The Power Transition under the Interaction of Different Systems—A Case Study of the Guangdong–Hong Kong–Macao Greater Bay Area

Abstract

Power transition is the top priority in energy transition. All existing power transition paths have been studied under the same system; thus far, no basic research has investigated what paths are involved and how they cooperate with each other under the interaction of different systems. Taking the Guangdong–Hong Kong–Macao Greater Bay Area (GBA), featuring a “one country, two systems” approach, as an example, this research identified and quantified the best path for the GBA’s power transition and explored the mode of cooperation during the power transition among the three regions under the interaction of different systems. The results showed that a combination of multiple low-carbon technologies is the best option for the GBA’s deep power transition, which can be characterized by the following components: “gas increase, nuclear increase, coal guarantee, and low proportion of renewable energy”. In this scenario, the GBA can achieve a carbon peak of 167 million tons of CO₂ in 2023. Before 2030, the GBA needs to first develop class H gas power, photovoltaic power and nuclear power while phasing out subcritical and below thermal power cogeneration, and subcritical and below coal power. After 2030, a significant increase will be needed in the installed capacity of distributed gas power to replace some class E and F gas power units. Distributed rooftop PV power generation will be the mainstream method of renewable energy generation. Power generation through waste incineration can also provide a prominent contribution to urban biomass power. Under the interaction of different systems, breaking the technical barriers among the three regions would represent a breakthrough for establishing a cooperative power transition. A “one primary system, two auxiliary systems” theoretical framework of cooperation is proposed, and the scope of its application is revealed. This study can provide a case reference for the establishment of a win–win cooperation mechanism for energy transition in different countries.

1. Introduction

The power industry has the highest carbon emissions, accounting for 42% of the carbon emissions of all industries in the world and as high as 51% in China [1]. In the context of a global energy transition, the deep transition in the power industry has become the key to energy transition in different countries, making the exploration of technical paths for deep emission reductions a popular topic in practical and theoretical research. According to the research results in China and internationally, the paths of deep emission reductions in the power industry fall into two categories: the use of a very high proportion of renewable energy and the combined use of multiple low-carbon technologies.

The path of category 1 involves the use of a very high proportion of renewable energy (mainly wind and solar) to achieve deep emissions reductions. As of mid-2021, more than 550 papers have described research on a 100% renewable energy system and demonstrated its technical feasibility [2]. For example, studies have mentioned that using 100% wind–water–solar energy in all energy sectors in 139 countries would prevent a global warming of 1.5 °C and millions of deaths from air pollution each year by 2050, thereby reducing social energy costs. These roadmaps, although far more radical than those required by the Paris Agreement, are still technically and economically feasible [3]. According to a study of a single country, all end-use energy demand in the United States can be met when only wind, solar, water, energy storage and demand considerations are coupled in the energy system [4]. Large-scale use of wind and photovoltaic resources can reduce carbon emissions by 80% compared to that in 1990 without incurring the highest cost per kilowatt hour of electricity [5]. In addition, a high proportion of wind, photovoltaic power and transmission networks can help reduce carbon emissions in Europe by 95% [6]. In the zero-carbon scenario, wind and solar energy will become the main power sources in China in 2050, accounting for 70% of power generation [7]. However, these studies have also drawn criticism from some quarters. Critics note that they do not adequately consider factors such as the variability of wind and solar, all aspects of system costs [8,9], the scalability of some storage technologies [10], resource constraints [11,12], social acceptance constraints, energy consumption outside the power sector, limits to the change rate of economy energy intensity [12] and limits on capacity deployment rates [12,13]. Some critics review these studies using four new viability criteria for a reliable power system that meets the electricity demands of this century, arguing that efforts to date appear to have vastly underestimated the challenges of removing fossil fuels from our energy system [14]. Nevertheless, others have noted that the feasibility standard evaluation method adopted by skeptics is not important. The 100% renewable energy scenarios proposed in the literature are not just feasible but also viable [15]. Apparently, the transition path toward the adoption of high-proportion renewable energy is currently in a dynamic game stage.

Category 2 relies on a wider range of low-carbon technologies, including wind, solar energy, “solid” power sources (such as nuclear, geothermal and biomass energy) and fossil energy (coal, oil, natural gas) with carbon capture and storage (CCS). These studies do not completely deny the feasibility of category 1. Instead, they analyze the shortcomings of the path of category 1 and suggest that relying on a wider range of low-carbon technologies would be the best approach to the deep power transition. For example, some studies have evaluated the results of research on the high-proportion renewable energy transition path in the United States and pointed out errors, arguing that wind and solar energy, although very effective in the low-carbon transition, have difficulty achieving zero emissions, and a broad technical combination is more likely to make the transition possible [10]. Other studies have noted that compared to relying solely on wind, solar energy and energy storage, solid power generation technologies (nuclear, coal, gas) can significantly reduce emission reduction costs [16], ensure energy supply security [17] and guarantee the power balance and peak regulation flexibility in the power system [18,19]. In addition to the low-carbon transition on the power side itself, the coordinated combination of technology innovation on the consumption side and the supply side is also the key to power transition. Some studies have confirmed that synergy between the PV power systems and the battery-powered electric ferries (BEF) can significantly reduce the critical excess electricity production (CEEP), the operating system costs and the emissions of CO₂ [20]. Other studies pointed out that all-electric ships seem to be a promising option for the future development of the short-sea shipping sector [21].

