China's Renewable Megabases Still Send 42% Coal Power Through Key Grid Lines

Wind and solar account for around 20 percent of the electricity flowing through China's ultra-high voltage direct current transmission network, largely unchanged since 2021, while coal makes up 42 percent, according to a report published by Global Energy Monitor. The finding lands even as China builds more large-scale wind and solar capacity than the rest of the world combined, with 664 gigawatts of solar and 698 gigawatts of wind either planned or under construction as of June 2026, representing a third and a quarter of global capacity respectively. The report identifies inadequate transmission infrastructure as the central constraint limiting how much of that renewable capacity actually reaches consumers as clean power.

 

How China's Megabase Model Is Supposed to Work

 

China's energy megabases policy is built around a specific geographic logic: green power is generated in the sparsely populated north and northwest, where land is abundant and solar and wind resources are strong, and sent via ultra-high voltage direct current transmission lines to power the densely populated cities and factories of the east, where most electricity demand is concentrated. That model depends entirely on transmission capacity keeping pace with generation capacity, since renewable power generated in remote regions is worthless to distant population centres without the lines to carry it there.

The report finds that transmission buildout has not kept pace with the scale of generation being planned. Some 315 gigawatts of megabase capacity will require outbound transmission by 2030, a volume the report estimates would need 27 dedicated UHVDC lines, while China's current five-year plan for 2026 to 2030 targets only 10. That gap between required and planned transmission infrastructure means a substantial share of megabase renewable capacity risks remaining stranded, generating power that cannot reach the grid connections needed to deliver it to consumers, regardless of how much wind and solar capacity gets built.

 

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Why Coal Remains Embedded in the Transmission Mix

 

Among the 11 transmission lines currently proposed specifically for megabases, the combined capacity mix is 129 gigawatts of wind and solar against 40 gigawatts of coal, producing a projected electricity flow split almost evenly between renewables and coal. Report author Aiqun Yu, senior East Asia strategist for Global Energy Monitor, argued that proportion is difficult to reconcile with Chinese policymakers' stated framing of coal as playing only a supporting role in the country's power system, since a near 50-50 split in projected transmission volume suggests coal is functioning as a primary rather than a secondary component of these lines.

The mechanical reason coal remains embedded is straightforward: wind and solar are intermittent, generating power only when weather conditions allow, whereas transmission lines and the industrial and residential demand they serve require a continuous, reliable power supply. Without adequate storage or other backup mechanisms, grid planners have defaulted to pairing renewable capacity with coal generation to guarantee the line delivers consistent power regardless of weather, embedding fossil fuel capacity directly into infrastructure nominally built to expand renewable energy delivery.

 

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What a Different Design Could Look Like

 

Yu's recommendation is that renewable megabases should pair intermittent wind and solar with energy storage technologies rather than coal to provide that backup reliability, a solution that would allow the transmission lines to remain predominantly renewable rather than defaulting to fossil fuel capacity as the reliability backstop. The report points to one project already reflecting that alternative approach: a proposed UHVDC line from Inner Mongolia's Kubuqi region to Shanghai, where renewables make up more than 60 percent of planned transmission volume, backed by 9,000 megawatt-hours of energy storage and only 2.64 gigawatts of coal, notably lower than the roughly 4 gigawatts of coal capacity found in comparable projects.

Yu described that project as a small step forward, language that acknowledges meaningful progress in the ratio of storage to coal while stopping short of calling it a solved problem, an assessment consistent with the project's continued reliance on some coal capacity even as it demonstrates a materially higher renewable-to-fossil ratio than the sector norm. Whether the Kubuqi-Shanghai model becomes the template other proposed megabase transmission lines follow, or remains an outlier against a broader pattern still weighted toward coal-backed reliability, will be a key indicator of whether China's renewable buildout translates into proportionally lower fossil fuel dependence in its transmission system or continues expanding both renewable and coal capacity in parallel.