Hybrid Electric Cars like the Volt Still Need the Trusty Internal Combustion Engine
Of course, electric cars are the future; manufacturers left and right are jumping on the electric bandwagon, and people are wondering where this leaves the old internal combustion engine. Actually, in an all-electric world the internal combustion engine, redesigned and revamped for service in a supporting role, would still be very important. The supportive role is in evidence in a car like the Chevy Volt. The way battery power works on the Volt is in some ways the opposite of what happens on a Prius. The gas-electric hybrid Prius runs primarily on a gasoline-fired engine; the battery and the electric motor only step in when the car runs very low speeds. The electric-gas hybrid that the Volt is, it runs on a battery-powered electric motor at all times, and only keeps a gasoline-fired generator at the back, to keep the battery pack charged should it run out after 40 miles. The Volt is the first of a line of real hybrid electric cars. The gasoline-fired generator doesn't have anything to do with turning the wheels. It is a low-speed engine locked in one setting, to provide the most efficient charging possible, is all.
This is a huge change of philosophy over the way things were done even recently. Better fuel efficiency has always meant tweaking the engine, designing more camshafts or valves for better ventilation; electronics and electricity only came in, finding better ways to control combustion and acceleration more efficiently. So much effort and love put into taming the internal combustion engine, all come to this - running at a set optimal speed, to turn a generator. They don't even get to turn the air conditioner or the power steering. They call such an engine on hybrid electric cars, a range extender. The Volt for instance, uses a four cylinder 1.4 liter engine borrowed from the company's models in Africa, Europe and Asia. Keeping the batteries charged on a Volt needs no more than 50 or 60 horsepower. Ordinarily, a 1.4 liter engine would not be very fuel-efficient if it drove the car by itself.
But every engine has an optimal point, a low speed where it will generate the most power for the least fuel, with the least noise and vibration. It is usually somewhere around 2500 rpm. Once hybrid electric cars with range extenders really take off, there will probably be dedicated engines built just for battery charging, and they will probably be half the size of what they use now. Early reviews of the Volt suggest that when the battery runs flat, the range extender engine can be pretty noisy when it kicks in. Pretty soon, lithium-ion battery pack technology will advance far enough to require less and less charging. Until then, the internal combustion engine, still travels with us wherever we go.