Technology effects in repowering wind turbines

Abstract

This research investigates, analyses, and quantifies the technological effects of wind turbine repowering (ie, where old turbines are removed and new turbines are installed at the same or a very close location, including the enhanced performance in energy production). In these cases, it is assumed that both old and new turbines are subject to the same wind regime, other than because of technological elements, such as hub height, and thus it is possible to isolate the effects of new technology from the effect of changing local wind conditions. This research is based on the analysis of empirical data on repowering turbines in Denmark and Germany, and on historical production data available for the Danish component of the data set. Technological innovations are expected to enable new wind turbines to capture more energy at the repowering site, mostly through larger rotors and higher hub heights, and this is what this study has analysed. The results show that new turbines in repowering projects are twice as high, have three times the rotor diameter, nine times the swept area, six times the nominal power, and nine times as much electricity as the old turbines. However, the most significant improvement is probably the increase of capacity factor of 7.1% on a per-turbine basis, or 9.7% on a per-production basis.

Sustainable Wind Power Plant Modernization

“…There are basically three distinct strategies for dealing with the wind turbines at the end of their lifecycles: decommissioning, lifetime-extension, and repowering. The aim of decommissioning is to disassemble the wind power plant after it has reached the end of its lifecycle and to then recycle them [41,42,47,48]. Lifetime-extension, in turn, includes measures to extend the wind power plant's lifecycle by replacing worn out elements with new ones.…”

“…In the world literature one usually finds analyses concerning mainly the assessment of wind power plant profitability and productivity after lifetime-extension and repowering [41,42,47,48], yet what is missing is a comprehensive assessment of the benefits as well as the ecological, energy, and economic costs arising from modernizations in wind power plant lifecycles. Ziegler et al [41] performed analysis of the technical, economic, and legal possibilities relating to lifetime-extension showing that the profitability of these processes depend on energy market prices and thus differ depending on the country.…”

“…Martinez et al [50] have shown that the repowering process causes an increase in the wind turbine's production of electricity at the same site with a smaller environmental impact. Studies concerning repowering have shown that such efforts give rise to an increase in both power and productivity [48]. There are no studies on the impact that standard replacements and modernizing replacements have (serving to extend wind power plant lifetime) on integrated efficiency.…”

Old Wind Farm Life Extension vs. Full Repowering: A Review of Economic Issues and a Stochastic Application for Spain

“…The literature gives various capacity factors, such as the figure proposed for the Gamesa G-850 kW (Alava, Spain) by Albani and Ibrahim [48] of 21.7%. Lacal et al [49] analyse technological effects in wind turbine repowering in Denmark and Germany and give an average capacity factor of around 22% for turbines removed in 2015 and 42% for newly installed ones. Ramírez et al [28] also study Spain's wind power output, analysing different turbines at different sites including Gamesa G-850 kW turbines (Alava, Spain), and propose 23.4% in the Valencia region.…”

“…The worldwide average capacity factor has increased considerably in the last thirty years, and it is not unusual for a sample from a country to be above 30%. The U.S. Department of Energy proposes an average capacity factor of 41% for the U.S., and Lacal et al [49] assume 41.1% for recently installed turbines in Denmark. Looking at Spain, Irena [65] recognises an increase of 16% (from 27% to 33%) in the weighted average capacity factors for new onshore wind projects from 2010 to 2016.…”