The previous post looked at how data center waste heat can be used for district heating, fish farms, greenhouses and swimming pools. But while a data center gives off heat steadily all year, demand where the heat is used shifts with the time of day and the season.
When heat is spare at one time and needed at another, it can be stored and drawn on when needed, or the spare heat can be turned into cooling. This post looks at ways to store data center waste heat, with real examples.
The timing gap between data center heat and heat demand
A data center gives off heat steadily as long as its servers are running. Heat demand such as district heating, by contrast, shifts over the day and far more across the seasons. In summer, when no heating is needed, a data center also needs equipment to release its heat separately, which adds to the cost of its cooling system.
Ways to store data center waste heat
| Method | What it does | Example or study |
|---|---|---|
| Storing a few days’ heat | Holds spare heat and releases it when demand is high | Analysis by an Austrian team (2026) |
| Seasonal storage | Holds summer’s spare heat until winter | EU THUNDER project (demonstration under way) |
| Turning heat into cooling | Runs an adsorption chiller on spare heat to make chilled water | Leibniz Supercomputing Centre (LRZ), Germany |
Storing a few days’ heat
According to an analysis an Austrian team presented at the 2026 IEA Heat Pump Conference, adding storage that holds a day’s or a week’s worth of heat let the same recovery system supply far more heat, lowering the cost of heat. Long-term storage holding a month’s worth, on the other hand, was not economic under the study’s conditions.
Seasonal storage
Seasonal storage, which holds summer’s spare heat until winter, is still at the demonstration stage. The EU’s THUNDER project, running from 2024 to 2027, is developing seasonal storage of data center waste heat using thermochemical materials, to be validated at a demo site in Bulgaria.
Turning spare heat into cooling
An adsorption chiller makes chilled water from heat instead of electricity. It offers a way to use data center heat even in summer, when no heating is needed.
The Leibniz Supercomputing Centre (LRZ) in Germany ran six adsorption chillers on heat from its supercomputer. In 2016, an average of 120kW of waste heat at 45°C produced about 50kW of cooling at 21°C, and the system ran for nine years until December 2024.
The bottom line
Data center heat comes out steadily, but demand where it is used shifts with the time of day and the season. Storing a few days’ heat lets the same equipment supply more of it, and turning spare heat into cooling puts it to use even in summer. Storing heat is what lets data center waste heat be used in more places.
Research is also under way into using heat pumps to raise data center heat to temperatures suited to drying and industrial processes. GIGAette’s IsoTES® is a constant-temperature thermal storage system that charges from whichever heat source fits — waste heat, renewable electricity or grid power — and releases the stored heat at a steady temperature.
If you would like to work out when and where the heat from your facility could be used, request a technical meeting.
Sources
- Heat Reuse, Sustainable Data Centers Roadmap — Innovation for Cool Earth Forum (ICEF) (2025-10) — seasonality of district heating; in summer, when heating is not needed, data centers need separate heat rejection, raising cooling infrastructure costs
- Datacenters – Valuable heat providers for decarbonisation? — Meltzer et al., 15th IEA Heat Pump Conference (2026) — daily and seasonal variation in district heating demand, 1-day and 7-day storage lowers the levelised cost of heat, 30-day storage not economic in that setup, heat pumps can raise temperatures up to 130°C for district heating, drying and industry
- THUNDER (THermochemical storage Utilization eNabling Data centre seasonal Energy Recovery) — EU CORDIS — seasonal storage of data center waste heat based on thermochemical materials, 2024-01-01 to 2027-12-31, validation at a demo site in Bulgaria
- CoolMUC-2 — Leibniz Supercomputing Centre (LRZ) — six adsorption chillers, in 2016 an average of 120kW of waste heat at 45°C produced about 50kW of cooling at 21°C, shut down 2024-12-13 after nine years
- Cover image: AI-generated (colour-adjusted)