At present, the production of green hydrogen is limited by the economic bottleneck of water electrolysis technology and the safety hazards of storage and transportation, and the construction of supporting infrastructure is slow, which hinders the commercialization process of large-scale application of hydrogen energy. Before the large-scale use of hydrogen energy, ammonia synthesis was seen as an effective means to undertake the conversion of green electricity into zero-carbon fuel.
From the perspective of energy storage, ammonia can be catalytically decomposed to produce hydrogen, which solves the problems of low cost, long-distance transportation and the "long tail" of hydrogen energy, and also solves the problem of how to use large-scale green hydrogen, continues the industrial chain of hydrogen energy terminal consumption, and further expands the scale of the hydrogen energy industry. From an energy point of view, the complete combustion products of ammonia are only nitrogen and water, which can replace part of coal to provide clean fuel for the power system, and can also replace part of fossil energy to provide clean fuel for engines. In this context, many countries are actively carrying out ammonia energy technology research and development and planning layout.
As another strategically valuable clean energy, ammonia energy provides a new choice for rapid adjustment of energy structure and acceleration of carbon neutrality. In the mainland, the production, storage, transportation, supply and other links of ammonia have been systematized, and there are good basic conditions for synthetic ammonia and ammonia utilization, which should occupy an important position in the global ammonia energy industry in the future.
Application value of ammonia
(1) Ammonia is a hydrogen carrier
Ammonia is a hydrogen-rich compound with a hydrogen-carrying capacity of up to 17.6% by weight and a volumetric hydrogen carrying efficiency of 150% of hydrogen. Ammonia can be liquefied at -33 °C (or 9 atmospheres at room temperature) compared to the very low liquefaction temperature of hydrogen at atmospheric pressure (-283 °C). In terms of cost, the liquid ammonia storage tank of the same mass is 0.2%~1% of the liquid hydrogen storage tank, and the unit volume weight density of liquid ammonia is 8.5 times that of liquid hydrogen.
According to the International Energy Agency (IEA), the total global demand for green and blue hydrogen will reach 7.5×107t in 2040. Based on this situation, to solve the problem of hydrogen energy supply and demand contradiction, we must first break through the bottleneck of low-cost, long-distance storage and transportation of hydrogen. At present, there are three commonly used hydrogen storage and transportation methods: high-pressure gaseous hydrogen transportation, liquid hydrogen transportation, and cryogenic hydrogen high-pressure transportation, but each method is difficult to operate, resulting in high transportation costs and low efficiency. In contrast, ammonia is easier to liquefy, store and transport. According to the calculation, the storage and transportation cost of liquid ammonia within 100 km is 150 yuan/t, and the storage and transportation cost of liquid ammonia within 500 km is 350 yuan/t, which is only 1.7% of the storage and transportation cost of liquid hydrogen. At the same time, the use of ammonia on-site hydrogen production and refueling stations can reduce the cost of hydrogen to less than 35 yuan/kg, which can save 100 billion yuan according to China's goal of building 10 000 hydrogen refueling stations by 2050. In addition, compared to hydrogen, ammonia has a narrower explosion limit range (16%~25%), a higher boiling point, and a lower possibility of fire and explosion. At the same time, ammonia has a pungent odor, and the human sense of smell can detect only a concentration of less than 5% of the dangerous level, and the leakage is easy to be detected, which is more safe and reliable. Therefore, ammonia is an excellent hydrogen storage carrier, and hydrogen and ammonia fusion can become the most potential new storage and transportation mode to broaden the application scenarios of hydrogen energy industry.
