Cough, splutter, chug, choke—is the way cars have been till now. Humm, whirr, whiz, glide—is the way they’ll probably be tomorrow. Sooner or later, whether it’s in a couple of decades or a distant century, oil-based fuels will be far too precious to squander on the world’s dwindling fleet of gas-powered cars. That’s when a confident majority of electric car drivers will peer back over the shoulder of history to a time—the twentieth century—when automotive technology took a drastic wrong turn. At least, that’s how many people think the story will go.
Electric cars use older technology than gasoline cars and, in their late-19th-century infancy, looked set to rule the world. The first electric car was built in 1834 and by 1900 some 38 percent of all cars were electric (according to Seth Leitman’s book Build Your Own Electric Vehicle, p.34). But oil was cheap and abundant and, in many ways, offered a better method of powering fast cars over long distances. Henry Ford’s mass-production of affordable gas-powered cars soon put paid to electric dreams. Fortunately, as people finally woke up to the environmental and economic drawbacks of petroleum in the late 20th century, technology turned full circle and cars powered by the zap of electricity started to return to our streets. But is it really inevitable that all cars will go electric? How long will it take? Before we can consider that question, it helps to ask something much more fundamental: how exactly do electric cars work? What’s so good about them anyway—and what are the drawbacks? Can you really go to work powered by a few buzzing electrons? Let’s take a closer look!
Electric cars are child’s-play; I know that, for a fact, because I built my first one at the age of eight. Now, admittedly, it wasn’t a Tesla Roadster or a Chevrolet Volt, but it had all the key features of any electric car. It was a toy I’d made with a construction set using a battery, electric motor, four little rubber-tired wheels, and a simple transmission built from ready-made gears. Real electric cars aren’t much more than this, though building one is certainly more of a technical challenge than snapping together a toy. All cars—gas, electric, hydrogen, or using any other “fuel”—are essentially energy conversion devices: they turn potential (stored) energy into kinetic (movement) energy. In a conventional car, the energy is stored in chemical form, locked inside the gas you’ve pumped in your tank; you release it through a chemical reaction happening inside the engine in which the hydrocarbon molecules in gasoline burn with oxygen in the air to release heat, which pushes the pistons that turn the wheels (this all happens inside the engine’s cylinders, so we call it internal combustion). Electric cars also use stored chemical energy, though they release it electrochemically, without any kind of combustion, as electrons ping from their slowly discharging batteries; there’s no burning of fuel, no air pollution spewing from the tailpipe, and no emissions of any kind are produced by the car itself.
So…. electric car or gasoline? Both have their advantages; both have their drawbacks. That’s why many of the electric cars on the road today are actually hybrids that incorporate both technologies side by side: they have a smaller than usual gasoline engine suited to nippy highway driving and an electric motor for all that stopping and starting in the city.
Hybrids come in various different flavors. In parallel hybrids, the engine and the motor both send power to the wheels; in series hybrids, only the motor powers the wheels, while the engine simply drives the motor like a generator, recharging the batteries. Full hybrids have powerful enough electric motors and batteries to drive the engine independently, while in mild hybrids, the motor is too puny to power the car by itself and simply assists the engine (or allows it to switch off when the car is idle in traffic). Ordinary hybrids charge up their batteries using power from the engine and energy recovered from the regenerative brakes (which we’ll come onto in a moment); plugin hybrids can also be “refueled” from a charging station or domestic power supply, have much bigger batteries, and can be driven by the motor and batteries alone, so work more like conventional electric cars.
Whatever the coupling of engine and motor, the basic idea is to combine the best of both worlds to boost fuel economy. The big drawback of a hybrid is that its around 20–30 percent more expensive than a comparable gasoline model. It’s likely to be 10 percent heavier (despite is lighter engine, it has an electric motor, batteries, regenerative brakes, and all the rest) and have more sluggish performance. But hybrids score far better on both safety and fuel economy than gasoline cars, which makes them popular with eco-conscious families who prize their green credentials.
