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

1. The role of natural gas in carbon neutrality

The concrete ways to achieve the goal of carbon neutrality mainly include reducing carbon emissions and increasing carbon absorption. At present, the main source of carbon dioxide in the environment is fossil energy combustion. According to the statistics of the International Energy Agency (IEA), the global energy-related carbon emissions have dropped to 315×108 t in 2020, but the global energy-related carbon dioxide emissions have continued to rise in the past decade (Figure 1) [5]. As the world's largest consumer of fossil energy, China also ranks first in the world in terms of carbon emissions, with the total carbon dioxide emissions exceeding 100×108 t in 2020 [6]. China has a special energy consumption structure due to its advantages in coal resource endowment, and the carbon emissions from coal combustion account for nearly 80% of the total emissions, far exceeding the world average. In 2020, China's coal use accounted for 56.8% of the primary energy structure, which also indicates that China's energy system is bound to usher in major structural adjustment and resource integration. The most fundamental way for China to achieve the goal of carbon neutrality is to reduce carbon emissions, that is, while expanding the renewable energy supply, reduce the consumption of high-carbon fossil energy such as coal and oil, especially control coal power and terminal coal use, and increase the use of clean fossil energy represented by natural gas [7-8]. Cultivate natural gas to gradually replace coal, increase the proportion of natural gas in power, industry and other industries, and become one of the main energy sources of China's modern clean energy system.

Increasing carbon uptake is also closely related to the gas industry. Carbon uptake includes natural carbon uptake and anthropogenic carbon uptake, the former mainly refers to carbon sink, carbon sequestration by plants through photosynthesis; The latter is mainly geological carbon sequestration through carbon capture, carbon utilization and carbon storage (CCUS) technology. Specifically, in the process of natural gas development, carbon dioxide is used to strengthen the exploitation of conventional natural gas, shale gas, coal bed methane and other resources, including carbon dioxide fracturing and displacement, to improve recovery efficiency and complete long-term effective storage of carbon dioxide. In addition, the natural geological environment such as the depletion of oil and gas reservoirs is used as a large-scale biochemical reactor to produce artificial methane, and it is stored in underground space on a large scale to realize the recycling of carbon resources and the synthesis and storage of natural gas. CCUS, combined with natural gas storage and pipeline network, is a key supporting technology to promote the clean utilization of fossil energy, and will play an important role in the development of renewable energy.

China's plan to complete the 30 years from carbon peak to comprehensive carbon neutrality faces great challenges. The author believes that China's current carbon neutral road should promote the diversification of energy development, gradually reduce the proportion of coal, greatly increase the proportion of natural gas and other low-carbon energy and renewable energy, and finally establish a sustainable energy system with natural gas, renewable energy and hydrogen energy as the main body.

2. China's natural gas development prospects

2.1 Research and judgment by major institutions at home and abroad

In 2020, China's natural gas consumption is about 3 240×108 m3, an increase of about 130×108 m3 over the previous year, accounting for 8.7% of the total primary energy consumption. Compared with 32.2% in the United States, 20.8% in Japan and 24.2% in Germany in the same period [9], the proportion of natural gas in China's energy consumption market is still relatively low.

In the context of carbon neutrality, the medium and long-term development trend and prospect of natural gas in China's energy market are more worthy of attention. This paper summarizes the medium and long-term forecasts of China's natural gas consumption by many domestic and foreign institutions and scholars based on different development scenarios, as shown in Table 1[1-3, 10-14]. The projections fall broadly into two categories: a peak year before the carbon neutrality target and a subsequent decline; Carbon neutrality targets have been increasing for years. The International Energy Agency, BP, Tsinghua University and other institutions predict that China's natural gas consumption will peak between 2030 and 2040, and the peak level is expected to be between 5 110×108 and 7 500×108 m3, which is a significant increase compared with the current level. The largest consumption appears in the 2.0 ° C scenario in the report "Research on China's Long-term Low-carbon Development and Transformation Path" [13] of Tsinghua University. Between 2050 and 2060, gas consumption is around 5,000 ×108 m3 in most scenarios. According to relevant reports and studies by petrochina and China University of Petroleum (Beijing), under various scenarios, China's natural gas consumption will still increase after the carbon peak. In the reference scenario of petrochina's World and China Energy Outlook 2050 [12], China's natural gas consumption in 2050 is about 6 700×108 m3, and in the scenario of hydrogen energy society and carbon neutrality, the natural gas consumption is 5 900×108 m3 and 5 500×108 m3 respectively. Research by Li, Children, et al., China University of Petroleum (Beijing) [3] shows that under the extreme conditions of their scenario A (0 coal and oil consumption), natural gas consumption in 2060 is 14 000×108 m3, the largest of all projections. There is a big gap in the predicted natural gas consumption of various institutions, mainly due to the different scenario selection. Some scenarios meet the needs of carbon emission and theoretical temperature control from the data perspective, but do not take into account the needs of national development and the actual safety operation of the energy system. In addition, the structure of energy consumption projected by different agencies is different, resulting in significant differences in consumption. In general, the importance and cleanliness of natural gas are becoming increasingly prominent, and the proportion of natural gas in China's energy consumption structure has a large room for increase, and the development potential is considerable.