tl;dr What is a likely value for fuel consumption for a small portable 4-stroke gasoline-powered inverter power generator in, say, litre / ( kilowatt * hour )?
At times I attend music festivals where you camp outside for a few days and go see bands perform in the afternoon and evenings. Some of them permit the use of power generators, and I got myself one as described above rated for max. 1000 watts continuous power draw. My group won't use that much, but that's what I got when I aimed for the smallest 4-stroke inverter model.
Among my questions is now how to estimate the amount of fuel to bring with me to a given event, and unfortunately the spec sheet and other resources shipped with the unit do not feature any fuel consumption figures/curves/tables.
I do have a rough estimate of the power draw and duration.
Typically the power generator will be run from the morning into the afternoon, let's say 08:00..14:00, which is when people hang out at the camp site killing time until the bands start. From afternoon on it's seeing the bands until late into the night, after which people come back exhausted and in various stages of inebriation and usually just drop into their tents – running a generator at that kind of time is a jerk move that is guaranteed to bring the rightful wrath of your camp neighbors upon you.
While the generator is being used you will run a fridge for the drinks, some music setup for nice tunes, and a bunch of small power supplies charging various devices such as smartphones and power banks. If you're fancy you might have a table fan for when it's really hot. So let's add these up:
- 80 W - (small) fridge
- 50 W - music
- 5 * 10 W - smartphones etc. being charged
- 40 W - table fan
That's 220 W of continuous power draw (the fridge will be running its compressor continuously because it starts out warm and is made extensive use of). Multiply that with the 6 hours of daily use and we get about 1300 Wh, and if the festival lasts for 4 days we're at about 5300 Wh, or 5.3 kWh, drawn at roughly a quarter of the generator's rated output.
So … how much gas does that roughly equate to? I have been searching around for some ballpark figures, but I only seem to find various tables that are too specific and not readily applicable to my problem.