Cars powered by fuel cells are also electric, though they use tanks of hydrogen to generate electricity and power an electric motor instead of banks of batteries. You can read more about them in our separate article on fuel cell cars.
Gas-powered cars and electric ones have a great deal in common and the key differences are the stored energy they use (gasoline versus electricity), the machine they use to convert it into kinetic energy (an engine or an electric motor), and the way the stored energy powers that machine (through a gearbox and transmission, in the case of an ordinary car, but often more directly in an electric car). Let’s examine the two key components of electric cars—the motor and the batteries—in a bit more detail and compare them with what we have in a conventional car.
Motors are quite different from gasoline engines—and not just in the fuel they burn. An engine needs to spin round relatively quickly to work efficiently (usually thousands of times a minute), but a car’s wheels seldom need to go anything like that fast. The power an engine can produce at any given moment may be very different from what the driver needs. For example, if you’re moving off from a cold start, or a traffic signal, you need the engine to produce a great deal of force (torque as it’s called) at a relatively low speed, whereas if you’re overtaking on a speedy highway, you’ll need the opposite: more speed and less torque.
There’s not a great deal you can do to control the output from a car engine because it’s a chemical machine, driven by an essentially simple chemical reaction between fuel and oxygen that produces useful mechanical power. In that respect, an internal combustion engine is just like the external combustion engine you’ll find on something like a steam engine. If you want more power, you need to burn more fuel more quickly—a basic law of physics called the law of conservation of energy tells us that—which is why operating a car’s accelerator is informally called “stepping on the gas”: burning gas faster makes more power and ultimately delivers more speed. Apart from the accelerator (supplying more or less fuel), the other two key controls of a conventional car engine are the gears (transforming the power coming from the engine so the wheels turn quickly with low force or slowly with high force) and the clutch (briefly engaging or disengaging the engine’s power from the gearbox altogether). And we need the gears and the clutch because of basic limitations in how an engine works—as a machine that enjoys spinning around thousands of times a minute, however fast you’re driving (the engine keeps turning, burning fuel and costing money, even if you’re stopped at a traffic signal).
The motor in an electric car is very different: up to a point, it has no “preference” whether it spins fast or slow—it’s pretty good at delivering the same torque at any moderate speed. If you had an electric train set when you were young, you probably controlled the engine with a transformer that had a dial you could turn up or down. Starting off, you’d have the dial turned down low to make the train move slowly (by feeding a relatively small electric current to the motor inside it); you could go faster simply by turning up the current to make the motor spin more quickly. There’s no clutch in a toy train and (usually) no gearbox either: the electric motor drives the train wheels directly, and does so equally well whether the train is going fast or slow.
In theory, an electric motor can drive a full-sized electric car just as simply as a toy train, without the clumsy old gearbox and transmission you’d use in a conventional gasoline-engined car. In practice, electric cars are clearly more complex. Toys are small and move fairly slowly, while real cars are much bigger and go faster. When a real car corners, its two outside wheels are traveling around a curve of bigger radius than its two inside wheels but in exactly the same time, which means they have to spin slightly faster. (The same is true of toy cars, but the effect is too small to notice.) That’s why real cars need complex transmissions with speed-adjusting gears called differentials that allow one pair of wheels to go at a slightly different speed—faster on the outside of a curve, slower on the inside—than the other.
The same happens in an electric car when it goes around a corner, and that rules out any kind of simple transmission (for example, a single electric motor driving the two back wheels from a common axle). One solution is to have a front-located electric motor driving the same kind of transmission as an ordinary gasoline car, using a driveshaft (propeller shaft) and differential in the usual way. Another is to do away with the driveshaft and have a motor, gearbox, and differential unit between two of the wheels (either front or rear) and driving them both. A third option is to have two front or rear motors (with or without gearboxes), each driving one wheel independently. The final option is to use two or four hub motors (in-wheel motors), which are motors built into the wheels themselves. That raises a different technical issue: how to build a motor that’s lightweight, compact, and still powerful enough to drive a car (although if there are four hub motors, you need to generate only a quarter of the total power with each one).
