This is the most common type of back-up generator. However, there are probably more cons than pros, see for yourself:
Pros:
- usually pretty compact
- can be used in remote areas
- cheaper up front costs
Cons:
- loud
- extra fuel costs
- lots of maintaining
- low power output
- needs refueling, sometimes even several times a day
This type of generator is only good for small things, like powering a fridge for a day, or powering some lights for a little while. They are also perfect for camping and running power tools in the field. It can't handle a lot, and should never be expected to.