Olive - 1 - Description

For a long time I have been interested in relationship between sustainable energy sources, climate and terrain.  An attempt to produce a megalithic chunk of software using downloaded data was instructive but failed to produce anything useful.  Software like pet dragons acquires names and this code was called Druid.  Rather than give up on the concept I recently adopted a completely different approach.  The concept was to build some simple equipment and to take one or two short data-shots each day from my back yard.  Over a period of a year this would produce a few hundred data points which hopefully would provide enough samples to draw some conclusions but not so much that it could not be assimilated.  Because hardware was involved, the name changed to Physical Druid and the equipment was called Olive.

Olive attempts to measure solar irradiance.  The sensors are two very small horizontally mounted solar panels.   Because they are flat they have a good cosine response.  During a data-shot one of the sensors is shaded from the direct rays of the sun and therefore only receives diffuse irradiance, the other is not shaded and it's output is a combination direct and diffuse irradiance.  Combining the output of the two sensors it is possible to estimate direct normal irradiance.

The current produced by a photocell is proportional to the irradiance it receives.  A resistor is connected across each cell and the voltage across the resistor is also proportional to the irradiance.  The voltage across the resistors is only a few mV which is too small for the analogue-to-digital converter on the Arduino Nano so a TS358CD op-amp is used to get the output into the range 0 - 5 volts.  The Arduino Nano is a brilliant piece of equipment, I first used it on a small dynamometer and found it easy to use for both control and measurement and it works well with Olive.  The Nano connects to a Raspberry Pi model 2 which acts as data logger powered by a 20,000 mA power bank.  A data-shot consists of approximately 16,000 observations over an eight minute interval.  During a data-shot a photo of the sky is taken with my mobile phone.

The observing site is real-world rather than ideal.  Olive sits on pillar on the wall which separates my back yard from the street, the quality of the measurements will improve as the sun gets higher in the sky.  On the plus side, Olive is a good conversation starter.

Data from Olive is fed to an evolving suite of programmes on a Raspberry Pi 3, I'm still figuring out how to use the stuff.  The basic presentation consists of a plot of the sensor output, a cropped and resized version of the phone photo, a graphic showing the attenuation of the irradiance by any passing cloud.

To give the observations some context, some data from the Global Forecast System has been added.  The objective is to attempt to explore the results using machine learning methods.

Doris B - Diodes and dynamometers

If simplicity is a virtue then my first attempt at making a dynamometer could be regarded as sinful.  This more successful machine consists of a wooden pulley bolted to a bicycle hub generator.  The pulley is turned by fishing line attached to a weight, a 10 watt resistor acts as a load.  An Arduino measures the voltage across the resistor and senses the rotational speed as the weight falls, all this provides enough information to estimate the input and output power which in turn suggests the efficiency of the system.

The generator turns out AC but to charge batteries it is necessary to convert the output to DC.  When developing anything, a good rule is "first make it work, then make it work better".  Initially, a standard silicon bridge rectifier was used.  This had a voltage drop across the diodes of 0.7 - 0.8 volts.  I flirted with the idea of smart diodes based on mosfets but this required greater knowledge and skill than I possess.  A simpler alternative was a bridge rectifier made up of Schottky diodes.  These have a voltage drop of around 0.2 volts.  The effect was to increase the power available to do something useful as shown in the graph below:

For a given speed, the output is roughly 0.3 watts higher with the Schottky diodes, they also increase the system efficiency by about 10%.

The diodes are rated at 100 volts to accommodate the generator when it goes open circuit.

The next step is to use the dynamometer to investigate the use of pulse width modulation to manage the load.  The objective is to use the power curve to optimise the relationship between the rotor and the generator.

Doris B - The experience box

I was in a bar chatting to one of my sons (he's 31).  There's some overlap in our work experience and we were talking about product development and he came up with the description "first we make things, then we break them" which is a variation on one of my mantras "if you want to learn fast, make mistakes fast".  This gives me great faith in the next generation.

Oddly, I've just cleared some space in my work room by dumping less than successful bits of wind turbine into a box.  This includes three rotor designs, two generator, several attempts at making drag buckets and does not include several Meccano constructions which have been dismantled.  Work had been progressing steadily but I came to the conclusion that the generator I was using was probably 15 years old albeit in good order.  It might have benefited from being stripped down and the bearings cleaned but I was uncertain about the state of the magnets.  As I'm about to invest some time and energy in this project, I thought it would make sense to start with a brand new one.  The new one is slightly smaller and lighter than the original, so the bucket carrier and the dynamometer ring will have to be remade.  A slightly tedious task but an opportunity to remove some defects.

