The flow of power to most electric vehicles (EVs) today is unidirectional – grid to car – but vehicle-to-grid (V2G) technology could make that connection a two-way street. Ahead, researchers see a happy place where electric vehicles support the grid as dispatchable storage resources.
At this point in the journey, though, it’s easy to feel like there’s a nagging voice behind us, kicking the front seat impatiently and uttering a plaintive “Are we there yet?” No, we’re not there yet. Before V2G technology goes mainstream, we need to navigate some pesky infrastructure, economics and technology speed bumps that are slowing us down.
Give and take
Bloomberg New Energy Finance predicts that “electric vehicles will account for 54 percent of new car sales by 2040.” Given such forecasts, “a third of the global light-duty vehicle fleet will be electrified by 2040.”
There’s a lot of potential juice in that fleet. According to a University of Delaware V2G website, “One properly designed electric-drive vehicle can put out over 10kW, the average draw of 10 houses.”
For power providers, that battery storage resource sitting in your garage could be used to smooth fluctuations in renewable generation, support load shifting, deliver peak capacity and defer system investments. Among the grid services EVs could provide are operating reserves and frequency regulation.
“Electric vehicles are well suited to providing regulation services because they can provide both the load for regulation-down services by charging the battery and regulation-up services by discharging to the grid on demand,” writes researcher Darlene Steward in a September 2017 report published by the National Renewable Energy Lab. “Unlike many generation sources, batteries – and especially the batteries in vehicles – can respond to signals from the grid almost instantaneously.”
Steward’s report is titled Critical Elements of Vehicle-to-Grid (V2G) Economics. In it, she maintains that “the requirements, costs and benefits of V2G must be balanced among the three primary stakeholders: vehicle manufacturers, vehicle owners and grid operators.” Some parts of that balancing act are easier than others.
There are already a few vehicles on the road that are capable of bi-directional electricity flow. That is, instead of sending power from the battery to the drive train, they can send electrons to the grid. “But, for the majority of EVs, that capability has not been made available inside the vehicle by the manufacturer,” explains Rajit Gadh, a professor at the UCLA Henry Samueli School of Engineering and Applied Science and founding director of the UCLA Smart Grid Energy Research Center. Gadh says making vehicles V2G-ready is “not a complex matter.”
What prevents manufacturers from making the change? Gadh thinks part of the delay is the potential wear and tear on the batteries themselves.
There are only a certain number of charge-discharge cycles in a battery’s life span, he says. “If you do what is called a deep charge and discharge for the grid, you are eventually going to wear out the battery, even if you don’t drive the vehicle at all.” Often, he adds, car manufacturers warranty vehicles for a certain number of miles, and V2G capability has the potential to leave those manufacturers stuck with a guarantee that comes due before these miles get driven because the battery was used up for an unintended purpose.
Gadh sees a potential solution. “We’re getting more and more data from research around the world showing that if you do a shallow depth of discharge – say 10 percent – you’re not wearing out the battery as much as if you’re doing an 80 percent depth of discharge,” he says. Such findings are preliminary, and Gadh says more study must be done.
Meanwhile, how do we compensate owners for the right to tap their batteries? “It’s a matter of economics,” Gadh notes. “We still must fine-tune the technology – e.g., deep versus shallow discharge options – and market incentives to make V2G profitable for all”.
Where there are markets, there are regulators. The Electric Power Research Institute summarized regulator issues in a 2016 report titled Vehicle-to-Grid: State of the Technology Markets and Related Implementation. Among the considerations they pinpointed were these three:
- Regulators need to define the primacy rules among different grid benefits.
- Competitive energy suppliers in restructured markets need to develop products and services that allow customers to participate in V2G-based grid services.
- Utilities need to develop methods to capture and return to customers the value that V2G provides to their distribution infrastructure.
Rajit Gadh is working on that last item. His research involves multiple facilities, cooperation with two California utilities and, around the UCLA campus, charging stations fitted with EVSmartPlugs™ that perform remote monitoring and control of EV charging. The plugs also collect critical data that feeds various algorithms Gadh and his team are testing for distributed monitoring and control.
The scholars are exploring how to get maximum V2G power flow from each vehicle while balancing the driving needs of vehicle owners. Ultimately, the research team hopes to enable applications such as reactive power compensation and voltage regulation.
Gadh says grid operators will need “situational awareness” before they can control EVs effectively. That includes awareness of the local power system, any distributed generation nearby and state-of-charge on the various plugged-in vehicles. There also must be a way to communicate instructions to the battery. Those last two information-related items will require standardized communications protocols and, fortunately, standardization efforts are underway.
Even if we get the communications standards in place … and the grid-support payback … and the V2G cars themselves on the road … will consumers buy them? Not without more charging infrastructure. It’s such a pervasive concern, there’s even a name for it: range anxiety. And, according to a recent New York Times article, it’s just one of two consumer worries. The other is what the Times calls “charging time trauma.”
“Compared with a five-minute pit stop at your local gas station, charging an electric vehicle is a glacially slow experience,” wrote Times reporter Eric A. Taub. “Modern electric cars still often need an entire night to recharge at home, and even at a commercial fast charging station, a fill-up can take an hour or more.”
In most residential settings, consumers can charge EVs through a standard, alternating current outlet. It delivers between 1 and 1.5 kilowatts of electricity, which means it takes around 30 hours to charge an EV similar to a Ford Focus. Add a professionally installed 240-volt charger, and charge time drops to about 5.5 hours on a system that provides between 7 and 9 kilowatts.
Even Tesla’s “supercharger,” which works only for Tesla vehicles, takes around 75 minutes to give a car some 300 miles of range.
This past October, the U.S. Department of Energy decided to pledge up to $15 million for research projects to enable extreme fast charging.
Let’s hope we see some extremely fast results on this DOE investment. Without fast charging, V2G potential is unlikely to hit the fast lane anytime soon.