Development and contribution of natural gas industry under China's carbon neutrality goal

2.3.6 Biological natural gas

Biogas is produced by purifying biogas, one of the products of anaerobic fermentation of biomass, to natural gas grade quality, and can be used for power generation, or directly as building heating or industrial boiler fuel for heating, and can also be used for cogeneration. In China's townships and rural areas, biogas can not only effectively increase the supply of clean energy, but also provide ancillary value (the fermentation process produces organic fertilizer), which has strong development potential. Bio-natural gas can also be transported by relying on the existing natural gas pipeline network, which greatly improves the convenience of use and transportation. According to the guidance of the National Development and Reform Commission, the National Energy Administration and other ministries, China will accelerate the development of bio-gas industry. It is expected that the annual output of bio-gas in China will exceed 100×108 m3 by 2025, and exceed 200×108 m3 by 2030 [27]. At that time, bio-gas will also become a favorable supplement to China's natural gas market.

2.4 Main use scenarios of natural gas in China

2.4.1 Gas-fired power generation

With the in-depth promotion of electrification in the process of carbon neutrality in China and the significant increase in the proportion of renewable energy generation, renewable electricity, mainly solar power, will become the main power source in the future. However, the volatility, intermittency and other drawbacks of wind and solar power generation can easily lead to problems such as frequency instability of the power system, which affects the safe and stable operation of the system. At present, the proportion of renewable energy generation in Germany has exceeded 50%, and the high proportion of installed renewable energy access has led to increased fluctuations in the power grid, and the German power grid has been unable to independently complete the adjustment task, and it is necessary to participate in peak regulation with the help of neighboring countries to ensure the stability and security of the power grid. It can be seen that when the scale of renewable energy generation in China reaches a certain level, more adequate power supply is needed to achieve independent grid regulation.

Gas-fired power generation has the advantages of rapid response, stable operation and flexible deployment, and will become an important regulating power supply, shouldering the tasks of peak load and valley filling, frequency and phase regulation and emergency black start of power system. By the end of 2020, the installed capacity of gas power generation in China will be 9 751×104 kW, accounting for only 4.4%[28]. In 2019, China's natural gas power generation was 2 365×108 kW·h, accounting for 3.2%, which was much lower than countries such as the United States and Japan (38.6% and 35.0%) in the same period [9]. It is expected that in 2060, the national power consumption is 15×1012 ~ 20×1012 kW·h, only calculated according to 15×1012 kW·h, according to relevant experience, the peak load reserve power accounts for 20% (3×1012 kW·h), if it is borne by gas power generation, It consumes 5,010 ×108 m3 of natural gas (60% thermal efficiency). It can be seen that in the future, gas-fired power generation will become the main force of natural gas consumption.

2.4.2 Industrial use

Industry is the most important area of energy consumption and carbon emissions, in 2019, China's industrial energy consumption accounted for more than 60%, and industrial carbon emissions accounted for 70% of the total carbon emissions in the year. Coal is the main fuel of China's industry, especially in steel, building materials, non-ferrous metals and other energy-consuming industries, therefore, the industrial field of carbon emission reduction needs to vigorously promote the "gas instead of coal", reduce the burning of high-carbon fossil energy, increase the use of natural gas and other clean energy. In 2019, China's industrial gas consumption reached 1 060×108 m3, accounting for 34.8%[29], but it was still low and not enough to significantly reduce industrial carbon emissions. Therefore, in the future, it is still necessary to increase the market share of natural gas, as well as the coverage in the high-energy manufacturing industry, and actively promote the clean development of the industry.

3. Coupling development of natural gas and renewable energy

3.1 Basis of coupling development

According to the white paper "China's Energy Development in the New Era" [30], by the end of 2019, China's consumption of clean energy such as natural gas, hydropower, nuclear power and wind power accounted for 23.4% of the total energy consumption, and non-fossil energy accounted for 15.3%. China's total installed capacity of renewable energy power generation is 7.9×108 kW, accounting for about 30% of the global total, among which the installed capacity of hydropower, wind power, photoelectric and biomass power generation reaches 3.56×108 kW, 2.10×108 kW, 2.04×108 kW and 2 369×104 kW, respectively, ranking first in the world. In addition, China is also rich in geothermal resources, and only the total dry hot rock resources are preliminarily estimated to be about 856×1012 t of standard coal [31]. In general, China has abundant reserves of renewable energy resources and broad prospects for development. Remarkable achievements have been made in the development of some renewable resources, but there is still huge potential for exploitation and utilization. Natural gas has the characteristics of high combustion efficiency, diverse ways of development and utilization, convenient transmission, distribution and storage, and less external restrictions, so that it can be used to make up for the disadvantages of renewable energy, both of which also have the resource base and development conditions of high-quality coupled development and support for energy green transformation. Under the strong drive of low-carbon energy structure, the coordinated development of natural gas renewable energy will become one of the important directions of China's energy development.