Value of ammonia energy applications

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 volume-carrying efficiency of 150% that of hydrogen. Compared with the very low liquefaction temperature of hydrogen at atmospheric pressure (-283 °C), ammonia is capable of being liquefied at -33 °C (or 9 atmospheres at room temperature). In terms of cost, liquid ammonia tanks are 0.2% to 1% of liquid hydrogen tanks for the same mass, and liquid ammonia is 8.5 times denser per unit volume weight than liquid hydrogen.

According to the International Energy Agency (IEA), the total global demand for green and blue hydrogen in 2040 will reach 7.5×107 t. Based on this scenario, to solve the problem of the contradiction between the supply and demand of hydrogen energy, the first step is to break through the bottleneck of low-cost, long-distance storage and transportation of hydrogen. Currently, the three commonly used hydrogen storage and transportation methods are high-pressure gaseous hydrogen transportation, liquid hydrogen transportation, and high-pressure transportation of deep-cooled hydrogen, but each method is difficult to operate, resulting in high transportation costs and low efficiency. In contrast, ammonia is easier to liquefy for storage and transportation. According to the calculation, the storage and transportation cost of liquid ammonia within 100km is 150 RMB/t, and the storage and transportation cost of liquid ammonia within 500km is 350 RMB/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 refueling station can reduce the cost of hydrogen to less than 35 RMB/kg, according to the goal of building 10,000 hydrogen refueling stations in China by 2050, it can save 100 billion RMB. In addition, compared with hydrogen, ammonia has a narrower explosive limit range (16%~25%), a higher boiling point, and a lower likelihood of fire and explosion. At the same time, ammonia has a pungent odor, and the human sense of smell can detect a concentration of only 5% or less of the dangerous level, so leaks can be easily detected, which is safer and more reliable. Therefore, ammonia as an excellent hydrogen storage carrier, hydrogen-ammonia fusion can become the most promising new type of storage and transportation mode, broadening 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 the water, and the product of complete combustion is pure and carbon-free, therefore, as a renewable energy source with strategic value, ammonia can be burned directly to realize clean energy supply. Ammonia combustion has a low air-fuel ratio and can provide more energy under the same 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 produces a low calorific value when burned, it has a high octane rating and good resistance to detonation, which can increase powertrain output by providing a higher compression ratio. In the case of direct-fired ammonia refueling, operators can upgrade and convert existing gas stations into ammonia refueling stations, with conversion costs 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, synthetic ammonia technology has been successfully developed and industrialized production. As the world's second largest chemical, ammonia has a complete industrial chain structure and a mature international production and trade system, and its raw materials come from a wide range of sources, so that large price fluctuations caused by supply and demand imbalances can be avoided in the long-term application process. Promoted by the background of carbon neutrality, the hydrogen source used in ammonia synthesis will inevitably be developed from industrial hydrogen source to the way of hydrogen supply by water, and the required energy will inevitably be developed to the way of energy supply by wind, light and other renewable energy sources, and ultimately realize the green ammonia production of low-carbon routes. Currently, the price of liquid ammonia per unit of energy is equivalent to or lower than that of gasoline in most countries. In particular, China is the world's largest producer and consumer of synthetic ammonia, and the synthetic ammonia industry is spread throughout the country, with a good foundation for popularization and application.