The authors of the present study believe that there is no absolute answer regarding the path a given country should take in the energy transition. Both of the aforementioned deep transition paths have their own advantages. The power systems in different countries and regions have different characteristics and natural resources; therefore, the transition paths vary. On the one hand, it is of vital importance to find the transition path most suitable for the local conditions; on the other hand, it is also crucial to seek complementary advantages and opportunities for cooperation in power transition among regions to achieve the global energy transition and limit global warming to 1.5 °C. However, the abovementioned studies were all conducted at the national level and were explorations of electricity transition paths under a single institutional system. The transition paths, program design and policy formulations of these systems are thus not influenced by any potential resistance that might arise as a result of institutional differences between systems. How can countries with different institutional systems break institutional constraints and achieve win–win cooperation in the energy transition? Currently, there is no relevant in-depth research or universal theoretical framework addressing this question, and addressing this gap is the main purpose and innovation of our study.

The following is a brief introduction to the study area. Known as one of the world’s four largest bay areas, the Guangdong–Hong Kong–Macao Greater Bay Area (GBA) is located in the southern coastal area of China, bordering the South China Sea (Figure 1). The GBA consists of two special administrative regions—Hong Kong and Macao—and 11 cities in Guangdong Province: Guangzhou, Shenzhen, Zhuhai, Foshan, Huizhou, Dongguan, Zhongshan, Jiangmen and Zhaoqing (Figure 1). Occupying a total area of 56,500 km², the GBA had a GDP of CNY 11.99 trillion in 2019 (approximately 11.7% of China’s total GDP), with a total population of 72.65 million (approximately 5.2% of China’s total population). As one of the most open and economically dynamic regions in China, the GBA has an important strategic position in the country’s development blueprint. What distinguishes the GBA most prominently from the other three major bay areas is the principle of “one country, two systems, three regions”. Under this principle, the innovation and integration of the three regions is the key to the GBA’s integrated development.

The GBA is one of the most energy-consuming city clusters in China. In 2019, its social power consumption was 548.3 billion kW·h, accounting for 7.3% of the country’s total power consumption. Outsourced power accounted for nearly 50% of this total. In the overall supply and demand structure, Yunnan, Hubei, Guangxi and Guizhou exported electricity to Guangdong, and Guangdong exported electricity to Hong Kong and Macao (Figure 1). As an area that began the construction of its power infrastructure at a very early time after the reform and opening up, the GBA still uses coal as its main energy source, accounting for more than 50%. Nearly half of the units have been in service for more than 20 years, and the average coal consumption of thermal power units is approximately 309 g of standard coal/kW·h, which is only average at the national level. This outdated infrastructure goes against the GBA’s positioning as an area with advanced and efficient development, making a deep power transition an urgent need. However, the particularity of “one country, two systems, and three regions” makes the power transition of the GBA different from the other three major bay areas in the world, providing an appropriate case in which to research the power transition under the interaction of different systems.

The key factors influencing the power transition are technology and policy. Our previous study on policy scenarios [22] notes that “The carbon emission constraint starts to work only when the auction ratio of CEA is increased to 50% and the auction price is increased to 60 CNY/ton (Scenario p3). When the auction ratio of CEA is 100% and the auction price reaches 120 CNY/ton (Scenario p5), a low-carbon transition of the power sector in the GBA can be achieved”. The GBA does not currently have a complete carbon emission trading system and is subject to the restrictions of the mainland carbon emission trading system. The ideal policy scenario is unlikely to be realized in the near future. Under such a scenario, technological progress will be the key to the GBA’s power transition before 2035, which should be given priority consideration at this stage. The purpose of this study is to explore how to achieve a deep power transition and carbon emission reductions through technological progress, as well as how to achieve carbon emission reductions through technological collaboration among three regions under different institutional systems, which is a more realistic and easier path for the GBA. In summary, taking the GBA, which is characterized by the “one country, two systems” approach, as an example, this study aims to address the following three key issues: (1) Based on the status quo and the resources of the power system in the GBA, we believe that the deep transition should involve the combined use of multiple low-carbon technologies. A quantitative verification through scenario analysis is needed to determine whether this speculation is correct. (2) After confirming the best orientation of the power transition, we need to analyze the specific path of the deep transition and the sequence of steps involved in applying different low-carbon technologies. (3) We need to determine the means through which a breakthrough can occur in the cooperative efforts of the three regions to achieve the power transition under the interaction of different systems and explore the framework for developing this cooperative framework within the GBA.

2. Materials and Methods

2.1. Types of Local Power Generation and Their Potentials and Trends

The current local power generation within the GBA includes coal power, gas power, nuclear power and renewable energy power. Under the constraints of a deep power transition, including the resource endowments and policy guidance of the three governments, there are great differences in the potential and trend of each type of power technology in the GBA (seen in

Table 1. The status quo, potentials and trends of various power generation technologies in the GBA.

