There are conversion kits out there, some dual and triple fuel. Haven't tried it, so I can't vouch for them. Just search for "generator propane conversion". Expect to spend around $200 - $300.

I have had a generator backup system in place and in use for almost twenty years. Your needs and your opinions may be different than mine, but I want to throw out a few things for you to consider.

1. Capacity. 17.5kW, or even 10kW, is a lot of juice, and it will need a lot of fuel. What do you really need for an emergency? We did the list then gave it some critical scrutiny. The only things we felt we had to keep powered were the boiler (oil-fired, responsible for heat and domestic hot water) and the refrig/freezers. We added a couple of domestic light circuits and a microwave. Result: we can make do with judicious use of a 3.4kW generator. Advantages: much less fuel usage, much less noise and much less expense. We don't rely on any 220v motors, so this works for us - if we needed to power a well pump, it'd have to be bigger.

2. Fuel and storage. Whatever you decide about size, think about fuel storage. IMO propane is the safest to store, but a big above-ground tank is an eyesore (BTDT). Gasoline, in any useful quantity, is a headache from lots of perspectives: fire safety (including local fire code and insurance issues), fuel rotation (even stabilized fuel doesn't last forever), etc.

3. Operation/maintenance. Unless you buy a commercial unit (and maybe even if you do), you need to make sure you are prepared to deal with maintenance and repair issues. Do you have enough of the right oil? Most small gas engines will use more oil than you'd guess in continuous operation, and you also need to be able to change the oil. Do you have spare spark plugs? Do you have spares for frequently-needed parts, and the ability to identify and replace those parts? Particularly if you buy a generator powered by a small gasoline engine, be aware that even the "commercial" quality units are not made for continuous operation in *critical* applications, and to the extent that you go down the chain in terms of quality that becomes even more true. All kinds of things break or need replacement...spark plugs, fuel filters, recoil starters, diodes in the generator, even the breakers in the transfer switch can go south just when you need them most and can't get replacements.

4. Other electrical issues. Make sure you factor in the current drawn by motors when they start,not just when running...but remember that some of them are (and all could be) in your control, so you can time when they hit the generator. Another issue: not all generators provide safe power for solid-state appliances, including microwaves, computers, etc.

Food for thought.

Two other things to think about:

1) Diesel fuel is essentially identical to #2 heating oil. You can add a tank simply to feed a diesel generator and not pay diesel fuel road taxes for a stationary application. Even better if your house uses oil heat.

2) Co-generation. This is using the waste heat from the radiator of the generator to heat the house. This makes more sense when building the house then when adding on a generator.

All good things to consider one more reason for the “want” of a large generator, is for my well. The pump is a 3 phase 5 horse. It has its own transformer to change from 220 2 phase to 3 phase so I don’t have worry about that but it is 40 amps or 8800 watts plus 5000 or so for regular load i.e. fridge, furnace, ect so I need 14000 watts or so but if I am going that big I might as well get one the will drive the 5 ton ac.

Yike. I know zilch about well pumps, is this typical?

Anyway, all I can say is that whatever you can do to reduce your energy needs will reduce both your daily operating costs and also the (size) cost of a generator to back it up. And, as has already been pointed out, keep in mind the amount of fuel you're going to have to have on hand to run the thing for whatever amount of time. I agree that propane would be the way to go (unless you've got some sort of large storage container for gasoline already, like an in-ground tank, that you're fueling your vehicles from). Good luck.

I guess it depends on what your philosophy of dealing with an emergency is. I read something in another forum yesterday about making sure the home theater system was working after a hurricane - that's a personal choice, but it wouldn't be what I'd try to do. In the next paragraph, the person wrote about how they had cars stopping out front of the house and had people coming inside looking for things because their house was brightly lit while the rest of the neighborhood was dark. I'm not sure I want to attract that kind of attention.

I think that you need a consultation with an electrical engineering firm.

Generac makes a very good generator. I know there are people that disagree with me but I prefer Diesel over nat gas or gasoline. Diesel has more energy per gallon than nat gas/propane and lasts longer in storage than gasoline. 17 KW is a lot of power, 10 KW is cheaper, goes farther on available fuel, and if you manage your enegy use will give you more power than you need.

17.5KW is way too much for any type of home emergency preparedness (if you can get unlimited fuel, it's not an emergency). Don't plan on running a whole-house AC system in a long-term power outage. If you absolutely must have AC, put a high efficiency window unit in one room and have everyone stay in that room during the hot parts of the day (it's not so bad). 1KW is enough for that. 17.5KW is for running a hospital or something like that.

I like the idea of propane because of storage stability and because gasoline may be very scarce and hard to hold onto. A 400lb propane cylinder is less likely to walk away.

Actually, what he is likely to need is a consultation with the state public utilities commission. <img src="/images/graemlins/grin.gif" alt="" />