(2) Ammonia is a clean fuel
As a carbon-free compound, ammonia can be synthesized from nitrogen in the air and hydrogen in water, and the product is pure and carbon-free when completely combusted, so as a strategically valuable renewable energy source, ammonia can be directly burned to achieve clean energy supply. Ammonia combustion has a low air-fuel ratio, and can provide more energy under the same air intake (air) conditions, making it a high-power clean fuel. At the same time, the heat loss ratio of ammonia combustion is much lower than that of fuels such as hydrogen, gasoline and diesel, and the heat loss carried away by the exhaust gas is small. Although ammonia has a low calorific value when burned, it has a high octane number and good knock resistance, which can increase the power output of the powertrain by providing a higher compression ratio. In the case of direct ammonia refueling, operators can upgrade existing gas stations into ammonia refueling stations, and the transformation cost is an order of magnitude lower than the investment cost of a new hydrogen refueling station, which is equivalent to the investment cost of a new gas station.
(3) Ammonia has a mature industrial system
At the beginning of the 20th century, ammonia synthesis technology was successfully developed and industrialized. As the world's second largest chemical, synthetic ammonia has a complete industrial chain structure and a mature international production and trade system, and the raw materials used in it come from a wide range of sources, which can avoid large price fluctuations caused by the imbalance between supply and demand in the long-term application process. Under the background of carbon neutrality, the hydrogen source used in ammonia synthesis is bound to develop from an industrial hydrogen source to a hydrogen supply method of water, and the energy required is also bound to develop into a way to supply energy from renewable energy sources such as wind and solar, and finally realize the low-carbon route of green ammonia production. At present, the unit energy price of liquid ammonia in most countries is equal to or lower than that of gasoline. In particular, China is the world's largest producer and consumer of synthetic ammonia, and the synthetic ammonia industry is all over the country, with a good foundation for promotion and application.
Status quo of ammonia energy application
Ammonia's energy and energy storage properties make it have great potential for growth in new markets such as power fuels, clean electricity, and hydrogen storage carriers. Under the vision of the dual carbon strategic goals, ammonia will build an ammonia energy system, which is of great significance to the development of a low-carbon society. On the one hand, ammonia can be used directly for energy supply. Ammonia is considered to have the potential for decarbonization applications in power generation and heavy transportation. Direct combustion of ammonia or co-combustion with conventional fuels for power generation is conducive to the construction of a clean power system, and ammonia is used as a motor fuel, which is conducive to solving the carbon emission problem in the transportation sector. Ammonia, on the other hand, can be used indirectly for energy. Ammonia is used as a hydrogen storage medium, and the use of catalytic technology can realize ammonia-hydrogen conversion, which can break the traditional hydrogen storage and transportation mode and lay the foundation for the development of "ammonia-hydrogen" green energy industry.
(1) Ammonia internal combustion engine
Ammonia has a high octane number and good resistance to shock and explosion, which can increase the output power by providing a higher compression ratio. Ammonia is thermally efficient as 50% or even nearly 60% when used as a fuel for internal combustion engines. The theoretical air-fuel ratio of ammonia is low, and more ammonia can be added to the internal combustion engine to compensate for its low calorific value. Obviously, ammonia also has some significant combustion defects when used as a fuel. Compared with gasoline, diesel and other fuels, the minimum ignition energy and laminar combustion rate are lower during ammonia combustion. Therefore, ammonia is often blended with fuels with better combustion performance to improve its combustion characteristics. In addition, in the actual process, due to insufficient combustion and oxidation, it is easy to convert the nitrogen contained in ammonia fuel into NOx gas emissions with stronger greenhouse effect. Therefore, a targeted control strategy for combustion and exhaust gas treatment is essential to reduce NOx emissions. According to the ammonia combustion mechanism, temperature and pressure have a significant impact on the formation of NOx, and controlling the temperature within the thermal denitrification temperature range and increasing the pressure as much as possible are the two conventional means to restrict the formation of NOx, the latter is usually used in internal combustion engine systems. In addition to this, NOx generation can be reduced at the end of combustion using a selective catalytic reduction (SCR) system or a strategy of fuel overabundance and exhaust gas recirculation.
