When it comes to energy storage solution for building’s HVAC, Ice-TES (or ITES) is the only one that has reached a commercial scale in recent years. However, Ice-TES tends to fall down from its peak dramatically. Why? Because people finds that it simply can not save energy!
Theoretically, just like anything, Ice is also a kind of Phase Change Material (PCM). Ice also adsorbs energy when melts from solid to liquid. It is a change of phase, just like BocaPCM does. However, in real practice, they have a prominent and significant difference that make PCM-TES an Ice-Tes alternative, that is:
their freezing points of temperature.
-5°C, the water in the TES tank will freeze into Ice pieces. We all know, theoretically, Ice freezes at 0°C. But in reality the water we used is not pure water. It freezes around -5°C or -6°C, depending on the pureness of the water. This means that you must have an ambient temperature as low as -5°C, or you need to spend a great deal of energy (and electricity bill money) to get down to this temperature to freeze the water. then it turns into Ice piece. Alike, chilled water, though cheap, is generally precluded from the medium for most of the effective energy storage applications nowadays.
8°C, the Phase Change Material encapsulated in panel inside the TES tank freezes into solid state and a large amount of latent energy will be released. Once it melts when you needed it to, an equal amount of energy will be absorbed from its immediate water environment thus produce coolness. This means that even the ambient temperature could be low enough to freeze the PCM. In Boca's case, the chilled water leaving from chillers at 6℃ is low enough to freeze the PCM. There is no need to spend extra energy to reach this temperature.
PCM-TES is technically 4 times more efficiency than Ice-TES, but share only 3% of TES market. Why?
One of the reasons is that the know-how of PCM is rather demanding and there are a lot of misunderstanding of the both.
Be careful, a TES system will be running for more than two decades.
So let’s us help you clarify the facts from this PCM vs Ice comparison so that you can make the right selection at the very beginning.
-5°C to -6°C, depending on the pureness of water and the type of machinery used for producing Ice.
8°C, or other temperatures, can be customized. Spend less or no extra energy to reach this tempearture.
TES Storing Capacity
Water-based TES, LOW.
From 2.5 - 4.1, LOW.
From 5 - 7, systemwise. Very HIGH.
Drawing or spraying water in the course of producing Ice will cause rusty steel freezing plates. Maintenance cost HIGH.
PCM encapsulated in HDPE panel, securely stacking up. No pollution and tidy. Maintenance cost VERY LOW.
Making of Ice
Hard to spray water evenly enough to control the quantity of Ice produced.
PCM filled in panel stacked up uniformly and the quantity of panels is fixed. Easy to calculate and control how much iced panels are in place.
Extra chilling load and pipe works are needed.
Common chillers are just fine. No extra chilling loading and pipe works.
Extra Water Treatment
Spray water to make ice. Great amount of extra water needed to be taken care of.
No extra water to be treated in the course.
Ice needs as low as -5C low-temperature Glycol chillers during charging, it can only be applied to new construction. Special design and facility for Ice making is not friendly to renovation project.
No Glycol chillers required.It can be applied to all existing & new buildings. Also applicable to common chiller plant design. Easy to incorporate into existing HVAC.
TES tank has to be large enough to accommodate the Ice pieces. Space requirement is harsh.
Relatively flexible tank size. Moreover, TES tank can be built indoor or outdoor, rooftop or domestic, surface mounted or buried.
Real time Operation
Ice-TES can shift on-peak chiller plant load to off-peak hours, but cannot manage the electricity demand peak in real time. The running and related facilities also made it difficult to apply to different operation modes.
PCM-TES can shift on-peak chiller plant load to off-peak hours & also optimize chiller from time to time. You can apply electricity demand peak management in real time. Design and operation modes are friendly to manipulate.
Initial investment is high and hard to recover, especially when electricity tariff is removed.
Really help save energy. Initial investment is 30% higher but could be paid back within 5 years.
Save electricity Money?
Claim to reduce 1/3 central air conditioning running cost only because of lower tariff rate during off-peak hours at night.
Reduce 2/3 central air conditioning running cost because of lower tariff rate during off-peak and most importantly, higher efficiency all the time.
Consume 100% more electricity during charging at night due to very low freezing temperature at -5℃.
Consume 40 - 60%+ less electricity for all the running time.
Save the environment?
Hardly ever! It has nothing to do with energy saving.
Sure! Help reduce a significant amount of CO2 emission.
TES definitely contributes to energy saving. The question is you have to eye for the real deal. Ice-TES, widely used for a decade, has been proved to be barely a real energy saving solution. Down through to here, you must have noted all the necessary facts about Ice-TES and PCM-TES for a wise decision. Just go for the real deal.