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| Fig. 1: Can ice be efficiently used to create energy? (Source: Wikimedia Commons) |
Have you ever heard someone say that they are turning off their Air Conditioning unit in order to save electricity and, thus, save money? This is an ensuing issue in our society. The amount of energy to cool our homes and buildings is large and, consequently, it costs a lot to perform this action. Ice Energy, a company based in Santa Barbara, California, takes a different route to try and solve this problem. This enterprise aims to reduce the energy used by normal Air Conditioning units. It attaches to any normal AC unit then uses an ice charging system that stores electrical energy in the form of ice (over night) and utilizes this energy during the peak energy demand levels of the day. [1] But does it succeed in its overarching goal? Does this somewhat simple solution actually resolve these high costs? I will discuss both sides to these questions, but ultimately side with it not being a complete solution.
The ice energy system (called the Ice Bear) basically works off of a branch of physics called thermodynamics: where heat and temperature are used to create energy or work. The hotter an object is, the more energy it has because the atoms that make it up move faster. [2] The Ice Bear integrates into the already existing AC by adding a new ice evaporator coil into the unit. Ice Energy claims that their system works in two basic modes: ice charging and ice cooling. At night, the Ice Bear system goes into ice charging mode where it freezes 450 gallons of water in the tank and thus stores electrical energy in the form of ice. Then, as the daytime temperatures rise, the Ice Bear goes into ice cooling mode, where it takes over the AC unit by pushing ice cold refrigerant to the regular AC unit and through the Ice Bear installed coil. [3] This lasts at least six hours, and then the regular Air Conditioning begins again. This process repeats as night and day alternate.
The Ice Bear integrates into the already existing AC by adding a new ice evaporator coil into the unit. Ice Energy claims that their system works in two basic modes: ice charging and ice cooling. At night, the Ice Bear system goes into ice charging mode where it freezes 450 gallons of water in the tank and thus stores electrical energy in the form of ice. Then, as the daytime temperatures rise, the Ice Bear goes into ice cooling mode, where it takes over the AC unit by pushing ice cold refrigerant to the regular AC unit and through the Ice Bear installed coil. [3] This lasts at least six hours, and then the regular Air Conditioning begins again. This process repeats as night and day alternate.
The second law of thermodynamics says that
| Q' = Q + E |
| E > Q' (1 - Tin/Tout) |
where Tin and Tout are the inside/outside temperatures (respectively) in degrees Kelvin, Q is the amount of heat that you are pumping out, and E is the electrical energy required to do this. [2]
Now, in theory, Ice Energy's whole foundation says that, at night when Toutin equals the freezing point of water. The difference between this temperature and room temperature is GREATER than the night/day temperature difference in most places that use air conditioning. So the amount of electricity you use is actually greater in an ice bear system. Ice Energy claims to reduce the amount of energy used by AC units by 95%. [1] This is a bold declaration and by analyzing the thermodynamics equation, this statement is false. In theory, the whole foundation of ice energy should work. It should save energy and it should save money. But when it is put to the test, its method simply does not work as easy as it may seem.
Overall, the idea sounds great to most. The system will just cool water over night, storing energy, and then use this to power AC units during the daytime when it is most needed. But this conclusion overlooks much of the physics that stand behind such a method. When you dig deeper into the equations and components that make up the whole process, you may find that Ice Energy does not work as perfectly as it may seem.
© David Wilczynski. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] I. Penn, "New Ways to Put Energy in the Bank," Los Angeles Times, 11 Oct 15.
[2] R. T. Balmer, Modern Engineering Thermodynamics (Academic Press, 2011), pp 651-56.
[3] B. Whitman et al., Refrigeration and Air Conditioning Technology, 7th Ed. (Delmar Cengage Learning, 2012).
