The coal argument is a red herring: auto emission reduction and fossil power plant emissions reduction are two separate problems and are not necessarily linked by the idea of moving pollution from the local area to a remote area.

Auto emissions can easily be reduced by electric cars. Coal emissions, which are vastly more complex, can be reduced by scrubbers and switching to natural gas as interim solutions until, over time, the plants can be replaced by renewable energy and a smart grid.

One must remember that internal combustion engines are very ineffecient, wasting over 70% of their fuel in the form of emissions and heat. Electric cars, approach 80% efficiency.

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Lad says: "One must remember that internal combustion engines are very ineffecient, wasting over 70% of their fuel in the form of emissions and heat. Electric cars, approach 80% efficiency."

I like EVs and I'm a strong supporter of moving to a more green power infrastructure but EVs aren't quite that efficient. Least not yet.

EVs are only as efficient as the power plants providing the power and the laws of thermodynamics that govern ICEs also govern power plants.

Your local power plant's thermodynamic efficiency might be:

- in the low 30s if it's an old nuke plant
- in the high 30s to low 40s if it's an older fossil fuel plant
- in the high 40s if it's a newer fossil fuel plant that uses super critical steam
- in the mid to high 50s if it's a combined cycle plant

Even so, you're still going to have losses:

- going through the power lines to your house.
- going through the wiring in your house.
- going through the charger (converting electrical energy into chemical energy)
- going from battery to motor (converting chemical energy into electrical energy)

And then, finally, you're going to lose as much as 10% going through the motor.

You might even lose power in ways I'm not accounting for. For example, last year Martin Eberhard blogged that 25% of his Tesla's battery power went to maintaining its operating temperature.

Settng all that aside...

You also point out that a smart power grid allows us to better use our existing generating capacity. And that's something that you and I can both support.

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mister nomer ,
What about the cost of pulling the oil out of the ground, transporting it
half way round the planet , refining it , transporting it to point of sale , etc, when you
add all these up I would be surprised if the petrol engine reaches 10% efficiency !

Oh yes then there's that thing about wars in unstable parts of the planet , propping
up dictatorships that are abusing their populace , destroying the ecosystems in
areas like the niger delta , and don't even start me on the tar sands !

Yes I would take an electric car anytime , you guys just crack me up !

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It depends on your state's electricity generating mix how much comes from coal. I buy wind power for an extra 1 cent per kwh for my house. It costs me an extra $5 every month. When I get a PHEV or EV I will continue to buy wind power.

Btw there is a natural gas cogen power plant near my house that is 70% efficient.
http://www.mge.com/images/PDF/Cogen/Other/Cogen_FactSheet_TechSheet.pdf

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You can see your states electricity mix by going to this URL:
http://apps1.eere.energy.gov/states/energy_summary.cfm/state=CA

Copy the URL and change the state from CA to wherever you live.

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andrichrose - Easy there... = )

My post was merely about the word "efficiency", what it means depending on how you define it, and the differences between thermodynamic efficiency and electrical efficiency. It's a subject I find much interest in, but then that's just me.

If you're going to talk about the efficiencies and environmental impacts of oil production then we probably should also do it for coal and uranium mining and natural gas production as well. Together, they supply almost 90% of U.S. power requirements. Strip mining anyone?

And, if you're going to talk about those kinds of efficiencies then we should start talking about wheel-to-well efficiencies. ABG has covered these in depth. Lots of good comments too -- especially about the underlying engineering assumptions necessary to come up with those measurements which again is what I was trying to talk about in my initial post.

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Hi Paul,

Thanks for the DOE link. I'm just starting to go through it. With regard to the cogeneration plant being 70% efficient. Here's something to keep in mind:

The West Campus Cogeneration Facility uses a natural gas burning turbine (essentially a big jet engine) to burn natural gas to produce electrical power. Then they take the exhaust and use that to heat water. Then they use that steam to turn a secondary turbine and use leftover steam to heat the campus.

This is essentially a combined cycle plant. You burn natural gas in turbine and then use the exhaust to heat a working fluid - water - and use that to turn a secondary turbine.

The reason they're saying the efficiency is 70% instead of say something in the mid to high 50s, is that the West Campus Cogeneration Facility is counting the leftover steam in their calculation.

So, yes, 70% of the thermal energy is being used for something but the electrical power generation by itself is not 70% efficient. It's more like 55% of the thermal energy is being used to produce electrical power, 15% is being used to generate steam, and 30% is lost as waste heat.

Perhaps a better term here for them to use is "utilization" instead of "efficiency".

P.S. Please bare in mind that 55% is still pretty darn impressive and 25 years ago would've caused mechanical engineers to shed tears of joy.

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There's a good article in the IEEE spectrum about gas vs PHEV/BEV. It mostly focuses on grams of C02 per mile (taking into account well to wheel), which may be more important than efficiency:

http://www.spectrum.ieee.org/mar09/7928


Anyways, let's just hope someday we there are affordable solar panels and affordable electric cars. Then we can stop saying well-to-wheel, and start staying sun-to-wheel, or wind-to-wheel.

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To all you people whining that EVs will still leave an emissions footprint, what do you ride around in now?

A bike?

Because if you ride around in a car its a little hypocritical to complain about EVs needing sometimes dirty powerplants. The fact is the emissions footprint from EVs is still smaller even when the power source is coal. Add to that the fact that over the vehicle's lifetime (say 15 years) the amount of cleaner energy producers available will increase, while the dirtiest energy producers will decrease. If you want to keep driving your gas guzzler because EVs are yet 100% emissions free from point-of-source, thats fine, just know you're a hypocrite.

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Thermodynamic efficiency is important if you are using expensive oil/gas/coal.. but with nuclear?.. the vast amount of energy available in uranium vs. its low cost makes it not an important consideration. Perhaps it is economical to extract more power out of an existing nuke plant but not from a perspective of saving nuclear fuel.

If it was really important, coal could be made into a clean fuel..


..............................
EVs are only as efficient as the power plants providing the power and the laws of thermodynamics that govern ICEs also govern power plants.

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Keep that "theory" to yourself. In the US the most bland ugly cars are the ones that sell the most. Toyota has sold over 1.5million hybrids with the pruis being a top seller. What does that say about your "theory" that Toyota didn't want to sell too many. Toyota has itself admitted that it sells more hybrids when the car has a distinct design. This design by Mitsubishi obviously takes that into account.

FYI, the more automakers sell, the lower the costs and the higher the profit margin. Your suggestion that automakers would deliberately mass-produce models they wanted to under-sell is a little out of touch with reality.

And I'd by this imiev (especially the "sport") in a heartbeat.

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