A generator is any device that produces energy. Typically when someone refers to a generator they mean either a gasoline, diesel, or propane electric generator.
Generators and Survival
The ability to have electricity after grid power has been lost greatly increases comfort and sometimes provides for critical needs such as a respirator of CPAP machine. A generator is the simplest way to produce this power. There are several considerations to make for this strategy to work, such as fuel storage and noise, but a generator can be implemented quickly during an emergency situation for short term use. If you want to be able to produce electricity during a long-term survival situation, you will want to consider an alternative power system.
Portable generators are smaller, mobile generator that usually use gasoline, although Propane and Diesel version are available. They produce less power and generally wear out faster than standby generators.
Standby generators are permanently installed generators that are wired into your home electrical system. They usually last longer and are more efficient than portable generators, but have a significantly higher purchase and installation price.
Generator Fuel Types
Propane/Natural Gas generators are usually implemented as a "standby" generator. Meaning that they are installed permanently and will automatically start when power is lost. Many prefer these generators as large quantities of LP are easy to store, especially if you already have an LP tank for heat and other utilities. Propane generators also generally run on natural gas, which eliminates the need to store propane for those connected to the grid. While the natural gas grid can fail, it is less failure prone than the electrical grid. How much propane to generate a KWh of power?
Gasoline generators are the least expensive and most common internal combustion driven generators, they are typically used in a portable configuration. They are quick and easy to set-up and use, gasoline is cheaper than diesel(as of 3/13/2008), and very portable. Unfortunately, gasoline generators are less efficient and wear out more quickly than most propane or diesel generators.
Diesel generators are almost as common as gasoline generators and are more common in the commercial sector. Diesel generators have much longer up-time between maintenance than gas, are quieter, more efficient, and can be run on many alternative fuels such as waste vegetable oil if modified. Diesel generators are commonly available as either portable or standby generators.