Beyond the Smart Grid: Utilities Will Still Need Electric Storage

Despite assurances that the smart grid will helpthe U.S. ease into the renewable energy era, experts said recently thatelectronic intelligence by itself won't solve one of the energy industry's mostpressing problems: What will we do when the wind's not blowing?

That simple problem- largely ignored amidst a rising flurry of corporate and government activitysurrounding the smart grid - can still only be solved by old-fashioned energystorage techniques, experts say. Such techniques include "pumped hydro,"compressed air energy storage (CAES), and mammoth battery farms, in addition tothe smart grid.

"While the need forpumped hydro and compressed air may be less if you have a substantial smartgrid, you're still going to need storage," says Haresh Kamath, a projectmanager for the Electric Power Research InstituteInc. (EPRI). "The storage will be closer to the customers, butyou'll still need batteries and flywheels and all the balancing resources."

Renewables Dilemma
Energy industry engineers believe that little has beensaid about energy storage because it has been overshadowed by attention to thesmart grid. The global market for smart-grid software is expected to triple inthe next five years, with such corporate giants as Cisco Systems Inc., GeneralElectric Co., IBM Corp. and Siemens AG helping to boost sales of the technologyfrom $4.5 to $16 billion annually.

The flood of smart gridparticipants is largely connected to growing mandates for use of renewables.Such states as California and Colorado are looking to have renewables make up30 percent of their energy. The European Union is moving aggressively, callingfor 20 percent renewables by 2020, while Great Britain is shooting for 30percent, despite the fact that it got just 1.4 percent of its energy fromrenewables in 2005.

The problem with using suchhigh percentages of renewables, however, is that their contribution can quicklydrop off to zero when the wind isn't blowing and the sun's not shining. Becausepower plants can't store gigawatts-hours of energy for days on end, utilitiesneed so-called "balancing resources" - that is, sources of energy to pick upthe slack when the wind's not blowing.

That's where the smart gridcould help. In its most basic form, the smart grid could provide pre-arranged
"demand management," enabling utilities to turn off certain loads at times ofpeak demand.

"Instead of having yourwater heater turn on at six o'clock at night, when demand is high, it couldturn on at midnight, when demand is lower," says George Crabtree, seniorscientist and Distinguished Fellow in Argonne NationalLab.'s Materials Science Div. "The idea is to move things around a little to help take the peak off the demand."

Engineers say the smartgrid will also help utilities by providing data in real time, sometimes fromthe simplest and most obvious sources. Electric meters, for example, will beable to communicate with utilities, "telling" them what's happening in aparticular area at a certain instance in time.

"The whole idea of thesmart grid is to have more control over what happens on the load side," Kamathsays.

Still, experts say it's notclear that the smart grid's capabilities will be able to compensate when 20 to30 percent of the country's power is suddenly lost because the wind fails toblow.

Energy Storage Solution
For that reason, most experts believe the U.S. will need sources of electrical storage when the country's ratio of renewable power reaches between 10 and 20 percent.

Though seldom discussed, the idea of storage has been around fordecades. Utilities have long used "pumped hydro," for example, in which poweris employed to pump water up a hill in off-peak hours. Technically, pumpedhydro is considered viable because it allows utilities to employ the potentialenergy of the pumped water (as it flows back downhill) to spin a generator andcreate electricity at times of peak demand. Similarly, utilities have proposed the use of compressed air energystorage (CAES) in caverns below ground, and have begun building giant batteryfarms in which energy from wind and solar can be stored for later use. InAlaska, for example, the Golden Valley Electrical Assn.now uses a 27 MW battery farm as a back-up to its electrical grid. Morerecently, a concept called vehicle-to-grid, in which parked electric cars send energy from their batteries back to the grid, has also gained favor in certain sectors.

The bottom line, say experts, is that the U.S. can't employ anenergy diet of 20 to 30 percent renewables and expect the smart grid to pick upall the slack on cloudy, windless days. To make it happen, they say, thenation's electrical system will need to add storage in conjunction with thesmart grid, and will also need a more effective system of transmitting powerfrom region to region. In the meantime, experts say the need for storage isgoing to grow in conjunction with the increase in renewable forms of energy."It's not unusual to have a whole day with no wind," Crabtree says. "You canhandle today's percentage of renewable energy with little or no storage. But ifwe're going to a 20 percent or 30 percent penetration of renewable energy, wewon't be able to do that anymore."

For more information:
Electric Power Research Institute Inc.
Argonne National Lab.
Golden Valley Electrical Assn.

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