Cloud Poles

Google Earth and KML are useful tools for visualizing a varied range of datasets. A project which is well into extra time involves correlating the attenuation of solar irradiance with the cloud cover contained in the Metar reports used in aviation.  This project has, and still does present many challenges.  One of these has been the variations in the data contained in the Metar reports.  For example an international airport or big military base might report cloud up to 30,000 feet whilst a small aerodrome supporting general aviation might only report low cloud up to 6,000 feet and stations equipped with automated observing equipment  will report up to 12,000 feet.  The Cloud Poles were an attempt to make variations in reporting visible on a map, this is still work in progress.

Each reporting station is marked with a pole, each layer of cloud is represented by a polygon positioned on the pole to represent it's base height and the extent is indicated by the diameter of the polygon.  The surface color of the polygon is set by the base height, those representing low cloud are red, the polygons for medium level cloud are green and the high level ones are blue.  If no cloud is reported the pole is yellow and blue if there are one or more reported layers.  A yellow pole does not necessarily mean a clear sky, it may mean that medium and high level cloud has not been reported. The example shows cloud reports for Texas at noon on a randomly selected spring day in 2011.

The "front" end of the cloud poles application is a relatively small number of lines of Python code accessing an SqLite database.  The attraction of kml is that for some tasks, it can be constructed using nothing more than a text editor.

As I have messed with weather and related data in an effort to understand wind and solar energy, the combination of Google Earth and kml has provided a quick and easy way to explore ideas. for example, looking at the location of old windmills.  This could have been done just using Google Earth alone, but by using elevation data from the SRTM mission, it was possible to produce contour maps in the form of bitmaps and then overlay these on Google Earth.  This work suggested that many windmills are sited on ridges (hence the large number places called "mill hill") and on slopes exposed to the prevailing wind.

I did not develop the idea, but it is possible to use bitmaps displaying small graphs and use this a placemarks.  Each placemark can either have its own image file or select one from a palette by specifying an offset into a single, specially compiled image file, sadly, I did nor preserve an example of this work.

Solar Wine Bottles

Back in 2008 I wanted to learn something about solar thermal devices, the simplest (and cheapest) thing I could think to mess with was a bottle of water.   I chose to do this in winter because even under an English sky, solar devices will do something useful in summer, but winter is more of a challenge.

The first attempt was just a randomly selected bottle with a thermometer pushed through the cork, this was left lying around in the garden and on a sunny day there was a 10 deg. C temperature rise and on a cloudy one, cold water was still cold water.  My understanding of the heating process is that the sun's rays warm the glass bottle and the bottle warms the water it contains.  I never got my head around the extent to which the sun's rays acted directly on the water.

The next attempt involved three different coloured wine bottles; clear, green and dark brown with the temperature being measured indirectly with a thermistor.  The 2nd December produced cold fingers and this set of curves:

Dark objects absorb radiant heat more readily then light coloured ones and this is reflected in the graph, the dark brown bottle produced a greater temperature rise than the clear one.

The bottles were uninsulated and the temperature stabilised when the the heat gain and loss balanced.  I tried putting a glass cylinder around a bottle, the effect of this was not dramatic, possibly because the effect of the insulation was offset by by the reduced energy gain.  My perception of solar thermal design is that it is a balancing act between maximising the radiative energy gain and minimizing the convective and conductive losses.

When looking at the results I was struck by how easy it is to get a 10 - 15 deg. C temperature rise.  A domestic gas boiler typically takes in water at 10 deg. C and heats it to 50 deg. C a rise of 40 deg. C.  Maybe a role for thermal devices in a seasonal, cloudy climate is as a feed water heater, if the boiler feed water temperature is raised from 10 deg. C to 20 deg. C there is a 25% saving in gas.

Somewhere in the dim and distant past I had read that the performance of solar stills might be increased by adding charcoal (I have no idea if that is correct).  This made some sort of sense, a carbon particle suspended in liquid might act as a microscopic solar panel warming the water around it.  I created a lot of mess trying to make carbon black with a candle and even more mess trying to get the stuff to go into suspension (a little knowledge of chemistry would have helped).  After messing with several household substances (ink, edible colourings etc.), I opted for gravy browning which is not ideal, but it is blackish, unlikely to harm the dog and cheap.

On the 6th January, I produced this curve which suggests the dyed water water warms up faster than clear water (at some time in the future, I would like to see if this result is repeatable).  A couple of years later, my son bequeathed me a leaking tube of black ink which appeared to be carbon based and would have been ideal, however, there is a limit on the amount of bizarre behaviour one family can tolerate.

LED Lighting in an Edwardian House

LED lighting is becoming a mature technology.  It is an affordable technology and in the right environment can reduce energy consumption and costs.  It has taken some time and some product evolution to make them work in our Edwardian semi, but progress is being made.

