Electric cars, which have come and gone at least twice since the dawn of the automobile era, are back. The first mass-market EVs are here and more are rolling silently over the horizon. The Obama administration loves cars with cords and wants 1 million on the road by 2015.

That's an ambitious, but not impossible, goal. Most major automakers promise to have an electric vehicle or plug-in hybrid in showrooms by then. Their commitment seems solid, and some are making big promises. General Motors just announced its second plug-in hybrid, for example, and Nissan says its factory in Tennessee will be able to crank out 150,000 EVs annually by 2013. Nissan CEO Carlos Ghosn boldly predicts battery electric vehicles will comprise 10 percent of the global market by 2020.

So where will we plug them in?

This is not an insignificant question, but neither is it the major hurdle some suggest. We'll plug in mostly at home, often at work and, if we need to, at a growing number of public chargers. Some bet swappable batteries will alleviate our range anxiety, while others envision fleets of quick-charge trucks rescuing stranded drivers. Optimists say we'll soon see batteries that can take us hundreds of miles, making the issue moot.

"There are a lot of possibilities coming, and it's not just about home charging, or quick-charging, or removable batteries," Ghosn told Wired.com. "It's about a lot of pieces of technology coming together to make charging much easier."

These pieces are falling into place as big players like General Electric and NRG Energy join smaller outfits like Coulomb Technologies, Ecotality and Better Place in rolling out the infrastructure. We've already got more than 1,300 public charging stations nationwide and thousands more coming. Uncle Sam is spending more than $100 million to help install 22,000 residential and public charging points nationwide by 2014, and ABI Research says we'll see more than 1.4 million residential and public chargers in the United States by 2016.

For all this investment, the charging station you'll use most already is here.

"A lot of people ask me, 'Where will we plug in?'" said Dan Davids, president of the advocacy group Plug-In America. "Two words: At home."

The simple fact is, most of our charging will be done at home while we're sleeping. That's exactly how early adopters like Davids, who's driven a Toyota RAV4 EV for more than four years, keep rolling. It isn't as expensive as you might think. The average cost of electricity in the United States is 11 cents per kilowatt-hour, and the Department of Energy pegs the typical annual electricity cost of the Nissan Leaf, for example, at $561.

The fact we'll do most charging at home suggests our infrastructure needs aren't as great as EV naysayers claim. A survey of 3,000 people who would consider buying an EV found 61 percent would prefer plugging in at home. Just 14 percent had any interest in public chargers, said Thilo Koslowski, an analyst at Gartner, which conducted the survey. A similar survey of Southern Californians by Electric Power Research Institute found 95 percent prefer charging in the garage.

“The majority of consumers are just fine with charging up at home," Koslowski said.

Further supporting this point, the range provided by many EVs is sufficient for many – but obviously not all – commuters. Most EVs claim a range of 100 miles, which typically translates to an EPA-certified figure in the 70s. You aren't commuting from the furthest exurban rings of, say, Atlanta, with that, but a lot of people will be fine. A survey of 120 families who spent a year driving the Mini E in California, New York and New Jersey found the car's claimed range of 100 miles met 90 percent of their driving needs.

Even if home charging is sufficient for most of our needs, there's a wrinkle in that plan: One-third of Americans live in rental housing. They may not have the option of installing the 220-volt charger needed to juice their car in seven or eight hours. They may not even be able to plug in their car's 110-volt trickle charger, which does the job in twice that time. That is changing, albeit slowly, as developers and residential property owners – City Ventures and Equity Residential among them – begin installing chargers or pre-wiring parking lots and garages to handle them.

Still, it's naive to think electric vehicles will achieve anything approaching mainstream popularity if people can't plug in anywhere but home.

"Buyers over the next couple of years are the typical early adopters who do not need much encouragement to get the latest technology," said David Alexander, an analyst with ABI Research. "[But] public recharging will be necessary to engage the broader market."

ABI estimates there will be 820,000 residential chargers and 642,000 commercial charging stations nationwide by the end of 2015. Of those public stations, about 73,000 will be Level 3 "quick chargers" that can charge a battery to 80 percent capacity in about 30 minutes. Alexander says all that hardware will cost roughly $4.95 billion to install.