The annual installed capacity of compression-ignition internal combustion engines in the transportation and power generation fields such as heavy trucks and ships is huge, and the current fuel oil is the main one, and the carbon dioxide emissions produced account for 3%~4% of the world, and the demand for carbon emission reduction is significant. The International Maritime Organization (IMO) has set targets for reducing carbon emissions in the shipping industry, stating that carbon dioxide emissions should be reduced by at least 70% by 2050 compared to 2008. Therefore, by 2050, at least 15% of long-haul ships should use ammonia or hydrogen as fuel. The high volumetric energy density properties of ammonia fuel allow for improved hull space utilization, and only minor changes to conventional combustion engines, changes in compression ratios, and replacement of corrosion-resistant lines are required. As a result, ammonia is considered a clean fuel suitable for ocean-going vessels.
In January 2023, the world's first ammonia floating storage and regasification barge jointly developed by NYK Shipping Co., Ltd., Nippon Shipyard and Japan's Ishikawajima-Harima Heavy Industries (IHI) was approved in principle by Nippon Classification Society. Japan plans to complete the demonstration of pure ammonia-fueled ships by 2025 and carry out promotion and application after 2025. China is also actively promoting the demonstration of ammonia-fueled ships, and in March 2022, an ammonia and LNG dual-fuel carrier designed and built by China State Shipbuilding Group was successfully launched. It is expected that by 2035, the economics of ammonia-powered ships will be on par with those of conventional fuel-powered ships.
At present, there is no systematic study on the thermodynamic characteristics of ammonia combustion under different working conditions, such as combustion rate, flame stability, ignition characteristics, NOx generation characteristics and unburned ammonia emissions. The combustion kinetic model of ammonia is also in the stage of continuous verification and improvement. In general, the mainland is in its infancy for ammonia combustion applications, but the complete production, storage, transportation and transportation system of synthetic ammonia has laid a good foundation for its new application in the energy field. Relevant research should be closely integrated with the needs of the industry to promote technology development.
(2) Ammonia gas turbines
Research on ammonia for gas turbines began in the 60s of the 20th century, but was discontinued due to factors such as the low cost of fossil fuels and technical constraints at that time. Compared to internal combustion engine applications, gas turbines typically burn gaseous fuels with unlimited combustion chamber volumes, making them a better match for ammonia fuels. However, the defects of ammonia combustion still exist, and combustion stability and pollutant treatment are still the focus of large-scale applications.
For the first time in Japan, a 50 kW micro gas turbine has achieved dual-fuel combustion power generation, generating 44.4 kW of power and combustion efficiency of 89%~96%. Japan's IHI achieved ammonia co-firing on a 2 MW gas turbine with a blending ratio of up to 70% and low NOx emissions in a cyclone burner (see Figure 1). Recently, Mitsubishi Electric Corporation announced that it has begun research and development of the world's first ammonia 40-megawatt gas turbine system, which is fueled by pure ammonia, with the goal of commercializing it around 2025. The U.S. has partnered with IHI to develop a gas turbine roadmap. At present, there are few related studies in China, and they tend to focus on theoretical research and basic research.
Fig.1. Structure of NH3/natural gas cyclone burner
(3) Ammonia-fired boilers
The mainland's energy structure of "rich in coal, poor in oil and low in gas" has led to a huge installed capacity of coal-fired power plants in the mainland. The carbon dioxide produced by coal-fired power generation accounts for 34% of the mainland's total carbon emissions, and carbon emission reduction is one of the important ways to successfully achieve the mainland's "dual carbon" strategic goals. Carbon dioxide capture, utilization and storage technology is the key means, but this technology has the problems of long transportation distance and high construction investment cost of capture, storage or utilization. The flexibility of ammonia combustion offers a new option for achieving significant carbon reductions in the power sector. In the short term, due to the production and cost constraints of green ammonia, coupled with the poor combustion stability of pure ammonia, it is not possible to realize the application of pure ammonia combustion instead of coal. In contrast, the ammonia-doped combustion method can use the existing power plant facilities without large-scale transformation of the boiler body, which has become a feasible option to reduce the carbon emissions of coal-fired power plants at this stage.
