• Energy Research

Equity and efficiency are two important factors guiding the mitigation of anthropogenic emissions to achieve the Paris climate goals. Previous studies have proposed a range of allocations of global carbon budgets, but few have quantified the equity–efficiency interaction. Based on an investigation of the existing allocation literature, this study conducts a novel analysis using a ‘mixed’ allocation ‘big-data’ framework to understand the equity–efficiency interaction in the distribution of global carbon budgets under 2 °C and 1.5 °C warming targets. At a global scale, a carbon Gini coefficient and aggregate abatement costs are used as quantitative metrics to reflect equity and efficiency, respectively. Results show an equity–efficiency frontier that reflects the opportunity for the international community to co-improve equity and efficiency on top of existing allocations. However, the frontier also features strong trade-offs to further improve equity and efficiency if national allocations are to be achieved individually. Our analysis verifies that such trade-offs are sensitively dependent on the level of global connection and integration. Linking national mitigation actions and potentials can help promote equity–efficiency synergies and contribute to the efficient achievement of the Paris Agreement's temperature and equity goals.

Abstract In coping with climate change, China's CO2 mitigation targets should keep in step with the achievement of the long-term goal of holding temperature increase to well below 2 °C above pre-industrial levels by the end of this century (this is referred to as the 2 °C goal). Many previous papers have highlighted the implications of different effort-sharing principles and schemes in determining national contributions to global mitigations. In this paper, China's energy transformation towards the 2 °C goal until 2100 is examined in an integrated-assessment model in light of different effort-sharing principles to understand how the application of such schemes may alter China's energy system transformation on a pathway to this long-term goal. Across scenarios, China's non-fossil energy will account for 50–70% and 85% of primary energy consumption in 2050 and 2100, respectively in the scenarios in this study. Fossil energy with carbon capture and storage technologies and non-fossil energy will dominate power generation in China over the long run. Coal will be phased out in end-use sectors and electricity use will expand regardless of the effort-sharing principles. The sensitivity analysis of long-term steady-state levels implies that the ultimate level that emissions could reach will have great influences on the energy system transformation in China.

Abstract Transportation plays an important role in achieving deep decarbonization. This paper examines how the sector might be decarbonized in China in light of three national decarbonization scenarios toward the Paris Agreement goals, using Global Change Assessment Model 4.0 (the Tsinghua University version), which includes a detailed representation of China's transportation. Results indicate that while barely affected by meeting the Nationally Determined Contribution, China's transportation sector might need significant changes beyond 2030 to decouple associated CO2 emissions from GDP growths. Supporting national mitigation has more pronounced implications on freight than passenger transport services, and arouses a radical shift of transport fuels away from fossil-based liquids to clean alternatives. Decarbonizing China's transportation toward 1.5 °C is in many aspects similar to toward 2 °C, but lowers final energy use and ramps up clean fuels at an observably higher pace. In our 1.5 °C scenario, oil-refined liquids tend to phase out in the second half of the century, whereas clean fuels provide 62% (18–36% in 2 °C scenarios) and 98% (68–91% in 2 °C scenarios) of China's transport energy by 2050 and 2100, respectively. Fuel carbon intensity improvements are responsible for the majority of China's transport mitigation in our decarbonization scenarios, followed by energy intensity improvements and transport service reductions.

Abstract In the long-term stabilization targets of greenhouse gases concentrations, various carbon emission rights allocation schemes have been proposed. To compare and evaluate them, the most essential is the equity-efficiency tradeoff. This paper measures the equity and the efficiency in the global rather than the narrower national perspective. Specifically, the equity of the first allocation is quantified by the carbon Gini coefficient defined by per capita cumulative emission, and the economic efficiency to accomplish obligations is described with the discounted global abatement costs. Under 20 key allocation schemes, the numerical comparison on the equity-efficiency tradeoff side is carried out through the Equitable Access to Sustainable Development model. Our studies indicate that the equity and the efficiency of future emission space allocation approximately show a three-stage relationship.

