1.    Electric cars have arrived, but the pace of adoption will be slow.
2.    There are several different types of cars that plug in, and their electric ranges vary.
3.    In the early years, most charging will be done in garages attached to private homes.
4.    You have to consider where and how you use your car(s) if you consider buying electric.
5.    Electric cars are cheaper to “fuel” per than gasoline cars, and they have a lower carbon footprint too—even on dirty grids.

(1) Electric cars have arrived, but the pace of adoption will be slow.

Last year, roughly 17,000 plug-in cars were sold in the United States—more than were sold in any year since the very early 1900s. But to put that number in perspective, total sales in 2011 were 13 million vehicles, meaning that plug-in cars represented just one-tenth of 1 percent. Sales this year will likely be double or triple that number, but it remains a stretch to reach President Obama’s goal of 1 million plug-ins on U.S. roads by 2015.

Both the Nissan Leaf and the Chevrolet Volt sold more units last year than the Toyota Prius did in 2000, its first year on the U.S. market. But 12 years after hybrids arrived in the U.S., they now make up just 2 to 3 percent of annual sales—and about 1 percent of global vehicle production.

Automakers are understandably cautious when committing hundreds of millions of dollars to new vehicles and technologies. They worry that a lack of public charging infrastructure will make potential buyers reluctant to take the chance on an electric car. Moreover, each factory to build automotive lithium-ion cells—an electric-car battery pack uses dozens or hundreds of them—costs $100 to $200 million. Battery companies will only build those factories if they have contracts in from automakers, who will only sign contracts to boost production if they can sell tens of thousands of electric cars a year in the first few years.

Eight to 10 years from now, most analysts expect plug-ins to be roughly where hybrids are today: 1 to 2 percent of global production, with highest sales in the most affluent car markets (Japan, the U.S., and some European regions). That translates to perhaps 1 million plug-in cars a year. There are, by the way, about 1 billion vehicles on the planet now.

The adoption of increasingly strict U.S. corporate average fuel-economy rules through 2025, however, will spur production of electric vehicles. And California has just passed rules that require sales of rising numbers of zero-emission vehicles, on top of the Federal regulations.

(2) There are several different types of cars that plug in, and their electric ranges vary.

The two main plug-in cars that went on sale last year, the Nissan Leaf and Chevy Volt, use somewhat different technologies, and this year will see a third variation arrive, the 2012 Toyota Prius Plug-in Hybrid. Each works slightly differently, and their electric ranges vary considerably, roughly proportional to the size of their battery packs.

The Nissan Leaf is a “pure” battery electric vehicle. It has a 24-kilowatt-hour battery pack (it uses 20 kWh) that delivers electricity to the motor that powers the front wheels for 60 to 100 miles. That’s it. On the plus side, this is the simplest setup of all, and battery electrics require very little servicing beyond tires and wiper blades. On the minus side, if the driver is foolish enough to deplete the battery—the car makes strenuous efforts to warn against this—the car is essentially dead until it can be recharged.

The Chevrolet Volt is a range-extended electric vehicle. It has a 16-kWh battery pack (of which it uses about 10 kWh) that powers an electric drive motor for 25 to 40 miles. Once the pack is depleted, a gasoline “range extender” engine switches on, not to power the wheels but to turn a generator to make more electricity to power the drive motor that makes the car go. The 9-gallon gas tank provides about 300 more miles of range, and the Volt can run in this mode indefinitely. But 78 percent of U.S. vehicles cover less than 40 miles a day, so many Volts that are plugged in nightly may never use a drop of gasoline.

Finally, the new plug-in Prius is known as a plug-in hybrid. It too has an electric drive motor and a gasoline engine, and its 4-kWh battery pack gives 9 to 15 miles of electric range. But like all hybrids, the gasoline engine switches on whenever maximum power is needed, so even if the battery pack is fully charged, those fast uphill on-ramp merges mean the engine will fire up for maximum power. Toyota says that if it’s plugged after each trip, many drivers can cover more than half their mileage on electric power.

Today, all three cars cost $35,000 to $40,000 before tax incentives. That’s up to twice as much as a gasoline car of the same size. And each one has pros and cons. The Leaf has the longest electric range, and will never emit a single pollutant. The Volt offers the quiet, quick pleasure of driving electric, but with unlimited range. And the Prius Plug-In brings low charging time and higher electric range to the familiar, trusted Prius range.

(3) In the early years, most charging will be done in garages attached to private homes.

There will soon be more public charging stations than there are gas stations in the U.S. That’s a little deceptive, since most gas stations have a dozen or so pumps, while the electric-car charging stations have one or two cables. But it points out the relatively low cost and fast installation pace of charging stations, aided in some cases by Federal incentives.

Nonetheless, ask any automaker and they will tell you they expect the bulk of electric-car recharging to occur overnight at charging stations installed in garages attached to private homes. And electric utilities very much want that to happen as well. Charging overnight, during their period of lowest demand, has many advantages: It can stabilize the distribution system, and it represents new demand and new business for them. Many utilities are launching rate plans that incentivize overnight charging, to discourage daytime charging that might occur when the load from factories, home air conditioners, and the like is highest.

