Repowering
Replacing ageing generating equipment at an existing site with newer, usually larger and more efficient technology, most commonly applied to wind farms after 15 to 25 years.
Early wind farms occupy some of the best sites, often with turbines of 0.5–2 MW on 40–80 m rotors. Replacing them with modern machines on the same land typically allows far fewer turbines to produce much more energy, reusing grid connections, access roads, permits and community relationships.
Two forms are common:
- Full repowering: old turbines and foundations removed and replaced. Typical outcomes in German and Danish projects: turbine count reduced by 40–70%, installed capacity doubled or tripled, annual energy up 2–4 times.
- Partial repowering: new blades, nacelle components or control systems on the existing tower and foundation, common in the US where tax-credit rules reward it; yield gains typically 10–30%.
Gains come from larger swept area, greater hub height, lower specific power and better availability. Repowering raises capacity factors from the 20% range typical of 1990s fleets to 30–40%.
Europe has more than 30 GW of wind capacity reaching 20 years of age by the late 2020s (WindEurope). Barriers include new permitting procedures, tip-height limits and setback rules that were looser when the original farm was built. EU legislation (RED III) now requires faster permit procedures for repowering. Decommissioned blades raise recycling questions; several manufacturers have committed to landfill bans and recyclable resin systems. The term is also used for hydro plant modernisation and solar module replacement.
Related terms
All terms →- Capacity factor
The ratio of the energy a power plant actually produces over a period to the energy it would produce running at full nameplate capacity for the whole period.
- Swept area
The area of the circle traced by a turbine's rotating blades; wind turbine power output is directly proportional to it, and it grows with the square of rotor diameter.
- Hub height
The height of a wind turbine's rotor centre above ground or sea level; taller hubs reach stronger, steadier winds and are a main driver of rising capacity factors.
- Wake effect
The reduced wind speed and increased turbulence downstream of a wind turbine, which lowers the output and raises the fatigue loads of turbines located behind it.
- Degradation rate
The gradual annual loss of a PV module power output over its life, typically around 0.5% per year for crystalline silicon.