The application of ammonia fuel in boilers is in its infancy, focusing on small-scale or pilot-scale research. Japan was the first to explore ammonia-fueled power generation and is accelerating the decarbonization of its power system. IHI of Japan has built a 10 MW ammonia doping combustion demonstration plant, and is also promoting the implementation of a 1000 MW power plant ammonia doping experiment, which will achieve 20% ammonia mixed combustion in the future. In order to achieve a high rate of ammonia co-burning in high-pressure burners, IHI is developing an easy-to-supply liquid ammonia direct injection combustion technology to further advance the development of ammonia blending (see Figure 2). Two units in mainland China took the lead in achieving engineering verification, namely the first 8.3 MW pure ammonia burner jointly developed by Anhui Energy Group and Hefei Energy Research Institute, which was successfully ignited at one time and operated stably for 2 h at a time at 300 MW thermal power units, and the 40 MW coal-fired boiler built by China Energy Group to achieve the world's largest proportion of ammonia mixed combustion (35% ammonia), which marks that the ammonia mixing technology of coal-fired boilers in mainland China has entered the world's leading track. The existing demonstration results of China Energy Investment Group Co., Ltd. show that the NOx pollutants generated after ammonia combustion are lower than those under coal-fired conditions under the condition of ammonia doping ratio and ammonia injection position. If all existing coal-fired power units are burned with 35% ammonia, 9.5×108 t of carbon dioxide emissions can be reduced per year. According to relevant calculations, when the coal price is 1400 yuan/t and the carbon price is 500 yuan/t, the economy of ammonia-doped power generation can compete with coal power.
Fig.2 Schematic diagram of ammonia/coal co-combustion cyclone burner
(4) Ammonia \u2012 Hydrogen fuel cell
A fuel cell is a device that converts chemical energy directly into electrical energy, which is theoretically more efficient and environmentally friendly. Ammonia has a high hydrogen content, a simple reforming hydrogen production device, and the product does not contain carbon monoxide that causes fuel cell poisoning, which has significant advantages as a raw material for fuel cells, and is bound to become a research hotspot. In the indirect ammonia fuel cell system, only the ammonia decomposition hydrogen production device needs to be installed at the inlet of the existing fuel cell gas, and a good ammonia \u2012 hydrogen conversion can be achieved based on the mature technology. Using the existing fuel cell technology, ammonia fuel can achieve a power density similar to hydrogen fuel at the same temperature, and can replace pure hydrogen for new energy vehicles. Ammonia \u2012 The cost of hydrogen fuel cells on the end-user side is only 1 yuan/(kW·h) or 0.25 yuan/km, which has significant economic benefits. But there are also some issues that need to be balanced: the hydrogen produced by ammonia decomposition needs to be purified and compressed, and the process consumes a lot of energy. In addition, the integration of the ammonia cracking reactor and the hydrogen compression system will increase the overall system process. At present, ammonia fuel cells are still in the initial research stage, and the performance is not perfect. In order to meet the needs of commercialization, it is also necessary to overcome the problem of long-life operation stability.
The development trend of the ammonia energy industry
(1) The status quo of the synthetic ammonia industry
At present, the production process of synthetic ammonia has not yet been green. Based on the traditional synthesis process, the global annual production of synthetic ammonia is about 2×108 t, which is mainly produced in four countries: China, India, Russia and the United States, and is traded globally. China and India are also major importers of ammonia, while Russia is the main exporter, with about 70% of ammonia (about 1.7×108 t) exported (see Figure 3).
Fig. 3 Details of ammonia production and import and export
In mainland China, the demand for synthetic ammonia has been expanding in recent years, supported by fertilizer prices (see Figure 4). By the end of 2021, China's synthetic ammonia production capacity was about 6.488×107 t, accounting for about one-third of the global production capacity, a year-on-year increase of 14.5% over 2020. The development of ammonia energy will drive the rapid development of the upstream, midstream and downstream industrial chains of synthetic ammonia. Synthetic ammonia is mainly divided into three major uses, namely agriculture (urea and other fertilizers), industry (chemical raw materials, flue gas denitrification) and energy storage (new uses).
