- 2079 Shrawan · 6 marks
Combined cycle gas turbine versus hydro
Short answer
CCGT uses fossil fuel, efficiency 50-60%, low capital, short 2-3 years construction, firm all year, but high fuel cost and emissions. Hydro uses renewable water, efficiency 85-92%, nil fuel cost, long construction, long life, excellent load following, but high capital and environmental impacts. For Nepal hydro is preferred.
Compare Combined Cycle Gas Turbine power plant with hydro power project considering various possible aspects.
A combined cycle gas turbine (CCGT) plant uses a gas turbine and recovers its exhaust heat to drive a steam turbine. A hydropower plant uses the potential energy of water through a water turbine.
Comparison
| Aspect | CCGT plant | Hydropower plant |
|---|---|---|
| Energy source | Natural gas / oil (fossil) | Water (renewable) |
| Efficiency | About 50–60% | About 85–92% |
| Fuel cost | High, price volatile | Nil |
| Capital cost per kW | Low to moderate | High (civil works) |
| Construction time | Short, 2–3 years | Long, 4–10 years |
| Location | Near gas pipeline or load centre | Fixed by river and head; often remote |
| Transmission | Short lines | Long lines often needed |
| Starting time | 10–30 min (GT), hours for full CC | A few minutes |
| Load following | Good | Excellent; best for peaking and frequency control |
| Reliability | Firm all year if fuel is supplied | Seasonal (run-of-river); firm if storage |
| Life | About 25–30 years | 50+ years |
| Maintenance | Hot-gas path parts, HRSG; skilled staff | Simple; sediment erosion of runners |
| Emissions | CO₂, NOx (less than coal) | Nearly zero in operation |
| Environmental/social | Air pollution, cooling water | Submergence, resettlement, river ecology |
| Ambient effect | Output falls with temperature and altitude | Not affected |
| Suitability for Nepal | No domestic gas; imported fuel costly | Large potential; main source |
Remarks
CCGT is cheap and quick to build but depends on imported fuel; hydro has high initial cost but very low running cost and long life. For Nepal, hydro is clearly preferred, while CCGT suits countries with gas supply as flexible mid-merit plants.
✓ Answer checked by Claude Opus 5.5 (high effort)
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