Hitachi stores heat to ease the power demand of data-centre cooling

Hitachi Vantara reported on 27 October that two Duraflow cooling units are operating at its data centre in Zaltbommel, the Netherlands.[1]

A material that melts and resets

Duraflow’s explanation starts with salt hydrates sealed inside plastic panels. Melting absorbs heat while limiting the material’s temperature change; solidifying releases that heat again. The supplier uses this cycle to condition room air, with fans moving air through the system instead of compressors continuously doing the cooling work.[2]

Its general technical description places the material’s transition around 25°C. Cooler outdoor air at night lets the panels solidify, restoring their ability to absorb heat during warmer conditions. This connects the design to the available outdoor temperatures and the timing of the heat load. It also explains why a cooling-capacity rating and the duration of stored cooling answer different questions.[2]

Moving the work across the day

The broader engineering principle is established thermal storage. A US Department of Energy factsheet explains how storing cooling separates its preparation from the moment it is needed. A flatter electrical demand profile can reduce the peak that supporting equipment must accommodate. The same document identifies sites whose electricity service is already at capacity as a useful setting, because thermal storage can help avoid upgrades to transformers and switchgear.[3]

That changes the investment question. A facility may gain value from reducing the size of an electrical peak, as well as from using fewer units of electricity over a year. The DOE guidance treats electricity tariffs, demand charges and the site’s consumption profile as separate inputs to the economics. A lower peak and a lower annual bill are related benefits, but they are not the same calculation.[3]

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