Energy sources in Nepal and wind scope

Energy sources are grouped by how long they have been widely used and whether they are renewable.

Conventional and non-conventional sources in Nepal

Traditional biomass is still the largest share of total energy use; imported petroleum is the second; hydropower supplies almost all grid electricity.

Technology of wind energy

Wind power converts kinetic energy of moving air into electricity.

 Wind -> Blades -> Hub -> Gearbox -> Generator
                                       |
                            Converter/Transformer
                                       |
                                Grid / battery
 (tower, yaw drive, pitch control, controller)

• Rotor: 2 or 3 blades (HAWT) or vertical-axis (Darrieus, Savonius).
• Gearbox: steps up low rotor speed to generator speed (not used in direct-drive types).
• Generator: induction generator, DFIG, or permanent magnet synchronous generator.
• Controls: pitch control, yaw control, brake, and power electronics for grid connection.
• Power: $P = \frac{1}{2}\rho A v^3 C_p$, with $C_p$ limited to 0.593 (Betz limit); practical 0.35–0.45.
• Cut-in speed about 3–4 m/s, rated about 12–15 m/s, cut-out about 25 m/s.

Possibility and scope in Nepal

• The SWERA study (Solar and Wind Energy Resource Assessment, AEPC, 2008) estimated a wind potential of about 3,000 MW in areas with good wind power density.
• Promising sites: Kagbeni and the Kali Gandaki valley (Mustang), Khumbu, Palpa and some mountain passes, where valley winds are strong in the afternoon.
• Early projects: a 20 kW turbine at Kagbeni (1989) failed soon due to poor maintenance; later small wind–solar hybrid systems (e.g. Dhaubadi, Nawalparasi) were installed by AEPC.

Scope (opportunities):

1. Electrify remote mountain villages as wind–solar–battery hybrid mini-grids.
2. Wind is often strong in the dry winter season when hydropower output is low, so it complements run-of-river hydro.
3. Telecom towers, trekking lodges and tourism areas.

Limitations:

1. Detailed long-term wind data is scarce; winds are site-specific and turbulent in valleys.
2. Transport of large blades and towers on mountain roads is difficult.
3. High cost per kW, lack of skilled maintenance, and strong competition from cheap hydropower.

Wind therefore has good scope as small and medium hybrid systems in specific windy valleys rather than large wind farms.