METMASTS FEATURE
OFFSHORE METEOROLOGICAL STATIONS A HIDDEN CHALLENGE
BEST IN CLASS
ACCOUNTING FOR A SMALL PROPORTION OF INVESTMENT AND EFFORT SPENT ON A PROJECT, THE METEOROLOGICAL STATION IS EASILY OVERLOOKED. BUT DESIGNING AND INSTALLING A ‘MET MAST’ DEMANDS A HIGHLY INTEGRATED APPROACH AND UNDERSTANDING OF THE COMPLEX STRUCTURAL DESIGN. FOR PROJECT DEVELOPMENT TEAMS IT CAPTURES MANY OF THE CHALLENGES ENCOUNTERED IN DEVELOPING THE PROJECT.
CAPITAL RISK
The mast, which can cost anything between £4 and £10 million, is normally installed before the project has reached the financing milestone of full planning consent. This timing means that the installation happens before ‘financial close’, putting the developer’s capital at risk if consent is refused.
For example, Cirrus Shell Flat wind farm development was shelved in 2008, six years after a met mast was installed.
GIVEN ALL THIS, WHY BOTHER WITH A MAST IN THE FIRST PLACE? Met masts are installed early in the project development phase, with the objective of taking accurate wind measurements in order to increase confidence in the wind speed predictions.
The measured data alone gives an improved understanding of the site’s wind regime. But the value of the data can be increased by comparing them to measurements made over a much longer time period at a weather station nearby. The process known as ‘measure- correlate-predict’ involves identifying correlations between the long-term data and the measured on-site data.
In essence, understanding the correlation enables synthesis of the long term record for the specific site
– effectively providing a statistical view of wind speed over a much longer time span. Ultimately, the technique increases the certainty of wind speed predictions, and by inference, power production, over the life of the project.
The highest possible level of certainty about wind farm production is an important element of securing finance at the best available terms, a potent driver of the cost of energy.
Although they are not the only means of understanding the wind speed at a site, the consensus view is that a mast is the best option for decreasing the uncertainty in wind speed predictions. the figure below shows possible measurement alternatives and how the uncertainty levels compare.
STRUCTURAL DESIGN CHALLENGES It is tempting to assume that the met mast structure is fairly simple, especially when compared to a highly dynamic wind turbine.
While this might be true to some extent, the mast’s offshore foundation is not a static structure and dynamic loads need to be considered. Lattice towers and their foundations must be robust enough to withstand the wind and waves at the site without comprising the quality of wind measurements.
102
www.windenergynetwork.co.uk
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116