Buildings, a.k.a. energy storage devices

Automating demand response systems can help grid operators give renewable energy more, well, utility.

When it comes to operating a large commercial building, energy efficiency tools and strategies are nowhere near as sexy as solar panels or wind turbines, but their costs are generally lower and the pay-back is generally faster. More importantly, smartly managing how and when a building draws energy from the electric grid can enable utility and power brokers to reduce the amount of non-renewable power that is generated in the first place.

A report from the Lawrence Berkeley National Laboratory's Environmental Energy Technologies Division (EETD) shows that automating demand response systems -- the means by which utility customers agree to reduce energy consumption during periods of peak load on the electrical grid -- can:

  • reduce the likelihood of blackouts,
  • lower power bills for customers,
  • boost buildings' energy efficiency,
  • and reduced greenhouse gas emissions.

It's hard for grid operators to rely on renewable energy sources because they are intermittent. Wind blows mostly at night, for instance, when power demand is lower than during the day. Battery storage systems are being developed to store renewable energy so that it doesn't go to waste and can be used to offset power that would otherwise come from, say, a coal-powered plant.

But this kind of battery technology is still nascent and very expensive, whereas demand response systems have been in development for decades, the article notes. Besides, buildings are, in a way, a different type of energy storage device, it says:

Thinking of buildings as energy storage devices is a key to understanding how demand response can be an active player in a Smart Grid system. Just as batteries store energy chemically, buildings (including refrigerated warehouses) store heat (or retain coolness) in their thermal mass.

The thermal mass can allow buildings to shed as much as 80 percent of their normal power demands for short periods of time. For example, researchers estimate that some buildings can lower HVAC-related electric demand by 60 percent for two-hour periods.

The effort to better understand power demands and balance peak energy loads with renewable energy isn't just a good practice. In California, at least, it's a mandate. State law requires that 33 percent of power come from renewable sources by the year 2020.

Image: Strupey/Flickr

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