- Asked 8/21
- 2070 Bhadra · 8 marks
Thermal, hydro and solar PV plants compared
Short answer
Thermal is firm, dispatchable, 30–40% efficient, with high running cost and pollution. Hydro is 85–92% efficient, dispatchable 0–100%, starts in minutes, but needs high capital and long construction. PV is intermittent, 15–22% efficient, low capital, very low maintenance, and best as a complement to hydro.
Compare the operational characteristics of thermal, hydro and solar PV plant on the basis of reliability, grid connection, efficiency, operating range and maintainability.
Thermal plants burn fuel to produce steam for turbines; hydro plants use the potential energy of water; solar PV plants convert sunlight directly into electricity.
Comparison
| Basis | Thermal plant | Hydropower plant | Solar PV plant |
|---|---|---|---|
| Energy source | Coal, oil, gas | Water | Sunlight |
| Reliability | Firm if fuel available; availability about 70–85% | Firm with storage; RoR seasonal; capacity factor about 50–65% | Daytime, weather dependent; capacity factor about 15–20% |
| Grid connection | Synchronous; near load centres; inertia and voltage support | Synchronous; remote sites; long lines; black-start ability | Inverter based; no inertia; harmonics, voltage rise; near load possible |
| Efficiency | About 30–40% | About 85–92% | About 15–22% |
| Operating range | Above about 40–50% load; start in hours; slow ramp | 0–100%; starts in minutes; fast ramp; best for peak | Follows sunlight; not dispatchable; MPPT |
| Load position | Base load | Peak (storage) / base (RoR in wet season) | Daytime energy supply |
| Maintainability | Complex; many auxiliaries and staff | Moderate; sediment erosion, civil works | Very low; cleaning, inverters |
| Running cost | High (fuel) | Very low | Very low |
| Capital cost | Moderate | High | Low and falling |
| Construction time | 3–4 years | 4–8 years | Months |
| Life | 25–30 years | 50+ years | About 25 years |
| Environment | CO₂, SO₂, NOx, ash | River ecology, submergence | Land use, panel disposal |
Remarks
- Thermal suits base load where fuel is cheap; hydro is the most efficient and flexible; PV is cheapest to build but intermittent.
- In Nepal, hydro is the backbone, PV complements it in the dry season, and thermal (diesel) is kept only for emergency.
✓ Answer checked by Claude Opus 5.5 (high effort)
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