Every car is an electric car inasmuch it uses a battery to get the engine spinning when you first start off. Historically, cars were the pioneers of rechargeable batteries. Long before we had laptops and cellphones, windup torches and all the rest, back when most of us routinely used batteries one minute and threw them away the next, cars were demonstrating the possibility of using batteries over and over again. The only trouble was, car engines used big and heavy lead-acid batteries that weren’t good enough to power vehicles at high speeds, over long distances, for long periods of time.
Today’s electric cars mostly use lithium-ion batteries, exactly the same technology you’ll find in your laptop or ebook reader. They’re relatively light, fairly good at storing useful amounts of power for their weight, last several years and hundreds of charges, and perform reasonably well at the varied range of temperatures most car drivers routinely encounter round the world (though not always that well in the extremes you can find even in hotter and colder US states). That doesn’t mean they’re perfect. The main problem with car batteries is that they still can’t carry as much energy as gasoline per unit of mass; in other words, they have a lower energy density. Lithium-ion batteries are likely to remain the popular choice for electric cars for the foreseeable future, though alternatives such as nickel metal hydride (NiMH), which are safer and cheaper, and other lithium-based technologies (including lithium-nickel-manganese-cobalt, lithium-phosphate, lithium-manganese, and lithium-cobalt) are also waiting in the wings. Supercapacitors (also called ultracapacitors) are another promising alternative. A bit like a cross between batteries and capacitors, they offer much faster charging times.
At first sight, electric cars are green cars: sometimes they’re even referred to as ZEVs (zero-emission vehicles)—and the official fueleconomy.gov website actually quotes zero grams of CO2 emissions per mile for most electric cars. Now while it’s true that the car itself makes no pollution and produces no CO2 emissions in the place where you drive it, it’s also misleading: unless your electricity comes from a wind turbine or a solar panel, some emissions are still produced in the process of electricity generation in a distant power plant somewhere). Even with that qualification, electric cars are no worse than the greenest fossil fueled cars—and that comparison will only get more favorable as electricity generation becomes greener.
Electric cars are considerably more efficient than gasoline cars because electric motors are inherently more efficient (about 80 percent) than internal combustion engines (a mere 30 percent for the engine alone, much less for an entire gas-powered vehicle), which waste a high proportion of the fuel they burn as useless heat. How do the figures work out in practice? The 2015 Volkswagen e-Golf Automatic A1 (list price $35,445) manages an average (city and highway combined) 29 kWh (kilowatt hours) per 100 miles (equivalent to 116 mpg) for an annual fuel cost of $550 per year, where a 2015 gasoline version of the same car (list price $17,995–$29,095) comes in at just 30 mpg for an annual fuel cost of $1300 per year. Tesla claim an even bigger difference: an annual 30,000-mile running cost for a Tesla Model S of $1,048 (at $0.12 per kWh) compared to a typical gas car’s $5,318 (based on $3.90 per gallon of fuel).
Hybrid cars achieve their higher efficiency and fuel economy largely by switching from gasoline power to electricity whenever it’s favorable, such as sitting still in heavy traffic. Where a typical car (a four-cylinder, 1.8-liter Honda Civic) driven by gasoline might achieve around 31mph, its equivalent hybrid (four-cylinder, 1.5-liters) manages a far more impressive 45 mpg (combined)—about 50 percent better.
It’s not just the engine that makes an electric car more efficient. With regenerative brakes, you’re not throwing energy away every time you stop and stop: the car’s electric motor becomes a generator so that when the brakes are engaged, the car slows down as your kinetic energy turns to electricity that recharges the battery.
David MacKay sums it all up neatly in his book Sustainable Energy Without Hot Air: “Electric vehicles can deliver transport at an energy cost of roughly 15 kilowatt hours (kWh) per 100km. That’s five times better than our baseline fossil-car, and significantly better than any hybrid cars. Hurray!”
