Seven Windmills

Last weekend I purchased a small booklet entitled "Windmills of Sussex" at a car boot sale.  This work was an expanded version of "Seven Sussex Windmills" which was probably published sometime in the 1970's.  If you like second hand books, car boot sales can represent the high and low points of book hunting.  There are two rules, first, the probability of finding something interesting is inversely proportional to the distance travelled and secondly, If you like a book, buy it then and there because it won't be there next week.

Windmills are interesting because they are sited at locations for which there is no obvious source of wind speed data other than the mill itself, so how did millwrights and owners decide where to build.  In the 19th century there was a substantial number of millwrights equivalent to the wind turbine industry of today and part of their expertise must have been a knowledge of wind and terrain.  Whilst there are descriptions of wooden post mills being dragged from one location to another by teams of oxen which suggests that if a location proved to be unsuitable, there was a chance of moving on.  However, the this was not possible with the large brick built structures that appeared on the latter half of the century, therefore getting it right first time was important.

When I first became interested in wind energy, it became clear that the variation in wind speed over a small area can be very large.  In the coastal town where I live the wind coming of the sea can be a smooth 10 m/s on  the seafront, my backyard can be calm and the foothills gusty.  The variation is due to terrain and surface texture.

The SRTM dataset collected by the Space Shuttle in 2000 is a good tool for displaying terrain.  I wrote a very basic programme to draw custom contour maps centered on a given location.  These can also be used as overlays with Google Earth which provides some additional context.  One, trivial exercise consisted of walking across the South Downs from the seaward side, over the crest and down the landward side with a wind speed meter and relating the results to reports from an airfield a few km to the west (This is described in a previous post).

The plots below are for the "Seven Sussex Windmills", the location of each being obtained from Wikipedia:

Argos Hill

Clayton

Nutley

Polegate

Shipley

Punnett's Town

West Blatchington

With the possible exception of the Polegate mill, all are located on hills, ridges or open ground.  A similar exercise with wind farms produced similar results.  What I would like to know more about is seasonality of milling with wind.  At a guess, its seasonal peaking around August and September after the harvest has been gathered in.  If it is seasonal, the location of the mill would be influenced by the prevailing wind after the harvest.

References

Windmills of Sussex, Brian Austen, Sabre Publishing 1978

SRTM - Wikipedia

Windmills in East Sussex (Wikipedia)
Windmills in West Sussex

The wind, mobile phone and the Space Shuttle

How to make this stuff exciting.....

Recently I was chatting to a neighbour discussing the usual things that people who live in the same street do, the vagaries of the council, chainsaws etc..  He is a journalist who sometimes does features involving large industrial plants, and I was envious when he showed me some photos of himself and others wearing hard hats and dayglow jackets and almost jealous when he flashed up a photo of an offshore jack-up construction vessel involved in high voltage electric cable installation.  This is an outburst like that of a comedian which went something like this "...I want to be a real actor... and wear tights".

A screenshot......

This exchange did highlight one of the problems with software and by implication things like energy management.  Much as I love software, it is difficult to make it exciting.  As a project manager, I was often faced with the problem of making the product and the people who produce it interesting.  Often a software development team is just a load of men and women sitting around an office, occasionally, drama erupts as a QA/QC person challenges challenges a programmer on a feature which then becomes an exchange of comments on dress sense, harmony is restored when it is agreed that the client/management was clueless and did not know what they wanted.  Hint - don't listen to the vocal minority of users but seek out the silent minority as more often than not, they will tell you what you need to know to stay in business.  No wonder that the most common expression of software is a screenshot.  Someone sitting in an office in a hard hat just invites comments on the level of building maintenance.

My experience is in decision support systems, but I have been intrigued by the way that cars have become software products, although I have yet to hear two owners discuss which version of software their car is running.  Like many engineers I was drawn to cars and motorbikes as a young man.  In the 1970s a petrol engine was a collection of more or less independent mechanical systems.  For example, the timing of the spark which ignited the air/fuel mixture in the cylinders was determined by something known as the advance and retard mechanism.  One form of this was a centrifugal governor whose origin dates back to the steam engine, as the engine speed increased, the relative position of the distributor shaft was adjusted so that the spark plug fired earlier in the compression stroke.  Similarly, the carburettor was a venturi which sucked more fuel into the airstream as the engine speed increased, often greater control over the air/fuel mixture was given by a needle valve mounted on a damped and spring cylinder which retreated further into a housing as the vacuum in the manifold increased as the driver's foot opened a butterfly valve.  A modern petrol engine is a system of sensors and actuators coordinated by a computer.

Device for measuring the voltage produced by an ignition coil

This approach resulted in significant gains in fuel efficiency. During my later student days I was the proud owner of a 997cc BMC Mini (as designed by Sir Alec Issigonis) this had a kerb weight of around 650 kg.  Three or four students could move a Mini around a car park by picking up the rear wheels, this was great fun if it was not your Mini.  Despite careful driving and regular maintenance I remember fuel consumption as being around 40 mpg.  The modern BMW version of the Mini has a kerb weight of around 1,100 kg and fuel consumption in excess of 60 mpg.  I guess that the engine management system is produced by men and women sitting around an office.

How to make things attractive is a theme that runs through energy management. An example is LED lighting which with careful design and installation can lead to a significant reduction in domestic electricity consumption, since we have been replacing CFLs with LEDs our consumption is drifting down to around 5 kwh/day or about half of what we were using 5 years ago.  If every household could cut its consumption, the pressure to build new fossil/nuclear generating capacity is reduced.  The automotive industry has demonstrated its ability to develop technology, is something similar possible with domestic energy consumption?  An interesting line of enquiry is the application of the storage systems being developed to electric vehicles for home and office use.  For example, adding  5- 10 kwh of storage to a house enhances its ability to use off peak resources and use the grid to obtain electricity generated from sustainable sources.

How do you pose with an LED light and look as purposeful as a man in a hard hat and dayglow jacket who is operating a large crane?