Electric cars use twice as much oil as Diesel vehicles

Last updated on February 19th, 2018  

The vast majority of the electric power in the world is generated by oil, natural gas, or coal and it is this coal/oil/natural gas generated electricity that powers the vast majority of “electric” cars.

These “electric” cars consume far more oil, natural gas, or coal than a gas or diesel vehicle would for the same miles driven.

Rather than referring to coal, natural gas, and oil, I am just going to say oil. And I am going to compare a light duty diesel vehicle to a typical electric car.

Are you ready to be shocked?

Efficiency of Oil/Gas/Coal burning vehicles
(higher is better):

Diesel     47%
Gas        34%
Electric   18%

The percentages are the efficiency of a particular energy conversion process.

Generally energy conversion from one form to another loses some of the energy as part of the conversion process. Generally the lost energy is lost as heat.

When you have multiple steps in a conversion you multiply the efficiencies together to get the cumulative efficiency.

Oil or Coal burning power plants are 35% efficient at converting oil to electricity. Natural Gas plants are slightly more efficient.

Energy efficiency from the oil drum all the way through to the energy becoming mechanical energy meant to drive the wheels of the vehicle:

Diesel      47%
Gas         34%
Electric    18%
Electric Car Efficiency:

oil to electricity 35% -> transmission line 90% -> battery charging 85% -> battery discharging 85% -> through electric motor 85%.

So the potential energy in oil goes through:

0.35 * 0.90 * 0.85 * 0.85 * 0.85 = 18% efficiency to get through the electric motor

18% of the energy in a barrel of oil makes it through the electric motor.

Gas vehicle Efficiency:

oil to gas 90% -> transportation 95% -> through engine 40%

34% of the energy in a barrel of oil makes it through the gas engine.

Diesel vehicle Efficiency:

oil to diesel 90% -> transportation 95% -> through engine 55%

47% of the energy in a barrel of oil makes it through the diesel engine.

Relative energy output out the motor/engine in barrels of oil:

(this is relative mechanical energy at the output of the engine/motor needed to do the same work (produce the same amount of mechanical energy)) (which is simply the inverse of the efficiency times barrels of oil)

Electric Car: 5.5 barrels
Gas Car:      2.9 barrels
Diesel Car:   2.1 barrels

All these vehicles will go the same distance but the electric car uses around twice as much oil to do it.

Please note that light duty diesel cars and trucks in the US which use the SCR/DEF pollution control system are basically zero emission. (VW did not use the SCR/DEF system)

Please research the numbers yourself and plug in whatever numbers you find. The numbers you may find will not materially change the comparison.

In fact, I have been overly generous to the “electric” car. The real efficiency number for electric vehicles, which you can find for yourself, is much lower.

But Elon says

Elon Musk says that the energy used to refine oil could instead be used to power electric cars.

By where does the energy to refine oil come from?

In the vast majority of cases it comes from oil, or coal, or natural gas!

When electric cars make sense

Electric cars  make sense if you are running them on hydro, wind, solar or nuclear.

If you are going to run your electric car on oil, coal, or natural gas, you and the environment are far better off with a diesel vehicle.

But how can this be?

How can what I have written above be true given what everyone else says?

Follow the money. Those who sell oil, coal, and natural gas are happy to have you using twice as much of it.

What about the future?

If you have the choice of nuclear or hydro go ahead and use it for your electric vehicle.

If not save yourself and the planet by getting a diesel vehicle with a SCR/DEF pollution control system.

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