11,000 watt-hours equal about a gallon of gasoline

[esldude]

Was doing some pondering on relative energy needs when doing a conversion. It came to mind that I needed to know how much energy at the driven wheel from electricity equals that from gasoline. So taking into account relative efficiencies and energy contents of gasoline it works out to somewhere around 9000 watt hours will equal about one gallon of gasoline. When I look at watt per mile ratings of converted motorcycles or small cars this appears to be roughly correct.

This is a helpful short cut when considering conversions. If converting a motorcycle for instance that gets about 50 mpg, you will need 9000 watt-hours of battery storage to get 50 miles of similar performance. Of course this ignores an increase in weight that the conversion may cause. It still isn't off by much except in unusual circumstances it appears.

[Edited title to reflect a general electric motor efficiency of 80%.]

 

[Drunkskunk]

I think if I researched that right, its 9000 WH for raw gas. But an ICE gets 25% or so efficancy, so figure 2200 Watt hours of actual usable power.

 

[esldude]

25% is the number I used. 9000 w-hr's takes into account ICE inefficiency.

I actually went about the conversion more than one way getting similar answers.

One of the simpler ones is using Brake Specific Fuel Consumption which is typically around
.5 lbs/hp/hr for gasoline.

6.2 lbs per gallon. So 6.2/.5 gives 12.4 horsepower-hours per gallon.

One hp is of course 746 watts. 12.4 horsepower-hours times 746 watt/hp gives 9250 watt/hrs.
Or 9250 watt/hrs per gallon of gasoline.

 

[Link]

Gas has an energy density of 34.6MJ/l. That makes it about 131MJ/gal.

1Whr is 3600J.

131,000,000/3600=36,389Whr in a gallon of gas.

ICE about 25% efficient. 36,389/4=9,097Whr usable.

Motor about 80% efficient overall. 9,097/0.8=11,371Whrs electric equivalent.

So, if we have a car with a 1 gallon gas tank and a typical ICE, you'll need about 12,000 to see similar range between the two.

 

[truckerzero]

link i think you guys are off a little my idea is this.a typical electric generater puts out about 6,000 wh per gal of gas used so to figure out the wh at the engine crank we have to figure out the effiency of the generater motor and a 10 hp(7500 watt) engine makes 5600 watts of electric for a loss of 25 percent so if we take 6,000 wh plus 25 percent for the effiency loss of the generater motor we get 8000 wh pergal.One thing to keep in mind is a generaters ice engine is running at its peak effiency but unless a car is almost at its top speed its at a lower effiency because a ice engine is at its peak effiency when its almost maxed out anything less is less effiencent this is why a car with a smaller engine like a 4 banger instead of a six in the same car gets better milage even though the car still takes the same amount of energy to go down the road. see the 4 banger will have to work harder and therefore be closer to its peak effency.Think back to all the cars you owned and i bet the one that only toped out at 70 to 80mph was also the one with the best milage

 

[Link]

I'm using fudge factors for the efficiency, but I should be close to the actual battery equivalent to a gallon of gas.

Also, I'm only 16. I've never owned a car. It's quite likely that I will never own an ICE car, either .

 

[truckerzero]

e vehicls get pricy plan on doing a conversion for your first car/truck link

 

[Link]

Naturally. I would accept nought else !

 

[truckerzero]

cool i hope to atleast get a nice motorcyle project going by this winter i was thinking a harley sportster with a d and d motor lead acid batterys but when im done i want battery boxes that can cover the batterys and be chromed and make the battery cables look like those braided lines you see on custom hot rods you know make a e motorcycle but give it that harley chrome all tidyed up look

 

[HAL9000v2.0]

IMO you should add energy used to produce and transport 1L of fuel.

 

[Link]

Too subjective. It'll vary wildely depending on where you live, and probably won't amount to very much considering how much is transported at once.

Plus the logical extent of that would be to include the entire infrastructures of both fossil-feuls and power companies. Not something I'd care to work out. :?

 

[truckerzero]

5000 gal of fuel wold take less than 100 gal to deliver and thats based on 500 mile distance most of the time it is less

 

[CGameProgrammer]

This exactly demonstrates why series hybrids are important. Even if you cram so many batteries onto an EV that you actually have 12000 Wh (even after factoring in the Peukert effect), it would take you days to recharge! Whereas it takes 6 seconds to put one gallon into a tank, and the engine can generate the power from that gallon as you drive.

Of course I like EVs better, but hybrids are way more practical than battery-powered EVs and always will be!

 

[esldude]

Yep, I did neglect the inefficiency of the electric motor itself. So yeah some 11,000 w-h or so to equal
one gallon of gasoline.

 

[esldude]

This exactly demonstrates why series hybrids are important. Even if you cram so many batteries onto an EV that you actually have 12000 Wh (even after factoring in the Peukert effect), it would take you days to recharge! Whereas it takes 6 seconds to put one gallon into a tank, and the engine can generate the power from that gallon as you drive.

Of course I like EVs better, but hybrids are way more practical than battery-powered EVs and always will be!

