You can buy a smaller generator, like a 5000 watt model that is fairly portable and can be kept in your garage until needed. To use it you will need an electrician to install a manual/transfer switch. Then you can use the generator to power those items such as a refrigerator, sump pump and furnace. Here's a link to explain more about them.
http://www.handymanclub.com/document.asp?cID=55&dID=795