Engineers are utilizing underground rock formations as thermal storage to manage heat generated by data centers. The process involves pumping excess heat into the ground during summer months and extracting it for building heating during winter, leveraging the earth's natural ability to retain temperature.
Epic Systems in Wisconsin has implemented this technology across its 40-building campus. The company drilled approximately 6,100 wells at depths ranging from 90 to 240 meters to support a 3.5 MW data center. This integrated system reduces the campus's total energy consumption by 25% compared to similar local facilities.
The system operates by circulating water heated to 60 °C by data center cooling systems into the rock mass. In winter, this water is retrieved to provide heating for offices and public spaces, and even for snow-melting systems on sidewalks. Similar projects in the Netherlands and Germany demonstrate the viability of this approach for large complexes.
Scaling this solution requires careful management of thermal capacity, as rock formations can reach saturation limits. To mitigate this, Epic Systems expanded its drilling area. Experts suggest that repurposing over 141,000 abandoned mining wells in the US could significantly lower implementation costs for future projects.
Data centers currently account for 4.7% of total electricity consumption in the US, with projections estimating an increase to 12% by 2030. Given that cooling systems consume up to 40% of a data center's energy, finding efficient ways to reuse waste heat is becoming a critical priority for the industry.
