Nov 04 2009

Smart Grid: The View from PG&E

Posted by: Jonathan Marshall

They say all politics are local. So are many of the issues driving PG&E to invest in smarter grids, according to PG&E Senior Director Andrew Tang, who delivered a keynote address at today's GreenTechMedia conference on "The Networked Grid."

One of the major drivers behind PG&E's smart grid program is systemic: the need to manage and balance the large fluctuations in output from increasing amounts of solar and wind energy, as PG&E increases its reliance on renewable power.

But at least two other issues, which get much less attention, are intensely local.

One is the rapid but uneven rise in rooftop solar installations connected to PG&E's grid. Today PG&E has about 300 megawatts of customer solar capacity in its service area--almost 40 percent of the nation's total--and that figure is expected to hit about 1,000 MW by 2014.

But the distribution of customer solar installations within PG&E's network is "very lumpy and concentrated," Tang said. San Francisco has 1,520 connected to PG&E's grid; San Jose has 1,430 and Fresno has about 1,250. The median city in PG&E's service area has only 12.

Where rooftop solar is concentrated, grid management issues can arise. The passage of clouds overhead can lead to rapid changes in power output and voltage fluctuations. PG&E will need smart sensing devices to monitor such changes so they can be corrected--with flexible conventional generation, energy storage devices or demand response programs. The latter two are prime smart grid applications.

Another emerging issue is charging of electric vehicles. Tang said PG&E's service area could easily host half a million such vehicles by 2020.

An electric car that charges in four hours at 240 volts represents the same load as a full-sized house in San Ramon--or nearly three homes in San Francisco, where average residential power demand is much lower.

If large numbers of EV customers decide to plug in their cars when they get home from work, the result could be an unwelcome spike in system load in the late afternoon, requiring expensive new generation and distribution facilities.

That won't be a problem for some time in many parts of PG&E's service area. But in green-minded cities like Berkeley, where 18 percent of new vehicle registrations are already hybrids, electric vehicles could soon put a big strain on the local electric grid.

The answer, Tang said, will be a combination of smart meters and "smart charging" capabilities to deliver power to thirsty batteries only at night when other loads taper off.

"People have talked about home automation for two decades," Tang said. "We think some aspects of home automation are finally becoming feasible at reasonable price points. [PG&E's] role needs to be the enabler. Our SmartMeter(tm) has a home area network chip so you can know how much energy you are using right now and what the energy is costing you.

"We are also working on smart charging for EVs," he continued. "If we give people the technology to plug their car into the wall, knowing it will be charged by morning, it will be customer friendly." The key, he emphasized, will be educating customers about the benefits they soon will be able to enjoy from these smart grid programs.

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