Study on the Optimization Measures of Carbon Emissions in Chengdu's Territorial Space under the Trend of Clean Energy and Energy Structure Adjustment

. Clean energy refers to energy that has less impact on the environment and can be used sustainably. With the intensification of global climate change and environmental pollution problems, the development of clean energy has become a common concern for governments and enterprises. In this paper, the scale of carbon emission in Chengdu is measured by analyzing LEAP model, and the carbon sink capacity is measured by the change of land use structure. Based on the trends of carbon sources and sinks, we analyze the countermeasures that Chengdu needs to take to achieve the carbon peak by 2030. Finally, based on the vision of "carbon neutrality", suggestions are made for the optimization of Chengdu's territorial spatial planning in terms of building a green and low-carbon territorial spatial development and protection pattern, optimizing the territorial spatial layout and factor allocation, developing clean energy technologies, and increasing the proportion of clean energy use.


Introduction
Clean energy refers to energy that has less impact on the environment and can be used sustainably. Renewable energy sources such as solar, wind and hydro energy are increasing their share in global energy consumption. According to the International Energy Agency, the share of renewable energy in the total global energy supply in 2019 is 27%. Clean energy mainly includes renewable energy sources such as solar, wind and hydro energy and low-carbon energy sources such as nuclear energy. Compared with traditional fossil fuels, clean energy has the characteristics of low carbon and low emissions. Therefore, the development of clean energy can reduce the emission of greenhouse gases and thus slow down the rate of global climate change. In addition, clean energy can promote the transformation and upgrading of energy structure, improve energy utilization efficiency, reduce energy consumption and waste, and further reduce carbon emissions.
Increased carbon emissions are the main cause of the greenhouse effect, heat waves, sea level rise and other catastrophic weather and climate. To cope with these problems, China has proposed the development goals of peaking carbon emissions by 2030 and achieving carbon neutrality by 2060. Land use changes directly affect the distribution and structure of terrestrial ecosystems and alter their carbon storage and flux processes [1]. Some scholars have studied the carbon emission effects in Zhejiang and Liaoning provinces [2][3], established the relationship between energy consumption and land use, and accounted for the carbon emissions of different land use types.
There are some domestic studies on carbon emission measurement based on land use, focusing on the scale of carbon emission, but there are relatively few studies on the measurement of carbon peaking. This study takes Chengdu as an example, analyzes the change trend of carbon sources in the land space over the years, measures the change of carbon emissions based on energy consumption, combines the economic and social development trend, projects the time of carbon peak in Chengdu, and based on this, puts forward relevant suggestions for the optimization of land space planning and new energy development in Chengdu, in order to provide reference for achieving the carbon neutral development goal in 2030.

Study Area Overview
Chengdu is located in southwest China, the western part of the Sichuan Basin and the hinterland of the Chengdu Plain, with a total area of 14,335 square kilometers. 212.668 million people will reside in the city by the end of 2022, and the gross regional product will be 208.175 billion yuan. Chengdu has various land types. According to the type of landform, it can be divided into plains, hills and mountains, and according to the current type of land use, it can be divided into 8 categories, such as arable land, garden land and pasture land; the area of plains is significant, amounting to 4,971.4 square kilometers, accounting for 40.1% of the total land area of the city, which is much higher than the national level of 12% and Sichuan Province's level of 2.54%; the area of hills accounts for 27.6% and the area of mountains accounts for 32.3%. Chengdu is one of the important cities in western China and one of the cities with relatively fast development of clean energy in China. Chengdu has widely installed solar photovoltaic panels on city rooftops, parks and squares, and supplies electricity to residents and businesses through the power grid. According to the 2019 statistics, Chengdu has a total installed solar PV power capacity of 13,500,000 kilowatts, accounting for 0.06% of the total installed PV power capacity nationwide. Chengdu City has built several wind farms in and around the city to generate electricity from wind power. According to the 2019 statistics, Chengdu City has a total installed wind power capacity of 448,000 kilowatts, accounting for 0.07% of the total installed wind power capacity nationwide. Chengdu is also actively promoting other clean energy sources, such as geothermal energy and biomass energy. According to the 2019 statistics, the total installed capacity of geothermal energy in Chengdu is 200,000 kilowatts, accounting for 0.12% of the total installed capacity of geothermal energy in China; the total installed capacity of biomass energy is 15,000 kilowatts, accounting for 0.03% of the total installed capacity of biomass energy in China.

