During a power outage, a home generator is a great asset. It keeps refrigerated food cold, residents warm, and, of course, keeps the lights on. While a small electric generator can be bought for a few hundred dollars, one that will provide power to a house (in whole or part) is a big investment. There are many different types of emergency generators on the market; it's good to understand their pros and cons before you buy.
Diesel and Gas Generators Diesel generators or gas generators are generally used to power or provide light for work sites. Though they aren't designed to provide power to a home. With up to a 6000 watt outputs, the higher end models can provide some relief during a power outage. A gas or diesel generator is okay for plugging in a few lights or appliances for a few hours; just make sure to keep the generator outside as they produce carbon monoxide (an odorless gas that is very dangerous). The nice part about them is that they are portable and can be used for a number of tasks away from the home. The price, which will be less than most home generators, isn't bad either.
Natural Gas Home Generators These are the big boys; some can provide power to an entire house indefinitely. They run on either natural gas or liquid propane that is piped into the house from a municipal plant. This kind of emergency generator is permanently fixed to the outside of a house, not unlike a central air conditioning unit.
If your concerns are strictly to provide power to your home during outages, than these are the way to go. Since they have a direct gas line hooked into them, you don't have to worry about filling tanks. They are also set to turn on automatically when your power goes out, so you don't even have to turn them on.
Select Circuit
As the name implies, a select circuit home generator will automatically provide power to some, but not all, of your home's electric devices. The ones that get the power are determined before installation, and only those are connected to the generator. This saves money initially because the generator doesn't have to be as large, and it will save money as the machine is running as well by saving fuel. These will keep lights and appliances in important rooms (like the living room and kitchen) functioning for as long as the blackout persists.
Whole House Basically the King Kong of emergency generators, these are expensive to buy and to run. If you have the means, however, and want to be sure that everything in your house runs for as long as necessary, these are for you. They have liquid cooled engines like an automobile, and can produce up to 45 kilowatts of energy at a time. The price ranges from the $1000s to the $10,000s, but owning one will insure that you will never be left in the dark. Ever.

Jon Nunan is a freelance writer who draws on his experience in construction, ranging from landscaping to log home building, for his articles on home improvement.