Fig. 4 Synthetic ammonia production in China (2005-2020)
Similar to hydrogen, synthetic ammonia is classified into grey, blue, and green ammonia based on the carbon footprint of the hydrogen in the feedstock. The hydrogen in grey ammonia is derived from natural gas or coal and is prepared by the conventional Haber-Bosch high-temperature catalytic process. Blue ammonia is the capture of carbon dioxide from the gray ammonia production process. Green ammonia is based on the premise that renewable energy provides energy source, water is used as raw material to provide green hydrogen, and then nitrogen is prepared through new low-carbon technologies such as thermal catalysis or electrocatalysis. Green ammonia is an important way to absorb renewable energy and an important way to achieve carbon emission reduction. Ammonia energy is a supplement to hydrogen energy, and green ammonia synthesis will become one of the important applications in the field of hydrogen energy, and ammonia synthesis technology is bound to develop towards low-carbon synthesis technology in the future.
Green ammonia synthesis technology includes ammonia synthesis process under mild conditions and new ammonia synthesis process. The ammonia synthesis process under mild conditions mainly revolutionizes the ammonia synthesis catalyst, and through the development of high-efficiency thermal catalysts, ≤which can achieve low-temperature and low-pressure ammonia synthesis in the traditional Haber-Bosch process and reduce the energy consumption of the process reaction. In the short term, this method makes it easier to achieve large-scale green ammonia production. The new ammonia synthesis processes include electrocatalytic ammonia synthesis, photocatalytic ammonia synthesis, nitrogenase ammonia synthesis, plasma ammonia synthesis, etc., among which the electrocatalytic ammonia synthesis technology has attracted great attention (see Fig. 5). Electrocatalytic ammonia synthesis technology is the use of water in the electrolyte and nitrogen in the air to generate, its essence is to use the electrocatalyst under the condition of applying electric energy N≡N continuous hydrogenation and bond breaking, the formation of ammonia molecules, to realize the conversion of electrical energy to chemical energy, effectively reduce the reaction energy barrier.
Fig.5 Development process of ammonia synthesis catalysis
(2) The development trend of ammonia energy industry
Under the global trend of carbon reduction, the scale of hydrogen-related applications will continue to expand, and the market demand for ammonia will further increase. The growing demand for synthetic ammonia in the ammonia industry should not jeopardize the supply of fertilizers, let alone food production. In this case, the ammonia infrastructure must be expanded at a rate of 10~15 times. The ammonia industry is energy-intensive, accounting for about 2% of global energy consumption. In addition, about 3×108 tons of carbon dioxide are emitted annually during the production of synthetic ammonia, accounting for about 1% of the total global carbon emissions. Typically, for every 1 t of ammonia produced, nearly 2 t of CO2 is released. The pressure on energy conservation and emission reduction in the synthetic ammonia industry is huge, and green transformation is urgently needed. At present, the national policy of the mainland encourages the production of synthetic ammonia through green and low-carbon technologies, and by 2025, the proportion of energy efficiency production capacity in the synthetic ammonia industry will increase from 7% in 2020 to 15%. In the future, with the development of industry technology, more green and energy-saving production units will be added to the mainland, and the output of the industry will continue to grow.
