In short. A gas generator uses a spark-ignited engine on natural gas, biogas or similar fuel. It suits sites with reliable gas, steady load and sometimes heat use, but needs a safe gas train, careful load-step design and fuel supply planning compared with diesel.
Key differences from diesel
| Aspect | Gas set | Diesel set |
|---|---|---|
| Ignition | Spark | Compression |
| Fuel supply | Pipeline, CNG or biogas | Tank on site |
| Load step response | Often slower; check | Generally quicker. See transient response |
| Standby use | Depends on gas reliability | Common |
| Heat recovery | Often attractive | Possible |
Design points
- Gas pressure, quality and supply security.
- Gas train: filtration, regulation, safety shutoffs.
- Ventilation, leak detection and hazardous-area review.
- Step-load capability and possible battery or diesel support.
- Derating for temperature and altitude. See altitude derating.
- Exhaust and noise treatment.
Operation and maintenance
Spark plugs, gas filters, valves and oil need scheduled care. See preventive maintenance.
Standby considerations
A gas pipeline can fail in a regional emergency. For critical loads, consider on-site fuel storage or a diesel backup. See cleaner-fuel overview.
Illustrative example
A manufacturing plant with steady load and a pipeline installs gas sets for base power and keeps a diesel set for critical loads, since the gas supply could be interrupted.
Efficiency and heat recovery
Gas engines convert part of the fuel energy to electricity and reject the rest as heat in the exhaust and cooling water. Where a site needs hot water, steam or absorption cooling, recovering this heat raises overall fuel utilisation considerably. This is the basis of combined heat and power. It makes sense where heat demand is steady and close to the engine.
Gas set sizing notes
| Item | Consideration |
|---|---|
| Rating basis | Gas sets are often rated lower than a diesel of the same frame, especially at high ambient temperature |
| Load steps | Check the maker’s maximum single step |
| Minimum load | Light load operation reduces efficiency and can foul plugs |
| Altitude and temperature | Derate as per maker curves |
Operational points
- Warm-up before loading, as per maker.
- Gas quality monitoring.
- Scheduled spark plug and valve checks.
- Ventilation and gas detection tested.
- Exhaust emission checks at intervals.
Standby versus continuous use
For continuous or prime duty with stable gas supply, a gas set can give low fuel cost per kWh and cleaner emissions. For emergency standby, response time, step loading and fuel security are tighter, so many sites keep diesel for life-safety loads and use gas for production loads.
Parallel operation and grid interaction
Gas sets can run in parallel with the grid or with other sets, subject to synchronising equipment and protection. See synchronisation and generator protection.
Economics
Compare the full cost per kWh including fuel, maintenance, capital and any heat value. Reflect realistic gas price and availability. Run sensitivity cases.
The master engineering question
If the gas supply stops, which loads still have power?
What to send us
Send load profile and gas details. Send your application details.
Questions engineers ask
Can a gas set be standby?
Yes, if the gas supply is reliable or stored.
How are step loads handled?
Check maker data; may need staging.
Is gas cheaper?
Compare cost per kWh at your tariff.
What about safety?
Gas detection, ventilation and trained staff.
General guidance only. Use maker data.