Primary and secondary energy (102 m head)

Primary energy is generated by the flow available 100% of the time (minimum flow). Secondary energy is the additional energy from flows above the minimum, limited by the plant (design) discharge of 55 m³/s.

Power per unit discharge

$$P = 9.81\,Q\,H\,\eta = 9.81 \times Q \times 102 \times 0.76 = 760.47\,Q\ \text{kW}$$

Installed capacity $= 760.47 \times 55 = 41{,}826$ kW ≈ 41.8 MW.

Primary energy

Minimum flow = 18 m³/s (May).

$$\begin{aligned} P_f &= 760.47 \times 18 = 13{,}688\ \text{kW} \\ E_p &= 13{,}688 \times 8760 = 119.91 \times 10^6\ \text{kWh} = 119.91\ \text{GWh} \end{aligned}$$

Monthly energy (flow used ≤ 55 m³/s, 730 h per month)

$$\begin{aligned} E_{total} &= 760.47 \times 467 \times 730 = 259.25\ \text{GWh} \\ E_s &= 259.25 - 119.91 = 139.34\ \text{GWh} \end{aligned}$$

Answer: Primary energy ≈ 119.9 GWh/yr; secondary energy ≈ 139.3 GWh/yr; total ≈ 259.3 GWh/yr.