1. The importance of estimating wind and solar energy resources in the context of “dual carbon”
At present, wind and solar power have become important strategic directions for the development of China’s clean energy industry. According to the three-step path of the “dual carbon” goal, the proportion of non fossil energy consumption in China will continue to increase at three time points: 2025, 2030, and 2060, and ultimately reach over 80%. To achieve this goal, it is essential to significantly increase the installed capacity of wind and solar power generation. In recent years, the development and construction of new energy have developed rapidly, with an average annual increase in installed capacity. Technological progress has brought about a significant decrease in costs, enabling the industry to continuously expand in scale. From 2010 to 2019, the average cost of inland wind power, offshore wind power, and photovoltaic power generation worldwide has decreased by 39%, 29%, and 82%, respectively. Considering its ecological and environmental advantages in the future, demand will further increase and gradually develop into the mainstream of the energy industry. China has made it clear that by 2030, the total installed capacity of wind and solar power will reach over 1.2 billion kilowatts. As of the end of 2022, the installed capacity of wind power in China was approximately 370 million kilowatts, a year-on-year increase of 11.2%, ranking first in the world for several consecutive years; The installed capacity of solar power generation in China is about 390 million kilowatts, a year-on-year increase of 28.1%. In the next 10 years, there is almost half of the market expansion space for wind power and photovoltaics, with huge prospects and high expectations.
However, future climate change will have a direct impact on wind and solar energy resources themselves. For example, climate change will change the distribution of average wind speed in China, thereby affecting wind power and solar radiation distribution, thereby affecting the development and utilization of regional scale solar energy resources. Future extreme weather and climate events, such as rainstorm and flood, typhoon, lightning, high temperature and drought, low temperature and freezing, have obvious seasonal and regional characteristics. Extreme weather and climate events will directly affect the weather risk resistance of wind farms and solar internal devices. This impact will have an indirect impact on policy measures taken to address climate change, such as the implementation of the “dual carbon” target.
Therefore, in the context of climate change, it is of great significance to reasonably estimate the characteristics and trends of wind speed changes in China for future wind energy utilization planning. It will play an important guiding role in the selection of future wind and photovoltaic power stations, the estimation of wind and photovoltaic power generation potential, and the scientific evaluation of wind and solar energy development and utilization and climate environmental effects.
2. Current situation and technological bottlenecks in estimating wind and solar energy resources
2.1 Estimated technical means and latest results
The earliest research on the estimation of surface wind speed changes in China was based on the multi-modal results of the Third Coupled Mode Comparison Program (CMIP3). The estimation results based on single emission scenarios show that the annual average wind speed in the entire region of China in the 21st century shows a weak decreasing trend, and the degree of reduction becomes more significant with the increase of greenhouse gas emission concentration. Subsequently, a coupled model was used to compare multiple global climate models in the fifth phase of the plan (CMIP5), and the estimated results under high, medium, and low greenhouse gas emission scenarios also showed that the annual average wind speed in China in the 21st century showed a decreasing trend. As the concentration of greenhouse gas emissions increased, the degree of this decreasing trend increased in sequence, and the consistency of predictions between models also increased in sequence. In terms of regional differences, the estimated results of both CMIP3 and CMIP5 comparative plans indicate that the annual average wind speed in the western region of China is decreasing in the 21st century, while the annual average wind speed in the eastern region is increasing.
At present, some research has been conducted on wind and solar energy in China using regional climate models, but overall, there is still not enough. Jiang et al. conducted a study on the future changes in surface wind speed in China based on the simulation results of three regional climate models, and pointed out that by the end of the 21st century, the annual average wind speed and winter average wind speed in China have both decreased. Guo et al. estimated the results for future medium to high emission scenarios based on regional model sets and pointed out that China’s wind resources will slightly decrease in the future (3% to 4%). Based on the results of high-resolution regional model sets, Wu et al.’s estimation study under low, medium, and high emission scenarios showed that the average wind power density in four seasons in China showed a downward trend from 2020 to 2100, with autumn and winter being more significant. The annual average wind power density decreased by 0.36% to 1.14% every 10 years.
There is currently relatively little research on the estimation of solar energy resources, with only a few model-based results. Based on multiple global model sets, the estimated results under high emission scenarios indicate that solar radiation in the eastern and southern regions of China will increase in the future, while it will decrease in the Qinghai Tibet Plateau and northwest regions. The estimation results based on high-resolution regional climate models for low, medium, and high emission scenarios show that under different emission scenarios, solar energy resources in the central and western regions of China will increase in the future, while solar energy rich areas (northwest and northeast regions) will decrease. It is pointed out that the decrease in radiation is the main cause of future solar energy resource decline, but for the Qinghai Tibet Plateau, the decrease in wind speed is also an important influencing factor.