Even in performance, electric cars sometimes outclass gasoline ones. As we’ve already seen, electric motors can produce high torque even at low speeds, which means they can accelerate more quickly than gasoline cars that don’t produce their peak torque until they reach relatively high engine speeds. They’re also quieter and smoother. As Tesla have demonstrated, there’s no reason whatsoever why electric motors and batteries—once thought of as dull, worthy, and rather plodding— can’t power racy, exciting sports cars. A Tesla Model S can accelerate from 0–60mph (100km/h) in just 3.9 seconds, comparable to a high-performance gasoline-powered BMW M5 (and in at least one test, by Automobile magazine, rather better).
Size is no obstacle for electric power either. Diesel-electric trains (in which diesel engines power electric motors that provide the traction) have been around for years. In November 2014, truck manufacturer BelAZ announced a super-powerful new 500-tonne diesel-electric mining truck in which four giant AC motors are powered by two 16-cylinder diesel engines.
Maintenance is also less of a chore, because electric cars are generally simpler than gasoline ones. According to a 2012 report by the Institute of Automobile Economics, electric vehicles cost about a third less to maintain than equivalent gas or diesel cars. Why? An electric motor is an inherently simpler bit of kit than a gasoline engine with far fewer moving parts to wear out; if it uses no transmission or gearbox, that makes the entire car simpler still. Even the brakes last longer, since regenerative braking means you need to use the conventional (frictional) brake pads much less than in an ordinary car. On the other hand, some of the technology used in electric cars is relatively untested, which means it could be more prone to early failure even if it is, paradoxically, simpler and theoretically more reliable in the long run.
Electric motors and batteries are the two main points of difference between conventional and electric cars. Where motors are well understood and highly reliable, giant battery packs remain the Achilles heel of electric cars. Despite its environmental and economic drawbacks, kilo for kilo, a tank of gasoline can carry far more energy than a bunch of batteries (see chart below)—and that will remain the case for the foreseeable future. You can completely refuel a gas-powered car in a couple of minutes (as long as it takes to fill up your tank) and drive several hundred kilometers on the energy you’ve pumped in without stopping. But electric cars can take anything from half-an-hour to a whole night to recharge (“fill up”) and, even then, probably won’t get you further than a couple of hundred kilometers before the batteries run flat. Where a gas tank is a relatively compact thing that sits neatly out of sight, the batteries in an electric car are expensive (about a quarter of the cost of a Tesla, which still works out at around $20,000, bulky, heavy, and take up room you might use for other things.
Everyone who owns a cellphone or a laptop powered by lithium-ion technology will be fully aware that rechargeable batteries don’t last more than a few years (even less if you treat them badly)—and they can fail with little or no warning. In an electric car, there are banks of batteries, not just one or two cells, so you’re less at the mercy of a sudden failure and more likely to find a gradual deterioration in range with the same charging time. Since batteries are so expensive and remain the biggest questionmark in electric cars, manufacturers have done their best to reassure buyers with warranties of around 8–10 years (or 100,000–125,000 miles). Research by the US National Renewable Energy Laboratory (NREL) suggests current batteries could be made to last 15 years and a 2013 meeting of the American Chemical Society heard that batteries might well last 20 years, which is probably the maximum lifetime of most cars. If that sounds impressive and reassuring, bear in mind that many of us buy our cars secondhand (already several years old) and it’s far from uncommon to drive around in a car that’s 10 years old or even more. Another critical factor is that battery life depends on temperature: using rechargeable batteries in hotter climates (which includes states like Arizona and California, if experiences with the Nissan Leaf are anything to go by) can halve their lives.
The higher energy density of gasoline and its relative cheapness are two key reasons why the world still prefers dirty, polluting gas-powered SUVs over clean, green eco machines like the Toyota Prius and the Nissan Leaf. But the sheer convenience of the “oil economy” is important too. Wherever you live, you’re never that far from a gas station. Figures for 2014 from the US Census Bureau reveal that there are some 121,446 gas stations across the United States. By comparison, according to the Alternative Fuels Data Center, there are merely 21,597 electric charging stations. Now while it’s true that you can charge your car at home (unless you live in an apartment block), or at work (unless your employer is fussy about your stealing electricity), and there are effectively millions of charging points, sometimes you also need to charge up when you’re on the road, and so far the world simply isn’t geared up for that: if you’re driving a car, it’s assumed to be a gas-powered one.
