A Power Portfolio

摘要

At first glance, hybrid car economics just don't make sense. A conventional engine costs about $70 per horsepower—or, in electrical units, about $50 per kilowatt. Now add the extra cost of going hybrid: The power electronics required to convert horsepower to kilowatts run $6 a kilowatt, battery packs add another $25, and then you need electric motors, at $15 a kilowatt, to turn electricity back into shaft power to drive the wheels. For an SUV these and related electrical parts are going to run something like $5,000. Why pay for all that extra hardware when it ends right back where it began, in the mechanical power of a spinning shaft?