Since most power plants cannot be “turned down” at night to compensate for lower energy demand the energy they generate is wasted in off-peak hours and extra strain is put on the system during peak daylight hours, especially when it’s hot outside and people clamor for air conditioning.
There are a lot of ideas to deal with this problem, my personal favorite being to use plug-in hybrid cars to absorb low-rate electricity at night, then give back their energy during the day. Other schemes have involved using nighttime energy to pump water in reverse into reservoirs so that it can be used again the next day as hydro power.
One new idea, championed by a California company, Ice Energy, is to offer a device that makes ice overnight, then uses it to augment air conditioning during the day. Here’s how it works:
Their product is called the “Ice Bear” and basically it runs all night long making ice when it’s cool outside and electricity is cheap and more plentiful. Then, during the day, the ice is used as a chiller in conjunction with the existing AC to cool the building off. Apparently it ends up being vastly more efficient. Seems pretty smart to me!