Does higher load on a diesel generator set lead to higher fuel consumption?

For those who use diesel Generator Sets, the initial purchase cost of the machine is often far less than the subsequent operating costs, especially the fuel consumption. Therefore, fuel efficiency is key when using diesel generator sets.

Based on their understanding of car engines, many people believe that the fuel consumption of a generator set is directly proportional to the load; the higher the load, the more fuel it consumes. Is this really true?

Generally, the fuel consumption of a generator set is related to two factors: one is the fuel consumption rate of the generator itself, which usually cannot be significantly changed; the other is the size of the load. For the purpose of saving fuel, many people keep the load within the standard range of the rated load, but the fuel consumption is still not ideal. Why?

Generally, for diesel generator sets of the same brand and model, higher loads result in higher fuel consumption, and vice versa. This statement is generally true. However, in special circumstances, it's a different story.

In reality, the fuel consumption is lowest at 80% load. If the load of the diesel generator set is 80% of the rated load, one liter of fuel generates 3.5 kilowatt-hours of electricity; if the load increases, the fuel consumption will increase, which is what people often refer to as the direct proportionality between diesel generator set fuel consumption and load.

However, when the load is below 20%, it will affect the diesel generator set. Not only will the fuel consumption increase significantly, but it may even damage the generator set.

Therefore, the idea that the fuel consumption of a diesel generator set is directly proportional to the load is not absolute. To reduce the fuel consumption of a diesel generator set, it is best to operate the generator at around 80% of its rated load. Prolonged low-load operation will actually increase fuel consumption and may even damage the generator set.