Hydrogen energy is a hot field of new energy development, which has many advantages, but the storage and transportation technology is difficult and costly. In terms of storage, hydrogen is the lightest element on the periodic table, and it is easy to leak, so it requires high storage containers. In terms of transportation, if hydrogen is transported over a long distance, it needs to be liquefied, that is, its temperature is reduced to below -235 degrees Celsius under normal pressure, which leads to high energy consumption; If it is transported by pipeline, it is necessary to overcome the hidden danger of pure hydrogen and hydrogen-doped gas to the pipeline, and overcome the material problem of hydrogen pipeline. With the high cost of hydrogen energy, people begin to pay attention to ammonia.
Ammonia is one of the most important basic chemicals in the world and is widely used in modern industrial and agricultural production. Ammonia is composed of one nitrogen atom and three hydrogen atoms, which is a natural hydrogen storage medium. Under normal pressure, it can be liquefied when the temperature is reduced to -33 degrees Celsius, which is convenient for safe transportation; At present, more than 80% of ammonia in the world is used to produce chemical fertilizers. Therefore, in theory, renewable energy can be used to produce hydrogen, which can then be converted into ammonia and transported to the destination.
Besides being a carrier of hydrogen energy, ammonia is also a relatively cheap zero-carbon fuel. Its energy density is 1.5 times that of liquid hydrogen, and the combustion reaction products of ammonia and oxygen are water and nitrogen, and nitrogen accounts for about 78% of air, so the combustion process of ammonia achieves zero carbon emission.
Based on the above characteristics of ammonia, the industry began to pursue the integration of ammonia and hydrogen energy. On the one hand, it built a new hydrogen energy storage and transportation system; on the other hand, it began to use ammonia and hydrogen co-combustion fuel as one of the important ways to reduce carbon.
Enterprises in the engine and hydrogen fuel cell industries began to build ammonia-hydrogen supply chains to provide electrolysis equipment for the production of green ammonia; Gas and chemical companies invest in hydrogen production projects, build green hydrogen plants, provide power for hydrogen fuel buses, and apply 'hydrogen-ammonia conversion technology' to produce ammonia, so as to facilitate the transportation and export of hydrogen; The fuel used for power generation is also turning towards the mixed combustion of coal, ammonia and hydrogen.
The research and application of new technologies are also accelerating the development of ammonia energy industry. The world's first industrial application project of ammonia mixing combustion technology in coal-fired boilers was successfully put into operation in Shandong in early 2022, and the pilot test of ammonia mixing combustion ratio of 40 MW coal-fired boilers of 35% was realized for the first time in the world, which marked that China's ammonia mixing technology in coal-fired boilers reached the world's leading position.
In 2022, the first 8.3 MW pure ammonia burner in China was successfully ignited and stably operated on a 300,000 kW coal-fired power unit, which marked the key progress of the demonstration project of comprehensive utilization of ammonia energy for power generation. According to the technical path of 'green electricity → hydrogen production by electrolysis of water → ammonia synthesis → ammonia transportation → combustion with ammonia in thermal power plants', the proportion of combustion with ammonia in thermal power plants was gradually increased through experiments, achieving the goal of effectively reducing carbon dioxide emissions and total energy consumption of coal-fired power generation.
China is a big ammonia producer in the world, with an annual output of about 200 million tons. Experts pointed out that hydrogen-ammonia fusion is a forward-looking, subversive and strategic technical development direction of international clean energy, an effective way to solve the major bottleneck of hydrogen energy development, and an important technical route to realize high-temperature zero-carbon fuel.