Technology Types		Status Quo (2019)	Potential and Trend
Thermal Power Generation	Coal Power	The installed capacity was approximately 31 million kW, accounting for 50% of the total installed capacity. The existing coal power units consisted mainly of four types: ultra-supercritical, supercritical, subcritical and below thermal power cogeneration, and subcritical and below power generation. The overall power generation efficiency of the unit was low, and the average standard coal consumption for power generation was approximately 330 g standard coal/kW·h, which was lower than the domestic advanced level.	Guangdong Provincial Government and the Hong Kong Administration Government promised to prohibit the construction and expansion of coal-fired and oil-fired power generation units and to gradually reduce the coal power units.
	Gas Power	The installed capacity of gas power was approximately 18.35 million kW, and class E and class F power generation units each accounted for nearly 50%. The distributed generation units were just emerging, and there were only a few small units, accounting for only 2%. The unit consumption of the existing gas power units was not high, and the average power consumption was approximately 245 g standard coal/kW·h.	In the next 10 years, the installed capacity of gas power sets will exceed 30 million kW, and 10 new natural-gas-receiving stations or storage stations will be built in Guangdong Province. It is estimated that by 2035, the total natural gas supply capacity in the GBA will be up to 110 billion m3, 5-fold of the current natural gas consumption.
Nuclear Power	Nuclear Power	The installed capacity of the nuclear power units was 7.87 million kW from Shenzhen Dayawan nuclear power station (two 984,000 kW units, operated since 1994), Shenzhen Lingao nuclear power station (two 99 million kW units, operated at phase I since 2003, and two 1.086 million kW units, operated at phase II since 2010 and 2011, respectively) and Jiangmen Taishan nuclear power station (a 1.75 million kW unit, operated since 2018).	The maximum installed capacity of nuclear power units will be increased to 26.62 million kW by 2035.
Renewable Energy Power	Biomass Power	The installed capacity of waste incineration power generation units was 1.08 million kW.	By 2035, the population of the GBA will be approximately 100 million, and the amount of waste will be increased to 165,000 tons/day. If the proportion of waste incineration is increased to 80%, the maximum installed capacity of power generation will be increased to 3.29 million kW in 2035.
	Hydropower	The installed capacity of hydropower units was 1.42 million kW.	The available hydropower resources have been basically exploited, and there will be no new generating units by 2035. The installed capacity of hydropower units will be unchanged in this paper.
	Wind Power	The installed capacity of onshore wind power units was approximately 440,000 kW, and they were located in Zhuhai, Jiangmen and Zhaoqing in the Pearl River Delta Region. The offshore wind power projects were just started, with an installed capacity of only 30,000 million kW.	Approximately 1 million kW installed capacity of onshore wind power sets will be installed, mainly in Huizhou and Zhaoqing. The offshore wind power units are limited, mainly in Zhuhai and Huizhou. After 2025, the layout of offshore wind power units will be completed in the GBA, and the maximum installed capacity will be 1.62 million kW.
	Solar Power	The installed capacity of solar power units was only 1.45 million kW.	Solar power cannot be commercialized on a large scale in the GBA by 2035. As the land resources are limited, large-scale development of PV power generation units are not applicable in the GBA. However, there is great potential in distributed PV power generation. Based on the annual growth rate of 225,000 kW of distributed PV power generation units in the GBA, the installed capacity will be approximately 11.5 million kW by 2035.
Outsourcing Power		The outsourced power was 275 billion kW·h, accounting for 49.6% of the total power consumption. Of this amount, more than 70% came from the “West-to-east Power Transmission Project”. The average on-grid price was 0.249 CNY/kW·h, which was much lower than the benchmark price of 0.453 CNY/kW·h from grid-connected power generation units in Guangdong Province. The outsourced power has an overwhelming cost advantage compared to the local power generation units.	In this research, the costs and technologies of the outsourcing power and the local power generation are not discussed. To ensure the power supply safety in the GBA, the proportion of the outsourcing power should be essentially stable. As the power demand is growing faster than the construction of power generation units, there will be more demand for outsourced power before 2025. It is assumed that the proportion of outsourced power will increase to 51% by 2025 and 52% by 2035.

Note: The fuel-fired power generation mainly came from Hong Kong and Macau, and it was mainly used as a backup power source; therefore, it was not considered in this paper.

). For example, the GBA will substantially eliminate outdated coal power units and provide natural gas for centralized power generation. The class E and F gas power units are low in cost; however, their efficiency needs to be further improved. As the most developed economic region in China, the GBA should make every effort to deploy the most efficient, reliable and powerful class H gas turbines currently in commercial operation in the world. Nuclear power is the main tool to achieve carbon neutrality without emitting carbon dioxide while ensuring a continuous and stable supply of energy. With limited land resources, concentrated power demand, and a long coastline, the GBA has considerable potential for developing nuclear power. Distributed photovoltaic power generation is a new and promising method of generating power and comprehensively utilizing energy. This approach can improve the generating capacity of photovoltaic power plants of the same scale and can address the loss of power in boosting and long-distance transmission. Photovoltaic power generation projects built on the roofs of urban buildings are the most widely used and can be effectively applied in the GBA.

2.2. Scenarios and Parameter Setting

We designed three scenarios according to our purpose (seen in

Table 2. Scenarios and their descriptions.

Scenarios	Description
Business as usual (BAU)	The investment cost of renewable energy technologies available in the GBA decreases steadily under the current rate of technological progress. With the progress of the independent innovation of renewable energy technology and further localization of power generation equipment, the scale effect will gradually ramp up.
Renewable energy technology (T1)	Promote renewable energy generation vigorously, and the investment cost of renewable energy technology will be further decreased.
Multiple clean and low-carbon technologies (T2)	Promote renewable energy generation rationally, and the investment cost of nuclear power and high-efficiency gas turbine units will gradually reduce with the increase in locally manufactured equipment. Meanwhile, with the improvement of the natural gas receiving station and gas supply network in the GBA, the set gas price will gradually decrease from the current average gas price of CNY 2.5 per cubic meter to CNY 2.3 per cubic meter in 2035, which is close to the current gate price of the second west-east gas transmission line to power plants in various cities.

), and the AIM/Enduse model was applied for scenario prediction. Setting the parameters is the key step in scenario analysis. According to the analysis of the status quo, potential and trend of each type of power generation technology in the GBA (see Table 1), technical parameters, economic parameters, energy parameters, and carbon emission coefficients under the three scenarios are shown in Appendix A 

Table A1. Technical indicators and basic parameter settings.

