This study contrasts Chilled Water and Solid Ice Storage with EnergiVault, a hybrid solution securing the benefits of both systems whilst eliminating their performance limitations.
Cooling Flexibility
EnergiVault versus competing storage options
Feature | EnergiVault | Traditional Ice Tanks | Ice Bricks |
|---|---|---|---|
Energy density | High (slurry PCM) | Low | Medium |
Response speed | Instant | Slow | Moderate |
Footprint | Compact / modular | Large tanks | Modular |
Degradation | None | None | None |
Controls | Advanced optimisation-ready | Basic | Limited |
Use cases | Peak shaving, backup, optimisation | Load shifting | Load shifting |
- Poor discharge capacity - Low energy flexibility - Poor responsiveness to sudden cooling demand - Inefficient charging
- Poor temperature control - Low energy density - > 8x volume and higher footprint
- High capital cost - Limited lifecycles - Degradation over time - Low real turnaround efficiency - High-capacity connection - Storage without connected generation (Fault - Level) contribution; can add more generation instead
- Easy Integration with renewables to reduce energy and Co2 - High peak cooling versus input power - Ultrafast response to cooling demand - No lifetime degradation - >20- year lifetime - Highly scalable - Low footprint
Facilities managers and HVAC engineers are constantly searching for ways of reducing energy costs and carbon emissions through load shifting, load levelling and integration with on-site renewables.
A commonly used solution is chilled water storage, less common is solid ice storage.
Both these “cool storage” approaches can provide energy cost savings, reduce peak time non commodity costs such as transmission and distribution charges, provide peak cooling capacity and optimise on-site renewable generation, all in addition to back-up cooling for added resilience.
Traditional chilled water buffer tanks have been the industry standard for decades, but the physical and financial costs are becoming increasingly difficult to justify. A typical 220,000-litre insulated tank requires massive civil engineering works, including deep concrete foundations and extensive site preparation that can dominate valuable space. Beyond the construction disruption, these systems often come with high thermal losses and significant hidden fluid costs.
When attached directly to water chiller systems, these tanks require a mixture of water, 30% propylene glycol, and various chemical additives to prevent corrosion and bacterial growth. At current bulk prices, the glycol and chemicals for a single large tank can exceed £100,000. This is a substantial capital outlay that EnergiVault eliminates entirely. It simplifies the system design by removing the need for complex fluid management and expensive long-term chemical maintenance.
The EnergiVault thermal battery provides a far more efficient alternative by dramatically shrinking the physical footprint. It reduces the area required for a standard 220,000-litre tank down to a compact 6m x 2.2m space. While earlier phase change material technologies suffered from slow discharge rates, EnergiVault delivers an immediate response with peak discharge rates up to 1MW per battery cell. This allows it to match or exceed the performance of traditional buffer tanks in a fraction of the space.
For facility managers and specifiers, this represents a significant shift in cooling strategy. The installed cost is typically 40% lower than equivalent chilled water storage, and because the system is a removable, relocatable asset rather than a fixed concrete monument, it avoids the headaches of planning permissions and major civil works. It arrives complete with integrated charging and seamless BMS integration, offering a modular and sustainable solution that remains fully compatible with pressurised systems.
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Conventional CTES
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EnergiVault®
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Slow, low-power discharge
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Rapid, high-power cooling on demand
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Best for long-duration load shifting
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Built for peak shaving & fast response
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Limited role in resilience
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Supports N+1 and short-duration backup cooling
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Often oversized to meet peaks
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Reduces chiller and electrical oversizing
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Passive storage
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Active, controllable cooling asset
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Not just storage. Performance cooling.