| Gasoline | Widely available at service stations. For portable generators, fuel is commonly stored in approved containers; gasoline has a limited storage life unless properly treated and maintained. | Portable models are widely available, and gasoline can be convenient for short outages or occasional use. | Stored fuel can degrade over time. Gasoline is highly flammable, and refueling a hot or running generator creates a serious fire risk. | Short-term backup, recreation, and portable use where fresh fuel is easy to obtain. | Store and handle fuel according to local rules and the generator manual. Shut the generator down and let it cool before refueling. |
| Diesel | Available through fuel stations and delivery services in many areas. Long-term storage requires suitable conditions and attention to fuel quality. | Diesel engines are commonly used for heavy-duty and standby applications and can be well suited to sustained operation when correctly sized and maintained. | Diesel generators can be heavy and noisy. Cold weather can affect starting and fuel performance; emissions and maintenance requirements depend on the model and its use. | Frequent or extended backup operation, work sites, and larger standby installations. | Consider cold-weather requirements, exhaust emissions, noise, maintenance access, and the generator’s rated output. |
| Propane (LPG) | Stored in approved cylinders or tanks. It does not require the same liquid-fuel storage approach as gasoline, but tank size and refill access matter. | Propane can be stored for long periods in a properly maintained, approved system. Some generators can use propane as one of multiple fuels. | Available energy depends on tank capacity and the supply system. Output may differ from gasoline operation on dual-fuel models; cold conditions can affect vaporization and performance. | Homes or sites with an existing propane tank, or users seeking a storable fuel option. | Use compatible equipment, approved regulators and connections, and professionally installed tanks where required. Check model-specific output ratings for propane. |
| Natural gas | Delivered through a gas utility connection where available; typically not stored on site for ordinary residential generator systems. | A connected standby generator can draw fuel from the utility supply without routine refueling from portable containers. | Requires a suitable gas connection and correctly sized supply line. Service interruptions can affect availability, and installation is more involved than for many portable units. | Fixed home or business standby systems where natural-gas service is available and dependable. | Have the gas supply and generator installed and checked by qualified professionals. Confirm local requirements and the generator’s natural-gas output rating. |
| Dual-fuel (gasoline and propane) | Uses either gasoline or propane, so the owner needs access to and safe storage arrangements for the selected fuel or fuels. | Offers fuel choice when one option is unavailable or less convenient. Propane can be stored in approved tanks, while gasoline may be easier to find in some situations. | Switching fuels does not guarantee equal power or runtime. The generator may need to be shut down before changing fuels; follow the manufacturer’s instructions. | Portable backup users who value fuel flexibility and can manage two fuel supplies safely. | Compare output and runtime separately for each fuel, and never connect or change fuels in a way that conflicts with the product manual. |
| Selection note | Fuel choice is only one part of sizing a generator. Add up the starting and running power requirements of the equipment you plan to use, check the generator’s rated output, and consider runtime, noise, emissions, installation, and local safety rules. Actual performance and fuel consumption vary by model, load, fuel quality, and operating conditions. |