Key Takeaways
- China curtailed 360 TWh of wind and solar electricity in the first half of 2024 – a 49 % jump year‑on‑year, enough to power the United Kingdom or Mexico for more than a year.
- The waste stems from excess coal‑fired capacity, lagging transmission infrastructure, and market rules that guarantee coal generators a share of demand regardless of cheaper renewables.
- New coal additions (≈30 GW) far outpaced retirements, creating a system where clean power is switched off while coal generation rose 3.4 % YoY.
- Renewable-rich regions in the north and west cannot deliver output to industrial eastern hubs because transmission lines have not kept pace with the rapid build‑out of solar and wind farms.
- Similar curtailment trends are emerging in Australia, Japan, and India, highlighting a global mismatch between renewable generation and grid capability.
- Battery storage is repeatedly cited as the most effective remedy; co‑locating storage with solar plants can absorb midday surplus and release it when demand peaks, reducing the need to curtail.
- Policy signals remain mixed: the central government calls for tighter coal control, yet permit approvals have slowed while developers propose far more new coal projects than were approved.
- Without accelerated grid expansion, market reform, and storage deployment, China’s curtailment will continue to undermine its climate goals and waste vast amounts of low‑carbon electricity.
Introduction: The Scale of China’s Renewable Waste
In the first six months of 2024 China turned away 360 terawatt‑hours (TWh) of electricity generated by wind and solar farms – a volume sufficient to run the United Kingdom or Mexico for over a year. This figure represents a 49 % increase compared with the same period in 2023 and equals roughly half of the country’s total renewable output for the semester. Had that power been utilized, it could have covered the entire growth in Chinese electricity demand during the six‑month window and allowed coal‑fired generation to decline. Instead, coal output rose 3.4 % year‑on‑year, reversing a decade‑long downward trend. The phenomenon, known as curtailment, occurs when the grid cannot absorb electricity at the moment it is produced, forcing operators to shut down turbines or refuse the power outright.
What Is Curtailment and Why It Happens
Curtailment is the deliberate reduction of renewable output because the electrical network lacks the capacity to transport or store the instantaneous surplus. Electricity cannot be stockpiled on a wire; if supply exceeds demand at any given second, the excess must be discarded or the generating assets must be switched off. In China’s case, the root causes are twofold: (1) an overabundance of inflexible coal‑fired plants that continue to receive guaranteed output, and (2) insufficient transmission lines to move power from the resource‑rich northwest and north to the high‑demand industrial east. When solar panels peak at midday or wind farms blow strong at night, the grid often has nowhere to send that energy, so it is curtailed.
Coal Overcapacity Driving the Problem
Despite official pledges to curb coal, China added 30 GW of new coal‑fired capacity in H1 2024 – the largest half‑year increase in a decade and 43 % more than the same period in 2023. Retirements amounted to only 2.7 GW, while another 25.4 GW began construction and a staggering 274 GW remain in the pipeline, equivalent to roughly 22 % of the existing coal fleet. Long‑term contracts guarantee coal generators a share of demand (typically 60‑70 % of the previous year’s output), securing them grid space even when cheaper solar or wind is available. This “capacity payment” mechanism ensures that coal plants stay economically viable despite running fewer hours, directly crowding out renewables and forcing their output to be wasted.
Transmission Bottlenecks: Moving Power Across China
China’s renewable boom has been concentrated in the expansive deserts and grasslands of the northwest (Inner Mongolia, Gansu, Xinjiang) and the north (Hebei, Shanxi), where wind speeds and solar irradiance are highest. Yet the country’s electricity consumption is centered in the eastern coastal megacities (Shanghai, Guangdong, Jiangsu). The transmission grid linking these zones has not kept pace: line‑building lags behind the rate at which solar and wind farms are commissioned. Consequently, even when renewable plants are operating at full capacity, the physical pathways to deliver that power to load centers are congested or nonexistent, prompting operators to curtail rather than risk overload. Analysts warn that without a major upgrade of high‑voltage direct‑current (HVDC) links and intra‑regional interconnectors, the bottleneck will persist throughout the decade.
