We are sometimes asked about generators for survival, preparedness, and sustainable living. A good generator with a few gallons of fuel is a great thing to keep around in case of short (1-3 days) power outages, and for more common tasks like construction, but does it really make sense as a long term solution?
Whether you're planning for the Apocalypse or just want to be free from the grid, there are some things you should consider. Let's say, for five years, you are only going to run your generator for three hours per day- just long enough to keep the freezer and fridge cold. During those three hours, the generator will also run the well pump and oven so you can take care of your daily household hygiene and cooking needs. To meet these power requirements you will need at least a 4000 watt generator at sea level (higher elevations require a more robust unit due to decreased motor performance at altitude). The generator will require over 500 gallons of gasoline per year to run just three hours per day. The oil and oil filter must be changed every 50 hours (more during the break in period).
Ignoring the cost (which most of us can't do), you would need space to store the generator, 60 oil filters, 60 quarts of oil, and over 2500 gallons of gasoline (that's 50, 55 gallon drums, or 500, 5 gallon jerry cans). The fuel would need to be treated with something like PRI-G to keep it stable, and even then, 5 years is pushing it.
The above example is very limited, but it shows that, cost aside, storing enough fuel is a significant challenge, and keeping that fuel useable may or may not even be possible. We didn't even discuss the $11,000 + investment this would represent, or the need for spare parts, or what happens when the catastrophe lasts longer than the additives can keep the fuel stable, or the 73 decibel, “come loot me” signal you'd be sending three hours per day.
For these reasons, we consider generators great for short power outages and projects around the homestead, but absolutely terrible for any kind of sustainable living or long term survival.