I know gasoline is one of the most dense energy storage systems we have. I was curious, how much electricity would you need for the same energy in a gallon of gas? I did some checking, and found this site with some values and conversions. Further investigation (google) confirmed the numbers I used below.

According to the website, the amount of energy in a gallon of gasoline is 1.3x10^8 Joules.
I'll use the site's cost of 10 cents per kilowatt-hour for electricity.
The energy conversions section states 1 kilowatt-hour is equal to 3.61x10^6 Joules.
(1.3x10^8) / (3.61x10^6) = a little over 36, so there's 36 kilowatt-hours in a gallon of gas.
At 10 cents per kilowatt-hour, "filling up" on electricity would be $3.60 per "gallon".

ok, how about the powerplant efficiencies?
how much of he energy in gasoline does an internal combustion engine waste as heat, or idling?
how much energy does an electric motor waste?

If we're strictly comparing cost vs energy, I would be surprised if it were cheaper to use electricity vs gas.

However, where the real savings comes in, is a gasoline engine is only 30% efficient........ an electric motor is 90% efficient. So if we're powering an electric car, take the $3.60 and divide it by 3. = $1.20 per gallon equivalent.

quote Originally posted by lurker: ok, how about the powerplant efficiencies? how much of he energy in gasoline does an internal combustion engine waste as heat, or idling? how much energy does an electric motor waste?

Those are all important factors that vary wildly, and I wasn't trying to make a comparison of gas vs electric cars (way too many variables, including weight, distance on a "tank", performance (top speed, acceleration), etc, as well as the ones you stated). My point was, for the amount of energy you get in a gallon of gas, its cost is more reasonable than it first appears.

Edit to add: Gasoline can be run more efficiently than the 30% or so of a regular engine. Waste heat can be recycled via steam engines, stirling engines, etc. Here's one concept from BMW. It's not gasoline's fault it can't be used efficiently

[This message has been edited by kwagner (edited 07-17-2008).]

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[This message has been edited by JazzMan (edited 12-04-2008).]

Thanks for the link, I was just going to ask about something similar
I know there's those out there that have done EV fieros. I'd really like to know how much mpg you got when it had the gas engine, and how many miles you can go now with the electric one (plus how much energy your batteries store at full capacity).

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[This message has been edited by JazzMan (edited 12-04-2008).]

Thanks for the info this fiero shows a range of about 60 miles, and average 300 watt-hours per mile. Using the above comparison calculator, it's about 60% the price per mile of the gas one. It gets cheaper the more you drive.

Quick bit o' math:
300 wh = 1 mi (for the above fiero EV)
36 kwh = 1 gal (gasoline)
300 wh = 0.3 kwh
36/0.3 = 120
so, the gas equivalent would be 120mpg!

That's actually an interesting tidbit. Even though the EV gets the equivalent of 6x better mileage than my fiero, the comparison calculator said it was only 2x better per mile overall. Depending on the number of miles driven per year, indirect costs can really be a factor.

My work commute is now 5 miles one-way so even a (relatively) small amount of batteries could make a decent daily driver. The problem would be the conversion cost, and how many years it would take for it to pay for itself (aside from other benefits). I did, however, see this site: PoorMan's EV. Seems to do pretty good with such a small (and cheap) system, though I doubt I could duplicate it.

WHen they have to build more power plants to fuel our overnight plugged in cars, how much will the cost per kwh be? I would think it would rise. Also will these be nuke power plants.

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[This message has been edited by JazzMan (edited 12-04-2008).]

quote Originally posted by 2.5: WHen they have to build more power plants to fuel our overnight plugged in cars, how much will the cost per kwh be? I would think it would rise. Also will these be nuke power plants.

Just a guess but I would think that it would rise slightly to pay for the HUGE investment they just made (especially nuclear) and eventually lower to an overall lower price than before the plant opened.
and if its a newer design of reactor the above would probably be more exaggerated (more cost/cheaper energy)

I dont know what the difference would be with coal, I know if the AGW hippies get a hold of the coal plants that there will be no new ones ever built.

quote Originally posted by 4-mulaGT: I dont know what the difference would be with coal, I know if the AGW hippies get a hold of the coal plants that there will be no new ones ever built.

Oh, it does not stop there! They want to take away are hydro power dams here in WA. Can you inagine the cost of replacing one of those today?

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[This message has been edited by JazzMan (edited 12-04-2008).]

quote Originally posted by JazzMan: I'll be able to dig up some links for this when I get back Monday. JazzMan

Thank You

Hmmm... everybody ASSUMES electricity is cheaper. Maybe for now, but once everybody switches and "electrifies" their home and dumps their natural gas, propane, oil powered furnaces and appliances and similarly switch to electric vehicles - then what?? The old "supply and demand" phase will come up every month as electricity rates vary up and down with the seasons. But you will no longer have your $60/month (or whatever) electric bill you have now.

Whatever governments and business impose on you for "your own good" always ends up costing you more and ends up being FOR THEIR GOOD. Canada's a great example with the "Sin Taxes" on liquor, cigarettes, and now I suppose gasoline too with their "carbon tax". After they take more money out of your pocket, you see no benefits in the long run.

