The transition towards a clean energy system is arguably indispensable for combatting climate change and realizing low carbon development. With the launch of the Renewable Energy Law in 2005 for addressing the growing pressure on worsening air pollution, China has initiated to expedite the development of renewable energy, including solar, wind, and hydropower. Taking on a combination of subsidies, policy targets, and manufacturing incentives, China has swiftly grown to play a global leadership in terms of its magnitudes in both investment and accumulative installed capacity for reinforcing renewable power. The proportion of renewable power in national electricity generation promoted from 16.9% in 2007 to 28.0% in 2016. Such trends are widely expected to continue and accelerate in the coming decades. By 2040, renewable energy is projected to account for 38.3% of national electricity generation.  

However, China’s renewable power development has also been experiencing quite a few challenges. The most serious is renewable power curtailment, which indicates that a considerable proportion of installed renewable power capacity could not generate electricity accommodated by the power grid . According to China’s Renewable Energy Industries Association (CREIA), the average wind curtailment rate of the nation amounted to 15% in 2015. Moreover, in 2016, the situation continued to worsen. It incurred on average 17% of the installed wind power generation to discard across the nation, with curtailment rates reaching as high as 43% and 38% in wind power resource-abundant provinces like Gansu and Xinjiang, respectively. Within merely five years (2011–2015), China’s discarded wind power alone has amounted to 100 billion kWh, equivalent to the combined annual output of the Three Gorges Dam and Gezhouba Dam (two of the country’s top hydropower stations). High-rate curtailment of renewable power starts to impede the continued development of renewable energy sectors and regions, particularly in the areas customarily referred to as “Three Norths” - North, Northeast, and Northwest China, where the wind and solar resources appear affluent. The expansion to alarming levels of renewable power curtailment has drawn considerable attention to analyzing their causes and potential implications.

Given the scale of China’s renewable power sectors, reducing renewable power curtailment would not only accelerate the clean energy system transition in China but also exhibit essential ramifications for the global carbon emission trajectory. Furthermore, from a systematic and nexus perspective, high renewable power curtailment also entails a significant opportunity loss for reducing air pollution while saving critical resources, e.g., water. The water-energy-carbon nexus, as conventionally conceived, treats water, energy, and carbon emission being interlinked primarily in the process of power generation. The water resource is required in operations of power generation, including evaporation, cooling, and cleaning, which also primarily differentiates the fossil-fired thermal power generation from the renewable power generation. Meanwhile, burning fossil fuels in thermal power generation emits a tremendous amount of carbon dioxide. Compared with fossil-fired thermal power, renewable power generation utilizing wind and solar resources has a far lower intensity of water consumption and withdrawal as well as lower carbon emission factors. From the concept of water-energy-carbon nexus, such a large amount of renewable power curtailment not only wastes water resource but also hinders the realization of carbon emission reduction commitment and national environmental governance.

The reduction of renewable power curtailment could impose a remarkable influence on China’s renewable energy transformation. Such influence, however, is not of a unitary dimension; it requires a deepened, integrative assessment from multiple connected components of impact to derive associative causes and implications in a composite manner. Despite certain studies involved in examining the potential of renewable power development for carbon emission abatement, few have linked the curtailment effects with deprivation of potential savings on associated critical resources, e.g., water resource, and discussed the implications in an integrative way. Thus, based on such nexus philosophy, this paper, through discussing the series of causes and consequences of the renewable power curtailment in China, identifies the missing components and their possible implications of the curtailment. To disclose the effects of renewable power curtailment on climate and resource changes, the study analytically devises two experiments to assess the potential reductions in carbon emission and savings on water resource if a range of tentative curtailment reductions applies. The experiments manifest that reductions on the renewable energy curtailment would spawn notable reductions in carbon emissions as well as savings on water resource, given the fact that renewable energy, particularly wind and solar power, would require far less water use and emit no carbon emission in their generation than fossil-fired thermal power generation. The study demonstrates that the reduction of wind power curtailment would produce the most significant environmental benefits, followed by reductions in solar power and hydropower curtailments. The results highlight the urgency and significance of addressing the renewable power curtailment in China, which in turn requires synthetic introspection and rethinking on China’s power system transformation policy and its practices. Expected advancement in technical solution and market reform in China calls for enhancing the flexibility of the whole energy generation-trade system with increased, stabilized quotas for renewable energy production with coordinated action and planning. Alike, other countries are typical of confronting the pressure of accelerating the development of renewable energy by various policy incentives. During the transitioning process of replacing the traditional fossil-based energy with renewable energy, those countries could well have encountered the same curtailment problem more or less. Thus, our research on China’s experience and lessons on the renewable energy curtailment issue may well be able to offer a particularly valuable reference for the countries to make more appropriate renewable energy policies.

Thus, different from and additional to the previous reviews, the main purpose and intended contribution of this paper are to highlight the importance of the nexus perspective for comprehensively understanding and assessing the impacts of renewable curtailment as well as the potential co-benefits of reducing it. For this purpose, we first review the existing literature on the status quo and main causes of renewable curtailment (Section 2), so to set the context in which any policy insights derived from the paper need to be grounded. At the same time, we argue, based on the review, that the existing literature in general lacks a more comprehensive understanding and assessment of the broad impacts of the renewable power curtailment in China, in relation to climate, resources, and environment. We then focus the paper on how a broader nexus perspective is required to understand the full potential benefits of curbing and reducing growing renewable power curtailment (Sections 3 and 4), including an “illustrative” scenario analysis to highlight the climate (carbon emission) and water resource implications (co-benefits) for addressing the renewable curtailment challenge in China. As a result, the study offers insights to researchers and policymakers not only on the main characteristics of the renewable power curtailment challenges in China, but also for plausible methodologies to assess its full impacts.

该文章以“Review on Climate and Water Resource Implications of Reducing Renewable Power Curtailment in China: A Nexus Perspective”为题，发表在《Applied Energy》Volume 267, 1 June 2020, 115114