Tuesday 13th January 2015
Power from the sea – Creating a successful British Offshore Wind Industry
Matthew Knight BEng, CEng, MIET, Director of Strategy and Government Affairs for Siemens Energy
This was a very illuminated talk given by Matthew who has been heavily involved with wind generation at sea in the UK from its inception. He covered the topic from the early planning stages through to commissioning of the final article which included the infrastructure necessary to integrate the power generated ashore and into the national grid. The picture shows one such farm under construction and gives an indication of the support services necessary.
He started by drawing our attention to the political issues and the public’s perception of coastal wind farms and their acceptance of their presence on the landscape. Surprisingly, around 70 percent generally accept them with only 11 percent actually opposing. Politicians generally manoeuvre around the subject acting only for political advantage causing delay. There are, apparently, only a very limited number of MP’s that understand the subject and its implications for the country’s future power requirements.
Wind power is, of course, part of what we term “renewable energy” aimed at reducing the country’s carbon output to which we are legally committed. It is not the only way to reduce carbon output but it is the most efficient. The table below shows the different forms of generation against its carbon output together, importantly, with the time taken to bring it on line. From this it is quite obvious that a readily available backup is necessary for the most efficient forms of near carbon free generation with the build up of nuclear generation taking days and wind power only being available when the wind blows. Even with this restriction for wind a load factor of around 55 percent is obtained. So, although wind power is not the total answer, it makes a valuable contribution to our efforts for reducing the carbon output. In Europe the UK is planning to be the largest generator of power from offshore wind turbines. The different contributions by each state can be seen in the attached table below.
A complete picture of renewable energy sources planned for the UK by 2020 can be seen from the pie chart below although exactly what proportion of our total energy requirements it represents is not clear.
From the granting of a development licence for a typical offshore wind farm it takes around 6 years to obtain planning consent and get finance in place ready for the implementation phase of around 3 years. This implies that the engineering represents just one third of the workload!! Draw your own conclusions.
In terms of construction Siemens have a large plant in Demark and is in the course of constructing a plant in Hull in conjunction with Associated British Ports (ABP). The plant in Hull will be used mainly for turbine blade construction.
The full implementation of a wind farm to the point of integration into the grid is a complex affair as can be seen from the slide below. Each aspect of the overall project is shown below with an indication of the proportion of cost for each of them. We can expect to see each of these elements nearby when the Rampion farm (off the coast east of Worthing) is constructed. It is interesting to note that the transmission from the farm is via high voltage DC cables.
Matthew continued then to present the different parts of a typical coastal wind turbine starting with the blades saying how the aerodynamics have improved through continued development to some of the largest that are produced today forcasting that they are likely to be even bigger for some future designs, You can get some idea of the magnitude of these from the slide below where comparisons between the “Shard” and a Jumbo jet are shown. The blade under construction is shown at a fabrication plant in Denmark as is the transportation of one such blade along a motorway. Imagine one of these travelling down the A24 to Worthing – I think not!!
The speaker then went on to describe the different parts that make up a typical offshore turbine starting with the business end that generates the power, the nacelle. Here, the main components are the blade hub, gearbox and generator. The slide below shows a hub under construction. This is an enormous casting with 5 machined surfaces to take the blades, nosecone and gearbox interface. It also shows a diagram of an integrated nacelle showing the generator and associated electrical interfaces that take power and control cables to the power processing and control equipment in the tower.
The following slide shows the inside of a tower and the equipment it typically contains. Here, information from the many sensors around the turbine and in the blades ensures that its operation is kept within safe limits taking account of variable wind speeds and gusts. One can imagine the importance of this task when considering the forces involved with such high rotating masses on top of a very high pole where excessive rotational speed would result in self destruction.
Installation gives rise to a whole set of problems where one has both tides and wind to contend with in a very hostile environment. The slide above shows one solution whereby a reusable ship / platform is used bringing components from the shore to site. Upon arrival at the site it lowers support legs unto the sea bed to give a stable working platform. It must be quite a sight to see the blades erected. Looking at the hub many bolts have to be inserted by someone hanging below with the blade buffeted by the wind and dangling from a crane. There must be a huge sigh of relief after the first two have been inserted. In relative terms the rest of the installation must be a doddle! You can see the access for personnel from the platform to the bottom of the tower.
After finishing a review of the turbine Matthew continued to describe the rest of the equipment required for bringing power ashore from undersea cabling and substations necessary to process the power collected before it can be linked to the national grid for distribution.
This was a very illuminating talk covering every aspect of bringing power ashore from turbine fields and Matthew was thanked for the depth detail presented.
There are many more slides which accompanied the presentation and these will be available for viewing on our website at http://rceasussex.org.uk/category/report/talk/ in the near future. They are very detailed a very well worth a reading for those who were not able to attend the talk at Field Place.
Other sites on the subject which are well worth a visit include http://en.wikipedia.org/wiki/Wind_turbine_design and http://en.wikipedia.org/wiki/Wind_power