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3.4L S/C 87 GT www.fierosound.com
2002/2003/2004 World of Wheels Winner &
Multiple IASCA Stereo Award Winner

quote Originally posted by fierosound: Hmmm... everybody ASSUMES electricity is cheaper. Maybe for now, but once everybody switches and "electrifies" their home and dumps their natural gas, propane, oil powered furnaces and appliances and similarly switch to electric vehicles - then what?? The old "supply and demand" phase will come up every month as electricity rates vary up and down with the seasons. But you will no longer have your $60/month (or whatever) electric bill you have now. Whatever governments and business impose on you for "your own good" always ends up costing you more and ends up being FOR THEIR GOOD. Canada's a great example with the "Sin Taxes" on liquor, cigarettes, and now I suppose gasoline too with their "carbon tax". After they take more money out of your pocket, you see no benefits in the long run.

That was my point, my "hunch".

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[This message has been edited by JazzMan (edited 12-04-2008).]

quote Originally posted by JazzMan: Besides, with multiple ways to make electricity the potential for competition exists.

The enviros who are against fossil fuels are also against anything else that isn't wind or solar. They don't want nuclear plants for generating clean electricity, and would want to shut down power plants powered by coil, oil or natural gas, so the potential also exists for an electricity shortage and rolling brownouts. When I was in the Philippines, power and water would randomly shut down at any time - usually when it was least convenient (in the shower) - could very well happen here.

Also, not everything can be "electrified". It's unlikely you ever be flying in a battery powered airliner. Heavy industries like steel manufacture and others will still require natural gas for it's manufacture. While I agree "electric is the way to go" it's a long way from being the "solution to everything" for energy needs. The most efficient method of production is nuclear, but you won't be allowed to build any plants by the same people who stop you from using fossil fuels. I guess we're expected to switch to the Amish lifestyle.

What we need is a dilithium crystal mine in North America.

[This message has been edited by fierosound (edited 07-22-2008).]

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[This message has been edited by JazzMan (edited 12-04-2008).]

I guess everbody will start putting solar panels and windmills on their rooftop.

But you can bet once these start going in, cities will pass bylaws prohibiting them because they are an eyesore, cause glare blinding neighbours across the street - any number of reasons they can come up with. There's a reason you don't see the small satellite dishes on every apartment balcony or condominium rooftop. Bylaws of the complex or city.

For every solution, some level of government will come up with a problem.

quote Originally posted by ryan.hess: If we're strictly comparing cost vs energy, I would be surprised if it were cheaper to use electricity vs gas. However, where the real savings comes in, is a gasoline engine is only 30% efficient........ an electric motor is 90% efficient. So if we're powering an electric car, take the $3.60 and divide it by 3. = $1.20 per gallon equivalent.

I'm not sure that's entirely correct. _some_ electric motors are 90% efficient....most are not. Also, with any electricity source, line losses will also need to be factored in, along with the relative inefficiency of the electrical>>chemical>>electrical>>mechanical conversion processes involved charging the batteries (including the power it takes to run the power management systems). Line losses are anywhere between 5 to 15%, depending on the voltage of the line and the distance. The higher the voltage of the transmissions lines, the lower the line loss percent (but people generally tend to not want 500kV lines running through their neighborhood). Then, there's conversion losses in the transformers on the pole, etc, etc, so I would be surprised to see net efficiencies too much greater than what we have with gasoline/diesel (just an opinion, though).

quote Originally posted by fierosound: I guess everbody will start putting solar panels and windmills on their rooftop. But you can bet once these start going in, cities will pass bylaws prohibiting them because they are an eyesore, cause glare blinding neighbours across the street - any number of reasons they can come up with. There's a reason you don't see the small satellite dishes on every apartment balcony or condominium rooftop. Bylaws of the complex or city. For every solution, some level of government will come up with a problem.

Ya, "blight", more like "you can't have that you have to buy our power!"

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[This message has been edited by JazzMan (edited 12-04-2008).]

quote Originally posted by dsnover: I'm not sure that's entirely correct. _some_ electric motors are 90% efficient....most are not. Also, with any electricity source, line losses will also need to be factored in, along with the relative inefficiency of the electrical>>chemical>>electrical>>mechanical conversion processes involved charging the batteries (including the power it takes to run the power management systems). Line losses are anywhere between 5 to 15%, depending on the voltage of the line and the distance. The higher the voltage of the transmissions lines, the lower the line loss percent (but people generally tend to not want 500kV lines running through their neighborhood). Then, there's conversion losses in the transformers on the pole, etc, etc, so I would be surprised to see net efficiencies too much greater than what we have with gasoline/diesel (just an opinion, though).

The FB1-4001 is a commonly used motor for EV conversions and has an efficiency of 90%: http://www.electroauto.com/catalog/dcmotors.shtml

It's not special order or anything like that. 90% efficiency is pretty common. Charging systems as well can be 85-95% efficient. Line losses can be mitigated by using thick wiring (in car, not talking about power poles)

Technically, if we're talking overall efficiency, petroleum's 30% probably drops to 10% since it has to be pumped out of the ground, distilled, refined, pumped all over the place, trucked in, etc.

I figure when comparing costs, it's best to do it where you buy it. It costs 10c/kwh here. $3.99 a gallon.

[This message has been edited by ryan.hess (edited 07-22-2008).]

One thing to remember about efficiencies, when talking a system as a whole:
90% + 90% + 90% doesn't equal 90%. it's actually 72.9%, since they are multiplied together to get an overall (in this case vehicle) efficiency.

If we're going to consider the efficiencies of generation and transmission of electricity, we have to do the same for gasoline, which then results in an efficiency of less than 30% for gasoline.

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[This message has been edited by JazzMan (edited 12-04-2008).]