Have Renewables Really Overtaken Coal?

October 30, 2025

Renewables edged ahead of coal in global electricity generation during the first half of 2025, says Ember. Yet that headline hides a crucial distinction between how much hardware is installed and how much power actually reaches the socket.

The Generation/Transmission Miss-match

In terms of installed vs utilised generation across the world there is now 4.7 TW of renewable capacity versus 2.3 TW of coal. But utilisation tells another story. Coal fleets ran at an average 53 % capacity factor in 2024; wind delivered about 37 % and solar barely 20 %. In pure production terms, every gigawatt of solar added needs roughly two‑and‑a‑half siblings to equal a typical coal unit’s annual output. The gap between potential and delivered green electricity is widening as grids struggle to absorb the surging, variable supply.

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Curtailment – Flushing Energy Down the Drain

Grid constraints bite and those struggles show up as curtailment. National Grid ESO paid a record £1.9 billion last winter to turn off wind farms during bottlenecks, with constraint volumes up 15 % year‑on‑year. China’s solar curtailment rate climbed to 6.6 % in early‑2025, wiping out almost 11 TWh of zero‑carbon power. Similar bottlenecks are emerging from Texas to Tamil Nadu.

Battery Storage as a buffer

BESS to the rescue grid‑scale battery energy storage systems (BESS) are expanding fast: 49.4 GW/136.5 GWh came online worldwide in the first nine months of 2025, a 36 % jump on 2024. London‑listed funds Gresham House and Harmony Energy are commissioning multi‑hour lithium plants that turn Scotland’s excess night time wind into English peak‑time supply, while Fluence’s modular blocks have become the go‑to ‘spinning reserve’ in Texas and Queensland.

Hydrogen Generation – Soaking up Free Energy

Where storage is impractical, local electrolysers soak up surplus electrons turning electricity into hydrogen. Europe will have 17.5 GW of annual electrolyser manufacturing capacity by year‑end and more than 60 green‑hydrogen projects are already under construction. RWE’s 300‑MW plant at Lingen will feed 30,000 tonnes of hydrogen a year to TotalEnergies’ Leuna refinery under a 15‑year offtake. This reduces fossil gas demand and providing a flexible sink for wind‑rich hours.

More Dynamic Generation Requires Smarter Systems

Hardware alone will not close the utilisation gap. Siemens Energy is investing €1.3 billion in HVDC converter and STATCOM plants to speed up interconnections and voltage control, while its grid‑management software now orchestrates 100 GW of variable renewables in Germany and Chile with sub‑second fidelity. In Britain, National Grid’s Constraint Management Intertrip Service pays batteries and flexible loads to react instantly when transmission lines saturate.

Outlook Whether renewables can stay ahead of coal depends less on the next tranche of turbines and panels and more on how quickly grids adopt storage, hydrogen and sophisticated control. Judging by the growth curves of BESS and electrolysers—and the billions now flowing into modern grid tech—the momentum is finally shifting from raw installation to effective utilisation.

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