Supercharging More Electric Cars Risks Crashing the Grid—Here’s What Might Help

By Sabine Bergmann

Tesla claims to be the fastest on the planet, but BMW touts that it can go from 0 to 80 in less than half an hour. The electric car makers aren’t bragging about miles per hour—they’re touting percent battery charge.

The race for fast-charging stations is on: Tesla has more than 100 of these supercharger stations in North America. Both Oregon and Washington have invested in direct-current fast chargers (such as BMW’s) every 25 to 50 miles along their “West Coast Electric Highway,” one of the largest continuous networks of fast chargers on the continent. And thus technology has begun to clear a great hurdle to adopting the electric vehicle—the inconvenience of long charge times.

Factor in new legislation—such as California Gov. Jerry Brown’s Zero-Emission Vehicle Action Plan, an executive order designed to boost the state’s number of fully electric vehicles from a few hundred thousand to 1.5 million by 2025—and we can expect a new wave of electric vehicles to dart in within the decade, if not sooner.

There’s just one problem: Our electrical grids might not be ready.

A su­per­char­ging Tesla com­ing on­line would “feel” to the grid as if 120 houses came on­line for half an hour—like an en­tire neigh­bor­hood pop­ping up in the middle of a city.

The average California household uses energy at a rate of less than 1 kilowatt* (amounting to 19 kilowatt hours per day, according to the U.S. Energy Information Association). BMW’s new direct-current supercharger charges at a rate of 24 kilowatts, which seems like a lot until you realize that BMW’s charger is small potatoes compared to most DC fast chargers, which hover around 50 kilowatts. And Tesla? Tesla’s superchargers come in at a whopping 120 kilowatts.

Supercharged vehicles haven’t used more energy to charge—they’ve just used it faster. When it comes to the grid, that’s a huge difference, because timing is everything.

Scott Moura is an assistant professor in civil and environmental engineering at UC Berkeley, and a proponent of “smart cities”: urban centers that coordinate among their infrastructures. Traditionally, Moura says, cities’ electric and transportation grids remain separate, but with the advent of electric vehicles, the networks are “colliding.” The collision couldn’t be clearer than Moura’s example of a supercharging Tesla coming online, which he says would “feel” to the grid as if 120 houses came online for only half an hour. “It’s like an entire neighborhood popping up in the middle of a city, and then disappearing,” he says.

Even when electric-vehicle owners charge their cars at a much slower rate of 6 or 7 kilowatts per hour overnight, that can still be a problem. The demand for energy is spiking each evening just as electric vehicles typically roll in to charge, and just when the source of solar power is setting. If demand spikes too high in an EV-smitten zip code (cough, Silicon Valley), its transformers, built to handle modest residential loads, may blow out.

We’ve known what this might look like for a while now: In 2011, the Utilities Telecom Council trade group released a report highlighting the exponential rise in energy use that will come with the widespread adoption of electric vehicles. Gigaom, a blog dedicated to “humanizing technology,” followed up by painting a picture of “blown transformers (and) neighborhood blackouts” from mass electric-vehicle charging. The article noted that the electrical utility giant PG&E had flagged plug-in zealous Berkeley as a “hot spot” that may be vulnerable to grid overload.

This hardly means we shouldn’t give the green light to green cars, which do move us away from dependence on fossil fuels. But they also present a problem: If California is going to go for 1.5 million of them by 2025, we need to know what to expect, and crucially, where and when to expect it.

This is where Alexei Pozdnoukhov comes in. Pozdnoukhov, like Moura, works at Cal in smart cities research. He directs UC Berkeley’s Smart Cities Research Center, where a research initiative called the Smart Bay Project may provide us with the crucial information to prevent an electric-grid meltdown.Smart Cities Research Center tracking map

Here’s how it works: The Smart Bay model couples data about drivers (obtained mostly through tracking signals from their cell phones) and the transportation grid (using trackers such as highway detectors) to create a model of urban residents’ mobility.

So far, Smart Bay has collected more than a million data points, but Pozdnoukhov can choose how many to display on the model’s visual representation—a satellite image of the Bay Area and its transit systems. If he picks 50 data points, for instance, 50 green dots appear on the computer’s screen and scuttle around like fluorescent digital ants. It’s clear from the visual that if Pozdnoukhov’s team wanted to, they could track the daily patterns and behaviors for each ant. Each is, for the record, anonymous; but in the age of big data, concerns about potential privacy infringement are impossible to ignore. Pozdnoukhov says he’ll leave that conversation to experts in the social sciences.

Given the level of detail in the Smart Bay module, Pozdnoukhov’s team can estimate which areas are populated by residents likely to purchase electric vehicles and how those cars would be used. Such information can be a game-changer, a glimpse of what a world of electric cars would mean to the grid, as a recent collaboration of American, Chinese and Filipino researchers found through their study of taxi movements in Beijing.

Back in California, Pozdnoukhov and Moura have set their sights on modeling not just what could happen with the spread of electric vehicles, but what should happen: The professors hope to secure funding to explore how to better manage electric-grid demand by influencing the behavior of electric-car drivers. For example, giving those drivers financial incentives—such as offering them free parking and free charging hook-ups at BART stations—might lessen pressure on the grid.

Tesla is working to develop another possible solution: a 90-second battery swap. The company website shows a demo of model S Teslas trading drained batteries for fully charged replacements, a technology that the company hopes will give consumers the option to transfer the burden of charging back to the company. The company, in turn, could use that opportunity to charge batteries at times that are best for the grid, and even in locations where the grid is powered by more renewable sources.

