Is power or water best for cooling?
Cundall · Andrew Livesey
Cundall's Andrew Livesey compares direct and indirect evaporative air cooling, chiller-based liquid cooling and sea or river water cooling on the electricity-versus-water trade-off and argues that location decides the answer.
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Overview
The piece is a 2024 blog article by Andrew Livesey, a critical-systems partner at Cundall. It compares direct and indirect evaporative air cooling, chiller-based liquid cooling and sea or river water cooling on the trade-off between electricity and water. The author describes the cooling approaches. Indirect air systems separate hall air from a scavenger air stream; spraying water on the heat exchanger boosts capacity, and compressors are usually only needed in hot climates. Chiller-based liquid cooling raises PUE but can suit sites where water is scarce or the grid is clean.
His central argument is that location decides the answer. California's drought favours electrically driven cooling on a cleaner grid, while Poland has water but a fossil-heavy grid. The piece critiques PUE and WUE when used alone: WUE does not count water used in electricity generation and varies too much by climate for cross-site comparison. CUE is suggested as a more complete measure.
For waste heat, a Danish hyperscale project with Fjernvarme Fyn is used as an example: heat pumps lift to 70-75 C, with 165,000 MWh a year of heat expected at full build-out. The conclusion is that reference designs must be adapted to local climate, water and grid carbon; one-size-fits-all leads to inefficient, costly, late projects. Limit: it is a short expert opinion.
Key points
- Indirect air systems separate hall air from a scavenger air stream; spraying water on the heat exchanger boosts capacity, and compressors are usually only needed in hot climates.
- Chiller-based liquid cooling raises PUE but can suit sites where water is scarce or the grid is clean.
- WUE does not count water used in electricity generation and varies too much by climate for cross-site comparison.
- Danish hyperscale project with Fjernvarme Fyn: heat pumps lift to 70-75 C, expected 165,000 MWh/yr of heat at full build-out.
- Conclusion: reference designs must be adapted to local climate, water and grid carbon; one-size-fits-all leads to inefficient, costly, late projects.
- CUE is suggested as a more complete measure than PUE or WUE alone.
Using it in design
- When a user selects a cooling topology, show a three-way comparison of energy (PUE), water (WUE) and carbon (CUE using local grid intensity) for the chosen site.
- Warn when a reference design is reused in a different climate or water-stress zone without re-running this comparison.
- Consider the possibility of exporting waste heat in site selection (heat pumps to 70-75 C).
- Do not use WUE alone for cross-site benchmarking.
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Who should read it
Designers and sustainability consultants deciding cooling topology and site.
Related standards
- ISO/IEC 30134-2 (PUE)
- ISO/IEC 30134-8 (CUE)
- ISO/IEC 30134-9 (WUE)
Publication details
- Authors
- Andrew Livesey
- Publisher
- Cundall
- Year
- 2024
- Document language
- English
- Source type
- Expert / community
- Access
- Free to read
- Licence
- Copyright retained; citation only — the publisher’s terms apply to the original document
Citation
Andrew Livesey (2024). Is power or water best for cooling?. Cundall. https://www.cundall.com/ideas/blog/power-vs-water-whats-best-for-cooling
Events on this subject
Browse the events calendarAll content and rights belong to the respective authors and publishers. SoSo CAD provides only the citation, its own summary and a link to the source, and is not responsible for the sources' content.
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