Another unknown is whether and how much electric-car drivers will expect to pay for public charging. At 10 cents per kilowatt-hour, it costs about $2 to fully charge a Nissan Leaf for 70 to 100 miles. But 2 hours of charging, or 20 to 25 miles’ worth, takes less than a dollar of electricity. So what will drivers pay? A buck? Five bucks? The market will tell us, in time.

In the end, public charging is likely to be like public WiFi. In some places, it’ll be provided free as an amenity(think big-box stores who’d love to trade 50 cents of electricity for the opportunity to keep you in their building for a couple of hours). In others, providers will mark up the power and owners will pay for the convenience (think pricey city-center parking lots that charge $25 or more a day).

But early adopters of electric cars will already have navigated local zoning codes, home wiring changes, and contractor visits to get their own 240-Volt “Level 2” charging stations installed. Owners can get their electric cars to remind them—via text message or e-mail—if they forget to plug in to recharge at night. Soon, plugging in the car may be just as unremarkable as plugging in a mobile phone every night.

(4) You have to consider where and how you use your car(s) if you consider buying electric.

Plug-in cars are not for everyone. They still cost more than the gasoline competition, though their running costs are far lower. And the limited range of battery electric cars may make them impractical for households with only a single vehicle. Range-extended electrics and plug-in hybrids solve that problem, but the complexity of two powertrains plus the pricey battery pack makes them more costly than regular hybrids.

Potential buyers should consider two factors: range and climate. If the miles you cover each day in your car are highly variable, electric cars may cause more “range anxiety” than if you commute the same predictable daily distance. If you drive much more than 60 miles round-trip during a day, a battery electric like the Leaf won’t do it.

And the range of an electric car falls significantly in cold weather. Hybrid owners in cold climates already know their gas mileage goes down each winter; electric cars exhibit the same pattern. Batteries are pretty much like humans; they like to live around 70 degrees. If it’s a lot colder, they’re simply not able to deliver as much power. Worse, it takes a lot of battery energy to heat the cabin in winter—though a bit less to run seat heaters, which is how electric car designers try to keep occupants comfortable without having to warm up the entire interior.

In early years, most plug-ins will likely be sold to affluent buyers who have two or three cars in the household. And a disproportionate number of them will live in California. By some estimates, sales of electric cars within California will total those of the next five states put together.

(5) Electric cars are cheaper to “fuel” per than gasoline cars, and they have a lower carbon footprint too—even on dirty grids.

Retail car buyers act irrationally. Often, we more car than we really need, and we also put too much weight on initial purchase price—or the monthly payment—and not enough on the total cost of ownership, including maintenance and fuel cost.

Fleet buyers, on the other hand, are hard-nosed spreadsheet jockeys. They’ll pay more up front for a car if they save money over its entire lifetime. And electric cars can be a fleet buyer’s dream. Battery electric cars require almost no maintenance—tires and wiper blades are about it. Even brake pads and disks last far longer, because the car is slowed largely by “regenerative braking,” or the resistance provided when the electric motor is used as a generator to recharge the battery pack.

Best of all, they’re incredibly cheap to run on a per-mile basis. Electricity costs from 3 to 25 cents per kilowatt-hour in the U.S., but at 10 cents per kWh, fully charging a Nissan Leaf for 70 to 100 miles costs a little more than $2. Those 100 miles would cost $12 in gasoline in a conventional car that gets 33 mpg, with gas at $4 a gallon. Over 10,000 miles a year, that could be $1,000 in savings. Nissan warranties its battery pack for 8 years or 100,000 miles, so you might be looking at savings of close to $8,000 in fuel costs, plus the lower lifetime maintenance cost. Does that make up for the price differential between a Leaf and a regular compact car? Not completely. But knock off the $7,500 Federal tax credit, and you get closer. Many states, localities, and corporations offer additional incentives as well.

Ten years hence, lithium-ion cells will likely cost about half what they do today. Gasoline cars, on the other hand, will be more expensive in real dollars due to the cost of more efficient gasoline engines. Those gasoline cars will get better fuel economy, but battery costs are likely to fall faster (6 to 8 percent a year) than fuel economy will rise (3 to 5 percent).

Then there’s the environmental argument. A well-respected 2007 study done jointly by the Electric Power Research Institute (EPRI) and the Natural Resources Defense Council (NRDC) analyzed the “wells-to-wheels” carbon emissions of driving a mile on gasoline versus driving that same mile using grid electricity. Against a 25-mpg car, an electric car was lower in carbon even if it were recharged on the nation’s dirtiest grids, using almost entirely coal power.

Up the ante to a 50-mpg car (e.g. today’s Toyota Prius), and on a few of those dirty grids, the carbon profile of 1 mile on gasoline in a Prius is slightly lower than on grid electricity. But in coastal states whose grids are relatively cleaner, electric cars are a win on emissions and greenhouse gases against any gasoline car at all.

By. John Voelcker

John Voelcker is the editor of Green Car Reports. This piece was originally published at the Rocky Mountain Institute and was reprinted with permission.