Market Mechanisms Locking In Coal Generation
Beyond physical constraints, China’s power market design reinforces coal’s dominance. Generators receive capacity payments for being available to produce electricity, irrespective of actual output, and they are often obliged to sign annual contracts covering a large fraction of their historical generation. These arrangements create a financial incentive to keep coal plants online, even when marginal costs of renewables are near zero. Researchers note that the market effectively “guarantees coal both capacity payments and significant electricity sales,” undermining price signals that would otherwise favor cheaper wind and solar. As a result, coal’s share of generation remains artificially high, and clean energy is routinely sidelined.
Policy Signals and Regulatory Response
In April 2024 the central government called for tighter control of coal capacity and generation, leading to a sharp slowdown in new approvals – only 8.6 GW sanctioned in the first half of the year. Yet developers simultaneously proposed 70 GW of new coal projects and revived a further 20 GW, a quarter more than in the same period of 2023. This disparity illustrates the mixed messages permeating China’s energy policy: while top‑level rhetoric emphasizes decarbonization, local administrations and state‑owned enterprises continue to pursue coal‑heavy projects backed by existing approvals and financial guarantees. The National Energy Administration’s curtailed‑output figures (8.6 % solar, 9.1 % wind) are widely regarded as underestimates; independent analyses using weather‑adjusted data put the curtailment rate at 26.1 %, highlighting a significant reporting gap.
Global Perspective: Curtailment Elsewhere
China is not isolated in facing renewable curtailment. Australia’s National Electricity Market discarded 2.93 TWh in H1 2024, up 37 % and equal to 7 % of its wind‑solar output. Japan’s grid rejected 2.35 TWh, a 34 % increase, while India curtailed 8.13 TWh in the quarter ending June, about 14 % of its solar production for that period. In each case, the common thread is a build‑out of renewables that has outstripped the development of transmission and storage infrastructure. The International Renewable Energy Agency reports that the world added a record 692 GW of renewable capacity in 2023, three‑quarters of which was solar, bringing global renewable capacity to 5,149 GW – roughly half of all installed generating capacity. Without parallel grid and storage growth, curtailment will remain a systemic obstacle to the energy transition.
The Role of Battery Storage as a Mitigation Tool
Energy storage, particularly lithium‑ion batteries, offers a direct way to absorb excess midday solar or nocturnal wind output and discharge it during peak demand periods, flattening the supply‑demand curve that triggers curtailment. Chile exemplifies this approach: in 2025 it added 4 GWh of battery capacity, more than doubling its installed storage, with most new units co‑located alongside solar farms. The result has been a measurable drop in curtailment rates. Bulgaria similarly paired storage with wind projects to capture surplus generation. Analysts from Ember and Wood Mackenzie stress that battery deployment is the most scalable short‑term solution, especially when combined with market reforms that allow storage to provide ancillary services (frequency regulation, peak shaving). In China, investors are already shifting toward solar‑plus‑storage projects after the removal of guaranteed feed‑in tariffs, recognizing that stored power can be sold at higher evening prices rather than wasted.
Implications for Climate Goals and Future Outlook
If curtailment continues at current rates, China’s ability to meet its pledged peak‑emissions target before 2030 and achieve carbon neutrality by 2060 will be severely compromised. Every terawatt‑hour of discarded renewable electricity represents a missed opportunity to displace coal‑fired generation, prolonging reliance on the most carbon‑intensive fuel source. To reverse the trend, three parallel actions are essential: (1) accelerate transmission expansion, especially HVDC corridors linking renewable‑rich interiors to eastern load centers; (2) reform market mechanisms to reduce guaranteed coal allocations and enable renewables to compete on price; and (3) scale up battery storage and other flexible resources (pumped hydro, demand response, green hydrogen) to absorb surplus generation. Without these steps, the world’s largest emitter will keep wasting vast quantities of clean power, undermining both its domestic air‑quality objectives and the global climate agenda.
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