ACKNOWLEDGEMENTS December 1999.

Thanks to University Dar es Salaam Morogoro (now Sokoine University) , to Uni Dsm Bralup, to Martin Parkes, to Judy Parkes, to Roland Reichel from UniDsm Mechanical Engineering Department, and to everyone who worked with me on the windmill projects. When Martin was doing this work I thought maybe he was wasting his time, but when a little bit later we got into making prototype wind machines we quickly realised that good matching or gearing was extremely important and that of course the economics of WECs was the determinant factor in deciding their feasibility. I revamped this report 1995 but the internet was still only really starting at that point in time - it is now mature enough to be a suitable medium for this kind of study. Although this report is on Tanzania wind data, its findings are probably valid worldwide.

Postscript December 1999 - windspeed distributions in principal are meant to be logonormal. And for any given windrun produced by a windspeed cup counter anemometer it is possible in theory to have a wide variation of wind patterns - e.g. a very narrow band of windspeeds or a very wide band. This report in practice found no appreciable variation - i.e. not only a logonormal distribution but the same shape of logonormal for all instumented Tanzanian locations (but if you look at the graphs you can spot some which are a bit different). One would expect that sites which are coastal or lakeside would have some significant differences, but this was not shown in the data. If the algorithms found in this report are useable then they should eliminate a whole lot of experimental windsite evaluation measurement using sophisticated instruments - just use the old fashioned mechanical cup counter anemometer. And if the condition of these CCA's is suspect then just compare the last say 10 years data - despite variations from year to year the trend line for windrun per year should be horizontal - if it has a downward trend over some years then almost certainly the CCA bearings are becoming tighter, and the original value from some years ago should probably be used.

Apologies that some of the graphs are not too well labelled - I included them anyway - but most have a good explanation.

Any questions, especially since a lot of the explanation jumps steps, then just email me -

Alexweir@usa.net