Everything you need to Know About Different Fuel Types

As the electricity grid rapidly ages and as the threat of cyberattacks on the power grid looms increasingly larger, power outages may increase in frequency and duration.

Short-circuits along power lines, transformers and substations in the power grid may result in the disconnection or severance of the electrical connection, thereby resulting in an interruption of electric service for end-users of electric power. It is no surprise that an increasing number of homeowners have decided to invest in whole-house power back-up solutions, including residential standby generators to ensure the supply of electricity at all times to their homes. These residential standby generators, which are generally powered by an internal combustion engine, supply power to a part, or the whole, of the household during the power outage, thus ensuring that at least some parts of the house continue to have electricity even during a utility power outage.

4 Fuel types

Fuel type is important when choosing the right generator for your backup power. The most common fuel types for powering whole-house back-up generators are natural gas, diesel, propane and gasoline. Each fuel type has advantages and disadvantages. This article will walk you through what to consider when choosing the fuel type for your generator.

Natural gas

Natural gas has several advantages as a fuel for a residential standby generator. Natural gas is a clean burning fuel and generally the choice of most residential standby generators in states that are strict emission regulations. Natural gas is also transported around the country and to individual homes though pipelines. This makes natural gas a convenient choice since the procurement of the fuel can be made through local gas distribution companies and does not involve the homeowner having to transport the fuel and refuel a generator tank. While this infrastructure is convenient for the majority of the time, in the event of a natural disaster, the pipeline infrastructure could become compromised, leaving you without the fuel you need to power your generator.


Propane is a fuel that has properties that are very similar to natural gas (natural gas is primarily methane). Unlike natural gas, which is available to households through gas pipelines, propane is available in compressed gas cylinders and is widely used for cooking in the US. Residential standby generators that are fueled by propane are similarly connected to propane gas cylinders. Propane has a long shelf life and the propane cylinders are generally widely available and easily transportable. However, propane is not as convenient a fuel as natural gas because propane cylinders have to be replaced by the homeowner after use. Propane is relatively clean burning, like natural gas, when compared to diesel. Propane also has a lower energy density compared to diesel. Therefore, propane fueled generators tend to be more expensive to operate on an overall cost basis when compared to diesel generators.


Diesel engines do not employ a spark plug to initiate fuel combustion; instead diesel engines compress the air in the combustion chamber prior to fuel injection; this compression raises the temperature of the air. Diesel fuel is then injected in a fine mist into the chamber where the fuel ignites on account of the high temperature of the compressed air. However, this mode of fuel combustion in diesel engines also results in problems starting a diesel engine during cold temperatures. Because the diesel engine relies upon the high temperature resulting from the compression of the air in the engine chamber, cold temperatures make it difficult for the temperature of the air in the chamber to be high enough for the injected fuel to be ignited. Often, a glow wire is included with diesel generators to ensure ignition of fuel for generators that are expected to operate in cold temperatures. Most manufacturers recommend the inclusion of a glow wire or block heater with a diesel generator if the generator is expected to be operated at or under 32 degrees Fahrenheit.

For standby generators that are powered by diesel, tanks or reservoirs are added to power the generator. Diesel fuel stored in the fuel tank of a generator can be susceptible to water contamination due to condensation on the exposed inside walls of the fuel tank, resulting in fuel pump failures due to reduction in lubrication. In addition, moisture in fuel can also accelerate microbial growth in diesel which may clog fuel filters. In addition, diesel degrades due oxidation and exposure to oxygen, high temperatures, moisture, certain metals and alloys, dust and dirt. Diesel degradation leads to the formation of a fine sediment and a gum-like substance within the fuel which can result in soot deposits, clog filters and greatly diminish the performance of the engine. Additionally, naturally-occurring paraffin wax in diesel begins to crystallize around 32 degrees Fahrenheit and to gel around 15 degrees Fahrenheit and clogs tanks and fuel filters. Various additives are typically added to diesel to prevent the degradation and gelling of diesel when diesel fuel is stored for an extended period of time. On the other hand, diesel has a higher energy density than natural gas which makes diesel-powered generators more fuel efficient than those powered by natural gas. Diesel generators burn less cleanly, though and are generally considered to be noisier than their natural gas counterparts.


Most portable generators are designed to run on gasoline. Gas stations are everywhere and gasoline tanks are usually easy to come by. However, when a natural disaster hits, you are reliant on the gas stations nearest to you to have enough gasoline for the length of the disaster. Overall, gasoline has a shorter shelf life, volatile prices, and is highly flammable.

During times of natural disasters, especially those that necessitate wide-spread evacuation, gasoline fuel for a portable generator might be difficult to come by. If you go the gasoline route, make sure you don't keep it around too long, and you are careful in your handling to prevent spills.

In Summary

• Natural gas-fueled generators generally burn cleaner and can be connected directly to the natural gas supply of a household, thus avoiding the need for fuel storage tanks or refueling. Natural gas engines tend to run at a higher operating temperature than diesel engines, however, and the additional stress on the engine can result in lowered total lifespan of the generator.

• Propane is clean-burning and can be stored for long periods of time, but relies on the homeowner to know how and when to change it out. A more expensive option than others.

• Diesel engines tend to pollute the environment more than natural gas engines and are often subject to restricted runtimes in many counties. Diesel engine do not employ spark plugs which reduced maintenance costs; however, diesel engines also struggle to achieve proper operating temperature during cold weather necessitating the need for additional glow wires. Diesel also degrades over time without the addition of appropriate fuel additives. Diesel has a higher energy density, which tends to make diesel engines more efficient to operate per unit of electrical energy produced.

• Gasoline is mostly used to power portable generators; gasoline is flammable and volatile and degrades over time, making storage somewhat challenging, though gasoline is a commonly used transportation fuel, making it easily accessible. Gasoline engines are less efficient, per unit of electrical energy produced, compared with diesel engines.

Next steps

Once you have decided upon your choice of fuel for your residential standby generator, visit for a personalized assessment of you home power needs and for the right standby generator that will help you remain comfortable during the next power outage. Don’t get left in the dark, contact today!

Get started.

Use our Power Calculator to find out your energy needs.