# Mileage of a human on ethanol?
**URL:** https://boards.straightdope.com/t/mileage-of-a-human-on-ethanol/421317
**Category:** Factual Questions
**Created:** [October 2, 2007, 11:46pm UTC](https://boards.straightdope.com/t/mileage-of-a-human-on-ethanol/421317 "2007-10-02T23:46:49Z")
**Posts on this page:** 12
**Page:** 1
### Author:  [@The\_Controvert](https://boards.straightdope.com/u/The_Controvert)
#### Post date: [October 2, 2007, 11:46pm UTC](https://boards.straightdope.com/t/mileage-of-a-human-on-ethanol/421317/1 "2007-10-02T23:46:49Z")
From a caloric standpoint, how far does a human travel on a gallon of ethanol, and how does that compare to the most fuel efficient car that runs on ethanol?
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### Author:  [@Mangetout](https://boards.straightdope.com/u/Mangetout)
#### Post date: [October 3, 2007, 12:03am UTC](https://boards.straightdope.com/t/mileage-of-a-human-on-ethanol/421317/2 "2007-10-03T00:03:55Z")
Just to start the ball rolling:
1 US liquid gallon = 3.785 litres
3.785 litres of ethanol is about 4.79 kg of ethanol (density 0.79g/ml)
4.7kg of ethanol contains about 318,000 calories (7.1 calories per g)
Not sure how far that will get you (although if you put that much ethanol in a human all at once, it won’t go far at all).
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### Author:  [@Bagistan](https://boards.straightdope.com/u/Bagistan)
#### Post date: [October 3, 2007, 12:10am UTC](https://boards.straightdope.com/t/mileage-of-a-human-on-ethanol/421317/3 "2007-10-03T00:10:52Z")
It compares favourably.
According to [Energy efficiency in transport - Wikipedia](http://en.wikipedia.org/wiki/Fuel_efficiency_in_transportation#Humans), food energy consumption for human walking equates to about 1 litre/100 km of petrol energy consumption (\>200 statute miles per U.S. gallon). Ethanol energy consumption should be similar.
We’re better than Priuses, but worse than electric trains, but give us a bicycle and we’ll outperform even them.
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### Author:  [@Bagistan](https://boards.straightdope.com/u/Bagistan)
#### Post date: [October 3, 2007, 12:20am UTC](https://boards.straightdope.com/t/mileage-of-a-human-on-ethanol/421317/4 "2007-10-03T00:20:01Z")
[QUOTE=Bagistan]
We’re better than Priuses, but worse than electric trains, but give us a bicycle and we’ll outperform even them.
[/QUOTE]
I should add that this comment was based on the Wikipedia article’s table of efficiency
per passenger at average occupancy. We’ll walk further than the train itself will run on the same amount of energy in appropriate form.
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### Author:  [@The\_Controvert](https://boards.straightdope.com/u/The_Controvert)
#### Post date: [October 3, 2007, 12:20am UTC](https://boards.straightdope.com/t/mileage-of-a-human-on-ethanol/421317/5 "2007-10-03T00:20:49Z")
I guess a followup would be: how far could a human push a car using the calories from a gallon of ethanol?
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### Author:  [@Baffle](https://boards.straightdope.com/u/Baffle)
#### Post date: [October 3, 2007, 12:35am UTC](https://boards.straightdope.com/t/mileage-of-a-human-on-ethanol/421317/6 "2007-10-03T00:35:22Z")
For that matter, how does six humans walking (the max you can probably fit in a Prius if you use the trunk) compare to the fuel economy of the vehicle?
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### Author:  [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)
#### Post date: [October 3, 2007, 12:39am UTC](https://boards.straightdope.com/t/mileage-of-a-human-on-ethanol/421317/7 "2007-10-03T00:39:23Z")
Really you have to ask what is the amount of walking that a human can do after drinking a gallon of ethanol? The human isn’t going to convert it into a brisk walk, even if you spread it out so they don’t die. One step forward, four steps sideways, and crawl to the next bar. Add in the unfitness of people and I’d say they can get a lot farther using it in the car.
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### Author:  [@Xema](https://boards.straightdope.com/u/Xema)
#### Post date: [October 3, 2007, 1:20am UTC](https://boards.straightdope.com/t/mileage-of-a-human-on-ethanol/421317/8 "2007-10-03T01:20:01Z")
[QUOTE=Mangetout]
3.785 litres of ethanol is about 4.79 kg of ethanol (density 0.79g/ml)
[/QUOTE]
Shouldn’t that be 2.99 kg (3.785 \* 0.79) ?
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### Author:  [@Bagistan](https://boards.straightdope.com/u/Bagistan)
#### Post date: [October 3, 2007, 2:03am UTC](https://boards.straightdope.com/t/mileage-of-a-human-on-ethanol/421317/9 "2007-10-03T02:03:07Z")
[QUOTE=Baffle]
For that matter, how does six humans walking (the max you can probably fit in a Prius if you use the trunk) compare to the fuel economy of the vehicle?
[/QUOTE]
According to the aforementioned table in Wikipedia, a max occupancy Prius has about the same efficiency per passenger as walking. I assume this is calculated at five people per vehicle, though.
I wouldn’t take the fuel economy of humans listed in Wikipedia too seriously, though. The fact that it’s specified to three significant figures makes it seem somewhat unscientific.
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### Author:  [@Sigene](https://boards.straightdope.com/u/Sigene)
#### Post date: [October 3, 2007, 11:40am UTC](https://boards.straightdope.com/t/mileage-of-a-human-on-ethanol/421317/10 "2007-10-03T11:40:09Z")
Keep in mind that “calories” in a chemical thermodynamic sense are different then “Calories” in a food sense.
1 Food Calorie is equal to 1000 chemistry calories. (note the capital letter).
1 Calorie = 1 kilocalorie
Its confusing, and I hope the statistics and citations mentioned have already taken that into account.
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### Author:  [@Mangetout](https://boards.straightdope.com/u/Mangetout)
#### Post date: [October 3, 2007, 11:47am UTC](https://boards.straightdope.com/t/mileage-of-a-human-on-ethanol/421317/11 "2007-10-03T11:47:36Z")
[QUOTE=Xema]
Shouldn’t that be 2.99 kg (3.785 \* 0.79) ?
[/QUOTE]
:smack: Yes, you’re right - it was late.
There was also a decimal place error in my calculations somewhere, I think.
:smack: :smack:
Approximately 21,300 human-available calories in a US gallon of pure ethanol.
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### Author:  [@Bootis](https://boards.straightdope.com/u/Bootis)
#### Post date: [October 3, 2007, 12:12pm UTC](https://boards.straightdope.com/t/mileage-of-a-human-on-ethanol/421317/12 "2007-10-03T12:12:16Z")
[QUOTE=Mangetout]
:smack: Yes, you’re right - it was late.
There was also a decimal place error in my calculations somewhere, I think.
:smack: :smack:
Approximately 21,300 human-available calories in a US gallon of pure ethanol.
[/QUOTE]
Average standard calorie charts say walking a mile, for a 150lb person, at 2 miles per hour, burns 120 calories. So, 21,300 calories/gallon would get the average person about 178 miles/gallon.