Data source
The land use data involved in this study were obtained from Hechuan District Land Use Change Vector Data, Chengdu Statistical Yearbook 2022, Chengdu 14th Five-Year Plan for Energy Development, etc.

Total Carbon Emissions.
Carbon dioxide emissions are mainly measured according to the method specified in the Ministry of Ecology and Environment's "Guidelines for the Preparation of Provincial CO 2 Emission Peaking Action Plan" (Environmental Protection Office Climate Letter [2021] No. 85), which is obtained by summing the direct carbon dioxide emissions from energy activities and the indirect carbon dioxide emissions embedded in electricity transfers, i.e.
(1) Among them: is the total amount of CO 2 emissions, t; is the direct CO 2 emissions from energy activities, t; is the indirect CO 2 emissions from energy activities, t.

Calculation.
Direct CO 2 emissions from energy activities are calculated based on the consumption of different types of energy and CO 2 emission factors.

∏
(2) Among them: is the consumption of fossil energy of category i (in standard quantities), t; is the carbon dioxide emission factor for fossil energy of category i, t.
The reference coefficient for the conversion of fossil energy consumption into standard coal is based on the appendix of the China Energy Statistical Yearbook for each year. Carbon dioxide emission factors of fossil energy sources, using the latest national greenhouse gas inventory emission factor data, including 2.66 t CO 2 /ton standard coal for coal, 1.73 t CO 2 /ton standard coal for oil products, and 1.56 t CO 2 /ton standard coal for natural gas.

Calculation.
Indirect CO 2 emissions from power transfers into Chengdu can be calculated using the power transfers into Chengdu and the nationally recommended CO 2 emission factors for coal and gas power.

∏
(3) Among them: is the amount of electricity transferred in from non-fossil energy sources in category i.
is the carbon dioxide emission factor of electricity such as coal and gas power in category i, t.
The state-recommended emission factor for coal power is 0.853 t CO 2 /MWh and for gas power is 0.405 t CO2/MWh. For electricity generated from non-fossil energy sources, the corresponding CO 2 emission factor for the transferred electricity is 0 t CO 2 /MWh. The relevant parameters, as shown in Table 1.

Carbon absorption calculation
The amount of CO 2 uptake with is mainly affected by the area of woodland, garden and grassland, which is calculated as follows: Among them: ℎ is the total carbon uptake, t; is the area of class k land category, hm 2 ； is the carbon uptake coefficient of the kth land class； The carbon dioxide absorption rates of different land use classes are shown in Table 2.

Calculation of net carbon emissions
The net land carbon emissions from the regional land space are the difference between energy emissions and carbon dioxide uptake by each category, calculated as follows: Among them: is the net carbon emissions from land in national space, t

Net Carbon Emissions Measurement in Chengdu
According to the calculation model, using Chengdu land use change data and related statistical data, the carbon emissions and carbon sink absorption of Chengdu's land space in 2020 are estimated, and the main analysis results are as follows.
The total energy consumption in Chengdu will increase from 41.601 million tons of standard coal at the end of the 12th Five-Year Plan to 51.847 million tons of standard coal at the end of the 13th Five-Year Plan, with an average annual growth rate of 3.8%. Among them, the whole society uses 72.54 billion kilowatt hours of electricity, an average annual growth of 8.3%; natural gas consumption 6.98 billion cubic meters, an average annual growth of 4.4%; oil (refined oil) consumption 10.992 million tons, an average annual growth of 3.1%; coal and other energy consumption 4.335 million tons of standard coal, an average annual decline of 7.7%.The changes in total energy consumption in Chengdu, as shown in Figure  1.

