October 2009
Q: Is thermal storage right for you?
A: A time-tested heating technology known as electric thermal storage (ETS) and its air conditioning equivalent, called thermal energy storage, actually can save you money and provide comfort, according to research conducted by the Cooperative Research Network (CRN). By storing energy at night and using it during the day, these devices shift electricity use from periods of high demand (mid-afternoon to early evening) to periods of low demand (middle of the night to early morning).
ETS is a type of room heater that warms ceramic material in an insulated cabinet and has been around for 25 years. Stored heat continues to be released even after power to the appliance gets switched off.
Residential ETS models can be used as a primary heating system or as a supplement to reduce the burden on or expand central heating sources. Stand-alone ETS units are quick and easy to put in and are ideal for areas of the house that need additional heat, such as basement family rooms or bathrooms. Costs are significantly higher than portable heaters, ranging in price from $1,100 to $2,000. (Central heating systems generally average between $3,000 and $5,000.) But when used in conjunction with central heat, you can save money in the long run.
For example, a household that has both an air-source heat pump and an ETS heating system can see savings of $300 or more per year. At that rate an ETS unit will pay for itself in approximately four years. Maintenance costs are typically less than that of conventional systems because there are fewer moving parts.
On the cooling side, thermal energy storage systems produce cold water, ice or an icy slurry at night, when electricity costs less to generate. The frosty material gets stored before being used to cool circulated air the next day. These systems, sometimes called “ice harvesters,” are often used by large office buildings.
Look out for similar-sounding technologies that don’t deliver. Consumer Reports magazine recently tested a device that requires the use of a frozen gel pack. Consumers freeze the pack and slip it into a portable cooler. Although it seemingly operates like thermal energy storage, the publication found the gel pack did not effectively cool a room.
Rely on sound advice from your electric cooperative or a trusted and licensed installer when shopping for any heating or cooling system. If a system sounds too good to be true, or if the price is significantly lower than similar products, be cautious before you buy.
The Cooperative Research Network (CRN) arm of the National Rural Electric Cooperative Association monitors, evaluates and applies technologies that help electric co-ops control costs, improve productivity and enhance member service. This material was prepared by Brian Sloboda, a CRN program manager who specializes in energy efficiency.
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