Not sure I understand this. Some Trojan lead acid batteries hold 1200 watt-hours. So ten of those is 12,000 w-h. That isn't so much as to be unworkable. And charging those will only take a few hours. Sure a few seconds will replenish far more energy with gasoline. But for many day to day trips EV's are adequately practical.

I also once thought series hybrids were the way to go. But really it looks upon closer inspection that parallel hybrids will have an efficiency edge. Generating electricity involves an extra step of energy loss to then turn it back into energy with an electric motor when you can just let the ICE provide the energy directly and then augment or replace the ICE at times with the energy from the battery.

 

[CGameProgrammer]

OK, I was wrong about needing "days" to recharge, but the lead-acid version of the EV-1 stored 18700 watt-hours and took around 8 hours to charge, according to Wikipedia. 8 hours vs 9 seconds for the equivalent amount of gas.

 

[ngocthach1130]

You guys are looking at it wrong. When you fill up gas you're not actually recharging. More like replacing what is gone, adding more in a sense. To be able to get an electric equivalent to pumping gas would be swapping out the battery at the gas station...er battery station. If you were to try and get a gas equivalent to recharging battery would mean the fossil fuel production process. That takes millions of years. So recharging is a pretty marvel process considering the gas equivalent take a few million years and we're taking a few hours.

 

[truckerzero]

on speed of recharge the new supercapacitors can be charges as fast as you can feed them electricity so just a few seconds or minuts are more than passable but the energy density are not there yet but if it were to get there it would change ev cars forever if you could charge your car in 5 miniuts and had plent of charging stations a 50 mile range would be no big deal ps supercapacitors have a cycle life in the hundreds of thousands so buy it once and buy it for life .uh wait thats another companys slogan hope i dont get sued.

 

[CGameProgrammer]

You guys are looking at it wrong. When you fill up gas you're not actually recharging. More like replacing what is gone, adding more in a sense. To be able to get an electric equivalent to pumping gas would be swapping out the battery at the gas station...er battery station. If you were to try and get a gas equivalent to recharging battery would mean the fossil fuel production process. That takes millions of years. So recharging is a pretty marvel process considering the gas equivalent take a few million years and we're taking a few hours.

A gallon of gas costs $4 right now in the U.S. A 12 kWh battery pack could be $9000 or more. An even larger difference! So I don't think anyone will be swapping out batteries at a gas station any time soon. And you can't sell the old one for the same price as a new one since they degrade so a literal swap cannot be done for a low price. Therefore battery swaps will never happen.

 

[truckerzero]

a 12 volt 110 ah battery contains 1200 watts and costs 70 dollars x 10 =12k and would only cost 700 dollars sice you get 200+ cycles thats 3.50 a cycle 3.50 plus a 20% profit for the swapping station =4.30 round that to 5 bucks 5bucks a swap and 30 miles per charge = equivalant to 5 bucks a gallon in a 30 mpg car gas prices get any higher and it makes it possable only one problem if any alternative energy idea gains traction and they will drop the gas prices through the floor by uping oil production and every body will switch back to gas and the cycle will start all over so untill we actually run out of oil things will never change because OPEC controlls the price of oil by variing the production of oil and they seem to have gotten all the middle east producers on board and working together as a team and thats why they have been so successfull at running oil prices up
i think they are all pissed at bush and look at america as a common enemy and are all working together at the moment but a change in administration and attatudes tword america and they will get greedy(certan contries)break the production limits set by OPEC to try to make a little more money for them selvs and as production goes up the cost will come back down at least thats what im hoping for cause even if i had lots of ev's im still a redblooded american who likes loud noise making toys ie corvetts classic cars and harley davidson motorcycles

 

[safe]

...as production goes up the cost will come back down at least thats what im hoping for...

There are some things going on...

The overall demand for oil is headed straight up because of the demand from India and China.

The oil supply has "peaked" and we can expect that it will start a long slow decline.

There is a speculative boom in the oil markets that is driving the price up above the overall trend line. (think dot.coms, then housing, then oil)

So don't be fooled. The price will drop sometime soon because of the "bubble" ending, but the overall trendline is going to be up and up and up. It's simple supply and demand, there is increasing demand when the supply is decreasing.

The past "cheap oil" will never come back... it's over...

 

[truckerzero]

the india and china thing is deffanetly effect but remember there was a oil shortage and everyone thought we were going to run out in the 70's and 80,s but i guess we will have to see

 

[esldude]

Yes, but the shortage in the 70's and early 80's was purely political. It was the Arab oil embargo. They stopped shipping oil to make their point. It wasn't for lack of supply.

While there is a 'bubble' in oil markets, it is also true there is now a limiting supply versus the growing
demand in the near future. So this is very different from the 70's and 80's.

As Safe already said, cheap oil is gone, and won't be coming back.

 

[TylerDurden]

Big-oil will keep the price low enough for most folks to be wary of other options, until they (B.O.) own the other options.

 

[Dr. Shock]

The oil supply has "peaked" and we can expect that it will start a long slow decline.

A lot of OPEC producers have been lying about their reserves for decades, because OPEC apportions the percentage of the total oil to be pumped based on a member's stated reserves. This makes me think that the reserves are actually much lower than we're led to believe and we'll soon see substantial unexpected decreases of supply as well as increased demand.