Energy guzzlers of superlatives: A single new data center will soon require as much electricity as 20% of Zurich

Zurich is considered the undisputed digital model student of Europe. Gigantic data centers belonging to tech giants like Google, Microsoft, and Amazon are growing at a rapid pace in and around the Swiss metropolis. Fueled by political stability, a cool climate, and green energy, a veritable gold rush for data storage has ensued. But behind the gleaming high-tech facade, a massive, systemic problem is brewing: the insatiable energy demands of the server farms are pushing the local power infrastructure to its absolute limits.

Even today, these systems consume a significant portion of the city’s electricity demand – and with the advance of artificial intelligence, this demand is exploding. While grid expansion is barely keeping pace with this rapid development, and the transmission network often still relies on analog technology, the real danger of cascading effects and catastrophic power outages is growing. What was celebrated for years as an economic success story is increasingly revealing itself, upon closer inspection, as a highly dangerous “cluster risk.” The case of Zurich is far more than just a local phenomenon: it is a stark warning signal for major cities across Europe and dramatically illustrates why the unbridled enthusiasm for digitalization urgently needs to be reconciled with forward-looking energy and spatial planning before we literally run out of power.

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Zurich is considered one of Europe’s most important digital hubs. The combination of political stability, renewable energy sources, cool temperatures, a strong financial sector, and first-class telecommunications infrastructure has made the Swiss metropolis the preferred location for data centers of global hyperscalers. Google, Microsoft, and Amazon Web Services lease space from local colocation providers here. Switzerland boasts one of the highest densities of data centers per capita in Europe – over 120 server farms are already operational, and more than ten additional projects are planned for the next three years.

But what at first glance appears to be a success story turns out, upon closer inspection, to be a highly disguised, concentrated risk. The concentration of enormous electrical loads in a small area, the growing dependence of Zurich’s power grid on a single consumer category, and the structural limitations of the grid infrastructure have created a vulnerability that increases with every new permit. The euphoria surrounding digitalization and energy policy are diverging – with potentially far-reaching consequences.

The bare number and its meaning

The Zurich municipal electricity company, ewz, has documented the scale of the problem in a white paper: In the greater Zurich area, the electrical power consumption of data centers ranges from 118 to 190 megawatts – these are theoretical maximum capacities; actual utilization is generally lower. However, these figures are outdated, as they stem from earlier planning stages. Actual demand is growing rapidly.

For comparison: The total electricity consumption of the city of Zurich in 2024 was around 2,700 GWh per year, which corresponds to an average continuous load of approximately 308 megawatts. This means that the data centers in the greater Zurich area alone are approaching a load that, theoretically, amounts to between 38 and 62 percent of the average urban electricity load – and this share will continue to rise. To put it even more succinctly: ewz itself has pointed out in previous calculations that the 190-megawatt peak load of the data centers would correspond to a quarter of the total electricity consumption of the city of Zurich, with its more than 430,000 inhabitants.

The pace of this development is breathtaking. In Switzerland, the electricity consumption of data centers nearly doubled between 2019 and 2024 and currently accounts for around seven percent of total Swiss electricity consumption. A yet-to-be-published study by the Federal Office of Energy predicts that this share could rise to as much as 15 percent by 2030 – equivalent to the consumption of an entire nuclear power plant.

The power plants and their limits

The Zurich Cantonal Electricity Works (EKZ) are addressing the problem with unusual candor in their internal communications. With the increasing number of data centers, the challenges associated with grid operation have also risen considerably. Of the nine new substations planned or built since 2014, six were primarily constructed to meet the growing electricity demand of data centers. This represents a structural transformation of the grid infrastructure, driven primarily by a single consumer category.

Between 2009 and today, EKZ has connected six data centers to the Zurich power grid. Currently, eleven more data centers are under construction, in the planning stages, or have been requested. A planned data center in Volketswil is projected to have a connection capacity of 100 megawatts – this single location alone would account for 20 percent of the total electrical output of the city of Zurich. The implications for grid planning are clear: data centers are being prioritized as the primary drivers of demand for new substations – a redefinition of the city’s electricity infrastructure.

The capacity limit is no longer a theoretical question for the future. In Zurich, there is hardly any space left for new data centers – and electricity availability is even more limited, as the real estate services provider CBRE aptly describes. Some operators are already relocating to other cantons such as Aargau and Schaffhausen. But this only shifts the problem geographically; it doesn’t solve the underlying structural issue.

The network: A digital backbone on an analog foundation

A particularly worrying finding comes from within Zurich’s network control center itself. The more than 4,000 kilometers of power cables in the city of Zurich’s network are not digitized. When a power outage occurs in the medium- and low-voltage network, ewz (Zurich’s energy supplier) usually only knows the exact location of the fault when someone calls and reports it. In 2024, there were a total of 108 faults in Zurich’s power grid, 94 of which resulted in actual power outages for customers.

This fact takes on a whole new dimension in the context of data centers. A data center with a 100-megawatt connection is a critical load that requires a stable, redundant, and fast-responding network. If such a load fails or—more seriously—suddenly breaks down, it has an immediate impact on network stability. Conversely, a data center that loses power due to a network outage represents a critical infrastructure disruption for all services that rely on that location—from cloud services and financial applications to government IT systems.

ewz is investing in modernization: The new ControlStar control system from the Aachen-based provider Kisters enables advanced network security calculations, load flow analyses, and the integration of real-time data from the transmission system operator Swissgrid. This is an important step. However, digitizing a cable network spanning over 4,000 kilometers is a project spanning decades, while data centers are built in a fraction of that time.