Power Generation Technology	Investment Cost (CNY/kW)			Operating Cost (CNY/kW)	Carbon Cost (CNY)	Service Life (Years)	Annual Power Generation Hours (h)	Power Consumption Efficiency (gce/kW·h)	Price of Fuel (CNY/Ton Standard Coal)
	2019	2025	2035						2019	2025	2035
Scenarios BAU
Ultra-supercritical coal power	3300 (1)			150 (1)	According to the auction ratio and auction price of 5% and 20 CNY/ton CO2, respectively	40 (1)	4580 (4)	308 (4)	1000 (7)	1100 (7)	1200 (7)
Supercritical coal power	3300 (1)			175 (1)			4200 (4)	316 (4)
Subcritical and below thermal-power cogeneration	4400 (1)			225 (1)			4960 (4)	328 (4)
Subcritical and below coal power	4400 (1)			225 (1)			4200 (4)	336 (4)
Class E gas power	2900 (1)			200 (1)			4500 (4)	249 (4)	1880 (8)	1955 (8)	2030 (8)
Class F gas power	2900 (1)			200 (1)			4500 (4)	225 (4)
Class H gas power	4300 (1)			180 (1)			4500 (4)	210 (4)
Distributed gas power	8000 (1)			180 (1)			5800 (4)	190 (4)
Waste incineration power	25,000 (2)	22,000 (2)	20,000 (2)	315 (2)		30 (2)	5500 (5)	487 (5)	−194 (5)
Photovoltaic (PV) power	6000 (2)	5500 (2)	5000 (2)	200 (2)		20 (2)	1000 (6)	122.9	-
Nuclear power	10,000 (3)			600 (3)		60 (3)	7400 (3)		380 (3)
Hydropower	8800 (2)			300 (2)		40 (2)	2100 (6)		-
Onshore wind power	9000 (2)	8500 (2)	8000 (2)	300 (2)		20 (2)	1900 (6)		-
Offshore wind power	19,000 (2)	16,000 (2)	13,000 (2)	500 (2)		20 (2)	3000 (6)		-
Scenarios T1
Ultra-supercritical coal power	3300 (1)			150 (1)	According to the auction ratio and auction price of 5% and 20 CNY/ton CO2, respectively	40 (1)	4580 (4)	308 (4)	1000 (7)	1100 (7)	1200 (7)
Supercritical coal power	3300 (1)			175 (1)			4200 (4)	316 (4)
Subcritical and below thermal-power cogeneration	4400 (1)			225 (1)			4960 (4)	328 (4)
Subcritical and below coal power	4400 (1)			225 (1)			4200 (4)	336 (4)
Class E gas power	2900 (1)			200 (1)			4500 (4)	249 (4)	1880 (8)	1955 (8)	2030 (8)
Class F gas power	2900 (1)			200 (1)			4500 (4)	225 (4)
Class H gas power	4300 (1)			180 (1)			4500 (4)	210 (4)
Distributed gas power	8000 (1)			180 (1)			5800 (4)	190 (4)
Waste incineration power	25,000 (2)	20,000 (2)	18,000 (2)	315 (2)		30 (2)	5500 (5)	487 (5)	−194 (5)
Photovoltaic (PV) power	6000 (2)	4000 (2)	3800 (2)	200 (2)		20 (2)	1000 (6)	122.9	-
Nuclear power	10,000 (3)			600 (3)		60 (3)	7400 (3)		380 (3)
Hydropower	8800 (2)			300 (2)		40 (2)	2100 (6)		-
Onshore wind power	9000 (2)	7000 (2)	6000 (2)	300 (2)		20 (2)	1900 (6)		-
Offshore wind power	19,000 (2)	10,000 (2)	8000 (2)	500 (2)		20 (2)	3000 (6)		-
Scenarios T2
Ultra-supercritical coal power	3300 (1)			150 (1)	According to the auction ratio and auction price of 5% and 20 CNY/ton CO2, respectively	40 (1)	4580 (4)	308 (4)	1000 (7)	1100 (7)	1200 (7)
Supercritical coal power	3300 (1)			175 (1)			4200 (4)	316 (4)
Subcritical and below thermal-power cogeneration	4400 (1)			225 (1)			4960 (4)	328 (4)
Subcritical and below coal power	4400 (1)			225 (1)			4200 (4)	336 (4)
Class E gas power	2900 (1)			200 (1)			4500 (4)	249 (4)	1880 (8)	1805 (8)	1729 (8)
Class F gas power	2900 (1)			200 (1)			4500 (4)	225 (4)
Class H gas power	4300 (1)		4150 (1)	180 (1)			4500 (4)	210 (4)
Distributed gas power	8000 (1)		7500 (1)	180 (1)			5800 (4)	190 (4)
Waste incineration power	25,000 (2)	20,000 (2)	18,000 (2)	315 (2)		30 (2)	5500 (5)	487 (5)	−194 (5)
Photovoltaic (PV) power	6000 (2)	4000 (2)	3800 (2)	200 (2)		20 (2)	1000 (6)	122.9	-
Nuclear power	10,000 (3)			600 (3)		60 (3)	7400 (3)		380 (3)
Hydropower	8800 (2)			300 (2)		40 (2)	2100 (6)		-
Onshore wind power	9000 (2)	7000 (2)	6000 (2)	300 (2)		20 (2)	1900 (6)		-
Offshore wind power	19,000 (2)	10,000 (2)	8000 (2)	500 (2)		20 (2)	3000 (6)		-

