With offshore wind capacity set to quadruple by 2030, Nathan Neal discusses the additional considerations ahead of turbine installations
In November 2020 the Prime Minister announced his ambitious 10 Point Plan for a ‘green industrial revolution’, which will create and support up to 250,000 British jobs. Covering clean energy, transport, nature and innovative technologies, the plan will allow the UK to forge ahead with eliminating its contribution to climate change by 2050.
The UK already generates more electricity from offshore wind than any other country, harnessing the wind power our seas are well placed to produce. Government support to unleash the potential of this industry has seen the cost of offshore wind fall by two thirds in the last five years. By 2030, the UK aims to produce 40GW of offshore wind, including 1GW of innovative floating offshore wind in the windiest parts of the seas.
To integrate clean technologies such as offshore wind, we must transform our energy system, building more network infrastructure and utilising smart technologies, such as energy storage. Additionally, use of extra equipment on turbines that can monitor visibility, warn of the approach of severe weather and lower health and safety risks should also be considered
The importance of visibility and present weather sensors
All wind turbine parks are equipped with aviation obstruction (warning) lights, which for several created light pollution and led to residents objecting to wind farm development. To combat this, Germany has had legislation in place since 2004 requiring developers and manufacturers to install turbines with visibility sensor-controlled obstruction lights. These visibility sensors constantly monitor the local meteorological conditions and when the visibility varies, the light intensity for the warning lights is automatically adjusted.
For example, on clear days where the visibility is greater than 10km the light intensity is reduced to 10%. When the visibility is measured at 5km or higher, the light intensity is set to 30%. At all other times of lower visibility, it is set to 100%.
In addition to visibility data being used to control the obstruction light brightness on wind turbines, present weather sensors are often installed to enhance the readings. These sensors output the specific weather conditions being experienced by the sensor at the top of the turbine in addition to the visibility information. This is important when the turbines are subjected to freezing conditions and the blades can become coated in ice. Ice can greatly reduce the efficiency of the turbine and energy generation and in most cases, the turbines must be shut down and the blades de-iced before they can re-start. Having real-time weather data allows the operators to either plan for this eventually more proactively or to start their blade heating systems to reduce the ice build-up more effectively.
Detection of approaching storms
In many applications, a thunderstorm detector is used to help protect people and equipment from the dangers of a lightning strike by providing advanced warning of a storm's approach. This is especially true of tall structures sited on either exposed or flat landscapes where they are likely to initiate a lightning strike, as is the case for wind turbines. Detectors which rely on lightning alone are only effective if the storm is already producing lightning at a distance before moving closer towards the site. If the thunderstorm develops overhead, the first lightning strike of the storm will be very local and as there is no advanced warning and there is no protection.
In wind turbine applications, advanced warning of overhead lightning is of enormous benefit for installation teams as well as for operation and maintenance staff located on-site. Turbines are prone to lightning strikes and all staff on-site need to be warned of a storm's approach to make their way to a safe area. The same is true of offshore wind farms where the support vessels require warning of approaching storms to allow them to make their staff and operations safe.
With windfarms set to occupy sea footprint the size of London and power 3.4 million homes, it is vital that the structures are utilised to track weather conditions to not only keep up the efficiency of the turbine but to ensure the safety of staff who may be on site. With a renewables future already under way, it is hoped that more is still to come in terms of what can be done with these structures; the next few decades are set to be very exciting.
Nathan Neal is with Biral