Wind Power Project Repowering: Financial Feasibility, Decision Drivers, and Supply Chain Effects

Abstract

Executive SummaryAs wind power facilities age, project owners are faced with plant end-of-life decisions. This report is intended to inform policymakers and the business community regarding the history, opportunities, and challenges associated with plant end of life actions, in particular, repowering. Specifically, the report details the history of repowering, examines the plant age at which repowering becomes financially attractive, and estimates the incremental market investment and supply chain demand that might result from future U.S. repowering activities.Repowering as defined here includes two types of actions. Full repowering refers to the complete dismantling and replacement of turbine equipment at an existing project site. Partial repowering is defined as installing a new drivetrain and rotor on an existing tower and foundation. Partial repowering allows existing wind power projects to be updated with equipment that increases energy production, reduces machine loads, increases grid service capabilities, and improves project reliability at lower cost and with reduced permitting barriers relative to full repowering and greenfield projects.Repowering first emerged in the early 1990s in the California and Danish wind power markets and was followed by the Dutch and German markets in the 1990s and 2000s. Although repowering activity has occurred elsewhere, these locales remain the principal markets for repowering investments. Historically, repowering has been viewed as a means of increasing project productivity while offering an array of other potential attributes of interest. Fundamentally, however, profitability for a given project is the primary driver of repowering decisions. Given limited financing, the anticipated profitability at alternate greenfield sites is also relevant.Two distinct analyses were conducted to understand the plant age when repowering becomes viable. These analyses utilized NREL's System Advisor Model (SAM), a tool that enables the user to predict estimated cash flows from a variety of electric power generation technologies. Net present value calculations were utilized to enable comparisons across time.The first analysis involved creating "proto-typical" wind plants of four different vintages, with commissioning years of 1999, 2003, 2008, and 2012. Proto-typical plants are representative of the industry at the time of their construction and rely on market data from each of the commissioning years to derive installation and equipment costs, power purchase agreement revenue, net capacity factor, receipt of federal production tax credit payments, and operation and maintenance expenses. For each of these four plants, future investment decisions to repower, or build a nearby greenfield site, were evaluated for 2015, 2020, 2025, and 2030.The second analysis focused on three actual wind plants operating in the United States. These plants were chosen for varying vintages and geographical diversity and include a Northeast wind plant (15-20 years old), a Midwest wind plant (10-15 years old), an...

Technology effects in repowering wind turbines

“…Repowering wind turbines (or wind farms) brings a number of benefits. First, and most important, repowering will increase performance and electricity production of wind projects, as demonstrated under different circumstances by previous studies . This increase in performance is partly because the sites with the best wind conditions were often used in the 1980s or 1990s .…”

“…So far, the technological effects, efficiency gains, and performance improvements of actual repowering projects have not been researched in a detailed manner. Some evidence is available from theoretical studies . Some case studies have been performed on an individual wind farm basis (see, eg, Castro‐Santos et al and Villena‐Ruiz et al for actual repowering wind farms in Spain), then the focus has been economic or techno‐economic, rather than technological.…”

“…First, and most important, repowering will increase performance and electricity production of wind projects, as demonstrated under different circumstances by previous studies. 1,4,[8][9][10][11] This increase in performance is partly because the sites with the best wind conditions were often used in the 1980s or 1990s. 12 Compared with a greenfield project, financing conditions tend to be better for repowering projects because the wind resource is known already and planning costs will be lower.…”

“…Wind energy facilities, as other power generation technologies, are subject to ageing, inducing reduction of efficiency, output, and availability . In the case of wind turbines, it has been suggested that they lose up to 1.6% of their output per each year .…”

A plant‐specific model approach to assess effects of repowering measures on existing biogas plants: The case of Baden‐Wuerttemberg

“…These adjustments and measures may be considered under the term “repowering.” In traditional energy economics, the expression “repowering”—synonymously used to the term retrofitting—is according to Walters () defined as replacing old power plants or central components like steam generators or turbines to increase either the efficiency rate or the capacity of the plant as well as to reduce emissions. In the same sense, the term “repowering” is also broadly used in the wind energy sector and refers to replacing wind turbines with new ones and thereby increasing the capacity and full load hours (FLH), sometimes also decreasing the number of turbines in wind power farm (Lantz, Leventhal, & Baring‐Gould, ). In the biogas sector, the term “repowering” is widely used but there is no consistent definition (Effenberger & Lebhun, ; Fischer, Postel, & Ehrendreich, ; FNR, ).…”