What Does Mass Adoption of Electric Vehicles Mean for the Grid?

The adoption of plug-in vehicles, both gasoline-electric hybrids as well as full battery electric vehicles, continues to gain pace. At the end of August this year, 59,000 such vehicles had been sold in the USA, surpassing sales of plug-in vehicles for the whole of 2012. This trend will likely continue as manufacturers increasingly roll out new product offerings.

Next year, VW will launch an electric version of the Golf, Mercedes will offer U.S. buyers an electric version of their European B-Class, while BMW will launch the i3, the first of their electric-drive "i" sub-branded vehicles.

Legitimately, the increasing sales volume of electric vehicles has raised concerns regarding the ability of the nation's utilities to manage the additional load they will bring to bear on the grid. But the Texas-based, Pecan Street Research Institute has been studying the impact of EVs in the most electric vehicle-dense residential area in the country, and has discovered some comforting findings which suggest EVs won't crash the grid after all.

The institute's trial was conducted in an Austin, Texas neighborhood which has a concentration in excess of 50 electric vehicles in a half square mile, and analyzed over 2,500 vehicle charging events between June 1st and August 31st this year; a notable period since it coincides with hot summer months when peak electricity demand results from households running their air conditioners.

The concern at the outset of the trial was that EV drivers would come home from work and plug in en masse during the 3pm - 7pm peak hour period, coinciding with when the grid is already burdened with the additional load from all those AC units.

What they found, however, was only 22 percent of weekday EV charging occurred during those peak demand hours, and better still, those participants in the study who were taking advantage of time-of-use rates - favorable charges for using power at off-peak times - only plugged in during peak times 12 percent of the time. For utilities already meeting the demand for domestic AC use, this additional EV load is not a problem.

Perhaps ironically, however, the findings suggest that utilities in regions without significant use of air conditioning may be more prone to problems with EV energy demand, since their electricity distribution systems are designed for flatter and smaller energy use patterns in the first place. Such systems were not designed for the high and instantaneous electricity draw that air conditioning and electric vehicles necessitate, so even with lower-than-expected peak demand for EV charging, EVs could overburden those systems if not properly managed.

But maybe this can be viewed as an opportunity, not a problem. The Environmental Defense Fund indicates the U.S. is poised to spend around $2 trillion over the next decade replacing antiquated electricity infrastructure; providing the opportunity for grid upgrades to take advantage of electric vehicle connectivity.

We can already see the realization of this opportunity with the advent of electric vehicle-to-grid (eV2g) technology. SustainableBusiness.com reported in April that NRG Energy has commercialized a two-way energy interface between vehicles and the grid. This allows energy stored in the batteries of connected EVs to be sent to the grid in times of peak demand, while replenishing that energy back to EVs at off-peak times. This two-way connectivity creates the opportunity for EV owners to sell energy back to the grid, while allowing the grid to become more resilient in times of peak demand. Furthermore, as additional renewable energy is added by utilities, connected EVs will be able to smooth the intermittent production of wind and solar, since their batteries will provide mass distributed storage capacity across the grid.

So far, today's commercially available electric cars don't fully support eV2g technology, instead being one-way consumers of electricity. However, future generations of electric vehicles are likely to become smarter over time.

In fact, General Motors announced last week that their forthcoming Cadillac ELR - in essence, a luxury version of the Chevrolet Volt - will be "smart-grid ready" from day one. And though it doesn't appear this vehicle will be equipped to send power back to the grid, it will nonetheless offer some advanced features through GM's cloud-connected Onstar system. Autoblog Green reports that utilities will be able to manage the charging schedules of participating owners' connected vehicles, and in return, provide favorable and dynamic time-of-use pricing to owners during low energy-demand periods. Perhaps this is the next step in the evolution towards full eV2g capability.

Looking further ahead though, EVs may eventually augment the grid in a very powerful way. As the SustainableBusiness.com piece reports, if all automobiles in the U.S. were electrified, it would be enough to power the entire U.S. for half a day. That's a pretty impressive statistic and one which suggests EVs could provide an invaluable role in the energy equation down the road.

Image by OregonDOT