When the house was built in 1901 it was lit by gas, an extensive network of pipes can be found beneath the floorboards and in the walls.  The living room was lit by a gas chandelier and a mantle over the fireplace.  This scheme was short lived and electric lighting appears to have been installed around 1910.  Typically, each room had a single ceiling fitting and I guess there were some standard and table lamps for sewing, reading and writing.  Later owners added some wall lamps.  When we acquired the house in the early 1990s, the living room was illuminated with approximately 1,500 lumens supplied by one 100 and two 40 watt incandescent lamps.

In 2006 the household electricity consumption with incandescent lights was around 25 kwh/day, sometime around the end of the year I spent approximately £100 and replaced the incandescent bulbs with CFLs and the consumption quickly dropped to 10 kwh/day.  The early CFLs fell a little short of expectation, the life, whilst longer than that of an incandescent bulb was less than the 8,000 hours stated on the packet and there was a short delay before the bulb emitted enough light to read by.  After a couple of years, the technology matured, failures were rare and the price started to fall.  The information on the packaging suggests that the luminous efficiency of CFLs is about 50-60 lumens/watt which is a significant improvement on incandescents which are around 10 lumens/watt.  The great thing about CFLs is that they were a straight swap for the incandescents.

Sometime in 2012(?) I purchased a couple of LED lamps for a cost of around £25.  Whilst these entertained me, they did not win the hearts and minds of my family and have been banished to my workroom.  There were two issues, the first was that the light emitting element was a surface not a quasi sphere like the CFL, thus the diffuse light from the ceiling was lost making the room appear dark.  Secondly, the individual LED elements were small making them distractingly bright.  This fine example of  rustic Bauhaus is still my desk light:

The problem of glare has been partly solved by changing light shades to ones which provide an element of diffusion.  However, there is a limit to the amount of modification that is economically possible, replacing light fittings and adding new ones is expensive, not least because of the redecoration that is needed afterwards.

The attraction of LED lighting is the high luminous efficiency, current LED lamps seem to be capable of 80 - 100 lumens/watt.  Thus whilst we have been using 40 watts to light a room with CFLs, this might drop to 20 watts or less with LED's.  This is not going to have the effect that the migration to CFLs did, in part, because the process is taking place slowly, but out household energy consumption is drifting downwards.

For a couple of years, "360" degree bulbs which can substitute CFLs have been available.  The first ones I found were small with an output of around 300 lumens for 3 - 4 watts, a couple of these have replaced 10 watt CFLs in passages where lights are left on all night and we have probably achieved payback in about 12 months.

This lamp in the picture might be the breakthrough which displaces CFLs in our house given time.  This one appears to draw about 4 watts and produce about 400 lumens, the elements are larger than previous versions so glare is not such a problem and it fits in existing light fittings.  My guess is that larger versions of this will become available as the technology evolves.

Tariffs

A lot of the discussion centres on technology but the behaviour of consumers is also important.  There is a conflict between the business model of energy companies and the desirability of managing consumption to achieve sustainability and energy security.  The traditional business model requires that a business maximises sales whilst governments want us to consume less energy.  It is important that energy companies are profitable so they can function as reliable suppliers and make investments in infrastructure.

The most common energy tariffs are a combination of a standing charge and a fixed unit price.  Whilst this is simple, it does not provide consumers with much of an incentive to manage their consumption other than a fear of big bills.  Other designs of tariffs could be offered which might provide a positive incentive.  An offering must be fair (i.e. not become a trap for the unwary) and come with protection for vulnerable people (i.e. you don't want people sitting in cold rooms too frightened to turn on the heating) and they should be optional.

One possibility is to offer an incentive to cap the rate of consumption, The energy company benefits by having flatter demand and does not have to invest in capacity to meet peaks, such as the one that occurs in the early evening when people cook and sit around the house.  The graph shows the what a hypothetical consuming 12 kwh per day might look like, the left hand graph assumes as standard fixed rate tariff whilst the right hand one has consumption capped at 0.7 kw/hour.

The consumer might achieve this with some form of energy management, task shifting (i.e. running the washing machine at times when other devices are off) and maybe the integration of some storage. For a household with an electric or hybrid vehicle, the traction battery could also supply the home with energy during the evening, then charge itself overnight at off-peak rates.  As with any scheme there are challenges, one might be washing machines which draw 1 - 3 kw for a few minutes during their cycle.

Another possibility is a progressive tariff which provides a discounted rate up to some level of consumption, after which the rate increases, the graph is illustrate the principle with an arbitrary chosen threshold.

Whilst this tariff would be popular with low energy households, take up by high energy consumers would be low.  However, if combined with a smart meter located in a prominent location and not under the stairs), would provide an incentive for some to manage their consumption.