We're already on our way, though some will complain it's a slow start. We've got more than 1,300 public and commercial chargers available in the United States right now, and more coming. A look at a few major projects provides a glimpse of our coming electric infrastructure.

Ecotality is overseeing The EV Project, a campaign financed in part by the Department of Energy to install more than 15,000 chargers in 18 cities by mid-2012. Of those, 6,350 will be public chargers and 310 will be quick chargers. The feds have invested $100 million in the $230 million project. The company says about 25 percent of the chargers have been deployed; of those, about one-third are public chargers.

Ecotality will install 45 quick chargers at BP and Arco gas stations as part of a demonstration test project.

Coulomb Technologies is overseeing ChargePoint America, a program funded in part by the DOE to install 4,600 residential and public charging stations in nine cities. More than 500 have been deployed. The feds have invested $15 million in the $37 million program.

NRG has opened the first of 120 "Freedom Stations" planned for Houston and Dallas. The privately-funded stations, available to subscribers of NRG's "eVgo" service, include a conventional charger and a quick charger. The stations will be installed at Walgreens, Best Buy and other retailers.

San Francisco will install 80 public chargers in 20 parking garages this year. The free chargers will use hydroelectric power. That's important. Many studies show EVs emit less CO2 than internal combustion on a well-to-wheels basis even when using electricity from coal-fired plants, but their greatest potential lies with renewable energy.

Aerovironment is working with state transportation officials to install 30 quick chargers along Interstate 5 in Oregon under the West Coast Green Highway project. Another nine quick chargers are slated for I5 and Highway 2 in Washington.

The San Francisco Bay Area plans to install 30 quick chargers throughout the region over the next several years. "It's essential to do this regionally," said Robert Hayden, the city's clean air manager. "People move around, they commute. In order to alleviate range anxiety, people need to know they can plug in."

A growing number of campgrounds charge EV drivers a nominal fee to use the 50-amp, 240-volt hookups set aside for RVs. "The potential is there for the nation's private campground owners to help support the greening of the nation's transportation infrastructure," said Paul Bambei, head of the 3,300-member National Association of RV Parks and Campgrounds.

Better Place is still betting on swappable batteries. The technology has been embraced in Israel, is being tested in Japan and is headed for Australia and China. It hasn't generated the same excitement here, but Better Place and the Bay Area Air Quality Management District plan to install two swap stations in San Francisco and two in San Jose. The stations will service a fleet of 61 taxis. The first stations and cabs are planned for next year.

Better Place also is rolling out "a small number" of public charging stations in Hawaii.

AAA is rolling out one "quick charge" truck in each of six EV-friendly cities this year to see how it goes. If the program is a success, AAA says it could be expanded to other cities.

Most of the big EV projects are happening where most of the EVs will be located: on the West Coast and in EV-friendly metro-areas like Seattle, Washington; Austin and Houston, Texas; Boston; New York; Tampa and Orlando, Florida; and Phoenix. Auto industry hotspots Michigan and Tennessee (Nissan's North American home) also have projects underway. But we're also seeing small-scale projects like Plug-In Carolina, which is helping nine cities deploy more than 80 chargers.

Many of these public chargers will be installed outside restaurants, big box retailers and other places where people tend to spend an hour or more. Ikea, for example, will install chargers at 10 stores in four states. NRG is rolling out its "Freedom Stations" at Best Buy and other retailers. Walgreens plans to install chargers at 800 stores nationwide.

So how many chargers will we need to support all those electric vehicles? The folks at Ecotality have crunched the data – they've been installing chargers since the days of the General Motors EV1 – and say the magic number is 1.51 chargers per car.

"The 'one' is the charger in your garage," said CEO Jonathan Read. "The 'point five one' is the public or commercial charger."

Yes, the grid can handle this. One million, 10 million, even 100 million electric vehicles will not be a strain, said Mark Duvall of the Electric Power Research Institute.

"The United States produces 4,000 terawatt-hours of electricity a year," he said. "One million EVs would be about one one-thousandth of our annual electrical production."

