# How much would the energy eq. of 1 gallon of gas cost in a PHEV
**URL:** https://boards.straightdope.com/t/how-much-would-the-energy-eq-of-1-gallon-of-gas-cost-in-a-phev/361840
**Category:** Factual Questions
**Created:** [June 23, 2006, 7:22am UTC](https://boards.straightdope.com/t/how-much-would-the-energy-eq-of-1-gallon-of-gas-cost-in-a-phev/361840 "2006-06-23T07:22:59Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Wesley\_Clark](https://boards.straightdope.com/u/Wesley_Clark)
#### Post date: [June 23, 2006, 7:22am UTC](https://boards.straightdope.com/t/how-much-would-the-energy-eq-of-1-gallon-of-gas-cost-in-a-phev/361840/1 "2006-06-23T07:22:59Z")
Does anyone see problems with my math?
Plug in Hybrid electric vehicles are supposed to hit the market soon. Here is what I calculate for the cost of the equivalent of gallon of gasoline.
Gasoline is 125,000 BTU/gallon of which 20% is converted to mechanical energy. so 25,000 BTU = 26,376 KJ. 1 KWH = 3,600 KJ. Assuming 85% of battery energy is converted to mechanical energy in a PHEV that means you need 31030 KJ of energy to get the energy equivalent of a gallon of gasoline. With electricity at about 9.5 cents kwh and you need 8.6 KHW of electricity, that comes to 82 cents for the equivalent of a gallon of gasoline.
[http://www.onlineconversion.com/energy.htm](http://www.onlineconversion.com/energy.htm)
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### Author:  [@matt](https://boards.straightdope.com/u/matt)
#### Post date: [June 23, 2006, 8:01am UTC](https://boards.straightdope.com/t/how-much-would-the-energy-eq-of-1-gallon-of-gas-cost-in-a-phev/361840/2 "2006-06-23T08:01:41Z")
I went a different route - assumed 1 US gallon of gasoline weighs 2.72 kg and contains 47 MJ per kg energy, plugged in your 20% and 85% assumed efficiencies, and came out with 8.3 kWh required, which is close enough.
So no, I see no problem with your math.
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### Author:  [@Wesley\_Clark](https://boards.straightdope.com/u/Wesley_Clark)
#### Post date: [June 23, 2006, 9:10am UTC](https://boards.straightdope.com/t/how-much-would-the-energy-eq-of-1-gallon-of-gas-cost-in-a-phev/361840/3 "2006-06-23T09:10:56Z")
Sweet. Electric cars will run on the equivalent of 80 cent a gallon gasoline.
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### Author:  [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)
#### Post date: [June 24, 2006, 3:09am UTC](https://boards.straightdope.com/t/how-much-would-the-energy-eq-of-1-gallon-of-gas-cost-in-a-phev/361840/4 "2006-06-24T03:09:31Z")
There’s a group in Palo Alto called the [California Cars Initiative](http://www.calcars.org/) that’s working on plug-in hybrids and their website also suggests an equivalent cost of under one dollar per gallon.