In areas with the best renewable resources, the cost of green ammonia is estimated at US$689/t, which is higher than the price of grey ammonia (US$225/t). The price of green ammonia is forecast to fall to US$464/t by 2030 and US$295/t by 2050 (see Figure 6). At a carbon price of around US$127/t, green ammonia can compete with existing fossil ammonia production. After 2030, green ammonia is expected to achieve the same synthesis cost as gray ammonia through carbon capture, which also makes ammonia-using downstream chemical companies more motivated to use green ammonia instead of gray ammonia as a raw material. Although the energy density per unit volume of green ammonia liquefaction is not as high as that of traditional fossil energy, it is higher than that of green hydrogen. Of particular importance is the liquefaction and transportation of green ammonia, which generates much lower costs than green hydrogen. From the perspective of the whole life cycle cost of "production, storage, transportation, and use", the cost of green ammonia is lower than that of green hydrogen. It is foreseeable that green ammonia will be widely used in the energy field in the future, and the chemical industry will also realize the replacement of green ammonia with the traditional synthetic ammonia industry. It is predicted that by 2030, the annual production capacity of green ammonia projects announced worldwide will be 1.5×107 t (54 projects, the production capacity is 8% of the current ammonia market), and the annual production capacity of green ammonia planned and implemented in mainland China has exceeded 1.56×106t.
Fig.6 Production cost of green ammonia
5. Development plan of ammonia energy industry
Ammonia is transforming from the traditional agricultural sector to the energy sector. At present, green ammonia projects are being actively deployed at home and abroad, but most of them are pilot projects with a small scale and a production capacity of 2×104~6×104 t/a. On the whole, ammonia-doped power generation in the transportation field and ocean-going ship power fuel and power industry will become the main application scenarios of green ammonia.
(1) International aspects
Japan is an international leader in ammonia-doped combustion technology. On the basis of the development of the "hydrogen economy", Japan proposed the "ammonia energy economy" and took the lead in launching ammonia energy. In October 2021, the local government issued the sixth edition of its energy strategic plan, which clearly stated that by 2030, hydrogen and ammonia will account for 1% of Japan's energy consumption, replace 20% of coal in power plants, and achieve pure ammonia power generation by 2050. High-efficiency thermal power generation is an area where Japan excels, and the way to achieve carbon neutrality with ammonia will help Japan further lead the world. South Korea has announced that 2022 will be the first year of hydrogen and ammonia power generation, aiming to become the world's largest hydrogen and ammonia power generation country. South Korea plans to commercialize ammonia-fueled power generation from 2030 and increase the share of ammonia fuel in power generation to 3.6%. Australia makes full use of local solar energy to produce green hydrogen for ammonia synthesis using photovoltaic hydrogen production technology. The Australian government is laying out the ammonia energy trade, turning the prepared ammonia into liquid ammonia for storage, which is transported by sea to South Korea and Japan. In response to the oil crisis, the local Ministry of Energy has supported 17 green ammonia projects, using renewable energy to produce green ammonia as a whole, and has issued a plan to "convert renewable energy into fuel through the use of high-density liquid energy". The fourth meeting of the European Union Hydrogen Network pointed out that it is necessary to increase the production of green ammonia, and take green ammonia as one of the trading systems of hydrogen energy. Saudi Arabia is building the world's largest green hydrogen and ammonia plant, which is expected to be officially put into operation in 2024 and sold globally in the form of liquid ammonia.
At present, ammonia energy is at the forefront of international research in the field of transportation. Japan and South Korea are developing ammonia-fueled vehicles. In July 2020, South Korea's Hyundai Mipo Shipbuilding Co., Ltd. designed an ammonia-powered ship with a load capacity of 5×104 tons, which is expected to achieve commercial operation in 2025. On November 22, 2021, the world's first ammonia-powered cargo ship built by Norway's Yara, the world's largest ammonia producer, was successfully launched. On May 22, 2022, the world's first ammonia-powered zero-carbon tractor made its first run at Stony Brook University in New York. Russia is developing ammonia-fueled rocket engines.