Suggestions for optimizing the spatial function structure of the land
Based on the analysis of carbon sources and sinks in Sichuan Province, it is found that the current carbon emissions of Chengdu's land space exceed its carbon absorption. In order to achieve the development goal of carbon peaking by 2030, it is recommended to strengthen the use of clean energy, adjust the energy structure, and reduce carbon emissions.

Developing clean energy technology
We suggest that the Chengdu Municipal Government issue a series of policy documents to support the development of clean energy, such as the "13th Five-Year Plan" for the development of clean energy in Chengdu, to provide financial, tax, land and other preferential policies for clean energy enterprises. At the same time, promote clean energy technology: The Chengdu Municipal Government actively promotes clean energy technology, encourages enterprises to increase research and development investment, improve the level and market competitiveness of clean energy technology. Meanwhile, by establishing demonstration projects and promoting the use of clean energy products, etc., we can promote the application of clean energy in citizens' daily lives. Promote industrial upgrading: The Chengdu Municipal Government actively promotes the upgrading of the clean energy industry, encourages enterprises to increase investment, improve the production efficiency and quality of clean energy, and promote the development of the industry towards high-endization, intelligence, and greenization.

Anchoring important ecological space and consolidating the foundation of ecosystem carbon sink
Strictly adhere to the red line of ecological protection. Strictly control the occupation of ecological space, stabilize the existing forests, grasslands, wetlands, soil and other carbon sequestration role. Deeply promote large-scale national greening action. Consolidate the achievements of returning farmland to forest and grass, implement the project of precise improvement of forest quality, continuously increase the forest area and accumulation, and strengthen the ecological protection and restoration of grassland.

Developing clean energy and reducing carbon emissions
Developing clean energy is one of the important ways to reduce carbon emissions. Accelerating the research and development, as well as the promotion, of clean energy technologies such as solar, wind, hydropower, and biomass energy is crucial. Governments can introduce relevant policies to encourage enterprises to increase their R&D investment and improve the efficiency and cost advantages of clean energy technologies. Strengthening the construction of clean energy infrastructure, including grid upgrades and energy storage facilities, is also important [5]. Governments can provide funding support for the construction of clean energy projects and encourage social capital participation. Promoting the market-oriented operation of clean energy, establishing clean energy trading markets and carbon emission rights trading markets, and incentivizing the production and use of clean energy through tax incentives and subsidies are all effective measures. Promoting an energy consumption revolution and promoting low-carbon lifestyles and green transportation is also essential. Governments can formulate relevant policies to encourage residents to use clean energy products and reduce high-carbon emission consumption behaviors.

Insist on public transportation to guide urban development and create a green transportation system
In terms of transportation planning, we insist on guiding urban development by public transportation, laying out a public transportation system integrated with urban functions in the overall spatial planning of the country, optimizing the layout of public hubs and yards, creating an efficient and convenient green transportation system, reducing the proportion of small car trips, and reducing transportation carbon emissions.

Promote agricultural and rural emission reduction and carbon sequestration
Vigorously develop green low-carbon cycle of agriculture, promote the complementary agriculture and light, "photovoltaic + facilities agriculture" and other lowcarbon agricultural model. Research and development and application of sink-increasing agricultural technology. Carry out action to improve the quality of arable land, implement arable land protection projects, and improve soil organic carbon reserves. Reasonably control the use of chemical fertilizers, pesticides and mulch, implement the chemical fertilizer and pesticide reduction and replacement program, and strengthen the comprehensive utilization of crop straw and resource utilization of livestock and poultry manure.

Concluding remarks
Against the background of the increasing impact of the greenhouse effect on people's lives, it is important to explore the calculation method of net CO 2 emissions in Chengdu under the current situation to promote the development goal of Chengdu to reach the carbon peak by 2030. By quantitatively analyzing the scale of energy carbon emission and land use carbon sink in Chengdu, this paper proposes the idea of territorial spatial development that should strengthen the ecosystem construction, which has certain reference value for optimizing the territorial spatial planning of Chengdu.