I have a lot of friends and other people visiting this site that are preparing for Urban Survival and have been in communication with me who have bought or are planning on buying gas or diesel powered generators for power after the collapse.
I urge caution here. A small generator, man portable (maybe even a 5,000 KW version) may make sense for your particular circumstances and Urban Survival Plan, however you are dependent upon fuel of course. I don’t know how long we could count on finding fuel after a collapse and any large amounts of fuel you store, even at a safe location, will have a fairly short shelf life.
Civilian fuels are not treated as military fuels are. Gas and Diesel will go bad. Even under exceptionally controlled storage, I would not expect non-treated fuel to last more than 12-18 months.
Gas breaks down, oxidizes and the lighter components will evaporate leaving a lower octane mix. There were be some particles that may clog up your engine or fuel filters. Diesel is sensitive to breakdown as well producing what people call algae or mold which is really a acidic type sludge residue.
If your gas is a blend of alcohol (gasohol) I have been informed by reliable sources that it will deteriorate even faster than standard gas.
This points to some problems you would have to solve to make a generator viable – gas storage, gas stock rotation and treatment.
There are some off the shelf fuel stabilizers that would come in handy, chief among them are:
Gold Eagle Gas Stabilizer, useable in 2 and 4 cycle engines. Eight fluid ounces treats 20 gallons of gas. Approximate cost is around $10 per 8 ounces.
Sta-bil Marine Formula, Ethanol compliant Gas Treatment, useable in 2 and 4 cycle engines and engines using ethanol. Advertised to keep fuel fresh for 12 months. Can be found in a 32 ounce bottle which would treat 320 gallons of gas. Can be used for two years after opening the bottle, which you may do as you probably have storage containers less than 320 gallons, therefore treat using one ounce per gallon of fuel. Approximate cost of $35 per 32 ounce bottle.
Star Tron SFF Diesel Additive would be a good bet for diesel fuel in storage which can be get “moldy”. Star Tron advertises that this additive can stabilize Diesel for up to two years, with one ounce treating 16 gallons. Reasonable costs at $10 a bottle.
A combination of routine replacement of fuel storage stocks and a treatment plan can make alot of difference. However, I would highly advise Urban Survivalists not to put all their eggs in one basket. I would consider fuel storage first to run vehicles, not generators, and work to use other, renewable forms of energy meaning solar and wind, for bigger static power needs. Look at portable systems that can be disassembled and re-located as needed.
A good site to visit for alternate power sources and solutions would be: http://www.solarpowerharness.com