How much gas does a three cylinder motor use at 1000 rpm per hour?

Question

some one that i knew had a batter bank and a geo metro ran his hole house off of inverter said that his car would run for 20 days on one tank of gas at idiel , is there any truth to this?

Answer 1

I have no idea what a "batter bank" is....  Maybe that is a battery bank, I guess that makes sense.

Generally using a car engine to generate electricity is much less efficient than power from the power company.

Do the math, the 3 clyinder engin puts out maybe 50 horsepower at 1000 RPM.  That is about 37 kilowatts, if you had a way to get it.  A simple inverter can't handle that, and the alternator on that car can't handle that either.

A kilowatt hour cost about $0.08 around here.  So 37 KWHr would cost about $2.96.  Less than a gallon of gas.

This doesn't take into account that running a car engine at a low speed for long periods of time will be very bad for it.

I don't think there is any way it would be cheeper than the power lines.

Answer 2

A small car can put out maybe 50A from the alternator. This is about 1 HP, though at low speeds, engine probably using about 5 HP (and cooling fans, ignition, etc actually would use some of the electrical power, which I'm neglecting here).  At an optimistic 0.4lb/HP*hr of gas typical of gas engines used near their optimum specific fuel consumption, this is 0.34 gallons per hour. At $4/gal, this is $1.37 per 0.7 kW*hr, or $2 per kW*hr. My electricity costs 0.11 per kW from Gulf Power. He is paying (conservatively) 18x more. If he runs for several days on one tank, he must have an awfully large tank! I can confirm that a typical car can idle for something over 24 hours with a full tank (he must mean 20 hours, not 20 days).

If he has a sufficiently small energy demand, he could run it off such a system. However, no electric stoves/ovens, refridgerators, water heaters, A/C, washer/driers, heaters, toasters, or even many lights for such low power consumption.

If he can live like that, more power to him!

Answer 3

I refuse to believe a Geo Metro ran any significant length of time at 1000 rpm (without seizing up)...among many other aspects. Don't fall for it!