Ice can be utilised as energy storage (like a battery) to balance the energy grid. In instances where chilled water is used throughout the building provided by chillers, ice is formed when the chillers setpoint temperatures are changed to 0/-5 degrees Celsius as opposed to the nominal of 12/7 degrees Celsius during night/off-peak hours (Off-peak is usually between 23:00 and 07:00) where Eskom tariffs are low.
Ice is built up during these off-peak hours and are stored in dedicated ice thermal tanks and are melted during the day peak demand. This in effect reduces energy during peak demand (Eskom tariff is higher during peak demand than off-peak demand and is measured in R/kWh).
As per National Energy Regulator of South Africa (NERSA) it has been noted that the Eskom tariffs would increase by 9.61% during the interval of 2022/2023:
| 2021/2022 | 2022/2023 | |
| Price (R/kWh) | R1.34/ kWh (municipal rate) | R1.47/ kWh (municipal rate) |
| Percentage Price Increase | 15.06% | 9.61% |
Load Shedding Solution!
Ice Storage serves to continue cooling the building during the South African energy crisis where “load shedding” is implemented.
Design Criteria
Factors to consider when designing an ice storage system combined with a chiller plant:
- Application (Type of building requirements: HVAC, Process or District cooling)
- Method of ice melt (External or Internal)
- Operation strategies (Electric cost and rate schedules, full or partial storage, system modes of operation and conventional chiller operation)
- System sizing (Design day performance of cooling peak load calculations)
- Schematic flow diagram and system control strategy (Control philosophy and type of controls to be used)
- Type of Storage Containers/Tanks (Materials of construction, insulation, waterproofing and coil spacing and physical dimensions)
- Water quality and types of Glycol
- Commissioning and maintenance
For more information on thermal storage or a site visit contact us on info@sfigroup.co.za
Thermal ice storage is a proven technology that reduces chiller size and shifts energy from peak hours; when energy costs are high, to off-peak hours; where energy is less in demand and more cost effective. Imagine saving 8 hours of energy per day as the ice melts to cool; think about the energy savings per year!
