This is Important: What Would 1 Million Electric Cars do to the Grid?

tesla model s plugged in electric car photo

Photo: Michael Graham Richard
Well, it Depends... Not All Megawatts Are Created Equal
Power grid operators are looking at the coming wave of plug-in vehicles and trying to figure out what it will mean for them. A group of U.S. and Canadian companies just released a study titled Assessment of Plug-in Electric Vehicle Integration with ISO/RTO Systems (ISO = Independent Service Operator, RTO = Regional Transmission Organization) that looked into what would happen if 1 million plug-in vehicles were added to the grid in North-America. The findings are interesting.
mercedes plug in electric car photo

Photo: Michael Graham Richard
The study makes some assumptions. For example, it is expected that most of the initial plug-in electric vehicles (PEV) will be sold in urban areas, most on the US West Coast and Northeast. That probably a fair assumption... The study also assumes that out of the first million PEVs, 68.4% would be located in regions served by ISO/RTO providers (since the study was funded by them, they only look at the impact on their neck of the woods).

It's All About Timing
How much power this would require depends heavily on how charging is managed. If all the vehicles recharged their batteries at the same time, the study calculates a load of 3,785 megawatts (that's about 3-4 big power plants), but if the charging was staggered in time over a period of 8 hours, that would be reduced to 819 megawatts, and if you do the same over a period of 12 hours, you're left with only 546 extra megawatts.

That's nothing! One medium-sized power plant could provide that, and if it's during the night, you won't even have to build a new power plant since there's more than enough extra capacity off peak. Just gasoline refineries probably use a large fraction of that power, if not more (they use lots of electricity), so a move away from gasoline could be partly compensated. Other studies have shown that the grid absorbed pretty well all the big flat screen TVs that Americans bought in recent years (and those are mostly turned on during peak demand, not off peak like EVs).

"Plasma TVs, industry officials say, consume about four times the electricity as recharging a plug-in hybrid. Yet utilities have managed to cope with the increased loads as thousands of new televisions came on line." (source)

Smart Charging
Getting PEVs not to all charge at the same time is a challenge, but it's not the hardest thing we have to do. A smart grid that can communicate with PEVs could tell them when to charge within a time window pre-programmed by the car's owner (f.ex. "I need my car to be charged by 8 AM on weekday mornings"). On night when the wind blows and there's lots of extra power, more cars might charge simultaneously to take advantage of that. When the wind doesn't blow, the load will be spread move evenly over the off-peak period.

See also: Plug-in Hybrids Might not Need New Power Plants
Plasma TVs Draw More Juice from Grid than Plug-In Vehicles

Via Autoblog Green, Earth2Tech
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