Notes: In our previously published paper [22], the parameters of the three scenarios are designed according to the following: “⁽¹⁾ Based on Reference Cost Index of quota design for Thermal Power Engineering prepared by the General Electric Power Planning and Design Institute [27], and crosschecked by visiting, on-site, the thermal power plants in Guangdong Province. ⁽²⁾ Based on Costs of Power Generation from Renewable Energy Resources 2019 issued by the International Renewable Energy Agency [28], and crosschecked by visiting, on-site, the renewable energy power plants in Guangdong Province. ⁽³⁾ Based on the document, Analysis of construction cycle and cost change of nuclear power [34], and crosschecked by visiting, on-site, the China General Nuclear Power Group. ⁽⁴⁾ Based on the verified carbon emission reports of the thermal power plants in Guangdong carbon emission trading system from 2013–2019 [35]. ⁽⁵⁾ Based on the survey report on the resource thermal power plants in Guangdong province [36]. ⁽⁶⁾ Based on China Electric Power Statistical Yearbook 2019 [37]. ⁽⁷⁾ Referred the coal price from South China Coal Trading Center [38], and estimated by discussing with Guangdong Coal Industry Association ⁽⁸⁾ Based on the document Research on the influence of natural gas power generation on electricity market [39], and crosschecked by visiting, on-site, the Dapeng LNG Terminal”.

. Energy demand (product output) in this paper will reach 990 billion kW·h by 2035 according to our previous research [22,23,24].

2.3. Models and Methods

Models and methods have been described in detail in our previously published paper [22], which is quoted extensively in this section. The AIM/Enduse model is a bottom-up modeling tool developed by the National Institute for Environmental Studies of Japan and others [25]. The mathematical function of the AIM/Enduse modeling approach is a multiconstrained single-objective linear optimization system of equations, and its objective function is to minimize the total cost of the system per year. The initial fixed investment needs to be averaged annually using the equipment’s life cycle and depreciation rate, and the annual average initial investment cost in the tth year is calculated as follows.

$$C_{l,p}^t=B_{l,p}^t\times (1-{SC}_{l,p})·\frac{\alpha {(1+\alpha )}^{T_l}}{{(1+\alpha )}^{T_l}-1}$$

(1)

where $C_{l,p}^t$ is the average annual initial investment cost of production equipment l equipped with abatement equipment p. $B_{l,p}^t$ is the total investment of production equipment l equipped with abatement equipment p. ${SC}_{l,p}$ is the subsidy of production equipment l equipped with abatement equipment p. α is the discount rate, and T_l is the service life of the production equipment l.

The total cost of the system in the tth year can be calculated as follows.

$$\mathrm{T}\mathrm{C}=\sum _{l,p}\left\{C_{l,p}^t·r_{l,p}+\sum _{p_1}{C}_{l,p_1\to p}^t·M_{l,p_1\to p}+\left[g_{l,p}^t+\sum _k{g}_{l,k}^t·(1-{\xi }_{l,k}^t)·E_{l,k}^t\right]·X_l^t\right\}+\sum _m{\epsilon }_m·Q_m\to min$$

(2)

where $r_{l,p}$ is the number of newly built production equipment l equipped with abatement equipment p. $C_{l,p_1\to p}^t$ is the additional investment for the production equipment l with the abatement equipment improved from p₁ to p. $M_{l,p_1\to p}$ is the number of the production equipment l with the abatement equipment being improved from p₁ to p. $g_{l,p}^t$ is the unit operating cost (excluding energy cost) of the production equipment l equipped with the abatement equipment p. $g_{l,k}^t$ is the unit energy cost of the production equipment l consuming energy k. ${\xi }_{l,k}^t$ is the proportion of efficiency improvement of the production equipment l with an energy consumption of k. $E_{l,k}^t$ is the amount of energy consumption of the production equipment l with an energy consumption of k. $X_l^t$ is the number of production equipment l in operation. ${\epsilon }_m$ is the emissions tax of gas m, referring to the auction price of carbon emission allowances (CEA). $Q_m$ is the emission of gas m, referring to CO₂ emissions.

2.4. Data Sources

Considering that Guangdong, Hong Kong and Macao implement different systems and statistical measures, data collection and consolidation are difficult. In this study, it is necessary to have a scientific and logical judgment and evaluation of the current technical development of the power systems in the three regions, the potential of future power technologies, and the cost of power generation. These considerations all require the support of refined first-hand data, and traditional statistical data have lagged behind the demand. This is also one of the greatest challenges in carrying out energy transition research in the GBA. This study relies on two major projects from the CAE (the Chinese Academy of Engineering). Under the leadership of academicians and experts and with the support of the governments of 11 cities in the GBA, research of field power was carried out for three months in 2020. Comprehensive first-hand information (see

Table 3. Data sources.

Organized by		A special investigation group on “the medium and long-term energy transition in the GBA” composed of academicians and researchers
Duration		2 March~31 May 2020
	Data Content	Status quo, potential and cost of power generation technology	Trend and planning of power generation technology	Scenario parameter settings	Energy carbon emission factor
Data Source
Eleven city government departments (see Appendix B Table A2 for a partial list)		√	√	√	×
Scientific research institutions, enterprise visits/verifications (see Appendix B Table A2 for a partial list)		√	√	√	√
Expert questionnaires (154 valid questionnaires) 1		√	√	√	×
Studies and reports [26,27,28,29,30,31]		√	√	√	√

Note: ¹ The results of expert questionnaires have been analyzed and discussed in our another published paper, see the reference [26].

