More Energy Efficienct than Gasoline Cars?

More Energy Efficienct than Gasoline Cars?

Hey guys, so I had a friend of my actually provide some valid points on why an electric car may not be or are equally as efficient as a Gasoline car. I know there are many variations of electric/gasoline cars, but let's keep it general. Here were his main points (please help me if i'm wrong in answer his questions):

Q) Power plants are inefficient at producing electricity in the first place, coal loses over 66% energy while the rest (nuclear, natural gas) are maxed at 30%ish energy efficient.
A) Yes, there is a lot of energy lost, however the fact we can use renewable energy (which accounts for around ~ 6% total energy and growing) makes this a better bet. Even with that much energy lost, the end result is efficiency that's much higher than gasoline.

Q) That's not the only loss, then there is loss accumulating from transferring that electricity from the Grid to your house (or supercharger, etc).
A) Minimal, at most it's 7%. (

Q) That's not it though, then there is power loss from transferring the electricity from your house to your car (converting from AC to DC?)
A) At most this loss is around 10-15% (

Q) Not only that but batteries in general have charging loss, along with 'self discharge' loss?
A) Very minimal for litium ion batteries (2-3%)

Q) And doesn't the electric motor have energy loss as well (drive train?)
A) Yes, but again it's minimal since bigger motors are much more efficient at converting electricity to kinetic energy.

But not only that, some of the energy lost is regenerated via regenerative breaking (up to 5%?)

It would be helpful if you guys can help me fill these in or add anything else i'm missing!



Mel. | 15 juin 2013

Lali, did you forget to put in the gasoline part?

PorfirioR | 15 juin 2013

In general terms, your friend is not making a valid comparison if his argument includes the energy consumed in producing and distributing electricity without considering the same on the fossil fuel side. Gasoline does not magically appear inside the gas tank - it has to be distilled, refined, transported, stored, and pumped at gas stations that themselves use energy.

I have seen reports that it takes between 4kWh to 7.5kWh to produce one gallon of gasoline (enough to drive as much as 30 miles in an EV). Even Nissan used to tout that when marketting the Leaf ( but later decided to pull the ads.

Also, on a different perspective, renewable energy has never been a reason to go to war with another country.

Jolinar | 15 juin 2013

natural gas power plant with combined-cycle achieves 50-60% efficiency

Brian H | 15 juin 2013

The big payoff is the transfer from stored energy to forward motion. An EV loses about 10%, a gas car about 70% to waste heat. So at that stage, the EV is 7X as efficient! That advantage is insuperable.

mammal | 15 juin 2013

The very comparison I think is flawed - efficiency in and of itself doesn't give you an adequate answer. Cost per mile or CO2 per mile are apples to apples comparisons depending on the question (there of course may be hidden costs and subsidies to get at true cost, other environmental issues and risks involved in say coal mining vs. oil drilling).

As BrianH suggests, efficiency is brought up in discussing EVs and electric motors to help understand how batteries that have currently much lower energy density can propel a car a to similar distance - miles per pound if you will.

negarholger | 16 juin 2013

How is gasoline made ?
- first grow plants with less then 0.3% efficiency using sunlight
- second wait millions of years to compress the plant matter in caverns
- third drill a hole and pump it out the crude
- then use 1 gallon of gasoline to refine the crude to make 3 gallons of gasoline
- at last put it in your car and use 20% at best to go from A to B, but spew out 80% as toxic gases, heat and noise in densly populated areas

There is hardly any more inefficient process...
... my advice is hang out with smarter friends.

olanmills | 17 juin 2013

It is true, a lot of energy is wasted between the source (like natural gas or hydro or coal) and the motion of your EV moving forward.

However, the same is true of a gasoline powered cars too, and generally it's worse.

AlfredG | 17 juin 2013

The simplest approach is to start with actual consumption data. A rough estimate runs about like this:
The Tesla Roadster will travel about 5-7 Km per kWh. An older coal fired power station (worst case) emits 1000g of CO2 per kWh generated. The Roadster will therefore emit mostly less than 200g of CO2 per Km. Within the accuracy of these figures we can ignore transmission losses of usually less than 10% and in both cases Co2 is not the whole story. Now compare that with any other similarly quick sports car, which are typically in the 300-400 g/Km range. Only very recently "sports-hybrids" have become available that can match this (expensive).
As now rarely all electricity is from coal, I know of no other way to better electric traction.
Consider perhaps also that there is a huge difference whether exhaust gases are blown directly into the poor city dwellers faces or whether these are emitted hundreds of Km away from a high rise smoke stack.

