How Do Diesel Generators Work?
Diesel generators convert the energy in diesel fuel to electricity. They operate in a slightly different way to other types of generators.
Let’s look at how diesel generators work, what they are used for and why you might choose to buy one.
How do diesel generators work?
Diesel generators use a series of steps to generate AC (alternating current) electricity.
The process starts when a diesel (combustion) engine converts some of the chemical energy in the fuel to rotating mechanical energy. The rotating motor is then used by the AC alternator to generate electricity, while a wire moving through a magnetic field induces electrical charges.
This type of generator can be used for either prime or standby power. For example, a diesel generator might be used for prime power in a remote region with limited grid connection, or for standby or backup power during a blackout.
The machines come in single-phase which could suit household or small business use, or three-phase for longer-term or heavy-duty industrial use.
Generators should not be used concurrently with mains power, which is why they often come fitted with a transfer switch to prevent this from happening.
Why would you choose a diesel generator?
Diesel generators come with a range of benefits.
These include robustness, good longevity, relatively low maintenance needs, high efficiency and safety.
Diesel generators suit several types of scenarios:
• Tradespeople need a portable generator to use on work sites.
• People who live off-grid and need a reliable power sources.
• As a backup for a solar battery.
• For use at large-scale events.
• For farm and agricultural use.
• As a continuous power source on a remote mining site.
You could also use one as a prime source of power if required.
How efficient are diesel generators? How long do diesel generators last?
Diesel engines use compression heat rather than spark ignition to burn fuel and have greater thermal efficiency than other types of internal combustion engines.
This makes diesel generators very efficient machines, especially for continuous and heavy-duty use.
Diesel vs petrol generators: which is better?
Benefits of diesel generators:
At face value, diesel offers several advantages over petrol.
For example, diesel generators are more efficient in that they require as little as half as much fuel and don’t need to work as hard as petrol units to produce the same output.
So, while diesel costs more per litre, a diesel generator will use less fuel which can mean lower costs over time.
Diesel is also less volatile than petrol, making it safer to use. And because a diesel machine runs cooler than one run on petrol, and doesn’t need to work as hard, its maintenance requirements are lower.
Benefits of petrol generators:
On the other hand, there is a wider range of petrol generators on the market, and petrol models generally cost less to buy. Petrol is also less polluting than diesel as it produces fewer emissions. That said, a diesel generator requires less fuel which can equate to lower pollution overall.
The differences between the two types are also narrowing. For example, many newer petrol models come with built-in safety features, offsetting their higher safety risk. Also, while diesel generators are noisier, some models now come with noise-reduction features.
So which is best?
The answer really depends on why you want a generator.
• For short-term or intermittent use, you are unlikely to experience the cost-saving and efficiency benefits of diesel. This means if it’s a generator for modest use, such as a back-up or occasional power source, petrol would probably be your best bet.
• For high-use or heavy industry situations, diesel works out better in terms of long-term efficiencies.
What size diesel generator do I need?
Diesel generators come in a variety of types and sizes. This includes portable models from 6kVA to 11kVA through to 3-phase stationery generators up to 2,000 kVA or even larger.
You might choose a portable generator for trade, farm or home and back-up use. For intensive and continued use, you may need a large 3-phase stationary model.
To work out the right size, you need to consider:
• The power needs of the appliances or machines you want to run in terms of wattage, for both running and start-up.
• Whether you intend running several pieces of equipment at the same time. If so, you will need to add up the requirements of each to arrive at a total.
• Converting the wattage requirements to kVA. This is done by dividing the kW requirements by the generator power output factor (usually 0.8). So, for requirements of 7kW and a power factor of 0.8, you would need a generator of at least 8.75 kVA (7 divided by 0.8).
Once you have an idea of your size requirements, get in touch with our team to discuss the best generators to match your needs.
How much do diesel generators cost?
There are diesel generators to suit a range of budgets.
Portable diesel generators start at around $1,800 for a 6kVA unit through to $21,000 for 11kVA.
Larger diesel generators can range from $22,000 to $320,000 depending on size and features.
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.
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.
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.
