The global clean energy transition can appear slower than it really is when viewed only through worldwide energy consumption. Rising populations, economic growth and increasing energy demand allow both fossil fuels and renewable energy to grow simultaneously. However, looking at individual markets reveals that substitution is already occurring as cleaner technologies begin replacing older energy systems.
Historian Jean-Baptiste Fressoz argues that energy sources historically accumulate rather than replace one another. Wood continued after coal emerged, coal remained after oil expanded, and fossil fuels continue to grow alongside renewables. While global primary-energy statistics support this view, they can hide major changes within specific industries and regions. Energy technologies compete to provide services such as transportation, heating and electricity rather than simply competing within one global energy total.
Europe provides a clear example. In 2025, wind and solar generated 30.1% of European Union electricity, compared with 29% from fossil fuels. A decade earlier, fossil generation was almost three times greater than wind and solar. This crossover demonstrates that the clean energy transition is increasingly about replacement rather than simply adding renewable capacity.
Transportation shows a similar pattern. Global sales of internal-combustion cars peaked in 2017 and had fallen by nearly one-third by 2024, while electric vehicle sales exceeded 17 million. Because vehicles remain on roads for many years, changes in new-car sales take much longer to transform the overall fleet and eventually reduce oil consumption.
By the end of 2025, approximately 58 million electric vehicles represented less than 4% of the global vehicle fleet, yet they were already displacing more than 2 million barrels of oil demand per day. Oil displacement from EVs could reach around 5 million barrels daily by 2030 and 9 million by 2035. This illustrates how the clean energy transition becomes visible first in sales, later in installed equipment and eventually in overall fossil-fuel demand.
Energy efficiency also makes traditional primary-energy statistics misleading. Electric motors are much more efficient than combustion engines, while heat pumps can provide several units of heat for every unit of electricity consumed. Electrification can therefore reduce total primary-energy requirements while delivering the same transportation, heating and other useful services.
However, evidence of substitution does not mean fossil fuels will disappear quickly. Aviation, shipping, steel, cement, petrochemicals and other difficult-to-decarbonize sectors will continue requiring substantial technological development and investment.
Ultimately, the clean energy transition reaches a critical point when clean-energy growth becomes greater than the increase in total energy-service demand. Wind and solar supplied around 20% of global electricity by 2025, while annual installations increased from roughly 300 GW in 2021 to 815 GW four years later.
The transition is therefore neither imaginary nor instantaneous. It is a gradual process in which new technologies capture sales and investment first, replace existing infrastructure later and eventually reduce fossil-fuel demand. Global totals may still appear additive, even while fundamental replacement is already occurring underneath.