) was obtained after investigations into government departments, expert questionnaires, and enterprise visits/verifications. In particular, the data of 2019 are the most detailed and provide authentic parameter values for the base year; therefore, we choose 2019 as the base year. In addition, as carbon emission inspectors in Guangdong Province, the authors have been engaged in carbon inspections of thermal power companies across the province since 2013 and have a systematic understanding of electric power development and a good sense of how to select and set the scenario parameters.

3. Results and Discussion

3.1. Analysis of Scenario Results

3.1.1. Installed Power Capacity and Structure

In the BAU, T₁, and T₂ scenarios, the installed power capacity in the GBA will increase from 61.67 million kW in 2019 to 94.95 million kW, 103.16 million kW, and 101.78 million kW in 2035, respectively (seen in Figure 2). Some decommissioned units have been phased out, and the installed capacity and proportion of coal power units are decreasing year by year. The installed gas power capacity will remain essentially unchanged until 2025, and its proportion will decline annually after the phased peak in 2024. Class H units will be developing on a large scale due to lower investment costs for advanced gas power units. The proportion of distributed gas power will begin to increase in the later period. By 2025, gas power will surpass coal power and become the largest installed power source (Figure 3). The installed capacity of nuclear power increases steadily in all three scenarios. In terms of renewable energy, in the BAU scenario, renewable energy develops slowly, with the proportion of installed capacity slowly increasing from 7.2% to 8.7%. In the T₁ and T₂ scenarios, the large-scale development of offshore wind power and photovoltaic power will begin in 2024 and is expected to reach the upper limit in 2025 and 2035, respectively. The cap year for onshore wind power will also advance from 2032 in the BAU scenario to 2025. By 2035, the installed capacity of renewable energy will account for 19%.

3.1.2. Power Supply and Structure

The power supply consists of outsourced power and local power. Nearly half of the power supply in the GBA comes from outside the Bay Area. To guarantee power safety, the proportion of outsourced power will remain essentially stable, increasing steadily and slowly from 49.6% in 2019 to 52% in 2035; however, the structure of outsourced power can transition toward cleaner energy. For example, a clean energy threshold can be set to only increase the input of renewable energy in west-to-east power transmission, reduce the input of coal power, and increase the input of offshore wind and nuclear power outside the GBA to provide a higher proportion of green power.

For local power, the installed capacity structure of the power supply essentially determines the local power supply structure. In the BAU scenario, the largest change occurs in the proportions of coal and nuclear power, which change from 47.5% and 19.4% in 2019 to 22.4% and 39.8% in 2035, respectively. Gas power and renewable energy undergo a small change, increasing from 29.3% and 3.9% to 32.5% and 5.3%, respectively. In the T₁ scenario (Figure 4), the proportions of coal and nuclear power are essentially the same as those in the BAU scenario, and the proportion of gas power is slightly lower than that in the BAU scenario. Technological progress has brought maximum development to photovoltaic power and onshore and offshore wind power; however, the annual utilization hours are subject to natural resources, and the proportion of renewable energy power supply is still small, only 8.2%. In 2035, the proportion of coal power in the T₂ scenario will drop by 1.93% compared to that in the T₁ scenario, and the resulting power gap will be fully supplemented by efficient gas power units. Nuclear and renewable power generation will be the same as that in the T₁ scenario. Apparently, in the local power generation structure, nuclear power will have the largest proportion in all three scenarios by 2035. Despite the substantial increase in the installed capacity of renewable energy, the annual power generation hours are much shorter than other forms of power generation, subject to natural conditions and geographical location. In the future, the proportion of renewable energy in the power supply structure will not significantly increase.

3.1.3. Energy Conservation and Emission Reduction in the Power Transition

Energy consumption (EC) in the GBA’s local power sector will continue to grow from 2019 to 2035 (Figure 5). By 2035, the energy consumption in the BAU scenario will reach 107 million tons of standard coal. There is more renewable power in the T₁ scenario; therefore, energy consumption will be reduced by 1.3% compared to that in the BAU scenario. In the T₂ scenario, more high-efficiency gas power units are available, and energy consumption will be further reduced by 3.2% in comparison to the BAU scenario until 2035.

With the change in power supply structure, carbon emissions show a trend of rising first and then descending (Figure 5). In both the BAU and T₁ scenarios, carbon emissions will reach their peak in 2025, at 173 and 168 million tons of CO₂, respectively, and drop to 162 and 157 million tons in 2035, values that are 0.2% and 3.3% lower than those in 2019, respectively. The carbon emission peak in the T₂ scenario occurs 2 years earlier than that in the BAU and T₁ scenarios, that is, a peak value of 167 million tons of CO₂ will be reached in 2023, and carbon emissions will drop to 150 million tons of CO₂ in 2035, 7.7% less than that in 2019. The carbon emissions per kW·h are decreasing year by year, with an increase in the proportion of clean and low-carbon units of nuclear power, gas power and waste incineration. In 2035, the carbon emissions per kW·h in the three scenarios will drop to 342, 331, and 316 gCO₂/kW·h, respectively, values that are 42.9%, 44.7%, and 47.2% lower than those in 2019 (599 gCO₂/kW·h), which is a significant improvement in the degree of clean power.

3.1.4. Power Transition Costs

The power transition costs consist of the operating cost, investment cost and carbon emission cost. The transition costs in the three transition scenarios all show an upward trend, and the average annual increasing rate in the transition costs before 2025 is significantly faster than that after 2025 (seen in Figure 6). The transition cost in the T₂ scenario is the lowest, and the total transition cost in 2035 will be CNY 131.2 billion. From the perspective of composition, with the reduction in installed coal power capacity and power supply, the cost of coal power transition is on the decline year by year. The cost of gas power transition will increase annually until 2025 and will then remain essentially stable. There is no carbon cost for nuclear and renewable power generation; therefore, the costs of these two types of power generation are relatively low. After 2025, the GBA will see a markedly accelerated increase in the transition cost of nuclear power as it speeds up its nuclear power deployment.

