💻 AI’s dirty little secret — “100% renewable” claims crumble under real-time fossil fuel reality

🕒 Last updated on August 13, 2025

Across the United States, old industrial sites are being given a new purpose. An aluminum research campus is now a modern data center, powered by natural gas from nearby fracking wells.

Old sites, new energy demands

A retired coal plant is being rebuilt into a huge gas-fired power station, capable of producing up to 4.5 gigawatts of electricity—enough to power dozens of large data facilities.

These transformations are happening because the demand for electricity from data centers is exploding. According to Global Energy Monitor, nearly one-fifth of all new gas power capacity planned in the US will be dedicated directly to data centers. This rapid growth is driven by the need to train and run artificial intelligence models, which require enormous amounts of computing power.

While these centers are essential for modern technology, their energy needs are stretching power grids that are still mostly dependent on fossil fuels. At the same time, major technology companies often claim their operations are “100% matched” with renewable energy. However, this can mean they buy clean energy credits from anywhere in the world to offset their consumption, rather than actually using renewable power in real time from the local grid.

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The Irish case: a data center capital under pressure

To understand the balance between rising data center electricity demand and renewable energy supply, one can look at Ireland—now a hub for large “hyperscale” cloud providers. In 2023, more than 20% of Ireland’s total electricity demand came from data centers. By 2026, the International Energy Agency expects that figure to rise to nearly a third.

Data from Ireland’s central statistics office shows that electricity use by data centers in 2024 was more than 4 terawatt hours higher than in 2019. Over the same period, renewable electricity generation—mostly from wind—has also grown, but only at about half the pace of data center demand.

Wind power is the backbone of Ireland’s renewable energy supply. However, output changes depending on the season and weather conditions. For example, 2020 was unusually windy, while 2021 saw below-average wind speeds. The other years from 2019 to 2024 had similar wind conditions. This means that on some days, the Irish grid is more than 75% powered by clean energy. But on other days, when the wind is low, the grid relies almost entirely on gas.

Hourly electricity consumption data from Ireland’s grid operator shows that gas remains the single largest source of power throughout the year, followed by wind. Electricity imports form another part of the mix, though their source—whether clean or fossil-fuel-based—is not always clear.

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When looking at the daily breakdown, the seasonal pattern becomes obvious. Winter and spring tend to have more wind and cleaner electricity. Summer days are slower in wind speed, which means more fossil fuels are used. This pattern affects the actual power feeding data centers at any given moment. Even if a company buys clean energy credits, the physical electrons powering its servers in Dublin might still come from a gas plant.

Renewable credits vs. real-time power

Many technology companies highlight their use of renewable energy by pointing to clean energy purchases and credits. These credits represent electricity generated from renewable sources somewhere in the world. They can be bought to “match” the amount of electricity a company uses, even if the renewable generation happens in a different country, at a different time of day, or in a different season.

For example, a company might buy enough wind energy credits from a farm in another part of Europe to cover its annual energy consumption in Ireland. On paper, it can claim to be running on 100% renewable power. In reality, on a still summer evening in Dublin, the servers may be running on electricity produced by gas-fired plants.

This gap between reported renewable use and actual grid mix shows why the term “green” AI is complicated. AI models require continuous and reliable power. Renewable sources like wind and solar vary by weather and time of day, which means fossil fuel plants are still used to fill the gaps.

Charts of Ireland’s 2024 electricity supply show daily fluctuations in clean energy share. There are days with long stretches of high renewable generation and others where fossil fuels dominate almost completely. This variability highlights the challenge of ensuring that AI data centers, which run 24/7, are always powered by renewables in practice.

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Data from Irish energy monitoring groups, compiled from grid operators, also shows how the balance shifts hour by hour. For instance, windy winter mornings might see 80% clean power, but the same day’s evening peak might drop to below 30% renewables.

Across the US and Europe, this same pattern repeats: energy-hungry AI is driving a wave of new gas-fired power projects, while renewable energy growth struggles to keep pace. Clean energy credits can offset emissions on paper, but the reality on the ground—or on the grid—often looks very different.