Thermal Energy Storage (TES)
About
In line with Preload's tradition of designing and building reliable and maintenance-free prestressed concrete tanks, thermal energy storage (TES) tanks can serve as a vital component in highly efficient cooling systems. Preload’s insulated storage tanks provide universities, hospitals, and government facilities the capability to realize hundreds of thousands of dollars in savings on energy costs and increase sustainability and overall efficiency.
The TES Concept
Thermal energy, in the form of chilled water, is produced during periods of off-peak energy rates, and stored for use during high-demand /high-cost periods. Diffusers provide for turbulence-free flows, creating a sharp transition layer, or thermocline, thus allowing for the natural stratification of the warm water (top) and chilled water (bottom) layers within the tank. Warm and chilled water enters and exits through the top and bottom of the tank through an internal diffuser piping system.
How TES Is Used
One effective method for TES systems is a full charge and discharge cycle daily. BACKUP PROTECTION – In cases where heat sensitive/critical equipment are involved additional TES may be designed to maintain charge over longer periods of time and can discharge quickly.
Maintaining Stratification
An efficient diffuser system helps create stratification by distributing chilled water under laminar flow, and maintains stratification by prevent mixing, heat transfer, and energy loss. In addition to the insulating provided by the concrete wall, Preload TES tanks are equipped with an external system, engineered to protect the chilled storage and maintain stratification.
Preload designed and constructed octagon diffuser systems are recommended by ASHRAE/EPRI. This particular has been tested and performs 5-10% more efficiently than alternative systems.
Save On Energy Costs
Peak Power – As a means to encourage off-peak power usage, many utilities offer significantly reduced rates or surcharges during times of low electrical load.
Fewer Chillers– The ability to store chilled water means fewer chillers are required overall to meet the daily peak.
Chilling Cold – Chilling the water in the evening reduces ambient heat gain and energy loss.
Creating A Termocline
As water is chilled near 4°C it is at its most dense state, which ensures the chilled water will settle to the tank bottom until discharged.
Sustainability: Less Waste
Concrete is a highly sustainable material, with a smaller overall footprint than other alternatives. Also, the inherent thermal properties of concrete make it ideal for insulating chilled water.
Why Prestressed Concrete?
When prestressed, the compressive strength of concrete provides a structurally superior tank that may be partially or fully buried. This can have aesthetic value, increase usable land area, and save further by insulating naturally.