Why an electric motor is used in hybrid cars

[russ_watters]

I know I'm late, but...

As you've now taken MPG and MPGe which are comparable, as they are tank-to-wheel numbers (inc. charging loss which is acceptable to include). Then applied a factor that is then taking into account upstream efficiency on the EV but not on the conventional fuel.

Don't the upstream efficiency numbers of the EV exclude the same mining and refinement that the conventional fuel do? In other words, isn't the natural gas used in a gas turbine identical to what powers your stove? And isn't the fuel oil used in a power plant similar in its refinement to what is used in a car?

You've also got to be to be very careful about where you getting figures from.

So all we can safely conclude is: it is difficult to conclude anything just from a numbers exercise.

Understood, which is why for my purposes I tracked my fuel economy with a spreadsheet and made calculations based on my driving patterns to help decide if (not) I should by a hybrid or a regular gas car.

 

[russ_watters]

I would highly recommend that everyone ignore this comment.
As one of my hero's says; "We blow things up, so you don't have to."

I performed this experiment on my last vehicle, where if I thought I was going to be sitting for at least 20 seconds, I shut off my engine. My starter lasted a week. It may have been a coincidence, but I don't think so. Starters on regular vehicles are simply not designed to start your engine every 5 minutes.

Well, it isn't like I have the persistence to do this on a regular basis anyway, so I'm sure I'll be fine.

Unless you turn a gas engine off, it is using gas.

Didn't you say a while back that you'd purchased one of those fancy aftermarket fuel consumption gauges? Does it read out in gallons per hour? Or liters per minute. I really need to get one of those.

Yes, I have and it does. Once warmed-up, the engine does not use gas when coasting. Which therefore also means the fuel economy increases markedly when the engine is warm.

At idle, it uses about 0.5 gal/hr which if the car runs at 30mpg highway is 1/4 of highway fuel consumption at 60mph. That's an awful lot of gas wasted idling!

 

[russ_watters]

If your calculation continues upstream from the tank (battery) back to the well (power station), then it should be done on both sides. An actual gallon of gas has to be transported and refined (10-20% energy overhead).

As I asked-of Chris, doesn't a gallon of oil used to generate electricity also need similar refining and transporting?

 

[mheslep]

As I asked-of Chris, doesn't a gallon of oil used to generate electricity also need similar refining and transporting?

Sure, but then oil fired electric generation is less than 1% of US generation and falling. By contrast no refining step is required for natural gas.

 

[SteamKing]

When oil-fired generating plants were in operation, the fuel did not need to be highly refined like the motor fuels used in cars and trucks (i.e., gasoline and diesel). In fact, the residual fraction from the refinery (what was left after the gasoline and diesel was produced) was used for firing generating plants and for large ships which used heavy fuel oil for large steam or slow speed diesel propulsion plants. To be sure, the residual fraction was not used solely for fuel, but it was a by-product of the refining process.