Diesel generator Fuel Consumption in liters per hour.

The principle of thermal engine (or diesel engine or genset) electricity generation is quite simple. An electric thermal generator is a device that converts mechanical energy obtained from an external thermal source (fuel combustion) into electrical energy as the output.

So to propel the piston to make X amount of Kw you require an air fuel mix of Y to produce an an explosion.

So lets take a 4 pole 1500RPM set up to produce electricity at a frequency of 50Hz.

It really will not matter the brand of engine as physics dictates the power from the explosion give or take a few %.

Lets use a Cummins 6BT5.9G2 engine.

This engine will produce 80kW or 100Kva and at 100% load will use 214G/kW.h of fuel

214G of diesel is 0.248L.h

Simple formula or quick response not taking into account fuel density changes, 1kg of diesel = 1.163liters.

Therefore 80kW or 100Kva generator used to produce electricity at 1500rpm at 100% load

80kW X 0.248l = 19.84l/h

Now bear in mind that this is the perfect world calculation, 100% efficiency with no wear.

In general I explain to people that you are better to use 0.210l/kVA/hr, This equates for frictional loses etc.

Look at the chart below for approximate fuel consumptions.

Average Fuel Consumption – Litres Per Hour
Based on Percentage of load
Size Kva 100% 75% 66% 50%
10 2.08 1.56 1.3728 1.04
15 3.12 2.34 2.0592 1.56
20 4.16 3.12 2.7456 2.08
25 5.2 3.9 3.432 2.6
30 6.24 4.68 4.1184 3.12
35 7.28 5.46 4.8048 3.64
40 8.32 6.24 5.4912 4.16
45 9.36 7.02 6.1776 4.68
50 10.4 7.8 6.864 5.2
60 12.48 9.36 8.2368 6.24
75 15.6 11.7 10.296 7.8
100 20.8 15.6 13.728 10.4
130 27.04 20.28 17.8464 13.52
150 31.2 23.4 20.592 15.6
200 41.6 31.2 27.456 20.8
250 52 39 34.32 26
320 66.56 49.92 43.9296 33.28
350 72.8 54.6 48.048 36.4
400 83.2 62.4 54.912 41.6
500 104 78 68.64 52
650 135.2 101.4 89.232 67.6
750 156 117 102.96 78
1000 208 156 137.28 104

Some engines are a bit better than others but from what I have seen that is 0.206L to 0.215L per hour, when we start talking about the larger sets (750Kva +)it narrows the field as to suppliers of engines, it also makes understanding of fuel and power management more important to over all running costs.

We have only just priced up a 500Kva set to run an industrial site in peak as the diesel genset works out at $0.24/kW hour, this is cheaper than their supply from the grid during peak times.

If you would like to talk to one of our experienced team please do not hesitate to give us a call.

Share this post: