Image: London Array
Once completed London Array will be the world’s first 1 GW wind farm and almost double the British electricity supply from renewable sources. London Array will be built around 20km off the coasts of Kent and Essex in the outer Thames Estuary. The wind farm will be installed on a 245km2 site and will be built in two phases. The first phase, which is planned to be completed in 2012, will cover 90km2 and include 175 turbines with a combined capacity of 630MW. The second phase will add enough capacity to bring the total to 1 GW. This is enough to meet the electricity needs of 750,000 homes – around a quarter of Greater London or all of the homes in Kent and East Sussex.
Onshore construction started in July 2009 and offshore construction is scheduled to start in early 2011. Generation is expected to start before the end of 2011, while the second phase is scheduled to come on line by 2015.
The planning and installation of the foundations and turbines relies heavily on accurate hydrographical or metocean forecasts. Such forecasts play a significant role in minimising delays during the construction phase and further ensure that operations can be executed safely and within the predefined operational criteria.
In connection with the project DHI has been commissioned to develop the complete metocean forecasting system which is a prerequisite for efficient and safe planning and operations. The service comprises deployment, maintenance and operation of three wave and current buoys and a tide gauge. All equipped with iridium satellite communication for online data transfer. By applying data assimilation the online measurements are used to feed hydrodynamic models which predict the wave and current conditions. Combined with meteorological models this provides a complete 5-day forecast system for wind, air temperature, sea temperature, visibility, lightning risk, cloud height, water levels, wave heights and currents. Forecasts are disseminated via the Internet and as e-mails. In addition to the forecasts DHI provides in association with StormGeo a 24/7 hotline service including urgent storm/risk of lightning alerts.
DHI has also delivered metocean forecasts for other British wind farms such as Robin Rigg, Walney, Gunfleet Sands and Thanet.
DHI also plays a key role for the planning process for the second phase of the London Array Offshore Wind Farm. As part of the conditions for the construction of the second phase of this ground-breaking project it is required to establish the impact of the construction of the extension to the project on wintering Red-throated Diver Gavia stellata. DHI has been asked to undertake an independent assessment of the risk to the regional wintering population of this priority bird species of the extension through comprehensive modelling of the species' local habitat and estimation of the local population size potentially affected by habitat exclusion from the footprint of the wind farm site.
The assessment will apply state-of-the-art habitat models, which will enable us to identify the most important habitats for wintering divers in the development area based on analyses of the dynamics of diver distributions relative to the oceanographic dynamics of the Outer Thames Estuary. The oceanographic dynamics will be quantified using the same hydrodynamic models as for the forecasting system.