Did you know that when utilities like power plants choose standby generators, they go with diesel? Diesel has distinct advantages over gasoline, and it’s because of these advantages that large, industrial players choose it as an emergency power source.
There are few large standby generators that even run on gasoline, so comparing high-output gas and diesel generators is not practical. However, there are many low-output gas and diesel generators that compete. For those of you who are comparing these smaller gasoline and diesel generators, we’ve put together this list of reasons why diesel generators outshine gasoline counterparts.
Comparing Gas and Diesel Generators
First, it’s reasonable to compare similarities between gasoline and diesel engines. In several areas, the two perform about the same. In general, both gasoline and diesel generators:
- Run well in high ambient temperatures
- Are good for heavy start/stop loads
- Have readily available fuel sources
- Have similar fuel prices
- Are reliable
- Produce low emissions
- Deliver quick, “on-demand” power
- Are a proven technology
Gasoline Versus Diesel Fuel
How diesel generators are a better choice than gasoline begins with a look at gasoline at the fuel. Consider storage. Gasoline is more flammable than diesel. If you’ll be storing your fuel in an area that also has high heat sources or open flames (like a garage with a workspace), diesel is a safer option, as there’s not the risk of it accidently igniting.
Diesel also has a longer shelf life than gasoline. Under good conditions, diesel fuel will last between six and 12 months without additives. Gasoline, on the other hand, only has a shelf life of about three months without additives. A shorter shelf life means that gasoline must be treated and used at a rate of two to four times greater than diesel. That usage requirement can add significant costs to owning a generator.
Another advantage of diesel fuel is that it will likely be more obtainable than gasoline in an emergency situation. Because most vehicles and small, portable generators run on gasoline, competition for the fuel will rise when the power goes out. Diesel, however, fuels fewer cars and generators. This means you’ll spend less time waiting at the pump when you need to refill your tanks.
Looking at Gas and Diesel Fuel Efficiency
Diesel engines get better fuel economy simply because they do not need to burn as much fuel as a gas engine to get the same power. Diesel engines are also built heavier than gas engines to sustain the added stress of higher compression ratios. They also do not have an ignition system, so you will never have to give them tune ups.
Diesel Engine Noise and Gas Engine Noise
Old diesel engines are famously noisy. But contemporary models are not. Except for when they are idling, they run as quietly as gasoline engines.
When they are running at full throttle, gasoline engines can actually produce more noise than diesel. For gasoline engines to produce enough power and remain small, they have to run at higher RPMs than do diesel engines. They thus produce more noise. Most small gasoline generators run at 3,600 RPM. Diesels generally run around 1,800 RPM.
Diesel and Gas: Maintenance and Longevity
Diesel engines need less maintenance than do gasoline engines. Diesels have no spark plugs to replace and no carburetors to maintain and replace. An 1,800 RPM, water-cooled diesel can run 12,000 to 30,000 hours without needing major maintenance. A comparative gasoline generator will run 6,000 to 10,000 hours before needing major maintenance.
One reason why diesels last longer is because diesel engine burns cooler than gasoline. The extra heat gasoline produces wears on components. Another reason why diesel engine systems last longer is that diesel fuel exhaust isn’t as corrosive as gasoline engine exhaust.
Comparing Diesel Engine and Gas Engines for Extended Use
Last, diesel engines are better for extended use than gasoline engines. Most larger diesel generators are liquid cooled, while smaller, portable ones are air cooled. For extended use, liquid cooled models have the advantage because air-cooled models can overheat when used for long periods of time, especially with high ambient temperatures.
Diesel engines are also designed to work under heavy loads for extended periods of time. They actually perform better under heavier loads than under light loads, so they perform best when you actually need then, when they’re running. Gasoline generators are only built for intermittent use. They aren’t designed for major power outages.