Savings calculator
See what CNG would save you
Your generating set
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Equivalent to 80 kW prime at 0.8 power factor.
Estimated fuel use: 11.73 litre-equivalent/hour
Estimated annual fuel saving
₦39,543,735
a 54.4% reduction in fuel cost versus running on diesel alone
- Diesel only, per year
- ₦72,753,625
- Dual-fuel, per year
- ₦33,209,890
- You keep, per year
- ₦39,543,735
| Period | Diesel only | Dual-fuel | You save |
|---|---|---|---|
| Per day | ₦199,325 | ₦90,986 | ₦108,339 |
| Per month | ₦5,979,750 | ₦2,729,580 | ₦3,250,170 |
| Per year | ₦72,753,625 | ₦33,209,890 | ₦39,543,735 |
Cost per litre-equivalent
You save ₦924 on every litre-equivalent of fuel burned. This percentage does not change with load or hours — only with fuel prices and the substitution split.
If the achieved substitution differs
- 50% CNG / 50% diesel38.8% saved
- 60% CNG / 40% diesel46.6% saved
- 70% CNG / 30% diesel54.4% saved
- 80% CNG / 20% diesel62.1% saved
Field-achieved substitution depends on your load profile, kit calibration and gas supply. We verify it after commissioning.
Want this in writing for your specific generator?
Send us a photo of your generator nameplate and we will issue a full written technical & financial analysis — the same document we provide to every client — with figures worked to your actual duty cycle, plus a conversion quotation.
How this is calculated. Diesel and CNG are compared on a common energy basis, treating 1 litre of diesel as approximately energy-equivalent to 1 SCM of CNG (a “litre-equivalent”). Fuel consumption is taken from a reference curve for a 160 kW-prime diesel set and scaled to your generator’s prime rating, then the blended dual-fuel price is applied. Figures are estimates for guidance and are confirmed by a site survey.
Reading the result
What the calculator does and does not account for
Included
- Energy-equivalent pricing. One litre of diesel is treated as approximately energy-equivalent to one standard cubic metre of CNG, so the two fuels are compared like for like rather than by volume.
- Load-scaled consumption. Fuel burn is taken from a reference curve for a 160 kW-prime diesel set and scaled to your generator’s prime rating and the load you set. For trucks, it comes from the litres/100 km figure your own fleet records show.
- Substitution sensitivity. Because the achieved CNG share drives the whole result, you can see the saving at 50, 60, 70 and 80% substitution side by side.
- The right model for each engine. Petrol cars are calculated as bi-fuel — they run on 100% gas and switch back to petrol — while a converted diesel truck or generator is calculated as dual-fuel, where a diesel pilot is always retained. That is why the percentage saving on a car is so much higher, and it would be wrong to quote one figure for both.
- An efficiency allowance on 100% gas machines. A purpose-built gas machine burns no diesel, but a spark-ignition engine extracts less work from the same energy than the diesel it replaces. We add 10% to the energy a gas generating set needs and 15% for a heavy-duty gas truck, rather than pretending the two engines are equally efficient. Erring that way understates the saving, which is the direction an honest projection should err in.
Not included
- Conversion capital cost. The kit, cylinders, cascade and installation are quoted separately on a proforma invoice after a site survey, so you can weigh them against the saving shown here.
- Refuelling logistics. Time and vehicle cost for cascade refill trips depend on your distance to a CNG station and are not modelled.
- Route and station coverage. For trucks this is the big one. A corridor with no CNG station forces long diesel-only stretches, which pulls the achieved substitution below target. We measure it on a pilot vehicle before quoting a fleet.
- Maintenance differences. Dual-fuel running generally reduces soot loading, but service intervals remain per the engine manufacturer’s schedule.
- Power derate. Dual-fuel engines are commonly derated by roughly 3–8%; if your set runs near its limit we address this in the survey. A dedicated 100% gas machine carries no such derate — it is rated at its gas output.
- The value of a diesel fallback. A dual-fuel machine reverts to 100% diesel if gas runs out, so the worst case is that you stop saving that day. A 100% gas machine has nothing to fall back on, so gas supply stops being a convenience and becomes the whole plant. That risk is real and it does not appear anywhere in these numbers.
Want these figures worked properly for your set?
Send us your generator nameplate and we will issue the full written technical and financial analysis — with your actual duty cycle, a sensitivity table, and the technical considerations specific to your engine.
Or email sales@rorotechnologies.com