Google's electricity use rose 37% in one year. Where did it go?

The numbers

Google's 2026 environmental report, covering 2025, records electricity consumption of about 43 TWh, a 37% increase on 2024 and roughly 3.5 times the 2019 figure. The previous year's increase had been 27%. Spread over the year, 43 TWh is about 4.9 gigawatts of continuous draw, in the same range as the output of four or five large nuclear reactors, or the consumption of around four million American homes.

The efficiency paradox

In the same company, in the same period, the energy of a median Gemini prompt fell 33× and its carbon 44×, according to the inference paper Google published in August 2025. Better chips (TPU generations), better serving software, batching and smaller models did the work. If prompts had stayed at their 2024 cost, the volume Google serves today would need far more than 43 TWh.

The paradox is only apparent. Efficiency lowers the price of a prompt; a lower price means more prompts, more features that use them (search summaries, assistants in every product) and more training runs to make the next model. Jevons would recognise it. Google's chief sustainability officer put it plainly in the report: the AI build-out is outpacing grid decarbonisation.

What held the carbon line

Google matched 100% of its electricity with renewable purchases for the ninth year and kept its hourly carbon-free share roughly flat at about two thirds, which is harder than it sounds when consumption jumps by a third. The company signed a record 12 GW of clean-energy agreements in 2025 and says its footprint would have been five times larger without its contracts and efficiency work since 2018.

Operational emissions, Scope 1 and market-based Scope 2, fell 2%. Total emissions still rose 18%, because the chips and the buildings came with their own footprint: Scope 3 rose 25%.

Water followed electricity

Freshwater consumption rose 34% to 10.9 billion gallons, more than double the 2021 level, with data centres responsible for most of the increase. Google's fleet relies on evaporative cooling at about 1.15 litres per kilowatt-hour, so more kilowatt-hours mean more water almost arithmetically. Replenishment projects returned about 78% of it.

The index's view

Google holds the highest transparency score in the index and the best per-prompt disclosure. It ranks second rather than first because the carbon and water pillars score the direction of travel, and the direction is up. The profile shows both: a 90 for efficiency, a 60 for carbon, and the trend figure that explains the gap.