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Personal Transportation Modes Waste Energy

personal transportation modes

Even if we go electric and driver-less, only 2% of energy used actually moves a person. We need better personal transportation modes.

We humans travel a lot, mostly by car. You will hear lots of talk these days about the future of the automobile. Will our cars be shared or owned? Will they run on gas, electricity or hydrogen? Will they be autonomous or human controlled?

Sadly, we are asking the wrong questions. Regardless of ownership, fuel or control, our legacy personal transportation modes waste an awful lot of energy. Here’s how.

Most of the energy used for personal transportation modes converts to thermal waste. For the average modern car, only 12% of the energy actually gets to the wheels in city driving, 30% on the highway. Of this actual “power to wheels”, 95% is used to move the car itself.

Consider the weight of a single passenger as a percent of the total car weight. It’s around (180 ÷ 3,700) five percent. So, for a compact car with a single passenger in the city, less then one percent (0.6%) of the energy is actually used to move the person.

Electric cars are much more efficient in turning energy into motion. But when you consider “well to wheel” efficiency and factor in losses associated with power generation, electric cars are only 2 to 3 times better than the internal combustion engine. Do the numbers, and you find that even with electric cars, only 2% of the energy actually moves the person.

Personal Transportation Modes – Mass Transit Fails, Too

Unfortunately, mass transit does not really improve much on energy waste, despite rhetoric. Policy makers talk about “passenger-miles per gallon.” These metrics are great when an urban transit bus or commuter rail is fully loaded. A full bus or train can achieve 4 times the efficiency compared to two people in a car.

But when average load is considered during the full day, the advantage disappears. Urban transit buses outside the rush hour are actually less efficient than cars. Commuter rail fares a bit better as it is electric.

Since we are so entrenched in the automobile, we are rushing to reinvent the car with alternative fuels, autonomy and ride sharing. This won’t get us very far, as the basic model is broken. Instead, we need to focus on using energy to move people rather than machines.

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