There are three choices of fuel to run a *stationary, standby emergency generator; diesel, LP (Propane) and natural gas. How do you choose? Great question. After discussing this dilemma with commercial facility owners over the past 16 years, I’ve come up with the following list of benefits and/or Pros & Cons of natural gas vs LP Propane vs diesel generators

Diesel Generators Pros:

• Least expensive first cost… unless you’re looking for a Tier 4 non-emergency generator for use in a utility program.
• Good variety of sizes. You can find diesel generators from 10kW up to 3,000kW
• Can be installed anywhere
• Safety codes (hospitals) requiring fuel to be stored “onsite” make diesel the only option in many circumstances.

Diesel Generators Cons:

• Dirty/sooty on startup – cars and buildings down-wind can be affected by “diesel rain” and a poor (smelly) choice for private homes.
• High “hassle factor” – those were the words of an energy manager I spoke with who managed the generators for some 2,300 discount retail stores. What he meant was that the diesel engine generators caused him the most grief of any other piece of equipment he was responsible for.
• Prone to fuel related issues. Diesel fuel can’t be stored indefinitely. Depending on where you live, it might be years before you burn through a tank of fuel.
• In a large/long emergency, you’re limited to the amount of fuel you have on hand.
• Very limited availability of Tier 4 (non-emergency) rated engines – some manufacturers don’t offer any.

Natural Gas Generators Pros

• Clean, low cost power. No more smell than what you experience from your gas range.
• Good availability of sizes – same range of kW’s as diesel from manufactures like Generac.
• Best choice for homes, condos, apartments – anywhere people live.
• Unlimited fuel supply during long emergency outages. Did you know that Natural Gas is the most dependable of all utilities? 
• Meets the EPA emissions requirements for non-emergency operation = a popular choice for participation in Duke Energy’s or Tampa Electric’s generator programs.
• At current rates, natural gas converts to ~$0.08kWh electric, roughly the equivalent of Florida electricity costs. You aren’t spending any additional dollars when you’re generator is powering your facility.
• The huge natural gas reserves equate to stable, long term pricing.

Natural Gas Generators Cons

• Requires natural gas service from a utility.
• Additional installation costs if gas service is on the opposite side of the building
• More expensive than diesel for the same size power.

LP – Propane Generators

• The alternative to diesel, when natural gas isn’t available.
• Limited to ~150kW in size.

*What about a portable generator? 

Because the fuel has to be as portable as the actual generator, diesel tends to be the best choice. Yes, theoretically a portable generator could be powered by LP, however to have enough fuel for a reasonably long run-time, the physical size of the tank  Small, portable generators are almost exclusively gasoline powered.