The grid is sufficiently robust for the added load, he said, and utilities are making improvements as needed to prepare for the coming of cars with cords. Most of these vehicles will be located on the coasts, but here too EVs do not pose a threat. An electric vehicle draws about 700 or 800 watts, which is roughly what two flat-screen TVs require.

"Your getting an electric vehicle would be like your neighbor getting a hot tub," Duvall said. "It is not an unreasonable electricity demand. For any utility, even one with the densest level of EVs, it's a non-issue."

Still, there is a lot of talk about utilities managing loads and offering incentives for consumers to charge at night. But this is an effort to use excess generation capacity and offer EV owners the lowest possible rate by plugging in off-peak. Even in the highly unlikely event that every single EV owner plugged in at 5 p.m., when demand is highest, the grid can handle it.

"There's no possible way these things can crash the grid," Duvall said.

The grand opening of the first evGo 'Freedom Station' in Dallas. Photo: NRG Energy

How much we'll pay to use these chargers remains to be seen. Some will charge a nominal fee of perhaps a few bucks. NRG's "Freedom Stations" are available only to subscribers who pay $89 a month for a home charger, access to the public chargers and all the electricity they need. But many chargers will be free, offered by retailers to draw customers.

"We're seeing a lot more EV-friendly businesses," said Brian Wynne, president of the Electric Drive Transportation Association. "You're going to see a lot more businesses stepping in, because we're talking about pennies for a customer to park and plug-in while they're shopping. Retailers see a lot of value in this."

A single Level 2 charger costs $2,500 to $3,500 and another $1,500 to install it. Ecotality says it costs about $1.40 to $1.80 to charge a car and businesses that hold a charging station will see full return on their investment in five years.

A growing number of employers are offering charging as well. This is important, because our cars spend 10 or 15 percent of their time parked at work. Richard Lowenthall, chief technology officer at Coulomb Technologies, said roughly 25 percent of his firm's business involves installing chargers for employers. It costs an employer about $600 a year to install and operate a single charger, he said.

The government is spending more than $100 million through the Transportation Electrification Initiative to get the infrastructure ball rolling. But the companies getting a hand from Uncle Sam say they see a strong business case and don't want – or need – open-ended subsidies.

"We're capitalists," Lowenthall said. "We believe this market can only grow through capitalism."

David Crane, CEO of NRG Energy, was more direct. His company is going it alone, investing $25 million in evGo project because it firmly believes there is a lot of money to be made there.

"The electric vehicle could be the third great consumer electronics revolution of our lifetime, after the personal computer and the cell phone," he said. "The potential reward of this $25 million investment is so great that it outweighs the possible downside."

Still, we're seeing far more promises than plugs at this point, and the nation's largest charging network is a crowdsourced collection of early adopters' garages. PlugShare, the smartphone app creating an ad hoc EV charging infrastructure from individuals, now includes more than 3,500 charging locations. Most are EV owners and advocates happy to let you plug in.

So the cars are coming. The infrastructure will follow. There's no way of knowing at this point just what it will look like, but it almost certainly won't look like the fueling infrastructure we're using now. There are nearly 160,000 gas stations in the United States. We simply cannot match that, EV advocates said, nor do we need to. EV advocates say we need to move beyond our habit of driving until the tank is empty. Driving an EV means plugging in at night and topping off when you can during the day. It's called "opportunistic charging," and it is second-nature for EV owners.

"That shift in thinking takes you about three weeks," said Dan Davids of Plug-In America. "Then you don't even think about it."

It's a paradigm shift. But then, everything about electric vehicles is a paradigm shift – including when and how we'll "fill" them up.

"Everyone looks to the public charging network as the gas station of the future. It's not," Crane said. "The charger in your garage is the gas station of the future. Public charging stations are simply insurance."

Top photo: Public chargers lined up at Google HQ in Mountain View, California. The tech giant recently installed 70 chargers and has plans for 250. (Coulomb Technologies)

Video: Time-lapse video of the installation of the first evGo "Freedom Station" in Texas. (NRG Energy)

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