Prior to 2025, stagnation or falls in fossil generation only occurred in years with low or no electricity demand growth, such as in 2009 during the financial crisis or in 2020 during the Covid-19 pandemic. In contrast, 2025 is expected to see the sixth largest absolute increase in electricity demand ever at 831 TWh.

With growing clean power deployment, the link between demand growth and fossil generation growth has been steadily weakening. In the 2000s, most demand growth was met by increasing fossil generation, as well as rising nuclear and hydro output. In the mid 2010s, renewables, particularly wind, began to play a larger role in meeting new demand.

After the Covid-19 pandemic in 2020 and the demand rebound in 2021, fossil generation growth remained relatively low as solar deployment took off. Even in 2024, which saw very high demand growth, fossil generation grew only by a moderate 322 TWh (+1.8%).

This brings us to 2025. The record growth in solar and wind power, combined with moderate demand growth, looks set to avoid the need for an increase in fossil generation entirely.

Uncertainty in weather conditions for Q4 and incomplete data reporting for some countries mean it is yet unclear whether fossil generation will show a small increase or fall, but any change is likely to be minor.

Lower impact of heatwaves on demand in 2025

Temperature impacts on electricity demand were significantly lower in 2025 than in 2024, contributing to lower overall electricity demand growth. Hotter temperatures in 2024 (versus the 2015-2024 ten-year average) drove substantial increases in cooling-related electricity demand between June and September, particularly during summer heatwaves across the northern hemisphere in China, India and the US, as reported previously by Ember.

In contrast, 2025 temperatures tracked closer to the ten-year average. Only June and July saw substantial above-average temperature impacts on demand, driven by heatwaves in the US and China. India, the third-largest power sector, experienced notably milder conditions than in 2024, substantially reducing cooling demand. Globally, August and September 2025 saw much lower temperature impacts on electricity consumption.