Europe's drought is causing the shutdown of nuclear reactors.

      Nuclear reactors rely on water, which is why they are located near rivers and coastlines. Water helps dissipate heat from the reactor core, and if the water supply decreases or becomes too warm, the reactor must shut down. This situation is currently unfolding across Europe. On Thursday, Romania's state-owned Nuclearelectrica began shutting down the country’s only operational reactor due to low water levels in the Danube.

      Romania had taken extensive measures to avert this shutdown, including dredging the river and deploying rock-filled barges. Additionally, on August 3, the navy conducted a controlled underwater explosion on the riverbed to direct more water towards the cooling system at Cernavoda, the nation’s sole nuclear facility, which typically generates about 20% of Romania’s electricity.

      The issue is recurring across the continent, albeit for different reasons. In Hungary, rainfall raised the Danube enough to restart a turbine at the Paks plant, which generates nearly half of the nation’s electricity. Prime Minister Péter Magyar reported on Monday that two out of eight turbines are now operational.

      France, which derives approximately 70% of its electricity from nuclear energy, announced on Wednesday that it had reduced output at several reactors for environmental reasons. Earlier that week, three reactors at Gravelines were completely shut down due to a surge of jellyfish, which prompted automatic safety shutdowns. This occurrence marks the second consecutive year that jellyfish swarms have forced reactors at Gravelines, one of France’s largest plants, to close.

      This summer, France has reportedly had to shut a record number of nuclear plants due to extreme heat, wildfires, and drought conditions. Politico noted that the jellyfish appeared on the same date for two consecutive years.

      The situation with the rivers mirrors the challenges faced by the reactors. The Danube, stretching about 2,850 km, serves as both a freight route and a coolant. Meanwhile, the Rhine’s water level is low enough that cargo ships must navigate around exposed riverbed areas near Kaub in Germany.

      In the UK, Prime Minister Andy Burnham convened the government’s Cobra emergency committee on Wednesday in response to the ongoing heat, wildfires, and drought. This marks the second Cobra meeting regarding heatwaves this year, as temperatures are projected to reach 38°C. Gareth Remond-King, who leads the international program at the Energy and Climate Intelligence Unit, noted that taking action now may be overdue. He emphasized that the current situation is part of a broader trend, indicating that this summer is indicative of worsening conditions if emissions continue to rise.

      Governments are considering improvements to cooling systems and scheduling maintenance during the hottest periods. While both actions are prudent, they do not change the fundamental issue that water availability is the limiting factor.

      The measures taken in Romania highlight the urgency of the situation. Dredging, the deployment of sunken barges, and controlled detonations reflect the actions of a nation facing immediate rather than long-term challenges, and these measures will need to be repeated whenever water levels drop again.

      According to an analysis published by Dutch bank Triodos on August 8, the economic cost of this summer's heat in the EU is estimated at €180 billion, equivalent to roughly 1% of the region's GDP. This figure warrants reflection, especially since forecasts predict the EU will see approximately 1% growth this year, suggesting that the heat could negate expected gains.

      Triodos attributes these costs mainly to reduced labor productivity, along with diminished harvests, increased food prices, constrained energy generation, higher electricity rates, and transportation disruptions.

      This situation is crucial for those developing AI infrastructure in Europe. Energy availability often does not connect with such developments. Data centers require substantial amounts of stable power and cooling water, both of which have become increasingly unreliable in areas where computing resources are being established. This week, Nebius announced it would lease capacity in South Wales, pledging around £1.7 billion across four UK locations.

      Others are also advancing in this area. Germany’s Uniper is investing €5 billion in data centers, while the UK is preparing to float Nscale at $51 billion for contracted computing capacity that has yet to be delivered.

      To clarify, data centers did not cause this summer's outages; the supply issues and the rising demand are separate but intersecting. This development is significant: Cernavoda’s two reactors provide about 20% of Romania’s electricity, while Nebius plans to add over a gigawatt of new capacity annually starting in 2027.

      The industry has already recognized associated risks. For example, Amazon is constructing a Texas data center equipped with its own gas plant to remain independent of the grid. Over 500 jurisdictions in the US now place restrictions or bans on new data centers.

      The challenge of water availability continues to emerge as a recurring theme, often treated as a localized issue. Google's $15 billion project in India faced opposition due to water and wildlife concerns, while Vantage