Repowering of wind turbines

The expression “Repowering” refers to power plant in general and includes all measures which improve the efficiency and capacity by means of retrofit to the latest technology. Considering a coal power plant, repowering could mean to install a new steam generator or a new turbine. Possible modifications on wind turbines are limited, thus repowering affects the whole plant in general and essentially the entire wind farm. In short, aim of the repowering is to use the existing renewable energy resources on site more efficiently, respectively in a technically adapted or improved manner.

Progressing technology provides the option for operators to improve the profitability of their site, or to cope with new technical or legal conditions. Frequently planned and often locally supported is to restore the landscape. The reduction of the number of plant is linked with a significant growth of hub heights and a reduction of the rotational speed.

The actual repowering of larger capacities and entire wind farms in Germany started since the amendment of the Renewable Energy Law in 2004 provides financial incentives for repowering projects. Since Germany runs short on productive sites onshore, the government and the wind energy industry place their hopes on repowering onshore before the offshore market will be opened up in a few years.

Animation (in German language only)
"Repowering Movie with friendly permission of the German Wind Energy Association BWE"

Presently, the individual capacity of a wind turbine has advanced enough to fulfil the initially formulated aim of doubling the capacity and reducing the number of plant by 50 . The 2 MW turbine class and upward emits considerably less noise and complies with the actual grid code to feed in larger capacities.

The history of repowering started in California with the scrapping of the first and second generation of wind turbines of the oldest plant and resale of usable plant until 1993. Reasons mentioned were technical progress, reduction of the plant density, and restoring of the landscape near tourist routes.

A change in the legal framework in Denmark ended in that until 2002 approximately 1800 wind turbines were replaced and mostly scrapped.

In special cases used wind turbines lend themselves for rebuilding on a new site after a thorough general overhaul and in most cases a new foundation. It is recommendable to assess the mechanical wear and to repair or to replace the affected components before being installed on the new site. Based on good operating conditions and experience with maintenance the second hand plant could allow more than 10 years of operation.

Since 2003 the second-hand market experiences steady growth with plants from Denmark, the Netherlands and Germany mostly being shipped to the Balkans and Eastern Europe.

Further information:

Holger Peters
inensus GmbH