The Effect of Upscaling and Performance Degradation on Onshore Wind Turbine Lifetime Extension Decision Making

Abstract

Abstract. Ever greater rated wind turbine generators (WTGs) are reaching their end of design life in the near future. In addition, first research approaches quantified the impact of long-term performance degradation of WTGs. As a consequence, this work is aimed at discussing and analysing the impact of upscaling and performance degradation on the economics of wind turbine lifetime extension. Findings reveal that the lifetime extension levelised cost of energy (LCOE 2) of an 18 MW wind farm comprising of 0.5 MW rated WTGs are within the order of £23.52 per MWh. Alternatively, if the same wind farm consists of fewer 2 or 3 MW WTGs, the LCOE 2 reduces to £16.56 or £15.49 per MWh, respectively. Further, findings reveal that an annual performance degradation of 1.6% (0.2%) increases LCOE2 by 34-41% (3.6-4.3%). IntroductionLifetime extension (LTE) is financially attractive in comparison to new investment and repowering due to the following identified root causes: the ageing of the current European wind fleet as illustrated in Figure 1; the more competitive allocation of onshore subsidies for new investments [1]; the trend of terminating repowering subsidies as observed in Germany, Spain, Denmark, and the UK [2]; the demonstration of competitive lifetime extension levelised cost of energy (LCOE 2 ) [3]; and finally the comparatively little due diligence for the lifetime extension analysis (LTEA) as well as the hard-won, long-term stakeholder relationships with local communities. As a consequence, LTE of wind turbine generators (WTGs) has become a widespread objective within todays' onshore wind energy industry.As greater rated turbines have been commercially developed and installed in the past, there is an observable trend of greater WTG classes reaching their end of design lifetime as illustrated in Figure 2, depicting the current and future distribution of turbine classes reaching their 20th year of operation. In 2016, the distribution is predominantly composed of WTG below 0.5 MW and to a lesser impact of WTG in between 0.5 and 1 MW; however, this distribution is changing significantly over the next decade with the pre-dominant WTG class shifting towards installations in between 0.5 and 1 MW. Given this observable trend of greater scale turbines reaching their end of design lifetime, this paper is aimed at analysing the development of lifetime extension LCOE with varying turbine classes.

Risk‐based derivation of target reliability levels for life extension of wind turbine structural components

“…For components where fatigue is the design driver, this could mean that the end of the design fatigue life is reached, and the reliability of the structure is not proven sufficient any longer. Even if it can be shown to be sufficiently safe to operate for an extended lifetime, the profitability is not guaranteed and requires analysis 4 . Often, there is no debt in the wind farms unless the wind farm has been bought recently from another owner.…”

Probabilistic and Risk-Informed Life Extension Assessment of Wind Turbine Structural Components

“…Several studies examining the feasibility conclude that the amount of refurbishments needed for life extension is a very important factor, as well as the unknown power price [21][22][23]. Ziegler et al [24] investigated the effect of increasing maintenance costs on the feasibility of life extension compared to repowering.…”