Why EV fast-charging stations are going big on batteries

Batteries can keep grid costs and impacts in check — and earn money providing other services between charges.

Electrify America is installing batteries to allow its Baker, Calif. EV fast-charging site to grow — and eventually to help balance the grid. (Electrify America)
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The world will need lots of fast-charging stations to support the massive growth in electric vehicles as we move to clean up transportation systems. And for those fast-charging stations to be connected to the power grid quickly enough to meet rising demand, they’re most likely going to need some batteries alongside them.

This marriage of fast chargers and batteries is starting to happen at highway rest stops, fleet vehicle depots and urban charging hubs across the world. While batteries add significant costs to a fast-charging business case that’s just starting to take off, going without them may not be an option because many grids aren’t yet capable of supporting the immense new loads from EV charging stations. 

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I think there’s an inevitability to it, honestly,” said Andy Tang, vice president of energy storage and optimization for battery vendor Wärtsilä. Earlier this year, his company installed what may be the world’s largest EV-supporting battery project, two systems adding up to 100 megawatt-hours of storage to support Pivot Power’s Energy Superhub Oxford project in the U.K.

This is a forward-looking project designed to support rapid growth of high-voltage direct-current fast-charging stations in the area. It’s also looking ahead to how those batteries can serve multiple grid needs when they’re not being used to help charge EVs, he said. That’s an important consideration for a company seeking multiple revenue streams to pay off batteries’ costs, particularly in the early days when not that many EVs are on the road to buy the electricity they’re serving up. 

Fast-charging hubs everywhere will need to be looking at similar options to manage the stress they’ll be putting on the grid, Tang said. These charging stations are trying to give you an 80 percent recharge in 30 minutes, and they want to support multiple cars at the same time,” he said. You’ll have to bring batteries to the site.” 

Consider the latest projections of how many fast-charging stations will be needed to meet the Biden administration’s goal to make half of all U.S. auto sales electric by 2030. According to Atlas Public Policy, the country will need to invest $87 billion in charging infrastructure by 2030 to support that goal, with half of that investment going toward public chargers, and most of that for fast chargers. An April study from GridLab, Energy Innovation and the University of California, Berkeley projects the need for about 900,000 fast chargers for cars and 400,000 for heavy-duty vehicles by 2035.

The latest fast chargers can inject up to 350 kilowatts of electricity per plug, roughly the amount of grid demand from about 50 average U.S. homes. Bring a few of those fast chargers together at one site and you’ll have more than enough to overwhelm existing grid infrastructure, which was not built with those kinds of loads in mind. The cost and time involved in getting utilities to upgrade that grid infrastructure could present serious obstacles to getting chargers deployed, making batteries a better option. 

Finding ways to handle EV charging demand 

That’s certainly part of what’s driving Electrify America’s strategy for adding batteries to its fast-charging sites across North America. The company, formed out of Volkswagen’s Dieselgate” settlement, has procured more than 50 megawatts of batteries, of which 25 MW have already been deployed at about 125 locations, said Jigar Shah, the company’s head of energy services. 

All told, one in four of the company’s sites are expected to have batteries by the end of this year, he said. Other fast-charging network providers are taking similar steps — EVgo, a rival to Electrify America, has installed its own batteries alongside charging spots. 

Batteries are first and foremost a vital tool to reduce the cost of demand charges, Shah said. Those are the extra costs on utility bills based on peak electricity draw at any moment during a monthly billing cycle. Fast chargers make for an incredibly peaky” load on the grid, which means demand charges can add up to 90 percent of total electricity costs at charging stations — a deal-breaker for sites that may largely sit idle, making little money, in their first few years of operation. 

Beyond this, many of Electrify America’s sites lack sufficient grid capacity. That’s what motivated the company to add a megawatt of battery storage to its site in Baker, California, a rest stop along the busy Southern California-to-Las Vegas I-5 route. That upgrade will bring its total charging capacity to 2.2 MW at a site that only has about 665 kilowatts of grid capacity, he said. 

Southern California Edison, the utility that serves the Baker location, has instituted a demand-charge holiday” for EV chargers for the next five years to avoid discouraging their deployment in its territory, lifting that concern for the Baker project, Shah said. Still, we don’t want to wait the two to three years for SCE to upgrade the utility service,” he said. 

In fact, this is the company’s first instance of a non-wires alternative,” he said — a utility term for a project that strategically deploys distributed energy resources to avoid upgrades to the grid. The Baker project isn’t specifically linked to California’s program to reward utilities and distributed energy providers for finding ways to defray grid costs in this way, he noted. But California regulators are asking utilities to explore ways to mitigate the significant grid strains and costs that will come as the state implements its aggressive EV growth plans. 

That’s especially true when it comes to heavy-duty EV charging,” Shah said. This summer, Electrify America announced plans for 34 fast-charging stations at NFI Industries’ Ontario, California logistics center, the biggest U.S. electric truck charging project to date. The companies are exploring ways to ease grid stress by scheduling charging at different times of the day, which could reduce the need for grid upgrade requirements by the time the site opens in late 2023, he said.