The dynamometer is very simple, it consists of a length of fishing line wound onto a pulley, the line runs through a pulley/block on which a weight is hung.  As the weight descends, it turns the generator.  The Arduino works out the rotational speed and the energy generated, the rotational speed is also a measure of how fast the weight is falling allowing the input energy to be estimated which in turn allows the efficiency to be estimated.

The Kettle half full

I'd like to say that that this post was based on a rigorous analysis of a vast database, sadly it's based on four meter readings, but lack of data should not get in the way of a good argument.

Much of the debate on emissions focuses on tax and technology and both have a role to play but the elephant in the room is behaviour.  We choose to get on aeroplanes, we choose to drive cars with big petrol engines (like many young engineers I lusted after cars and motorbikes), on a hot Texas day who can resist the switch on the aircon and we often overfill the kettle.

Engineers are generally trained to get a result with the minimum effort, the logic that makes a better jet engine also applies to making tea, you should use the minimum amount of energy, as an undergraduate I got into the habit of filling my mug from the tap and tipping it into an empty kettle, something I still do.  The most common reaction from family, friends and colleagues is that this weird and unhygienic, a response to the latter is that a kettle is also a steriliser.

Recently our 1.7 litre kettle became the logical equivalent of a bucket and was replaced by a 1 kw 0.85 litre version, it still gets overfilled but by half a litre not a whole one.  It's not obvious if this explains our reduced our electricity consumption (and emissions) but it did not increase them:

In England, most kettles ceased to be zero emission devices when coal became the dominant domestic fuel in the 18th  century.  Most cooking ranges were lit in the morning and kept burning into the evening, which is why the kitchen was the centre of family life because it was the warmest room, a kettle left on the hot plate would always provide water for tea or coffee, there was no saving of fuel by doing otherwise.  The modern kettle also provides a similar supply of hot water but unlike the coal fired range the energy consumed is proportional to the volume of water being heated.

Kettle on a coal range (credit: Brighton Museums)

The zero emission kettle made an appearance during 19th century in the reception rooms of grand houses.  The downside of having a large house was that the kitchen was often in the basement, by the time a maid had carried the kettle up a flight of stairs, along corridors and halls to the sitting room where the lady of the house was entertaining, the water was no longer hot enough to make a decent cup of tea. The solution was a table top charcoal stove.

Doris B - Carpentry and Computing

The design is slowly moving forward. I’ve messed with small wind turbines before, but Doris B is an attempt to create some design rules. The objective is to get an output of 2.5 Watts in a 5 m/s wind. The current rotor is 0.7 metre in diameter with six buckets and s of the drag type. It’s had a couple of runs without instrumentation, but eyeballing the rotor suggests that its operating speeds are between 50 and 150 rpm. The current activity is figuring out the electrics and creating a functional data logger.

Almost any design of turbine will turn in a 10 m/s wind, but at 5 m/s the available energy is about 70 Watts/m2, which is not a lot, thus small things become important. The first attempt at creating a power box used a basic silicon bridge rectifier, smoothing capacitor and a voltage regulator. The voltage drop across the diodes in the rectifier was approx. 0.7 – 0.8 volts which is about 10 – 15% of the voltage of the generator, the rectifier will shortly be replaced with four Schottky diodes which hopefully will have a voltage drop of around 0.3 volts. The voltage regulator did nothing useful, three partially discharged Ni-Mh cells drew around 300 mA without the voltage regulator which is roughly a charge rate of 0.15 abd a reasonable working level. Removing the regulator cleaned up the power curve, which currently looks like this:

Part of the design is to match the power drawn by the generator to that generated by the rotor. With no load, the generator turns freely in a light wind. place a 10 ohm resistor across the terminals and it seems likely that it will cease to do so. Experiments with pulse width modulation of the load suggest that this is a potentially efficient way of optimising the relationship between the rotor and generator.