(2) Domestic aspects
The layout of domestic hydrogen-ammonia fusion industry projects is gradually accelerating, and the hydrogen-ammonia fusion technology path is gradually gaining popularity. The "14th Five-Year Plan" New Energy Storage Development Implementation Plan clearly points out that the application field of ammonia energy storage will be expanded, and the pilot demonstration of new energy storage technology relying on renewable energy ammonia production will be carried out, and it will be listed as a key demonstration. The "Medium and Long-term Plan for the Development of the Hydrogen Energy Industry (2021-2035)" released in March 2022 proposes to actively guide the transformation of synthetic ammonia and other industries from high-carbon to low-carbon processes, and promote the green and low-carbon development of high-energy-consuming industries. In April 2022, the Ministry of Science and Technology issued the Notice of the Ministry of Science and Technology on Issuing the 2022 Application Guidelines for Key Special Projects such as the National Key R&D Program "Advanced Structures and Composite Materials", proposing technologies related to ammonia energy, including distributed ammonia decomposition hydrogen production technology and filling mother station integration, ammonia fuel cells, and ammonia-doped clean and efficient combustion. Since the issuance of the above policy, many units have made layouts. Mingtuo Group Co., Ltd. and China Chemical Hualu Co., Ltd. will use green hydrogen and air separation nitrogen as raw materials to build China's first 1.2×106 t green hydrogen electrocatalytic synthesis of green ammonia project to promote the formation of a green and low-carbon industrial chain. China Hydrogen Energy Co., Ltd. plans to invest in the construction of a green hydrogen demonstration project in Urad Houqi Industrial Park, and at the same time use low-temperature and low-pressure catalytic technology to synthesize green ammonia with an annual output of nearly 3×105 t. Qinghua Coal Chemical Group Co., Ltd., Hening Chemical Co., Ltd., Han Hydrogen Technology Co., Ltd., and Sun Mountain Energy Development Co., Ltd. jointly established the Ningxia Ammonia and Hydrogen Industry Alliance. The Lanzhou New Area Hydrogen Energy Industrial Park project plans to build a demonstration application center with an annual output of 6×104 tons of green ammonia and hydrogen energy transportation applications as the core. Fuzhou University, Sanju Environmental New Materials Co., Ltd., and Zijin Mining Group Co., Ltd. jointly established the first "Ammonia \u2012 Hydrogen Energy Major Industry Innovation Platform" in China. Oushennuo Ceramics Co., Ltd., Delitai Technology Co., Ltd., and Foshan Xianhu Laboratory established and initiated a joint innovation R&D center for advanced zero-carbon combustion technology, becoming the first unit in China to carry out zero-carbon combustion technology for ammonia-hydrogen high-temperature kilns. China Petroleum & Chemical Corporation and Fuda Zijin Hydrogen Energy Technology Co., Ltd. have cooperated to build the country's first integrated demonstration station for ammonia hydrogen production and hydrogenation. Beijing Chong Ignition Energy Technology Development Co., Ltd. and Hefei Energy Research Institute will focus on hydrogen energy, ammonia energy, gas turbines and other fields. Shanghai Ship Research and Design Institute completed the design of a 1.8×105 t ammonia-fueled cargo ship. Jiangnan Shipbuilding (Group) Co., Ltd., in cooperation with Lloyd's Register and Wärtsilä Group, designed the ammonia-fueled VHA.
The application of ammonia fuel is developing slightly faster than the application of energy storage, and fuel cells are not the mainstream route of ammonia in the transportation field due to cost problems. Although the application of ammonia in the transportation field is still in the research and development stage, from the perspective of related projects, it mainly takes the route of internal combustion engines, and in addition, the development of domestic ammonia in the field of ships or faster than that of the automotive field. There is already the first specification document for ammonia energy ships in China, but the relevant documents on the application of ammonia in the automotive field have not yet been released, and the application space of ammonia fuel in the marine field is larger.
6. Measures for the development of the ammonia energy industry in the mainland
Making ammonia part of the world's solution to climate change requires ensuring that all synthetic ammonia is green, which is a daunting task. At present, synthetic ammonia has problems such as high energy consumption and high emissions, ranking first in the carbon emissions of industrial chemical production. In the short term, green ammonia still has challenges in terms of economy and application, but under the construction of the global ammonia energy economic system and the development of renewable energy, it will gradually become competitive in the future.
