Are electric vehicles the cars of the future? Sales numbers seem to imply so. More than 351,000 electric vehicles were sold in China, where government policies and subsidies promote zero emission cars, in 2016. Other parts of the world are strongly encouraging drivers to buy electric cars, using a variety of benefits and perks. Scandinavian countries offer drivers of electric cars a slew of perks, including free ferries and tax breaks on purchases and import taxes. Shanghai subsidizes electric vehicle purchases to the tune of $4,400 per car and also allows purchasers to avoid costly license plate auctions. At least some of these approaches will likely come soon to California, which has given itself the goal of putting 1.5 million zero-emissions vehicles on the road by 2025 and is threatening to ban gasoline cars altogether by 2040. Strangely enough, the easiest part of this process may be buying the cars–building charging stations will likely be more difficult.

The gas station is an at-times underappreciated part of America’s transportation infrastructure. There are about 9,700 gas stations in the state of California alone. On a busy weekend, many of them will have lines of cars waiting to fuel up. Thankfully, most of these stops take less than five minutes. That sort of turn around time will be difficult to match with any recharging capacity currently existing today.

David Booth, writing for Driving, a Canadian automobile website, crunched some of the numbers, finding that replacing a gas station with a charging station would strain the limits of existing technology.

“An [electric vehicle] that can guarantee 500 klicks (310 miles) requires at least 100 kilowatt-hours of battery. Do the math and a similar two-minute recharge would require three megawatts. That, for those who don’t have an electrical engineering degree, is 3,000 kilowatts,” he wrote.

“Now for some perspective: current fast chargers boast about 50kW,” he continued, adding that today’s limits are only one-sixtieth the capacity needed to match the refueling rate of the average gas pump. “Serving the same number of cars could theoretically require as many as 960 charging stations (and they’d still have to sit there for two hours to fully charge).”

Advances in technology will likely only bring this process so far. Engineers write that the 350kW rechargers needed to offer a 20 minute refueling would generate such large amounts of heat that their cables would need to be liquid-cooled. And on top of that, powering these vehicles takes a lot of electricity. If a busy gas station is able to service 2,000 cars on a given weekend, then fueling up an equivalent number of electric vehicles would need roughly 30 megawatts of power.

“Thirty megawatts, for perspective, is enough to power about 20,000 homes,” Booth concludes. “In other words, powering these service stations of the future will require about the same amount of electricity as a city of 75,000.”

What do numbers like these mean for the state of California?

The state has already taken steps to subsidize the construction of electric vehicle charging stations. In July, California’s Air Resources Board approved the Cycle 1 California ZEV Investment Plan. Under this plan, Electrify America, a subsidiary of Volkswagon, will build $800 million of electric car charging infrastructure over the next decade. The sum is a penalty for the auto-maker’s diesel-emission cheating scandal. The projects will be divided into four $200 million increments, each with a timeline of 30 months.

Part of the project’s first stage includes $45 million to build more than 350 community charging stations in communities around the state. Electrify America will also spend $75 million building fast-charge stations around the state. This works out to between 2,000 and 3,000 chargers. If one gas station would require as many as 960 chargers to replace, then the next result of Volkswagon’s massive investment in electric vehicle infrastructure would replace somewhere between two and four gas stations.

Utility companies are planning an additional $1 billion of investment in electric vehicle infrastructure. Given what they are attempting to replace, the vast sums seem a bit like drops in an ocean.

State legislators in California may be wising up to this as well. Last month, a $3 billion spending bill aimed at boosting rebates for the purchases of electric vehicles was amended in the state legislature. Language establishing a rough formula for higher rebate amounts was stripped out of the bill, as was the price tag of the bill. Instead, the new bill directed the state Air Resources Board to conduct studies on the best way to write and implement electric vehicle legislation, a much cheaper proposition.

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