From the perspective of cost types, the largest transition cost is operation cost, which shows an increasing trend year by year, accounting for more than 97% of the total cost (seen in Figure 7), mainly because the investment cost is evenly distributed each year; therefore, the annual investment cost is relatively small. In view of the current carbon emission auction ratio and auction price of 5% and 20 CNY/ton CO₂, respectively, in Guangdong Province, the carbon cost amounts to a relatively small proportion in these three scenarios.

3.1.5. Credibility Test

The accurate data of the power supply in 2020 and 2021 are compared with the predicted data (Figure 8). The predicted value in 2020 is 25.367 billion kW·h higher than the accurate value, and that in 2021 is 8.592 billion kW·h lower, mainly due to the impact of COVID-19 in the first half of 2020. In general, the errors between the predicted value and the accurate value in 2020 and 2021 are 4.52% and −1.37%, respectively, indicating that the predicted value is very close to the accurate value. Thus, the predicted results of this study are credible and can be used as the basis for subsequent analysis of the results.

3.2. Detailed Description of the Best Power Transition Path

The power transition aims for less total energy consumption and carbon emissions, and lower costs. By this standard, the T₂ scenario is the best choice. In this scenario, from 2019 to 2035, the proportion of the GBA’s installed capacity of coal power, gas power, nuclear power and renewable energy will change from 50.3%, 29.8%, 12.8% and 7.2% to 22.4%, 32.2%, 26.1% and 19.2%, respectively, and the proportion of power supply will change from 47.5%, 29.3%, 19.4% and 3.9% to 20.4%, 31.6%, 39.8% and 8.2%, respectively (Figure 9). To compensate for the power gap between nuclear power and gas power, the GBA has adopted a transition path composed of the following elements: “gas increase, nuclear increase, coal guarantee, and low proportion of renewable energy”. Due to resource constraints and great power demand, the proportion of renewable energy generation will not be in line with China’s overall transition goals even by 2060. This result exhibits the substantial regional differences in China’s power transition. This conclusion has also validated our hypothesis through quantitative research: the GBA’s deep power transition should be oriented towards a combination of multiple low-carbon technologies rather than a high proportion of renewable energy.

Therefore, low-carbon power technologies are applied to the GBA in stages and batches, depending on its energy system characteristics, the maturity of the technology required and the transition costs. From 2019 to 2025, the development of class H gas power, photovoltaic power and nuclear power will be the priority. Their installed capacity needs to be increased by 9.97 billion kW, 7.56 billion kW and 4.25 billion kW, respectively. In addition, the installed capacity of subcritical and below thermal power cogeneration and subcritical and below coal power will be reduced by 2.41 billion kW and 1.44 billion kW, respectively (seen in Figure 10), to facilitate carbon emission peaking in 2023. From 2025 to 2030, the installed capacity of nuclear power will remain fast-growing, with an increment of 7.25 billion kW. Class H gas power and photovoltaic power generation will grow steadily, with increments of 1.79 billion kW and 1.25 billion kW, respectively. In addition, distributed gas power has the advantages of high energy efficiency, cleanliness, environmental friendliness, high safety, peak shaving and good economic benefits. From 2030 to 2035, the GBA will increase the installed capacity of distributed gas power by 3.62 billion kW and continue to reduce the installed capacity of class E and F gas power units and subcritical and below coal power. With the increase in population in the GBA, an increasing amount of municipal solid waste will be generated, providing a large fuel source for power generation through waste incineration. From 2019 to 2035, the installed capacity of power generation through waste incineration will grow steadily, and this can serve as a model for urban biomass power generation.

3.3. Discussion on the Cooperation Mode of Power Transition among the Three Regions

3.3.1. Characteristics and Interrelationships of the Power Transition Paths of the Three Regions

The power supply and demand in the Pearl River Delta accounted for 89% and 90% of the total, respectively, in the GBA (based on data from 2019). Therefore, the transition of the power system in the Pearl River Delta will determine the overall transition path of the GBA’s power system, which demonstrates the overall elements of “gas increase, nuclear increase, coal guarantee, and low proportion of renewable energy” (Figure 11). The local power generation in Hong Kong is dominated by gas and coal, which accounted for approximately 73% in 2019, and outsourced nuclear power and renewable energy power accounted for 27% (of which nuclear power accounted for approximately 26%). Despite the government’s push into renewable power, resource endowments limit Hong Kong’s development scale. In the future, Hong Kong’s electric power will embark on a transition path characterized by “gas increase, coal guarantee, green power (mainly nuclear) introduction, and low-proportion renewable energy”. The local power generation in Macao is relatively small, and in recent years, it has been transformed from oil-based to gas-based power, with a high degree of clean energy structure. Approximately 85% of the power consumed by Macao comes from mainland China. Therefore, Macao’s energy transition path features “oil deprecation, gas increase, green power introduction, and low-proportion renewable energy”. The three regions work toward the common goal of “gas increase, coal guarantee and renewable energy development”. To develop nuclear power, the governments of Hong Kong and Macao have established clear policy instructions on the proportion of outsourced green power, which has become one of the driving forces for the GBA to vigorously develop nuclear power. Undoubtedly, the energy transition among the three regions has built a cooperative relationship of “joint efforts and mutual promotion”.

