Weather data: Forecasting for cost reductions
Offshore wind farms are built in areas where it has been determined, by monitoring with met masts and floating met buoys, that there is enough of the turbine ‘fuel’ under normal circumstances. It is not just the remote location and water depth that determines that you will not find any offshore wind farms in the Doldrums. The ability to provide accurate weather forecasting in the long term, short term, and extremely short term, provides the key to making wind energy in general a viable industry.
We shall discuss extremely short term forecasting at a later date as this has more to do with turbine operation, changing yaw, and pitch settings by reading the wind conditions only seconds ahead so that when that wind condition strikes the blades they are set for optimal output.
‘Under normal circumstances’ is now under scrutiny. What are the normal circumstances now? Whatever has caused the climate changes in recent years it is not just our grand parents who tell us that summer holidays have not been the same as when they were younger in Europe. Are these changes a trend or are they freaks of nature? Does this mean that the weather patterns are changing permanently or is nature just playing with us?
These questions are the reason why meteorological organisations throughout the world are using some of the largest computers in the world to ‘crunch’ more data. In the UK the Met Office’s supercomputer is one of the largest in Europe and can carry out 27 trillion calculations per second! The results provide more accurate information not only to find out where and how we are affecting the climate in the long term but also for industries such as ours to justify the huge investments we are making.
The more the better
The more data you have, the more accurate your forecasting will be. Lack of accurate data leads to uncertainty, and this data vacuum, in turn, worries investors. However the collection of accurate data is also expensive. A single met mast can cost €15 million, or more.
These factors led to the formation of NORSEWInD in 2008, an international consortium from Germany, Denmark, Norway, Latvia, the United Kingdom, the Netherlands, Belgium, France and Portugal. The 22 partners included meteorological organisations, universities, companies involved in offshore wind production, and consultancies who joined together to measure and collate wind data.
They created a network of over 30 offshore instrumentation data points in the Irish Sea, the North Sea and the Baltic. Aims included the production of an offshore wind atlas of these seas providing accurate and dependable information to the industry and to set a standard for the collection of such data world wide.
With an EU grant of €3.9 million from the EC FP7 programme, the partners provided the remainder of the €7.9 million budget. Abilities were called in from many various unlikely resources. For example, a network of over 20 LiDAR installations were placed, where possible, on existing offshore oil and gas platforms to reduce costs, thanks to oil giants such as Shell and Taqa.
Coordination of the programme was carried out by Andy Oldroyd, Technical Director of the UK company, Oldbaum Services. Even after the offshore wind atlas has been completed he remains eager to continue the collection of data.
One of the member organisations of NORSEWInD is the Dutch KNMI, Royal Netherlands Meteorological Institute. For some time now they have been producing and providing wind vector measurements near sea level using a satellite radar instrument, the Scatterometer. They have developed scatterometer software for near real time processing of data for operational use in forecasting. Their work makes use of scatterometers on board satellites from the European Space Agency, NASA / NOAA, EUMETSAT, and ISRO, the Indian Space Research Organisation.
KNMI are also working, experimentally, with the HY2A (Chinese) satellite. These measurements are used for hurricane or typhoon forecasting, in numerical weather prediction models, marine and ocean applications and for climatological applications.
The UK Met Office working with the ASCAT and OSCAT wind products provided by the KNMI is another example of cooperation between national meteorology services. This UK organisation offers various services to wind farm operators, from the Virtual Met Mast in the wind farm development stages to Visual Eyes and Wind Production Forecasts customised to the specific wind farm, to identify optimal times for wind generation in a 14 day customised weather analysis. A 36 hour alert panel gives the wind farm operator an even greater detailed breakdown of the conditions to come.
There is a constant effort by these organisations to provide higher resolution images with increased quality control.
Having determined where to build your offshore wind farm is not the end of the meteorologists’ input in the industry. The time scale changes from years and decades, to days, weeks, and possibly months. Accurate weather forecasting hours, days, and weeks ahead is an immensely important science to the industry and certainly more so offshore than onshore, simply because the investment offshore is so much greater.
The generation mix to the onshore grid operators and utility companies can be altered in planned phases. Accurate long term forecasting will enable them to book offshore generation slots with confidence. This in turn can mean that non sustainable energy powered units, such as the gas turbine power stations, can be taken off line, for the period of forecasted offshore wind energy.
Planned generation time is not the only reason to have accurate forecasting. Saving money is just as important as making money. Planned maintenance in non generation downtime periods saves expenses, and ensures efficient staff utilisation. Making the most of what wind there is on offer is what it is all about.