrogen fertilizer use in China is projected to have the potential to decline by 40 percent by 2050, driven by a combination of reduced arable land and more efficient fertilizer use.

a. Reduction of cultivated land: China's total cultivated land area is expected to continue the downward trend in the future, from 2 billion mu to nearly 1.8 billion mu, an estimated decline of 10%. Long-term over-cultivation has led to the decline of cultivated land quality, currently China's 2 billion mu of cultivated land has 4% of polluted land, 17.8% of low arable land and more than 80 million mu of unstable farmland, recuperation, return to forest and grass, rotation and fallow is imperative. At the same time, along with the process of urbanization, the rural population is expected to move out further in the future, resulting in some arable land wastage.

b. Improved fertilizer efficiency: Without affecting yields, we project that annual nitrogen fertilizer use per hectare in China has the potential to decline by 30% by 2050 (see Figure V). The per capita arable area of Chinese farms is much lower than that of Western countries, and small farmers lack the knowledge of scientific use of chemical fertilizers, leading to the problem of excessive and blind use of chemical fertilizers in China. The average amount of nitrogen fertilizer used in China's crop hectares is 306 kilograms, much higher than the world average and more than twice that of the United States. The problem has improved in recent years, and during the 13th Five-Year Plan period, the government actively controlled fertilizer use through farmer education and local supervision. In the future, with the integration of land ownership, large farms are expected to gradually replace individual farmers as the mainstream farming model. Large farmers use far less nitrogen fertilizer per hectare than small farmers; At the same time, large farmers are also more willing to adopt optimized farming techniques, such as the use of organic fertilizers, slow-release fertilizers and other new fertilizers, to further improve the efficiency of fertilizer use.

2. Existing carbon reduction technologies: Emerging gasifier and fuel electrification technologies are mature and, if widely applied in the industry, can effectively reduce carbon emissions by more than 50%, but will incur additional capital expenditures and operating costs. Due to the low overall profit level of the coal chemical industry, external thrust is needed to internalize the external cost of carbon emissions in order to improve the application space of these two technologies in the industry.

a. Emerging gasifiers: China's existing gasifiers are still dominated by old fixed beds, and their single-furnace production capacity is low and pollution treatment is difficult, which has been generally eliminated by modern coal chemical industry abroad. With the increase of carbon emission requirements, coal chemical enterprises need to actively replace production capacity, eliminate and upgrade the old fixed bed gasification technology with high coal consumption, and use new high-efficiency pulverized coal gasification and other technologies. It is estimated that by 2030, by upgrading gas equipment, the industry has the potential to reduce coal consumption per unit by 30%, thereby reducing carbon emissions by about 15%.

b. Fuel electrification: Coal-fired electrification, which can eliminate carbon emissions from coal (50% of the total), is a mature technology, but it significantly increases operating costs in high-temperature processes, and is estimated to cost more than $100 to reduce 1 ton of CO2.

3. Emerging carbon emission reduction technologies: CCUS and electrolytic hydrogen, two emerging technologies, are the starting points to solve the last mile of carbon emission reduction in the synthetic ammonia industry. Both of these technologies can reduce carbon emissions in the production process of synthetic ammonia by more than 80%, but they are still in the stage of technological exploration.

A. Carbon capture utilization and storage (CCUS) : CCUS has a good coupling with the development of coal chemical industry, because the carbon dioxide concentration is high, the capture cost is much lower than other industries. According to our estimates, the cost of CO2 capture per ton in the synthetic ammonia industry is about 80 yuan, while in other industries (e.g., cement, electricity) it is more than 200 yuan. This technology can be preferentially used in North China, Northeast China, Inner Mongolia and other places close to oil fields to reduce carbon emission costs through carbon dioxide flooding. In the next 30 years, if the development of CCUS is improved, the construction of transport pipelines and storage facilities, and the formation of industrial synergies with other high-carbon industries, it is expected to further expand the application of the industry.