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Natural Gas & Propane vs Diesel Home Generators

Updated: Mar 1, 2022

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In this episode, we will be discussing home generators. We are going to look at the differences between them. What makes one a better choice over another? Since there are many misconceptions about natural gas, propane and diesel-powered HOME generators, we will discuss them in greater detail, so stay tuned!


Thanks for tuning into our Generator Podcast. Our focus in this podcast will be the differences between Natural Gas, Propane, and Diesel Powered Generators. Many other companies would like to have you believe that natural gas or propane-powered generators are good choices for your home. It's just not true, and I'll explain why.

You may already be using Natural Gas or Propane for cooking and heating. So, you may want to use the same fuel to power a generator. But that's a bad idea. While a furnace has high efficiency, an engine does not. Furnaces burn fuel to create heat. Most of the heat is used in the home and does not escape out of the exhaust. That's why they are very efficient. Very little of it goes to waste. But, engines that use natural gas or propane are less than 35% efficient. 65% of the fuel energy is lost as heat.

Diesel fuel contains a lot more energy than propane and natural gas. The engines that use them are far more efficient. You use very little fuel, making them the least expensive fuel source for powering a generator.

Fuel cost is just one factor, and it does not matter to everyone, so let's talk about efficiency because it plays a significant role in the generator's quality and lifespan.

Home generators that use natural gas, or propane, use small engines that need to run at very high speeds. They do so to produce a normal engine's equivalent power. When I say normal, I'm referring to traditional generators that run at 1800 RPM, Not like natural gas and propane units that run at twice the speed, 3600 RPM

Think about it. Your car engine never even runs that fast on the highway.

Also, to reduce costs, natural gas, and propane home generator engines do not have a radiator. They are only air-cooled. They can, and often do, run, far too hot. This damages engine oil. Engine oil that gets too hot loses its ability to lubricate the engine, resulting in even more friction, heat, and wear.

Now, let's compare this to a diesel-powered home generator.

Diesel engines have no spark plugs, carburetor or ignition system to maintain. They are very simple engines with fewer parts. You only need to change the oil every 500 hours, not 100-hours. Best of all, they last well over 15 to 20 thousand hours. Diesel generators are also quieter since they run at half the speed. They are also the cheapest in fuel cost and consumption.

Since Diesel fuel is more like an oil, it also helps to lubricate and cool fuel injectors. Other fuels are solvents, so they break down oil.


If you want to power a generator with propane, you will need a "huge tank." It typically costs over $2000 to install one; a typical size tank has a 500-gallon capacity. But, it is never filled all the way. That has to do with the 80% fill rule.

The 80% fill rule is a preventative safety measure against the fluctuations that happen inside a tank. Propane, like water, will expand on hot days. Propane increases in volume nearly 17 times more than water over the same temperature increase. Propane containers are filled to a maximum of 80% of their capacity to allow for expansion. What you have is, at the most, only 400 gallons.

Let's assume you do not use your fuel for anything else and started with a full tank; you have just enough fuel to run a generator for four days. It's because the typical generator will consume 4 gallons per hour. At the current cost of propane, that will cost you $325.00 per day. Compare this to diesel-powered same size generator used in the same application. It will consume only half-a-gallon per hour.

Do you have natural gas?

There seems to be an endless supply of it, but you need more than double the volume since it has less than half the propane's fuel energy. To supply so much natural gas and maintain the proper pressure, the utility company will change your meter. You want the generator to be installed as close as possible because fuel pipes need to connect to the generator. The upgrades can be costly. What is the most expensive is all the natural gas you will use. It's two and a half times more than propane.

Unlike diesel-powered generators, natural gas and propane generators create a lot of deadly carbon monoxide gas. Diesel produces 98% less, making them safer.

Natural Gas is also explosive, so utility companies will automatically shut it off for fires, floods, or earthquakes. Some events trigger systems to shut off automatically. When it comes to fuel safety and storage, Diesel fuel is your best choice. You can toss a match into it, and it will not catch fire. But diesel fuel does have its issues.

Water is commonly found in diesel fuel due to condensation, handling and, environmental conditions. Diesel fuel tanks are always subject to water condensation because diesel fuel, unlike gasoline, has no vapour pressure to displace air. When a fuel tank is warm, the air expands and is forced out. As the tank cools at night, humid air is sucked back into the tank and, water condenses out on the cooler tank walls.

One way of mitigating this is just to keep your tank full. Water droplets are relatively easy to remove from fuel using a quality fuel/water separator. You should find them installed in all diesel generators. You can keep diesel fuel in a sealed container, and like motor oil, it will keep and be able to store it for years without it degrading.

You can have diesel fuel delivered to your home. It is called off-road diesel, or heating oil. It is the same fuel, but it has some red-dye added to it to distinguish it from higher-taxed on-road fuel.


Compare the warranty for a diesel engine to any other. Diesel engines are rated for thousands of hours and have very straightforward warranty policies. Natural Gas and Propane warranties are complicated and cover very little. To qualify for coverage, you must use a dealer to perform regular maintenance, and obviously, it's at a cost. Be sure to read the fine print. Merely using the generator for anything other than an emergency can void your warranty. With such a short engine life, much of the failures you can experience can be attributed to normal wear and tear.

So, what should you do? Here's what I suggest.

Power outages can happen at any time, for different reasons. They are happening more often and seem to last longer than before. When will the next major outage happen is anyone's guess. Having a generator that can run for days or weeks without fail is a no brainer. Current natural gas and propane offerings just don't cut it. It's not if they will die; it's when they will die. If you are in a big city with only a few hours a year of outages, natural gas and propane might be okay, not if things change.

Many of our customers have owned natural gas, propane or gasoline generators, and it failed; that's when they switch to diesel. Had they done some research, it could have saved them thousands of dollars like you are doing now.

Their choice they have now is should they buy the same thing again or switch to diesel. If you want to change, keep in mind, the other guys make nothing of theirs compatible with others. Not even the transfer switches can be reused.

With diesel, you pay a bit more upfront but so much less in fuel, service and maintenance. Diesel generators are safer, quieter and last over 20 times longer. You can use them full-time when needed.

New diesel technology engines are 95% cleaner than they were in the past. They make less noise and do not cost more when you add everything up. They cost less to install and are the most reliable.

Ask yourself this question. If natural gas or propane is better, why is it not used anymore in cars? Why is it not used in farming, construction, heavy transportation, shipping and aviation? You should now know the answer to this.

I hope this podcast helped, and you are now armed with more information to make a better choice on your next or even your first generator purchase.

Do you have a generator question we can answer? Let us know, and it could be featured in our next podcast.

Thanks for tuning in. Be sure to subscribe so you can hear our other podcasts. You can also visit

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