Brian H | 17 juin 2013

Exhaust gases in a power plant are controlled and filtered, far more effectively than a car can achieve. The smoke plumes so beloved of evirofreak photo collages are backlit steam. And the CO2 is eaten by downwind corn, which suffers a drop to about 0 ppm around noon, and has to wait for evening breezes to blow in some new supplies so it can start growing again.

evanstumpges | 17 juin 2013

Your friend did a pretty good job examining all of the areas where energy is lost in "well to wheel" analysis for an electric car. Technically, he could have taken it back one step farther with the energy required to mine/transport the coal before it is used at a power plant. I'd say 34% efficiency is on the lower end of the efficiency scale for a large coal fired powered plant. Newer plants can be upwards of 40% and cogeneration facilities can achieve well over 50% efficiency.

As others have pointed out, I think your friend may want to think equally carefully about where energy is lost in the process of turning crude oil into gasoline and transporting it (often around the world) to gas stations. Last time I did this type of analysis for electricity production in Iowa (about 3 years ago), I found electric cars to have a higher "well to wheel" efficiency than all but the very best eco hybrids like the Prius and Insight.

It should also be noted that efficiency isn't necessarily the most important factor to consider when looking for the most cost effective or green vehicle. There are many cases where less efficient vehicles cost less to refuel. In some cases, less efficient vehicles could even emit less CO2 depending on the carbon content of the fuel. And finally, efficiency can be much lower for a renewable energy system such as solar or wind, but does this really matter if it is cost competitive and much better for the environment?

The fact that electric vehicles can be powered exclusively by clean & renewable energy sources sets them far ahead of any ICE vehicle in terms of maximum "green" potential. For some customers, refueling electric vehicles from wind or solar is already a cost effective option. For others that time has not yet come, but there is little doubt in my mind that time will come as fossil fuel costs continue to rise over time.

lph | 17 juin 2013

Just as Brian said the electric motor of an EV has an unsurmountable advantage that over an ICE, however, the Ev is also the ultimate flex fuel car. It can run on coal, gas, gasoline, diesel, wood, plants, hydro, wind, nuclear and solar or if you can afford it even wine! It just needs the appropriate fuel to electric energy converter.
It also does not care where this energy is made. My home roof top collecting photons sounds just about right to me. No transportation costs and pollution.

xradr | 18 juin 2013

@ LPH -

I love it. "EV is the ultimate flex fuel car". In an oblique way, you are so right. Will have to use this one liner at cocktail parties!

TI Sailor | 18 juin 2013

We might also want to learn from history. See the following Wikipedia entry on the nationalization of private oil fields/reserves.

I personally would rather we keep most of our oil and gas in the ground, saving it for "rainy days" and non-fuel uses. One day or great-great grandchildren's grandchildren may ceremoniously thank us for our planning and foresight.

They might also be able to see blue skies and breathe comfortably.

TI Sailor | 18 juin 2013

Before Brian says it, please substitute "One day our..." for "One day or"...

Brian H | 18 juin 2013

Trying to guess which resources to preserve for descendants is a fools' errand. What ones from 1900 should our ancestors have been less wasteful of to save them for us? Their usage is irrelevant to us now; our usage now will be similarly irrelevant to our progeny.

RanjitC | 18 juin 2013

+1 Brian H. Brilliant as usual.

singh0833 | 20 juin 2013

Great ! Thanks a lot of all your insightful inputs, and I will surely relay that back to him for educational purposes.

jdepardo | 20 juin 2013

Your friend's argument about power plants doesn't apply here in Seattle, with hydrocarbons coming in at less than 1% of the fuel used to generate electricity. Hopefully, use of renewables will continue to rise in other cities...

emhcha | 6 juillet 2013

How an EV is powered
Coal (somewhat dirty)/Hydro (clean)/Thermal (clean)/Solar (clean)/Nuclear (clean)> power lines > Battery inside EV > Electric Motor

How an Internal Combustion engine is powered

Coal/Hydro/Thermal/Solar/Nuclear > electricity to power Offices to determine where to drill for oil > electricity to power drilling rig site + Camp to house all those workers > electricity to power Pipeline, tankers or ships to move oil to refinery site > electricity to power oil refinery to process crude oil > electricity to power another pipeline, tanker, ship transport stage > electricity to power a 24/7 gas station > electricity to pump into tank and then burn inside of engine

And you telling me that it’s worse than an EV that can use power directly from a power plant where it can use that electricity at 85-97% efficiency,

Where an ICE must use electricity first through several hundreds if not thousands of steps in order to produce gasoline which it can only burn with around 15-20% efficiency?

Where is your logic? (Directed to the challenged people that think EV’s pollute more)

tes-s | 7 juillet 2013

Simple economics provides the answer.

What is the fuel cost-per-mile of a comparable ICE?
What is the fuel cost-per-mile of an EV?

Remove all taxes and regulatory fees.

Another way to look at it is:
What are the CO2 emissions-per-mile of a comparable ICE?
What are the CO2 emissions-per-mile of an EV?

The answer for the EV will depend on the energy source (coal, oil, gas, hydro, nuclear, solar, etc). You can use a US average to get a general answer.

I think you will find that the ICE is at least double the EV in each category.