- Category: Articles
![Figure 1. Installed repowered capacity in the USA DNV fig 1 Repower capacity chart](/images/stories/Features/2021Features/MayJune2021Images/DNV-fig-1-Repower-capacity-chart.jpg)
In recent years, wind farm repowering has contributed an important fraction of overall US wind farm installations, as developers seek to capitalise on existing infrastructure, proven revenue streams, and tax credit eligibility. Partial repowering, as opposed to full repowering, remains the dominant form in the US market and typically involves reusing the existing foundation and towers, while replacing uptower components with new parts to attain higher performance and financial benefits from the asset. According to the ‘American Clean Power Market Report Fourth Quarter 2020’, partial repowering increased sharply from 2018 to 2019 and remained at roughly 3GW in 2020 (for reference, new US wind installations in 2020 accounted for roughly 17GW).
By Ali Ghorashi, Head of Section, Wind Independent Engineering, DNV, USA
- Category: Articles
![Figure 1. Elongation of bolt Figure 1 RD Elongation of Bolt](/images/stories/Features/2021Features/MayJune2021Images/Figure-1-RD-Elongation-of-Bolt.jpg)
Achieving and maintaining the right tension in bolted joints in wind turbines can help prevent system failures and associated repair costs. One loose bolt in a cluster of several hundred holding a structure together, often interdependently, can cause a domino effect that could, at worst, result in failure of the entire unit. As wind turbines continue to increase in size, the structures need to withstand ever higher centrifugal and bending forces, as well as vibrations – all factors that can affect the integrity of bolted joints. Correct bolt tensioning is, therefore, critical. But, accurate bolt tension is not only difficult to achieve, it can also be difficult to monitor. Danish engineering company R&D has developed an accurate system that uses both mechanical and ultrasonic measurements to determine the desired bolt tension in a way that also saves time. The solution can also digitally track individual bolts throughout their lifetime, ensuring the condition of the bolts is documented.
By Flemming Selmer Nielsen, Senior Specialist Engineer, R&D, Denmark
- Category: Articles
In Addition to Attractive Financial Returns, Investors Seek Environmental and Social Benefits
![Figure 1. The SFDR regulation and its stages in the relay race Rosa figure 1](/images/stories/Features/2021Features/MayJune2021Images/Rosa-figure-1.jpg)
By Rosa M. Tarragó, Strategy and Infrastructure Equity Specialist, Germany
- Category: Articles
![Figure 1. An oil rig being powered by a floating wind facility Morten Figure 1](/images/stories/Features/2021Features/MarchApril2021Images/Morten-Figure-1.jpg)
A recent project has investigated the potential for a renewable energy solution to reduce the emissions associated with the production of offshore oil and gas in the North Sea in a variety of scenarios. The project, involving Lundin Energy Norway, Floating Power Plant, Cefront Technologies, APL-NOV, Semco Maritime, Aalborg University and DNV GL, explored technical, economic and regulatory aspects of combining the offshore renewable energy and oil and gas sectors.
By Chris McConville, Anders Køhler and Morten Egedal, Floating Power Plant, Denmark
- Category: Articles
![Figure 1. Flow measurements on-site for the downwind situation of 2-B Energy in Eemshaven, the Netherlands Figure 1 WE4CE VGTUFTS](/images/stories/Features/2021Features/MarchApril2021Images/Figure-1-WE4CE-VGTUFTS.jpg)
The highest increase in annual yield a wind turbine can obtain is by increasing the rotor diameter. This is because the increase in wind power follows a mathematical ‘power of 2 law’ based on the diameter. For existing blade lengths and for the turbines that have already been running for a while, improvement is also possible by the use of flow changers. The amount of improvement is not to be underestimated and can bring a lot – at least up to 2.5% annual yield.
By Edo Kuipers, We4Ce, the Netherlands
- Category: Articles
![Figure 1. Portfolio benefit analysis – annual uncertainties can be reduced with a portfolio of diverse projects UL Figure 1](/images/stories/Features/2021Features/MarchApril2021Images/UL-Figure-1.jpg)
Almost 50% of installed wind capacity in the USA is at least eight years old, accounting for approximately 60GW of operational projects. Unlike greenfield development, these projects have been operating for several years, which provides valuable insight into topics such as project performance, operating costs and revenue, community relations, environmental risks, and other key aspects.
By Jeremy Tchou, Director for Due Diligence, UL, USA
- Category: Articles
![Figure 1. Foundation concrete volume: analytical versus FEM Aztec Picture1](/images/stories/Features/2021Features/MarchApril2021Images/Aztec-Picture1.jpg)
Larger turbines suppose an increase in loads that finally requires more prominent foundations. Those dimensions lead to flexible behaviour. With the current foundation volumes, we are at the boundary of applicability of some analytical expressions widely used in foundation geotechnical and structural calculations, especially in the early stages of design, as they assume the foundation to be a rigid body. Two possible scenarios arise. If the analytical expressions are on the safe side that will lead to overpricing with an overestimated foundation volume. On the other hand, analytical expressions could lead to unsafe foundation design.
By Matias Campos, AZTEC Engineering, USA and Maria Collado, TYPSA, Spain
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