Abstract: Combating global climate change calls for all countries to accelerate emissions reductions, and equity is an important guiding principle. A new indicator – the carbon Palma ratio, extended from the income Palma ratio and defined as the ratio of the total emissions of the top 10% emitters to those of the bottom 40% – is proposed, which provides a new perspective to inform the international community and the public of the distribution inequality of carbon emissions among individuals. The ratio is quantified within and across countries, by applying an elastic relationship between individual emissions and income. Results show that the carbon Palma ratios within most developing countries are overall high, suggesting them to focus more on coordinating regional and income differences and mainly guide high emitters to mitigate, so as to improve emissions and income equity simultaneously. The carbon Palma ratios within developed countries are comparatively smaller; however, the greater historical responsibilities to warming suggest them to substantially reduce emissions of all citizens, so as to enhance national mitigation contributions systematically. At a global scope, the current carbon Palma ratio is observably higher than within any country, reflecting an extremely severe inequality when looking at individual emissions beyond territorial limitations. The regional decomposition of emitters further suggests developed countries to take the lead in the post-Paris era in ratcheting up mitigation and climate finance ambition.

As the global trend toward affordable, clean and efficient energy systems continues to accelerate, there is a real need to enhance the holistic understanding of the nexus between energy and sustainable development. Based on bibliometrics, this review collates and connects the published evidence on the energy and sustainable development nexus, and shows that: 1) there has been a rapid increase in research on the nexus between energy and sustainable development in recent years; 2) nexus research methods mainly include network analysis model, econometric model, input-output model, system dynamics model, and integrated assessment model; 3) low-carbon, efficient and modern energy development has the potential to synergize with all aspects of sustainable development goals. However, there is also the risk of trade-offs with three-quarters of the goals, covering human well-being, material condition, natural environment, and partnerships; and 4) nexus research shows an evolutionary trend from duality to pluralism, from static to dynamic, and from theory to practice. Future research is expected to systematically assess the impact of energy development on larger cross-systems and how energy development could be synergized with comprehensive sustainable development.

Abstract China’s oil and gas consumption, which is not only significant to the industry but also related with national energy security, faces uncertainties in the future. This paper analyzes China’s oil and gas consumption under five representative scenarios toward 2050 using an integrated modeling. In the Nationally Determined Contribution (NDC) scenario, China’s oil consumption peaks at 705 million tons by 2035, and gas consumption ramps steadily up to reach 780 billion cubic meters by 2050. Oil provides 18% of China’s primary energy by 2030 and 15% by 2050, and gas 14% by 2030 and 17% by 2050. The 2 °C and the 1.5 °C scenarios control China’s 2050 oil consumption to 10% and 45% below the NDC level, respectively. Interestingly, more stringent mitigation tends to upscale China’s gas consumption before 2040. Compared with the NDC scenario, the oil-price scenarios present limited influences on China’s total energy consumption and end-use electrification but mainly feature a substitution between oil, gas and coal, non-fossil energy. Particularly, across our scenarios, China’s oil import dependence is projected to largely fluctuate around 70% toward 2050, and gas import dependence to reach 50–60% beyond 2030, implying a continuously high risk of energy resource supply and national energy security.

Abstract To reduce traffic congestion and protect the environment, license plate control (LPC) policy has been implemented in Beijing since 2011. In 2019, 100,000 vehicle license plates were distributed, including 60,000 for electric vehicles (EVs) and 40,000 for gasoline vehicle (GVs). However, whether the current license plate allocation is optimal from a social welfare maximization perspective remains unclear. This paper proposes a two-level Stackelberg game, which portrays the interaction between vehicle applicants and the government to quantify the optimal number of EV license plates under the LPC policy in Beijing. The equilibrium number of EV license plates derived from the Stackelberg model is 58,800, which could increase the social welfare by 0.38%. Sensitivity analysis is conducted to illustrate the impact of important influential factors — total license plate quota, vehicle rental fee, and energy price — on EV adoption. The LPC policy under COVID-19 is also studied through a scenario analysis. If the government additionally increases the total quota by 20,000, 24% could be allocated to GV and 76% to EV. One third reduction of the current vehicle rental fee could increase EV license plates by 10.5%. In terms of energy prices, when gasoline price is low, reducing electricity prices could contribute to EV adoption significantly, while that effect tapers off as gasoline prices increase.