One of the long-standing concerns over electric cars is just how much demand the electricity grid would have to cope with should millions of people start plugging in every night.

California will be a good test-bed for such concerns, with as many as 350,000 electric cars expected on the state's roads by 2020.

That's according to Southern California Edison (SCE)'s white paper, "Charged Up" (pdf document), via KCET. The utility currently has around 12,000 electric car drivers using its services, so 2020's figure will mean a real surge in demand--the sort of surge some utilities are a little worried about.

The Charged Up white paper outlines SCE's efforts to prepare for such an eventuality--and it may not be as negative as some previous reports have made out.

Customer habits helping transition

While SCE notes that the average electric car draws the same sort of power as the whole of the rest of a house combined, widespread use of regular 120V "Level 1" charging is resulting in far lower impact than some studies have predicted.

Around a half of SCE's existing electric car-driving customers use Level 1 charging as opposed to higher-voltage Level 2 installed chargers. If that proportion continues, grid load won't be quite as high as expected and the transition towards greater numbers of electric cars will put less strain on the grid.

Electric car owners are also doing SCE a favor by making best use of "end charge time" functions. Rather than plugging in and using up juice when they return from work, many users with programmable charging options are setting their cars to finish by a certain time instead--30 minutes before work the next morning, for example.

This spreads load on the grid, as each electric car charges at a different time depending on the battery's charge level. Short commutes help with this--electric cars are rarely charged from completely empty.

Constant upgrades

Even so, changes have to be made--and SCE has identified parts of the grid that need updating to cope with higher voltage demand. Several hundred thousand power distribution poles will need replacing or upgrading and other parts of the service will need improving too.

To its credit, this is already happening--SCE says it already sizes its transformers for the proliferation of high-power plasma TVs which have appeared over the last decade or so. And most existing changes are simply routine improvements--less than one percent of recent improvements has been directly attributable to plug-in cars.

There are other concerns too, which still need to be considered. Many modern electric cars are coming with higher-capability on-board chargers, which increases demand.

Electric car adoption could happen quicker than the utility estimates too, as will any change in the status quo regarding multi-unit residents: those in condos and apartments potentially interested in electric vehicles, but holding off as their building or complex doesn't have suitable charging provisions.

The positive thing to take from all this though is that major utilities are thinking long and hard about the demands of electric vehicles--and ensuring that as EV adoption increases, so too will the grid's ability to handle all those extra people plugging in.


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