(1) Improve the system of policy standards
In order to reduce the cost of green ammonia production faster and expand the scale larger, it is necessary to introduce and improve the policy and standard system, and gradually transition to zero-carbon production under the condition of continuous technological development. First, the government should introduce subsidy policies to encourage the synthesis of green ammonia to support the rapid transformation of the industry. Second, the government should establish industrial policies and safety standards to lay the foundation for the stable and sustainable development of the industry. Third, the government should formulate laws and regulations to provide a basis for the healthy development of the industry. Fourth, the government should promote the formulation of international standards and enhance the international discourse of ammonia energy in the mainland.
(2) Accelerate the clean transformation of the industry
Based on the development trend of mainland energy, it is suggested that the low-carbon production of ammonia energy in the mainland should be steadily promoted in the future: industrial by-product hydrogen will be used as a transition in the early stage, and green hydrogen will be gradually replaced in the later stage, and finally the large-scale development of green ammonia will be realized.
Specifically, in the first stage, ammonia is synthesized from hydrogen-rich production in industry. The high emissions from the ammonia synthesis process are due to the fact that the raw material hydrogen production is mainly from coal or natural gas. A large amount of hydrogen is produced in the production process of chlor-alkali industry, coal coking industry, propane dehydrogenation industry, etc., and the recycling of by-product gas can reduce carbon emissions in the process of hydrogen production, which is conducive to the construction of a low-carbon production route for synthetic ammonia. In the second stage, the key technology of mild conditions for the synthesis of green ammonia was broken through. Green hydrogen is produced using renewable energy electrolysis technology, which excludes water, gas or natural gas from the process. Then, the Haber-Bosch residual process is used to prepare the green ammonia. At the same time, we will make breakthroughs in the new technology of low-temperature and low-pressure hydrogen and nitrogen ammonia synthesis, and explore a new path for the complementary integration of renewable energy and low-temperature and low-pressure ammonia. At this stage, in order to achieve the sustained and rapid development of hydrogen-ammonia fusion, it is necessary to further reduce the cost of electricity and related hydrogen production equipment. In the third stage, a novel electrochemical catalytic nitrogen reduction technology is used to produce green ammonia. In conventional routes, hydrogen production accounts for 75% of primary energy consumption. Even if hydrogen is produced using water electrolysis from renewable energy sources, hydrogen production will account for 65% of the total cost. At this stage, the Haber-Bosch process will be abandoned, and the cutting-edge electrocatalytic nitrogen reduction technology will be used, eliminating the process of hydrogen production, and the ammonia will be directly synthesized through nitrogen electroreduction. This technology can significantly reduce the complexity of the green ammonia preparation process, reduce energy consumption by about 20% compared to the Haber-Bosch process, and is suitable for distributed ammonia synthesis regardless of scale. In the fourth stage, synthetic green ammonia will be applied to internal combustion engines, gas engines or boilers, and strive to replace fossil fuels with ammonia, greatly reduce carbon emissions, and contribute to carbon neutrality. Here, we will increase the research and development of ammonia fuel engine equipment, enhance the core competitiveness of major equipment, and break through the technical bottleneck of zero-carbon fuel application.
(3) Carry out the deployment of the whole industrial chain
The whole ammonia energy industry chain covers upstream ammonia preparation, midstream ammonia storage and transportation, and downstream ammonia utilization, which should be systematically deployed. In addition to the synthesis of green ammonia, in terms of storage, the technical, economic and safety factors should be comprehensively considered to solve the design and construction problems of large-scale liquid ammonia storage tanks. In terms of transportation, we will study the overall planning of the liquid ammonia pipeline network suitable for the energy development requirements of the mainland, develop a long-distance liquid ammonia pipeline transportation technology system, support the formation of a mature ammonia energy supply network in the mainland, and face the future ammonia fuel market and long-distance trade market. In terms of application, the direct or indirect utilization of ammonia energy should actively promote the establishment of ammonia application demonstration projects, enhance the strategic attributes of ammonia energy, and finally form a whole industrial chain of large-scale application of ammonia energy.
Article source: Hydrogen Cloud Chain