But Moura expects widespread battery-swapping will take quite a while to clear the institutional hurdles. For now, he suggests, it’s probably best to think small—presumably at the level of fluorescent digital ants.

* Corrected from a previous version
Share this article:
Google+ Reddit

Comments

Most EV owners are going to start charging at 12, 1 am at night, not a spike in energy use at that time. From article: “The demand for energy is spiking each evening just as electric vehicles typically roll in to charge, and just when the source of solar power is setting.”
nice news. we also support EV.
Please correct your article so that you don’t use kilowatts per hour. A Watt, kilowatt megawatt or gigawatt is a rate of transfer of energy. Thus “The average California household uses energy at a rate of less than 1 kilowatt per hour (amounting to 19 kilowatt hours per day, according to the U.S. Energy Information Association)” should read “less than 1 kilowatt”. Megawatts per hour is a unit that has a narrow applicability, mostly for how fast a power supply can increase its ability to supply (hydro is fast, most others slower) or how fast demand can build up (end of a popular sports event).
What a pile of utter nonsense. Other commenters have already pointed out the, frankly, child-like misunderstanding of basic energy units which really sums up the entire article. A rapid charger - even a Tesla SC - is peanuts compared to some industrial machines’ power requirements. Not all of them are on all the time and switch in and out willy-nilly. Besides, Tesla has made it clear that it wants to provide a serious dollop of energy storage buffer associated with every SC installation as well as offset the power supplied by them by PV arrays close by. Whilst this may take time to happen it is a very laudable ambition and one which should be applauded not derided (and yes, I am a Tesla share-holder). Furthermore, the fact that (hopefully) one day when the government and utilities wake up they will be able to use all those plugged in EVs as a ginormous, distributed buffer to help prevent brown outs thereby actually improving the reliance of the grid and helping utilities save money by not having to build yet more power stations capable of coming on line rapidly (so-called V2G - vehicle to grid). Complete twaddle.
Actually quite the opposite, EVs benefit the grid. Overnight charging eliminates the need for peaker plants. These peaker plants are the big reason why we have most electric issues. The overnight offpeak demand will be balanced out with the peak demand removing the need for peaker plants and having stable energy consumption. An average commute is 37 miles, that can be charged in about 1 hour on a Level 2 charger. The utilities already have tested where they can control charge demand of EVs. So during the 8-10 hour night the utilities easily juggle the demand and have all the cars recharged to full over night. As for superchargers, that is what the 500kwh - 1mwh battery is for.
Well written article that explains the intricacies of EV travel in the US. It will be interesting to see if Tesla can outsmart conventional grid use and be beneficial.
The flawed idea that EVs pose a threat to grid integrity has been written about and beaten already. I know several Directors and VPs in Electricity utilities and they state quite plainly that if all wheeled transport switched to electric it would suppose an increase of less than 20% of total consumption. Add to that that most of us EV drivers take full advantage of cheap night time power, as others have pointed out, and it is clear that rather than causing a problem we provide a solution (to the night time over supply that currently exists due to being unable to stop most coal and nuclear sources at night). I find it hard to see why you would write such an ill-informed and poorly researched article Sabine. Your background from what I can see in Linked in would suggest you would have taken more care to check your facts and science, and review previous articles prior to publication. Better luck next time. Mark
As others have mentioned, this is a non-issue. We’d be lucky to have EV adoption at a rate which threatened the stability of the electrical grid. The hypothetical placement of EV charging at BART stations is particularly delightful as there are already chargers from the first wave of EV adoption which are located in Walnut Creek: https://plus.google.com/u/0/108161928669055573248/posts/BfLPsA4CUre
No one has addressed the issue of the fact that the batteries will be an ecological nightmare and EV drivers are not paying toward road maintenance and building as those costs are in the gas taxes.
When? In thirty years when they have come to the end of there second life repourpoosing period, or after they have been entirely recycled due to the valuable nature of their internal components? We already pay an alternative vehicles tax in Washington state. Please come back to the forum only after you have actually paid attention and learned the nature of the topic at hand.
Allow me to, then. There is no ‘ecological nightmare’ associated with modern EV batteries as they are classified as capable of being disposed of as landfill. The same can, of course, *not* be said for fossil fuels (no, really!). Besides which, why would you want to throw away the aluminium and copper they contain when they could be so easily recycled? And that’s after the battery has been re-purposed for 10 years or more after it stops being useful for EV use? Non issue. As for taxing, yes, there is an issue here. But it would be extremely easy to get around and in some states of the US it already is by having a separate tax on EVs - hardly rocket science! MW
Why do EVs pay less tax? In order to encourage people to do the right thing and stop polluting. Obviously, as soon as they become mainstream they will pay as much tax as everyone. With some luck this will happen sooner rather than later. Bobbie, If you would also like to pay less tax then buy an EV. Its that simple.
No, Chicken Little, the sky is not falling. Actually, Tesla has in the works a plan to allow utilities to modulate the load placed on the grid through control of individual cars, much as they currently can modulate the use of AC during high load periods using devices placed on individual homes. This is done on a voluntary basis and with the goal of minimal inconvenience to any specific user. This capability will be worth some consideration on the part of the utilities, expressed as a credit on billings for customers who allow this practice, which would reduce the cost of the power consumed, and make the grid more efficient by leveling the load that it carries. That’s been a featured benefit of electric vehicles from day one, and it is amazing that folks still haven’t understood it properly.

Add new comment