The results of the above research can provide scientific references for the future development, utilization, and optimization of wind and solar energy in China, thereby better supporting long-term climate change mitigation commitments.
2.2 Estimate technical bottlenecks and future prospects
(1).Problems in estimating wind and solar resources based on global models: In the context of climate change, research on estimating wind and solar resources mainly relies on models. Overall, there are currently many results based on the global sea atmosphere coupling model, which indicate that all models in the fifth stage (CMIP5) and sixth stage (CMIP6) of the coupling model tend to underestimate the interannual variation of surface wind speed in China and cannot reproduce the observed downward trend. The study also pointed out that although CMIP6 has higher spatial resolution and more complete physical processes than CMIP5, its ability to capture local and regional forcing is still insufficient, especially in areas with complex terrain in China. In addition, there is relatively little research on the future changes in solar energy resources in China, and only some research results based on the CMIP5 global model indicate that the global model still significantly overestimates the simulation of surface solar radiation in China.
(2).Advantages of regional model estimation: High resolution regional climate models have significant improvements in describing small-scale forcing and topography in China’s regions. Research has shown that high-resolution regional climate models have certain simulation capabilities for the distribution of surface wind speed and solar radiation in China. Compared with global models, they have certain improvements and can better simulate the spatial distribution details and local variation characteristics of average wind speed and solar radiation. Therefore, it is an inevitable trend to estimate the future changes in wind and solar energy resources in China based on regional climate models, and it is expected to obtain more information on regional scale changes.
Problems in estimating based on regional models: Although some research has been conducted based on regional climate models, overall there is still not enough. At the same time, the regional model also has the problem of poor simulation of the trend of large-scale wind speed weakening in China in the past 50 years and excessive simulation of solar radiation values, which is related to the simulation bias of the global model driving field and the introduction of regional models. In addition, another important aspect is the limitations of the physical processes inherent in regional models. In the future, it is necessary to systematically evaluate and optimize the global model driving field, as well as optimize and improve the internal physical processes simulated by regional models. Multimodal ensemble simulation research can help reduce estimation uncertainty, but due to limitations in computing resources, the number of sets is still limited, making it difficult to provide qualitative conclusions. Therefore, more ensemble research on regional model results is needed in the future.
3. Preliminary results under current estimated technology
In recent years, the National Climate Center has adopted RegCM4 developed by the Italian Center for Theoretical Physics（ http://gforge.ictp.it/gf/project/regcm/ ）Dynamic downscaling experiments were conducted on regional climate models, and multiple sets of long-term simulations with a horizontal resolution of 25 kilometers were completed. The simulation area includes China and surrounding areas, with a period from 1986 to 2100. The period from 1986 to 2005 is a historical comparison period, and the period from 2030 to 2050 is a future change period. This article estimates the changes in wind and solar energy resources in China and its different regions based on the high-resolution simulation results mentioned above.
3.1 Changes in China’s Wind Resources from 2030 to 2050
Based on the above multiple simulation results, the seasonal and regional differences in the changes of wind energy resources in China from 2030 to 2050 were analyzed under future low, medium, and high emission scenarios (representing the peak radiation forcing of wind energy resources reaching 2.6 watts/square meter, 4.5 watts/square meter, and 8.5 watts/square meter, respectively, by 2100). Given that wind power density is a comprehensive indicator for measuring wind energy resources, first analyze the percentage changes in wind power density over four seasons and annual averages in China. It can be seen that from 2030 to 2050, except for summer, the wind power density in China showed a decrease in all other seasons, and the reduction was most significant in spring. The reduction values under the three emission scenarios were 25.2%, 20.9%, and 26.5%, respectively. Next is winter, with decreases of 15.3%, 11.3%, and 10.4%, respectively. In summer, it shows an increase, with the increase decreasing as the emission concentration increases. The increase values under the three emission scenarios are 13.1%, 6.5%, and 5.3%, respectively. (See Figure 1).