3.3.2. Cooperation Mode of Power Transition Based on Technical Innovation

As key factors to promote the energy transition, technical progress and innovation are needed in both renewable energy technology and clean power generation technology from fossil energy. The GBA has an outstanding technological innovation capacity. According to the 2020 Global Innovation Index (GII) Report [32], China’s comprehensive innovation capacity ranked 14th in the world: the Shenzhen–Hong Kong and Guangzhou clusters in the GBA ranked second in the innovation capacity of global urban clusters, behind only the Tokyo–Yokohama cluster. The GBA can leverage its technical innovation advantages to help the power sector with the deep transition. Therefore, breaking through the technical barriers among the three regions is an essential driving force for the GBA to establish the cooperation mode in the power transition. Relying on the advantages of the Guangzhou–Shenzhen–Hong Kong–Macao technology innovation corridor [33] and driven by the three governments’ efforts, the GBA may: (1) set up special projects for GBA power transition technology, open them to Hong Kong and Macao, and encourage proactive or independent participation by universities and research institutions; (2) establish a mechanism for the cross-border use of basic research funds for the power transition from provincial finance and set up a green channel for fund allocation in the GBA; and (3) accelerate knowledge production and transformation in the GBA and connect research centers with technological innovation enterprises and intelligent manufacturing enterprises to jointly build a shared technology information platform to build the GBA into a low-carbon technological innovation highland for power transition.

On this basis, the power system of the Pearl River Delta will be adopted as the main system, and the entry point for Hong Kong and Macao to be included in the overall system will be identified to build the “one primary system, two auxiliary systems” mode based on technical progress (Figure 12). Hong Kong’s power transition focuses on reducing its reliance on fossil fuels and leveraging technological innovation to accelerate the development and utilization of wind, solar and other renewable energy sources, among which research on solar power generation is a key task. Hong Kong leads China in policy development, such as introducing feed-in tariffs and providing a full range of technical and financial subsidies for solar schools in the territory, ahead of many other cities in Asia. In the future, Hong Kong may establish a solar community grant fund and even set up a solar community demonstration area, where low-carbon enterprises from Hong Kong and the GBA can settle to overcome their geographical separation to draw on each other’s strengths and achieve breakthroughs in both technology and policy. Since Macao has a high proportion of outsourced power, the key to its energy transition is to ensure stable and safe energy delivery. Thus, the quasi-CDM (Quasi-CDM: The Clean Development Mechanism (CDM) defined in the Kyoto Protocol can be applied in different countries. Macao, as a part of China that is governed under a different system, does not fall within the scope of application for the CDM; however, it has a similar cooperation mechanism. Thus, this paper has proposed quasi-CDM on the basis of CDM.) is planned to be used to incorporate Macao’s power transition into the GBA. That is, Macao will help accelerate Zhuhai’s energy transition through energy management experience and talent exchange, technical cooperation, development and introduction, as well as green finance promotion, and leverage the Macao–Zhuhai synergy to set an innovation example for the energy transition in the GBA.

In summary, the cooperation model of the power transition among Guangdong, Hong Kong and Macao can be summarized as “one primary system, two auxiliary systems”. Under this model, auxiliary systems are incorporated into the main system in different ways or through different mechanisms. In this study, the power system of the Pearl River Delta is the main system. Hong Kong will adopt the renewable energy policy pilot as the entry point and incorporate it into the main system in a “point-to-area” approach. Macao will take the quasi-CDM as the entry point and incorporate it into the main system through regional linkage.

4. Conclusions

4.1. Main Findings

(1)

A combination of the four low-carbon technologies, i.e., efficient coal power, gas power, nuclear power and renewable energy, is the best option for the GBA’s deep power transition, and the overall characteristics of its transition path are “gas increase, nuclear increase, coal guarantee, and low proportion of renewable energy”. The findings support the academic view of the deep transition path represented in category 2.

(2)

With the deep transition, the GBA can achieve a carbon peak of 167 million tons of CO₂ in 2023. Before 2030, the GBA needs to first develop class H gas power, photovoltaic power generation and nuclear power while phasing out subcritical and below thermal power cogeneration, and subcritical and below coal power. After 2030, a significant increase will be needed in the installed capacity of distributed gas power to replace some class E and F gas power units. Distributed rooftop PV power generation will be the mainstream method of renewable energy generation. Power generation through waste incineration can be one of the most prominent features of urban biomass power generation.

(3)

Under the interaction of different systems, breaking the technical barriers among the three regions is a necessary driving force for establishing the cooperative mode in the energy transition. This paper describes an innovative cooperation mode driven by government efforts and technical innovation, with the Pearl River Delta as the main system and Hong Kong and Macao as the auxiliary systems.

(4)

The “one primary system, two auxiliary systems” mode can be expanded into “one primary system, multiple auxiliary systems”. This framework is particularly applicable to countries (or regions) with substantial differences in power supply. Our study provides a theoretical framework for cooperation and a win–win innovation mode of energy transition among countries.

4.2. Existing Shortcomings and Research Prospects

Energy transition involves not only natural sciences related to energy technology but also social sciences in relation to policy mechanisms and human behavior. In this study, both the scenarios and the cooperation mode for power transition are devised based on technical innovation. The authors’ previous study shows that policy factors have a non-negligible impact on the power transition [22]. However, the extent to which a policy is implemented and whether it will produce positive or negative effects are closely related to all relevant stakeholders. Therefore, the power transition is a comprehensive, systematic transition that requires more comprehensive studies on technology, policies, stakeholders, public cognition, etc. Therefore, in the next step, the authors will continue to consider the influencing factors based on previous research and incorporate policy factors and the behavior of energy transition stakeholders into the research in an attempt to continuously adjust and improve the power transition path and cooperation mode in the GBA.