THURSDAY 19 NOVEMBER, 2009 |
Ice Battery - Renewable Energy Storage
During 2009, we've reported on all sorts of possible alternatives to traditional
for renewable energy storage - such as the lithium
, the Beltway
, the cavern
and even a virus
Introducing another possibility - the ice battery - and it's already on the
Air conditioning during the summer can be the largest single contributor to a
building's energy cost. A hybrid cooling system from Calmac
uses an ice bank thermal energy storage tank to make and store ice for use in
air conditioning systems when the wind isn't blowing or the sun isn't shining -
such as after dark.
For buildings without on-site renewable
power generation, the ice can be made at night during off-peak times
when electricity rates are cheaper and when cleaner baseload generation is used.
In this scenario, Calmac says their system can reduce cooling costs by up to 40
According to Calmac, for every kilowatt-hour of energy that is shifted from
on-peak usage to off-peak, there is a reduction in the source fuel needed to
generate it - between 8 and 30%.
The IceBank tanks are made of heavily insulated polyethylene and contain a
spiral-wound, polyethylene-tube heat exchanger surrounded with water. The tanks
are available in a variety of sizes ranging from 45 to over 500 ton-hours.
During the charging cycle, a solution containing 25 percent ethylene or
propylene glycol is cooled by a chiller and then circulated through the heat
exchanger inside the IceBank tank. The ethylene-based or propylene-based glycol
recommended for the solution is an industrial coolant that is specially
formulated for low viscosity and superior heat-transfer properties.
The ice is built uniformly throughout the tank during the charging process and a
full charging cycle of an IceBank tank requires approximately 6 to 12 hours,
which makes it viable to be used in conjunction with a solar
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