To deeply analyze the regional differences in wind resource changes, China is divided into eight sub regions: Northeast, North China, Southeast, Central South, South China, Qinghai Tibet Plateau, Southwest, and Northwest. It can be seen that from 2030 to 2050, the annual average wind power density in wind resource rich areas, including Northeast China, North China, and the Qinghai Tibet Plateau region, has decreased. Among them, North China has the largest reduction, with reductions of 19.7%, 11.6%, and 20.3% under the three emission scenarios, respectively. The reduction in Northeast China and the Qinghai Tibet Plateau is basically within 10%. The eastern, central southern, southern, southwestern, and northwestern regions of China have shown an increase, with the highest increase observed in the low wind speed areas of southern China. Under the three emission scenarios, the average annual increase in wind power density in southern China is 61.3%, 38.7%, and 40.8%, respectively (see Figure 2).
3.2 Changes in China’s photovoltaic resources from 2030 to 2050
Based on the above multiple sets of simulation results, the seasonal and regional differences in solar energy resource changes in China from 2030 to 2050 were analyzed under different emission scenarios. The calculation of photovoltaic power generation takes into account the comprehensive effects of solar radiation, temperature, and surface wind speed. Firstly, analyze the percentage change of photovoltaic power generation in four seasons and annual average in China. It can be seen that the average photovoltaic power generation in the four seasons of China from 2030 to 2050 has decreased, but the overall change is not significant, with a slightly larger decrease in winter. The reduction values under the three emission scenarios are 1.8%, 1.7%, and 2.2%, respectively. The average annual photovoltaic power generation in China has decreased under different emission scenarios, and the difference between different emission scenarios is not significant. The reduction range is between 1.1% and 1.3% (see Figure 3).
Further analyze the regional differences in the future changes of solar energy resources in China. From 2030 to 2050, except for South China and Southwest China, the average annual photovoltaic power generation in most regions of China (including Northeast, North China, Central, Central South, Qinghai Tibet Plateau, and Northwest) has decreased, but the magnitude of the change does not exceed 3%. The northwest region has the largest reduction in solar energy resources, with reduction values of 3.8%, 3.1%, and 3.5% under three different emission scenarios, respectively. The South and Southwest regions showed an increase, but the magnitude was relatively small, less than 3%. In addition, the simulation uncertainty in the Southwest region was relatively high (see Figure 4).
4. Main conclusions and policy recommendations
4.1 The possible impact and uncertainty of estimated results on industrial planning
Based on the current technological level, the estimated results of wind and solar energy resources in China under the background of climate change indicate that the overall wind and solar energy resources in China will tend to decrease from 2030 to 2050. The percentage changes in annual average wind power density and photovoltaic power generation are between 12% to 9% and 1.1% to 1.3%, respectively. However, considering the large interannual variability of wind power density and photovoltaic power generation (both above ± 10%), The result may not have a substantial impact on China’s future planning of wind and solar energy resources. In addition, it is noted that the seasonal and regional differences in wind energy resources are significantly greater than those in solar energy resources, and the increasing trend in low wind speed areas in South China has a favorable impact on the development and utilization of wind power technology in the region.
There are significant differences in the uncertainty of simulating future changes in wind power density between different seasons and regions. For example, although the changes in spring and autumn both show a decrease, there is a significant difference between different simulation results, with some simulation results showing opposite signs of change and set averages (see Figure 1). In terms of regions, the estimated uncertainty in the Qinghai Tibet Plateau and Southwest China is relatively high, and there are also cases where the change signs of individual simulation results are opposite to the set average (see Figure 2). Different simulation results show good consistency in simulating the seasonal changes of solar resources, and the dispersion between models is not significant (see Figure 3). However, for different regions, there are certain differences in the uncertainty of their simulations. For example, the uncertainty in the eastern, central southern, and southwestern regions is relatively obvious, and the change signs of individual simulation results are opposite to the set average results (see Figure 4).
Currently, the uncertainty of estimation technology comes from multiple sources. Firstly, the global model driving field used for dynamic downscaling has biases in describing the complex underlying surface and physical processes in China, and may introduce regional climate models, which can have a certain impact on the downscaling results. Secondly, the physical processes of the regional model itself also need to be improved. In the future, uncertainty in estimation can be reduced by improving the resolution of regional climate models, improving internal physical processes, and targeted model data correction work can also be carried out. Once again, due to the limited number of power downscaling simulations currently including low, medium, and high emission scenarios, it is difficult to provide quantitative conclusions and provide clear guidance and suggestions for future wind and solar energy development in China. Therefore, it is necessary to collect more simulation data in the future to help reduce the uncertainty of set estimation. In addition, for the estimation of wind and solar energy, the uncertainty between different simulation results is significantly greater than that of different emission scenarios, indicating that the selection of global model driving fields and the improvement of internal physical processes in regional models are crucial for predicting future changes in wind and solar energy.