Having said that, range is nowhere near as big an issue for electric cars as critics like to claim: the US Department of Energy points out that most people’s daily commute involves a round-trip of less than 30 miles. Technically, the sky is the limit for electric cars: with help from onboard solar panels, future electric cars might manage 500km (300 miles) or more on a single charge.
While fuel and running costs are lower for electric cars, the initial purchase price is often considerably higher; the list price of a Honda Civic Hybrid is $24,735–$27,435, while the comparable gasoline model comes in at just $18,290–$24,590. Concerns about things like battery life also make it harder for people to take the plunge. Sticking with what you know is always easier than taking an expensive risk. Some countries offer tax breaks for electric cars, but you still have to face that higher purchase price to begin with
Green-thinking environmentalists tend to see this issue in black-and-white: if cars have a future at all (they would prefer more public transportation and greater use of local goods to reduce the need for transportation altogether), it must be an electric one. Even setting aside concerns about emissions, electric cars are certain to become more affordable and economic as oil supplies dwindle. The bigger the demand for electric cars, the more economics of scale will kick in. The more electric cars there are, the better the infrastructure will be, the bigger the choice of models, and the greater the likelihood of hardened petrol heads switching allegiance to the clean and green. It all sounds so very positive, so very inevitable.
It’s easy to fall for strident statistics celebrating the “astonishing” growth in electric cars (so many hundred percent this year, so many hundred percent next) until you remember that there are still very few electric cars around: 100 percent growth from not very much is not much more. An October 2014 article in Forbes speaks of “skyrocketing” growth in electric cars in the (US) states of California, Georgia, Washington, Michigan, and Texas. In Texas for example, it cites a 128 percent growth in electric cars in just 12 months, which sounds extremely impressive until you look at the actual numbers: there are now 6533 electric cars compared to 2862 previously, but that’s less than 1/1000 of the total number of cars registered in Texas (7.7 million is the newest official figure I can quickly find, for 2004, but it’s accurate enough to make the point). In California, where Forbes highlights 77,000 registered electric cars, there are still something like 18 million registered automobiles in total (again, that’s the 2004 figure), so even in the most fervently supportive state, the proportion of electric cars isn’t much better (four in a thousand).
People have been predicting the demise of the internal combustion engine, caused by our surpassing “peak oil” production, for over half a century (especially since the energy crisis of the early 1970s)—and we’re still surrounded by a billion gas guzzlers. Better car design and efficiency have extended the life of this old technology far beyond what many people thought possible. Is there any reason why, 40 years on, in the middle of the 21st century, we’re not going to find ourselves in exactly the same position: a few more electric cars on the roads but the majority of us still rattling round in gas-powered crates? According to 2014 predictions by the US Energy Information Administration, even by 2040, around 80 percent of cars will still be using gasoline. A mere 1 percent will be fully electric, 5 percent will be hybrids, and 4 percent diesels. Dramatic environmental damage—a sudden acceleration in climate change or its human impacts—could change everything, but so could a meteorite impact from space or a global epidemic. However rational the arguments in favor of electric cars, and however much environmentalists would like things to be otherwise, the world has a huge attachment to dirty gasoline technology—and that’s unlikely to change anytime soon.
Electric cars have always been radically modern; from Woody Allen’s Sleeper to the 1.21 gigawatt-flux capacitor that powered Marty McFly’s DeLorean Time Machine in Back to the Future, they’re the very stuff of science fiction. Yet they’re science fact too: Apollo astronauts, you might remember, were bouncing round the Moon in the battery powered Lunar Roving Vehicle (LRV) about 25 years ago. No-one knows if electric cars will ever play a dominant role in the future, but they’ve certainly had an interesting past. Here’s a whistle-stop tour of electric car history… so far. I’ve not covered every invention and inventor; just a few key milestones to give you a flavor!