airbase repowering – HWS Towers

An innovative precast concrete structure for repowering of old wind turbines

HWS has developed the AirBASE RePOWERING, an innovative precast concrete structure for repowering purposes that allows to reuse the old foundations while making the most of the existing infrastructure in the wind farm.
This new product is based on HWS’ AirBASE technology: a new disruptive structural concept for wind turbine foundations, which is being successfully introduced in the wind energy market due to its cost-effectiveness.
AirBASE RePOWERING reuses the existing old foundation as ballast to improve the stability of the system, while adding on top two new precast girders in a cross-shape. The system is valid for any kind of soil and compatible with both shallow and deep foundations.

Among its advantages are cost savings of up to 45% when compared to construction of a new foundation, as well as being and environmentally friendly solution. In fact, the AirBASE RePOWERING respects the landscape by avoiding occupation of new sites, construction of roads and working platforms, and demolition of existing infrastructure. In addition, it could help simplify the permitting process required for installation of a new wind farm.
In conclusion, the AirBASE RePOWERING could become the optimum solution for repowering wind farms from the decade of the nineties, which are close to their end-of-life.

Repowering of existing wind farms

The first installation of a wind farm dates back to 1975 in USA. In Europe, VESTAS produced the first wind turbine in 1978. Since then, commercial installation of these machines has progressively increased reaching in 2019 a total installed capacity of 651 GW, among which 251 GW are in Europe. In both cases, onshore wind has a high share of around 90% of the given figure (source: Wind Europe & Wood Mackenzie).

Europe has committed to meet a 30% share of electricity generated by renewables in 2030. Nowadays, 15% of the electric energy produced by European countries (EU-28) comes from wind resource. To deliver on this objective, it is foreseen that the installed wind energy power will have to be doubled in the next 10 years. In the meantime, by 2030, 50% of the current cumulative installed capacity in Europe will have reached the end of its operational life. WindEurope estimates that the yearly repowering volume will grow from 1-2 GW in 2017 to 5.5-8.5 GW by 2027. The main markets will be Germany, Spain, Italy, Denmark, Portugal and France.

With this need to increase wind energy generation and the wind farms coming to their end-of-life period, the industry is considering the two following strategies:

Lifetime extension

Some of the components of an existing wind turbine are upgraded (e.g. generator). The overall external layout of the farm remains unchanged (e.g. hub height, siting, size) (…). Depending on the Member State, this option is also referred as refurbishment, enhancement, reactivation.

(Full) repowering

The old wind turbines are dismantled and new more powerful wind turbines are installed. This also involves replacing other elements like the tower and the foundation, which must be accordingly designed for the new turbine.

Onshore wind farm owners are currently finding much more attractive to extend the life of existing projects, since replacing foundations involves complexities and is expensive. However, as project life extension options are exhausted, owners will have to increasingly turn their attention to repowering.

This market demand has encouraged HWS to develop a new product: AirBASE RePOWERING.

This technology faces the challenges of foundation replacement, making repowering much more appealing.

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Source: WindEUROPE (www.windeurope.org),

June 2017, “Repowering and Lifetime Extension: making the most of Europe’s wind energy resource. THE EUROPEAN WIND INDUSTRY’S VIEWS ON MANAGING WIND ENERGY ASSETS AT THE END OF THEIR OPERATIONAL LIFETIME”