4.2 Countermeasures and suggestions under the “dual carbon” goal
4.2.1 Strengthen the short-term climate information service capabilities for the development and utilization of wind and solar energy resources
According to the development goals of the “Outline for High Quality Development of Meteorology (2022-2035)”, it is necessary to strengthen climate resource assessment and planning in the future, promote the census, zoning, utilization, and safe operation stages of wind and solar energy resources, improve climate monitoring, prediction and its impact on resource development and safe operation, and evaluate technical capabilities. Analyze and judge short-term climate change, and improve the development and utilization plans of wind and solar energy, Promote peak shaving and shifting of wind and photovoltaic power generation, improve the intelligence level of the power grid, and ultimately improve the efficiency of resource development and utilization. The future extreme weather and climate events such as rainstorm and flood, typhoon, thunder and lightning, high temperature and drought, low temperature and freezing have obvious seasonal and regional characteristics, which will directly affect the anti meteorological risk ability of wind farms and solar internal devices. For example, sustained high and low temperatures will lead to overloading of the power system, reduced efficiency of photovoltaic module generation, and shortened battery life; Extreme low temperatures and thunderstorms may have an impact on the operation of wind turbines; Severe sandstorm weather can affect the acceptance rate of radiation, reduce the power generation of components, and increase the cost of power generation. Therefore, it is necessary to strengthen the capacity of climate information services and comprehensively improve the ability to respond to regional extreme events and risks.
4.2.2 Improve high-resolution estimation technology for wind and solar energy
The current estimation research focuses more on the changes in wind speed and solar radiation itself, and there are few estimated results on the exploitable amount of wind and solar energy technologies in China and its regional level. There is no conclusion on the contribution of future development and utilization under carbon neutrality scenarios to carbon reduction. Therefore, it is necessary to carry out refined estimation in order to obtain qualitative conclusions and provide scientific reference for the evaluation of ecological and environmental effects. The main reason for the lack of research on the exploitable amount and its contribution to carbon reduction is the lack of support from high spatiotemporal resolution (hourly) data. Daily or monthly scale data will cover many key wind and solar change signals, which cannot reflect the instantaneous and local scale evolution patterns of wind power and photovoltaic technology development. However, the refined estimation results of future wind and photovoltaic power generation have important guiding significance for power system scheduling, power load coordination, regional wind solar complementarity, conventional energy generation planning, and wind and photovoltaic power generation planning.
4.2.3 Coordinate seasonal and regional differences in the development and utilization of future wind and solar energy resources
Under the “dual carbon” goal, it is necessary to make overall arrangements based on the seasonal changes in wind and solar resources in different regions of China, adjust the power system scheduling plan, create a new type of power system, and formulate relevant policies for carbon reduction and reduction. In addition, regional change characteristics should also be taken into consideration, tailored to local conditions, and utilized reasonably. For example, there is an increasing trend in wind energy resources in the low wind speed areas of the eastern and southern regions of China in the future (see Figure 2), and correspondingly, these regions are economically developed and have obvious technological advantages to support. Therefore, efforts should be made to develop low wind speed technologies, which are expected to be the first to achieve carbon peak. In addition, further promoting the large-scale development and optimized layout of wind and photovoltaic power generation bases in the “Three North” areas with abundant wind and solar energy resources, improving development and utilization efficiency, and reducing the adverse effects of future wind energy resource reduction.
4. Strengthen the medium and long-term climate change service guarantee for wind and solar energy resources
Under the “dual carbon” goal, in addition to short-term climate services, the guarantee of medium – and long-term climate change services cannot be ignored, and the deep coupling between climate change services and wind and solar energy development planning should be strengthened. Future climate change and its associated composite risks will pose greater challenges to the development, supply and demand of wind and solar resources. In addition to short-term development and operation, power dispatch, and other climate service guarantees, medium – and long-term climate change services, such as providing medium – and long-term estimation results in the context of carbon neutrality and climate change, can provide scientific guidance for the development planning of the power industry. At the same time, it also helps to establish regional new energy development routes and effective adaptation strategies on the basis of the “dual carbon” goal, and achieve optimal allocation of regional resources. In addition, it is necessary to establish a comprehensive management system for wind and solar energy monitoring, forecasting, and estimation, comprehensively study the ecological, climatic, and environmental effects of large-scale wind and solar energy resource development and utilization, and provide scientific references for wind and solar optimization layout, climate change mitigation, and adaptation actions. To ultimately achieve the “dual carbon” goal, targeted suggestions and measures suitable for the development planning of wind and solar energy in China and at the regional level are proposed.