Choosing the best generator fuel for your home

Choosing a generator that meets your individual needs and budget is a major undertaking. Every time the power goes out in your home, your family’s comfort and well-being will be in the hands of your standby generator. Many factors go into choosing the best generator for your home, but generator fuel is perhaps the most important. There are four main types of fuel on the market: natural gas, propane, gasoline, and diesel. Determining the best generator fuel for your home involves balancing cost, availability, and personal preference.

A generator can only run as well as its fuel. Once you decide the kind of fuel you want your generator to run on, you’ll be much closer to figuring out the best generator for your home. To further assess your home power needs and find the right standby generator, try out our generator sizing calculator.

Natural gas-powered generators

Natural gas is a form of hydrocarbon gas containing mostly methane that is commonly used for cooking and heating in homes. When used as generator fuel, natural gas is automatically released when the power goes out, and a spark plug ignites the gas, starting the generator. Natural gas is easily distributed to homes throughout the country through a system of pipelines. If you purchase a natural gas-powered generator, you will need to have a professional connect your gas pipeline to the generator.

Once installed, you will have the advantage of having natural gas pumped directly into your generator, saving you the trouble of transporting fuel and refilling the tank yourself. In the event of a natural disaster, however, gas lines could be damaged, which would leave you without the fuel you need to power your generator.

Natural gas has other advantages as well. When compared to diesel and other fuels, natural gas is clean, making it the best option in states with strict emissions restrictions. It also typically allows the generator to run more smoothly and quietly.

Propane-powered generators

Propane is a highly refined fuel made up of hydrogen and carbon. It is an element in natural gas and is a by-product of natural gas processing and petroleum refining. When used as generator fuel, propane acts similar to natural gas but is heavier and burns slightly cleaner. It is also less efficient than gasoline and diesel.

Though more expensive than natural gas, propane is distributed in metal cylinders, meaning you won’t have to pay to hook up the generator to the gas lines. Cylinders of propane fuel are widely available in stores around the country and are easy to transport back to your home. Unlike diesel and gasoline, which degrade over time, propane has a very long shelf life, meaning you are free to stock up in preparation for the next outage. This makes propane a good option for people who rarely need to use their generator.

Gasoline-powered generators

Gasoline may seem like a good candidate for standby generators, but they are impractical and expensive to run. Few standby generators run on gasoline, but portable generators commonly use gasoline as their fuel source.

Purchasing gasoline for a generator is as easy as driving to your local gas station with a couple of metal canisters. Cost is reasonable in small quantities. Due to gasoline’s high volatility, the U.S. government limits gasoline storage to 25 gallons, which will fuel a generator for only two or three days. Gasoline also has a shelf life of less than one year. Most gasoline blends begin breaking down and absorbing moisture within a month. If gasoline is more than a year old, it may contain elements that wear engine parts down, damaging the generator.

Because gasoline must be purchased from a gas station, you will have to fuel a gasoline-powered generator yourself. This is inconvenient on a good day and potentially dangerous during natural disaster-related outages. When refilling a tank, be careful to avoid spillages. Gasoline has a low flash point, making it easily flammable. In the event of a power outage, gas stations may also be affected, meaning you could be left without power if an outage lasts more than a couple days.

Diesel-powered generators

Diesel is a liquid fuel source made from crude oil. Diesel engines are powerful and efficient and can be found in trains, trucks, boats, buses, and some cars. They are also the most commonly used standby generator fuel. Diesel-powered generators require less upkeep and can run for years with little or no maintenance. Because diesel has a higher energy density than other fuels, diesel-powered generators run most efficiently, saving you money over time. They also often have a lower upfront cost.

Though diesel-powered generators require little maintenance, they must be run at least once a month to avoid breakdowns. Diesel burns less cleanly than natural gas, propane, or gasoline; engines are subject to restricted runtimes in some areas. Additionally, diesel-powered engines tend to be noisier than other engines. Diesel can be purchased at locations across the United States and stored in containers. Like gasoline, diesel is a volatile substance; handling and storing it requires care.

Additionally, without the proper additives, pure diesel does not have a long shelf life. Diesel degrades when exposed to oxygen, high temperatures, moisture, certain metals and alloys, dust, and dirt, which can lead to soot deposits and clogged filters in the generator engine. Naturally-occurring paraffin wax in diesel also begins to crystallize around 32 degrees Fahrenheit and gel around 15 degrees Fahrenheit, clogging tanks and fuel filters. Various additives are typically added to prevent diesel from degrading when it is stored for extended periods of time in a fuel tank. Research products or talk with distributors to ensure the diesel you purchase has the proper additives.

Is diesel the cheapest generator fuel?

When it comes to making choices regarding generators, the cost may be the most important factor for you. The key is finding a fuel that is both cost-effective and energy-efficient. The two cheapest options are natural gas or diesel, but comparing the two is tricky. The price of diesel is higher than that of natural gas, but diesel has a higher energy density and thus burns more efficiently.

While the net cost of natural gas and diesel vary based on local prices and individual energy usage, on average, diesel is less expensive, especially when you take into account the cost of connecting a natural gas-powered generator to the gas lines on your property. To be sure, find out the price of natural gas and diesel per unit in your area and compare that to the energy capacity you would need your generator to run at. You can find out more about how to calculate the generator capacity your home needs here.

Starting a diesel-powered generator

Diesel engines do not employ a spark plug like other kinds of engines. Instead, they compress the air in the combustion chamber, which raises the temperature of the air. Diesel fuel is then injected into the combustion chamber in a fine mist. The high temperature of the air ignites the fuel, starting the engine.

On cold days, when the temperature is below 32 degrees Fahrenheit, this method could cause problems starting the engine. The compression of the air might not be enough to raise the temperature high enough to ignite the fuel. If you live in an area that regularly experiences temperatures below 32 degrees Fahrenheit, there are ways to ensure the engine will start. Manufacturers often recommend purchasing a glow wire or block heater, both of which help ignite the generator fuel in the engine even when outside temperatures are low.

If you do not want to worry about starting a generator on cold days, then diesel may not be the generator fuel for you. On the other hand, the lack of a spark plug means you are less likely to encounter maintenance problems.

Hybrid fueled-generators that use multiple generator fuels

If you can’t decide which generator fuel you prefer, why not buy a generator that lets you choose between multiple fuel types? Bi-fuel and tri-fuel generators give you the option to switch between fuel sources. These hybrid fueled-generators are most common for portable generators. They may give you the option between gasoline and propane, or gasoline, propane, and natural gas.

Though they tend to be more expensive, hybrid-fueled generators have the advantage of providing access to a wider range of fuel availability. For example, a bi-fuel generator that runs on natural gas or propane would allow you the convenience of connecting the generator to your gas lines and the security of knowing you have an alternative energy source available if gas lines break during a natural disaster.

There are also some new, environmentally-friendly hybrid fueled-generators that run on a mix of diesel, natural gas, or propane and a renewable energy source, such as solar or wind. These tend to have a high upfront cost but can save you some money on electric bills in the long run. The solar or wind energy is stored in a battery, and the generator fuel kicks in when necessary. Check out this blog post for more information about electric and solar home battery backup systems.

Next steps

Generator fuel is only part of the equation. Once you decide your fuel of choice for your residential standby generator, visit our website for a personalized assessment of your home power needs. We’ll help you find the right size and capacity for your home and budget.

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