Power generation economics: Among thermal, nuclear, hydroelectric, and fast breeder systems, which typically has the lowest operating cost per unit of electricity generated?

Introduction / Context:
Operating cost is distinct from capital cost. Hydroelectric plants have high upfront construction costs but low recurring costs due to the absence of fuel purchases and relatively simple operations.

Given Data / Assumptions:

• Operating cost focuses on fuel, routine O&M, and consumables.
• Capacity factor and site specifics vary but general trends hold.
• No carbon/fuel costs are required for hydropower during operation.

Concept / Approach:
Hydropower converts stored water potential energy into electricity without fuel. Nuclear and fossil plants incur continuous fuel and more intensive operations costs; breeder reactors are complex and costly to operate.

Step-by-Step Solution:
Compare fuel needs: hydro requires none; thermal and nuclear need continuous fuel supply.Compare routine O&M: hydro is relatively low.Conclude that hydroelectric has the lowest operating cost per kWh, on average.

Verification / Alternative check:
Utility reports show very low variable O&M and zero fuel cost for hydro relative to other generation types.

Why Other Options Are Wrong:
Thermal/nuclear: require fuel and complex operations. Fast breeder: advanced nuclear with high operating complexity.

Common Pitfalls:
Confusing operating cost with levelized cost or total cost; hydro can have high capital but low operating cost.

Final Answer:
Hydroelectric power plant