- Asked 7/21
- 2073 Magh · 8 marks
Thermal, geothermal and nuclear plants compared
Short answer
Thermal plants are firm and dispatchable with 30–40% efficiency, minimum load about 40–50%, and complex maintenance. Geothermal and nuclear are steady base-load plants with high capacity factors, but geothermal efficiency is only 10–20% and nuclear 30–35%; nuclear has very high capital cost and strict radiation safety.
Compare the operational characteristics of thermal, geothermal and nuclear plant on the basis of reliability, grid-connection, efficiency, operating range and maintainability.
All three plants use steam turbines, but the heat source differs: thermal plants burn fossil fuel, geothermal plants use heat from the earth, and nuclear plants use fission of uranium.
Comparison
| Basis | Thermal (coal/oil/gas) | Geothermal | Nuclear |
|---|---|---|---|
| Heat source | Fuel combustion in boiler | Steam/hot water from wells | Fission in reactor |
| Reliability | Firm if fuel supply is assured; availability about 70–85% | Very steady; capacity factor about 90%; reservoir may decline | Very steady; capacity factor about 85–90%; long refuelling outages |
| Grid connection | 100–800 MW units; near load or mines | Small to medium units (5–100 MW); only at geothermal fields, often remote | Large units (600–1600 MW); remote sites; needs strong grid |
| Efficiency | About 30–40% (steam), 50–60% combined cycle | Low, about 10–20% (low steam temperature) | About 30–35% |
| Operating range | Moderate; minimum stable load about 40–50%; start in hours | Base load only; little flexibility | Base load; load following difficult; start takes long |
| Maintainability | Complex: boiler, coal and ash handling, many auxiliaries | Corrosion and scaling from minerals; well maintenance | Highly specialised; radiation safety; strict regulation |
| Fuel cost | High | Nil | Low |
| Capital cost | Moderate | High (drilling) | Very high |
| Emissions | CO₂, SO₂, NOx, ash | Low; some H₂S | No CO₂; radioactive waste |
Remarks
- Thermal plants are the most flexible in location and output but polluting and fuel-dependent.
- Geothermal and nuclear are base-load plants with high availability and low fuel cost; geothermal is site-limited, nuclear needs very large investment and strict safety.
✓ Answer checked by Claude Opus 5.5 (high effort)
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