In 2018, the UK government declared that wind projects located on remote islands, such as the Western Isles, Shetland and Orkney, would be able to compete for Contracts for Difference (CfD), the administration’s main mechanism for supporting low-carbon electricity generation.
The scheme provides a price guarantee for developers on the energy generated from new programmes, which is vital in providing the certainty that investors demand.
The potential is significant. According to a government study commissioned in 2013, onshore wind generation on the main Scottish islands alone, could meet up to 3% of total UK electricity demands. That is equivalent to powering 2.4 million homes, or around half the output of a new-build nuclear power station, such as the recently shelved £20 billion Wylfa facility on Anglesey.
The next CfD auction is scheduled for late May, with up to £557 million in funding available to bidders. But to make competitive proposals for this support, developers need to further reduce the levelised cost of energy (LCoE) by cutting construction and operating costs while maximising yields at given sites.
The key to reducing construction costs lies in a collaborative, value-engineering driven design and construction process that faciltates innovative thinking.
A key part of this is championing early designer and contractor collaboration with the developer and candidate turbine suppliers in contributing to the design process.
This fosters a strong delivery team work ethic, and allows specific expertise from the different organisations to be captured, providing advice and input for every part of the programme. This can deliver particular improvements in areas that include solution development, buildability, construction sequencing, the planning application support document, construction cost estimation, and project risk management.
Ideally, this process should start ahead of the planning application, during the scheme’s development. This front-loading of the project-development phase costs are offset by a leaner, more buildable scheme, should it gain consent.
However, implementing a collaborative process post-planning but pre-construction also offers similar benefits through encouraging regional contracting and increased efficiency through a shared goal of reducing construction costs.
Harnessing manufacturer expertise
The turbine manufacturers are another group that should be brought into the process at an early stage.
This can reap benefits through obtaining site-specific wind and turbine-loading data, potentially allowing different models from the supplier’s range to be specified for use on different parts of the site.
This approach can deliver more production from lower-wind resource area on site, through turbines that are tuned for specific ranges of wind because they are designed with optimal blade width, pitch and profile.
Typically, turbine suppliers provide generic documents for access infrastructure and turbine-loading data, but these might not be the best possible solution for any given site.
Through early engagement, project-specific infrastructure requirements can be developed and fine-tuned to meet the proposed turbine supply, delivery, and installation programmes. These can all lead to potential cost savings by optimising areas that include access infrastructure layout, cabling arrangements, earthworks and foundation solutions.
Foundations for success
Another key consideration is the way in which turbine foundations are constructed. The vast majority of UK onshore wind farms installed to date have used in-situ reinforced concrete gravity and piled turbine foundations.
These can be challenging to construct in remote and inclement settings, particularly as they often call for multi-stage concrete pours in order to create the increasingly large foundations required to accommodate the loads from quickly evolving turbine technology.
Any breakdowns in concrete site-based batching plant or ready-mix delivery pose the risk of cold joints forming, potentially compromising the integrity, durability and operational life of these dynamic structures.
In Scandinavia, we often see rock-anchor foundations used as an alternative to gravity foundations, where the right geological setting prevails with strong bedrock close to the surface.
This method works by fastening the turbine foundation to the rock via post-tensioned anchors installed several metres into the underlying bedrock. This greatly reduces the size of the foundation and related concrete and reinforcement quantities, as well as reducing rock excavation and blasting.
This approach, where appropriate, has the potential to reduce construction costs and risks for new installations in remote locations, while offering environmental benefits through reduced forms of construction.
The construction and maintenance benefits of onshore wind power over offshore development make it a compelling option in areas where geography and demographics allow.
Taking an earlier, more integrated approach to project delivery can not only enhance these natural advantages but potentially reduce the scheme’s construction and operation costs. This has never been more important as the drive to deliver LCoE is paramount in our industry, requiring a high level of commitment from all.
The inclusion of remote island schemes in CfD bidding has handed developers the opportunity to ensure onshore wind continues to play a part in the energy mix in the years ahead. Effective collaboration with their supply chains will allow them to capitalise on this opportunity.
Mike Tavern is operations director for renewable energy infrastructure at engineering consultancy Sweco