New paradigms

Energy for artificial intelligence: Google relies on nuclear power for zero emissions

With an agreement with the Tennessee Valley Authority, the Mountain View giant secures power for its data centres thanks to 'Hermes 2', the first fourth-generation reactor authorised by the NRC, which will come into operation in 2030

20 August 2025

4' min read

Google raises the bar in the energy race for artificial intelligence (AI). The Mountain View giant announced an agreement with the Tennessee Valley Authority (TVA) to purchase electricity from "Hermes 2", an advanced nuclear reactor developed by Californian start-up Kairos Power. The plant will be built in Oak Ridge, Tennessee, one of the symbolic locations of the 'Manhattan Project' - the secret US World War II programme that, between 1942 and 1945, led to the development of the first atomic bombs, which were later dropped on the Japanese cities Hiroshima and Nagasaki - and which is now bidding to become the centre of America's nuclear renaissance. Commissioning is scheduled for 2030 and the plant will provide about 50 megawatts of power, destined in part to power Google's data centres in Tennessee and Alabama.

Big G is certainly not the first technology company to take an interest in the sector. For instance, Sam Altman, co-founder and CEO of OpenAI, through Oklo - of which he is chairman - has already started a path to build modular mini-reactors. Oklo, however, is a private start-up and there is not yet a PPA (power purchase agreement) operational with a large utility like the one signed by Google. Or think of Microsoft, which is investing in advanced nuclear power, especially in contracts to power data centres, but has so far focused more on projects in the development phase, without announcing such concrete partnerships on fourth-generation reactors. Or even toAmazon Web Services (AWS), which has invested heavily in renewables and hydrogen research but has not (yet) exposed itself directly on nuclear power. In short, Google is not the first to have thought about advanced nuclear power, but it is certainly the first digital giant to put down on paper a concrete agreement with utilities and start-ups for a new generation plant.

The choice of the Californian multinational is no coincidence: the expansion of artificial intelligence and cloud services has caused the electricity consumption of large technology companies to explode as they seek stable, CO2-free sources to meet their climate targets. Renewable energies remain crucial, but alone are not enough to guarantee 24-hour continuity. Nuclear power, despite the controversies and difficulties of the past, is therefore back at the centre of the energy strategy.

'Hermes 2', in particular, represents a quantum leap from the old systems. Instead of using water as a coolant, the reactor uses fluorinated molten salts, a technology known by the acronym FHR (Fluoride-salt-cooled High-temperature Reactor). This allows operation at much lower pressure because molten salts have a much higher boiling point than water. Translate this into lower accident risks and simpler and less expensive containment structures than conventional large reactors, which often take decades and colossal investments to complete.

The Oak Ridge project is also a test case for a new financing and management model. In the United States, in fact, the construction of new power plants has been almost at a standstill for years: the last two completed reactors, the Vogtle reactor in Georgia, have accumulated delays of seven years and costs over USD 18 billion more than expected. With 'Hermes 2' a different approach is being tested: Google and Kairos Power will assume the financial risks of the first plant, while TVA will guarantee the purchase of the energy produced. In this way, the costs and uncertainties will not fall on citizen-consumers.

For Google, the stakes are very high. The company has pledged to use carbon-free energy around the clock by 2030, but its emissions have risen again in recent years precisely because of the exponential increase in data centres and AI. Hermes 2 is the first step in a larger collaboration that aims to install up to 500 megawatts of new nuclear capacity by 2035. For comparison, today the 94 reactors in operation in the US provide a total of 97,000 megawatts and cover just 20 per cent of the nation's electricity needs.

Of course, there is no shortage of doubts. The energy certificates that Google will receive from the project will serve as proof of clean energy use, but several studies have warned that the environmental benefits of these instruments are often overestimated. Furthermore, "Hermes 2" will have to pass the regulatory process of the Nuclear Regulatory Commission, which has already authorised the construction but will also have to issue the operating licence. Finally, the question of costs remains: neither TVA nor Kairos have revealed the price per megawatt-hour of the electricity produced.

The fact remains that the deal marks an important step change. Large technology companies no longer limit themselves to buying clean energy on the market, but become protagonists in the development of new infrastructures, pushing with their own capital the adoption of technologies that utilities alone would perhaps not dare to experiment with. In other words, AI and the digital transition are also reshaping the future of energy.

If 'Hermes 2' keeps to schedule and proves to work, Oak Ridge will once again be, eighty years after the 'Manhattan Project', one of the decisive laboratories in American nuclear history. If, on the other hand, it were to stumble with costs, delays or safety problems, it would risk dashing the industry's hopes of a renaissance.