Thermal energy storage systems

[NB34]

TES systems and TES systemswith Cold air distribution. Why is this not mainstream in large single entity owned (not leased) buildings? If this could be implemented in buildings the peak electrical load as seen by the power plant could be reduced drastically, thus reducing power plant capacity? FPL (southwest florida power company) has offered great incentives for these types of systems, but they still are not as common place as they should be. I would like to hear peoples comments on these types of systems.

[US Iceman]

Most of the thermal storage projects have been done with chillers using either glycol to build ice or a chiller to store a large quantity of chilled water in huge tanks. There is not that many people who do large custom built ice storage systems like we might see in industrial refrigeration.

It's not impossible though.

You need to have a very good estimate of the load profiles to make sure the energy stored is sufficient to meet the cooling loads.

A retrofit may not be cost effective, but a new project could be if the power company is willing to underwrite part of the construction or equipment costs.

[Sridhar1312]

Dear US Iceman
Nowadays TES with combination of centrifugal water chillers and air cooled brine chillers along with CALMAC ICE TANKS or CRITOPIA ICE NODULES are quite popular and being used to shift the power usage to night when the quality of power is good.
Once dual tariff is made available TES will be more attractive, right now there is no dual tariff in INDIA.
It is always better to go for TES for 40% of Load as it will be more relaible.
Yes Retrofit may not be effective as introducing secondary refrigearnt (brine) for ICE forming will be costly and space required will be more.

[US Iceman]

...combination of centrifugal water chillers and air cooled brine chillers along with CALMAC ICE TANKS or CRITOPIA ICE NODULES are quite popular...


These are some of the methods I was describing i my earlier reply. I agree these seem to be the most popular methods. I think the reason for this is; more engineers are familiar with chillers, which can easily be de-rated for use with glycols fluids. The piping is relatively easy and follows the same principles as hydronic piping for chilled waters systems.

All of the engineering is in the piping, AHU's and duct work, and load profiles for shifting the energy use to Off-Peak (typically lower power costs at night).

In a traditional TES someone has to design the refrigeration system in addition to the refrigerant piping and equipment selections. This can be a quite involved process which many people are NOT familiar with. This is further compounded by the fact that these types of refrigeration systems do NOT have a performance stand that applies to their capacity or related power use. A factory packaged chiller will have this, so this removes a layer of doubt on the actual performace received from a factory chiller, instead of a field-erected refrigeration system.

[Scramjetman]

NB34, with different types of systems, there are trade-offs - benefits and penalties. One of the key penalties with TES is the area or footprint that it occupies. Ice tanks, chilled water storage tanks, ice harvester catch tanks etc all occupy floor space whether above ground or below ground and the costs of making the floor space available can be high.

Developers usually aren't interested in running costs (that's an issue for the owner who often hasn't bought the building until it is finished and offered for sale) although the balance is starting to change as more economic pressure is being brought to bear to create green buildings, and so it's all about productive floor area and construction cost. TES systems struggle to compete with this.

Usually it falls to Universities, Schools and other government institutions that have plenty of spare room on their property, or who have long term ownership plans, who go for TES systems.

The current private sector is driven by the bottom line and until enough legislative pressure is brought to bear or construction costs of these systems fall low enough, TES will be ignored in deference to conventional energy-hungry, low footprint systems.