TES is designed to take advantage of cheaper energy rates during off-peak hours, which is typically at night. During that time, chilled water is collected and stored in a thermal energy storage tank. Then, during peak rate times, the cooler water is integrated into the cooling system to provide greater efficiency and reduce overall costs.

Warm and chilled water enters and exits the tank through diffusers located at the top and bottom of the tank. These diffusers provide a stable, clearly-defined transition layer, or “thermocline” that keeps warm water at the top of the tank and chilled water at the bottom.

At the end of a distribution phase, the tank will contain mostly warm water. To “recharge” or cool the water, warm water exits through the top diffuser where it is sent to the cooling plant. It is then cycled back into the tank as chilled water through the bottom diffuser where it is ready to be used by the cooling system.


When you think of energy storage systems, you may think of the battery in your iPhone or the water heater in your basement. But Thermal Energy Storage (TES Tanks) solutions aren’t just for heating anymore. Today’s systems can also efficiently cool your home or commercial space through large, chilled water storage tanks.


Although the concept of stratified chilled water Thermal Energy Storage might be new to you, it’s been used successfully in thousands of applications and cooling systems over the past thirty years. Thermal Energy Storage tanks are specially insulated to prevent heat gain and are used as reservoirs in chilled water district cooling systems.

The secret to these cooling solutions is the special internal “diffuser” system that allows chilled water to be stored in two separate compartments so it can be charged and discharged simultaneously, depending on need.


Chilled Water Cooling Systems

Almost any chilled water district cooling system can benefit from a Thermal Energy Storage tank. Some common applications include:

  • Commercial buildings and industrial facilities
  • Data centers
  • Government buildings and facilities
  • Military bases and airports
  • College campuses
  • Natural Gas Power Plants

Turbine Inlet Cooling Systems

Turbine inlet cooling systems work by cooling of the inlet air to the compressor of a gas turbine system. The result is raised combustion turbine output in hot weather. For example, cooling turbine inlet air to 59°F increases output capacity by anywhere from 15% to 30% as compared to the same output at 100°F. A TES tank allows the electric generator to maximize power during the peak period by minimizing the parasitic load of chiller equipment.

Cold air is denser than warm air, and using colder, denser air at the inlet gives the gas turbine a substantial production boost. This cool air is especially effective when used with the compressor of a gas turbine system during hot weather – exactly when most peaking power generating turbines are brought online.

When ambient temperatures rise above 59° F inlet cooling provides the following benefits for a combustion turbine:

  • Increased Power Output
  • Increased Fuel Efficiency
  • Increased Steam Output in Co-Generation Systems

Mission-Critical Systems

  • Data processing centers
  • Military Bases
  • Homeland Security facilities
  • Hospitals
  • Technology-based companies

All have very demanding, mission-critical cooling requirements. Their equipment emits a lot of heat, which requires constant cooling, 24/7 – even during power outages or brownouts. That means not only having substantial backup power services, but also a reservoir of chilled water which can be utilized to protect their systems. The reservoir of chilled water in the TES tank provides immediate source cooling during planned and unplanned downtime of central plant equipment.


  • Reducing your yearly energy and operational costs
  • Preventing downtime of mission-critical operations
  • Deferring capital expenditures on equipment replacement of expansion projects
  • Improving efficiency and power output of natural gas electrical power generators
  • Providing a negotiating advantage in deregulated markets


The Pacific Tank team has a long and proud history of designing and building exceptional, TES systems that save our clients millions of dollars in life-cycle costs.

Reduced Electrical Demand Costs – By operating the chiller plant only during off-peak periods, we can help you reduce your on-peak electricity demands by as much as 40%. This eliminates your power demands during the most expensive hours, enabling you to dramatically reduce your annual costs without ever compromising performance.

Reduced Cost of Consumption – Our TES tanks allow you to take advantage of changing power rates. You’ll consume more electricity when rates are low, and less when rates are high.  They can also help mitigate the risk associated with “real-time pricing” where you might have as little as an hour’s notice of a substantial electrical power price increase. In a deregulated market, having a Pacifica Tank installation gives you more leverage when negotiating a favorable rate structure with your electricity supplier.

Reduced Power ConsumptionWith thermal energy storage, chiller operation is shifted to evening hours when ambient temperatures are lower. As a result, the chiller systems operate more efficiently and consume less energy for a given cooling load.

Cash Incentives for TES Installations – Because thermal storage helps postpone or avoid construction of expensive new generating stations, some electric utilities offer substantial cash incentives or rebates to companies installing thermal storage systems. These incentives are usually based on the amount of kilowatt demand that will be shifted from on-peak to off-peak.

Reduced Construction & Operating Costs – In both new construction and facility expansion projects, a thermal storage tank can be substituted for some or all of the chiller plant equipment. In this way, you can reduce both current capital outlays and future operating costs, yielding significant energy cost savings for years to come.

Facilities Expansion & Projects – A TES tank is an easy and economical way to increase the cooling capacity of your chilled water system, allowing you to defer or eliminate the need for new chiller equipment. And since the TES tank has no moving parts, you can leverage the excess off-peak cooling capacity of your existing chiller(s) without adding more components requiring maintenance to your system. The result is significant energy cost reductions because the peak load electric demand (due to chiller use) remains unchanged, even after your expansion project is complete.

New Construction Projects – Similar cost savings can be enjoyed in new construction projects. In some cases, the capital costs of a TES tank can be entirely offset by the reduction in capital costs for a smaller chiller system and its associated components.



Pacific Tank’s engineers are experts in 100% Recyclable welded steel storage tanks. Over the years, the team has provided customers with decades of continuous, day-to-day service and cost savings. All Pacific Tank projects conform to AWWA (American Water Works AssociationStandard D100, or API-650.

Welded Steel Thermal Energy Tanks have been proven to provide a reliable leak free and essentially maintenance free service when properly maintained as attested in thousands of tanks across this country and around the world.


Steel construction creates 100% all recyclable materials structure. Steel is 100% recyclable and can be recycled an infinite amount of times, saving energy and raw materials each time it is reprocessed.


TES tanks can be designed and built to the exact cooling requirements of each project in sizes from 50,000 gallons to 10 million gallons.


Thermal efficiency is the net cooling available for distribution after chilled water has been stored in the thermal energy storage tank. 

All of our TES diffusers are designed for maximum efficiency and no maintenance. Our diffusers are constructed of tried and proven coated steel piping and our slotted pipe design assures laminar flow of the water that preserves of the key “thermocline” layer that resides between the warm and cold layers of water. All support or fastening accessories are stainless steel, to assure no maintenance will be required.

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