Advantages and disadvantages of diesel plant

A diesel power plant generates electricity using a compression-ignition engine coupled to an alternator. It is mainly suited to small capacities, standby and peak duties, and isolated areas.

Advantages

1. Simple design and layout; few auxiliaries compared with a steam plant (no boiler, condenser or ash handling).
2. Quick starting and loading: can be started and put on full load within a few minutes, so it is ideal for standby and peak loads.
3. Small space required; can be located near the load centre, reducing transmission cost.
4. Low initial cost per kW for small capacities; short construction time.
5. High thermal efficiency (about 30–40 %), better than small steam plants; good part-load efficiency.
6. Less water is needed (only for cooling).
7. No standby losses: fuel is used only when the engine runs.
8. Fewer operating staff; easy operation and automatic control.
9. Fuel is easy to handle and store; no ash disposal problem.
10. Can be mobile (skid or trailer mounted) and works independently of weather.

Disadvantages

1. High fuel cost: diesel oil is costly and in Nepal must be imported, so running cost is high.
2. Limited capacity: unit size usually up to about 50 MW; not economical for large base-load stations.
3. High maintenance and lubrication cost; frequent overhauls of injectors, valves and liners.
4. Noise and vibration are severe; heavy foundations and silencers are needed.
5. Short life (about 10–15 years) compared with hydro (50 years or more) and steam stations (25–30 years).
6. Overload capacity is poor: engine cannot run long above rated load.
7. Exhaust pollution (NOx, smoke, particulates).
8. Cost per kW rises sharply with size.

Comparison summary