It’s much harder to manage charging patterns at public stations like its Baker site. But having a battery there can give the company more control over how much energy it’s pulling from the grid at any moment of time, which opens it up to test Southern California Edison’s latest time-of-use rates for EV charging, he said. 

Those rates match the ups and downs of California energy market prices, from lows during midday hours when solar floods the grid to highs in late afternoons and evenings when solar fades while air-conditioning demand remains high. Those are the same conditions that have put California’s grid under stress in the past two summers, and finding ways for EV charging to help ease those stresses will be an important step in making sure the state’s EV growth doesn’t overwhelm its available electricity supply. 

Adding energy arbitrage and resiliency for buildings

Batteries can do more than just balance EV charging loads. This week, fast-charging system maker Tritium and charging software-as-a-service provider ChargeNet broke ground on a project that will let a South San Francisco Taco Bell restaurant use battery capacity to reduce its own energy bills and exposure to grid blackouts in exchange for hosting EV-charging spaces in its parking lot. 

The project includes six 75-kilowatt chargers, an 80-kilowatt solar array on an awning shading those parking spots, and a 220-kilowatt-hour battery. When that solar-battery system isn’t keeping the site’s EV charging load within grid limits, it’s available to supply power to the Taco Bell when utility prices are high, Mike Calise, Tritium’s president of Americas, said in an interview.

An artist's rendering of the Taco Bell charging project. (Tritium)

You can pull your energy from the grid at night when it’s cheap, or you can pull it from the battery at peak,” he said. Diversified Restaurant Group, which operates the Taco Bell and 250 other Taco Bell and Arby’s restaurants in five states, plans to exchange the use of its sites for free access to that electricity price arbitrage, he said. 

In the event of a power outage — an increasing concern in a state that’s been subjected to wildfire-prevention blackouts over the past several summers — the Taco Bell’s battery and solar system will turn into a microgrid, effectively, sitting on this parking lot,” Calise said. Access to state incentives for EV chargers and backup batteries in low-income and disadvantaged communities helped the project pencil out economically. 

The concept of using batteries and EV charging equipment as a microgrid is being taken up by developers such as San Diego, Calif.-based EDF Renewables, which is using its PowerFlex subsidiary’s software to balance chargers’ interplay with the buildings they’re installed alongside, and Blueprint Power, the New York-based startup recently acquired by oil giant BP. It’s also a way for the EV charging systems to make money selling electricity in their early years of relatively low utilization as they wait for enough EVs to be on the road to validate their primary business case. 

Specializing batteries for EV charging and grid services

Dense urban environments are a particularly challenging field for high-intensity EV charging, Calise said. Tritium is providing its chargers for startup Revel’s Superhub in Brooklyn, the country’s biggest fast-charging hub outside of Tesla’s proprietary network. The Superhub is relying on Revel’s own EV rideshare vehicle fleet to make use of its chargers in its early years until the number of EVs owned by the general population grows to a level that will allow the site to make money from public charging. 

You have to bring [direct-current] fast charging into the high-population centers where most people live,” he said. But finding the physical space and adequate grid service to host charging hubs in dense urban environments can be tough. Revel chose a former pharmaceutical factory site with ample electrical service to host its hub, but not all EV charging hosts will be as lucky, he said. 

Revel still plans to install batteries at its Brooklyn site, however, to help mitigate demand charges. In August it announced its partner for that project, Seattle-based Electric Era, which has spent the past two years developing a battery fine-tuned for the EV charging backup role. 

I spent about seven and a half years building things that go into space and wanted to come down and focus on terrestrial problems,” said Electric Era CEO and co-founder Quincy Lee, a former SpaceX battery engineer. Specifically, the company’s lithium-ion battery chemistry, backed by about $3.8 million in venture investment, is designed to pack a lot of power density into a small space. 

Power density — how much electricity a battery can deliver at any one moment in time — hasn’t been as much of a focus for battery designers over the past half-decade or so. That’s because energy density — how much electricity a battery can store per unit of weight and cost — has been a more pressing issue for designing smaller and cheaper batteries to improve EV driving range. Applications that have needed power density, meanwhile, have largely been filled by supercapacitors, which can pack an enormous power punch for seconds at a time. 

But EV charging is crying out for a power-dense battery, Lee said. In a constrained city environment, there’s no extra power on the line, but there’s also no extra parking on the street,” he said. You can’t have shipping containers of batteries sitting there.” 

Electric Era has developed software to simulate and predict the interplay of batteries, EV chargers and grid constraints to ensure it can keep overall loads under the threshold that would trigger hefty demand charges while getting cars charged up on schedule. The same software is designed to provide grid services, whether that’s reducing demand during times of peak grid stress or responding to four-second signals for frequency regulation, he said. 

Of course, all of that optimization has to be done while not breaking the prime directive” of avoiding demand charges, Lee said. But getting it right will also be important for front-loading the revenue-generating opportunities that can get EV charging hubs through the early lean years of waiting for the EVs to arrive en masse, as well as making these hubs a supportive, rather than disruptive, part of the grid. 

When you couple the charger with the battery and use everything in full combination, you can unlock higher-order benefits that shift what used to be a dumb EV charging station into an intelligent virtual power plant,” he said.

Jeff St. John is director of news and special projects at Canary Media.