Putting Electricity Where The Rubber Meets the Road

In-wheel motors improve fuel economy and safety

4 min read
Illustration: E-Traction Worldwide S.C.A.
A Different Spin: The motor’s rotor (green) turns about the ­stator (purple), driving the wheel’s rim (gold) and the tire.
Illustration: E-Traction Worldwide S.C.A.

In-wheel motors improve fuel economy and safety The electric motors in hybrid vehicles do a lot to save fuel and cut emissions, providing the push that gets a hybrid going from a dead stop and the extra getâ''up-and-go for rapid acceleration or hill climbing. They also recapture some of the energy that goes to waste every time a driver applies the brakes. But engineers would like to make hybrids even more efficient by further exploiting the electric motor's virtues. One way is to increase onboard electricity storage so none but the longest trips require turning on the gasoline engine at all. Another approach is to eliminate the losses that occur as the torque generated by the motor is transferred to the wheels.

Several companies are proposing to curb these losses by squeezing electric drive motors into the wheels [see diagram, "A Different Spin"]. Generating propulsion power right where the rubber meets the road makes a surprisingly big difference.

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We Need More Than Just Electric Vehicles

To decarbonize road transport we need to complement EVs with bikes, rail, city planning, and alternative energy

11 min read
A worker works on the frame of a car on an assembly line.

China has more EVs than any other country—but it also gets most of its electricity from coal.

VCG/Getty Images

EVs have finally come of age. The total cost of purchasing and driving one—the cost of ownership—has fallen nearly to parity with a typical gasoline-fueled car. Scientists and engineers have extended the range of EVs by cramming ever more energy into their batteries, and vehicle-charging networks have expanded in many countries. In the United States, for example, there are more than 49,000 public charging stations, and it is now possible to drive an EV from New York to California using public charging networks.

With all this, consumers and policymakers alike are hopeful that society will soon greatly reduce its carbon emissions by replacing today’s cars with electric vehicles. Indeed, adopting electric vehicles will go a long way in helping to improve environmental outcomes. But EVs come with important weaknesses, and so people shouldn’t count on them alone to do the job, even for the transportation sector.

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