My love of the Arduino is growing steadily. Over my professional life, computing power has increased dramatically, CPU speeds are now measured in GHz, RAM in GB and storage (which is not necessarily local) in TB. The Arduino Nano was originally purchased as an analogue to digital converter for a Raspberry Pi, however, with experience, I’m realising the capability of the Nano. This should not be be surprising, my first programming experience was on an ICL 1900 which if I remember correctly had 16 Kb of magnetic core storage, static data lived on punched cards and if that was not enough the only option was a tape drive which required serious negotiating skills to access. Those machines were a great opportunity and so are the Arduinos. If you are used to working with GB databases, 1 Kb of EEPROM does not seem a lot, but it’s enough and there is the potential of IoT to explore.

Footnote – A month ago, my laptop died, it was expedient to hook up a Raspberry Pi. At some point I will have to replace the laptop, but the Raspberry Pi is doing fine, I have not done any serious analysis, but the energy I use whilst messing with computers might have dropped by 0.5 kwh/week (a guess)

Clouds and Irradiance from the sky

This was quick-and-simple study to look at the distribution of solar irradiance under a cloud sky.  The intention was to get some insight into the mounting of solar panels.  Under a clear sky, the greatest output is obtained by pointing them at the Sun.  For fixed mountings the optimum is facing south at an angle to the ground close to the latitude of the equipment.  This may not be the case under a cloud sky where the direct beam irradiance is attenuated and a higher proportion of the total is diffuse from the hemisphere of the sky.

The equipment was constructed from materials to hand which included a length of waste pipe, part of a broken bed and a roll of packing tape.  The main component was a light dependent resistor mounted at the base of a 300 mm length of white waste pipe whose translucence was reduced with a wrapping of parcel tape. The photo shows it in position sitting on top of a dust bin.

Operation consisted of setting the altitude to 15, 30, 45, 60 or 75 degrees, then rotating the instrument from 0 to 330 degrees in 30 degree increments and recording the resistance of the light dependent resistor.

The light dependent resistor has typical resistance of 20k at 100 lux. A simple calibration gave the relationship between resistance an luminescence of:

The results should be treated as relative irradiance which are consistent for the experiment, but are unlikely to represent accurate absolute values.

Overcast Sky - 26-Jul-2010 15:00: The irradiance increased slightly with altitude, but was relatively constant with azimuth.  The cloud was thick and low, there was a small break to the northeast, hence the higher irradiance in that direction:

The conclusion drawn from this observation is that irradiance from an overcast sky is more or less uniformly distributed around the sky, albeit at a level much attenuated from that expected under clear sky conditions.

Broken Cloud - 27-Jul-2010 14:00:  The early afternoon sky consisted of broken cloud, with the sun 

occasionally visible through the cloud.  Compared to the overcast sky the day before, there was significantly greater irradiance in the part of the sky in which the Sun was located.

Typically, in our part of the world, cloud described as broken, is a discrete layer and can sometimes have similar appearance to an overcast sky with only occasional glimpses of the blue sky above. This was the case on the day these readings were taken. There is an increase in irradiance in the direction of the Sun, but a significant amount of irradiance is coming from the sky as a whole.

Few Clouds - 28-Jul-2010 11:30:  As so often happens when there are a few clouds in the sky, there was some fluctuation in the readings. The maximum irradiance was to the south east at an elevation of 45 to 60 degrees.

The irradiance under a sky with a few clouds is similar to that of a clear sky with exception that there may be short periods of attenuation.

Clear Sky - 16-Aug-2010 15:00 - The irradiance is clearly coming from the sun's disk:

Under a clear sky the maximum irradiance received by a device is when it is pointing directly at the Sun. In this case the maximum irradiance was around 230 degrees at an altitude of 45 degrees which is close to the altitude and azimuth predicted by Sun-Earth geometry.

Doris B - Instrumentation

It’s a sad fact that almost everything I make gets built at least twice.  I’m trying to figure out what needs to go into the wind turbine’s “power box” and how it’s going to fit, then I’ll rebuild it so it looks less like a building site and use components with appropriate values.

It monitors the rectified output of the generator, the voltage across the load and the current through it.  This allows the power generated and being delivered to the load to be estimated.  A Fourier transform is used to determine the rotational speed.  The original intention was to work with AC output of the generator, but it proved a lot simpler to work with DC throughout the whole system.

The Arduino Nano has exceeded expectations, a previous attempt used op-amps and many other components, however, this time around, the only components used in the instrumentation are resistors for voltage divides and zenor diodes for protection.  voltages from three measurement points are fed to the Nano’s ADC.  After some processing with a couple of blocks of Python code running on a Raspberry Pi, the output looks like this:

Testing is being done using a 47 ohm resistor as a load, this keeps the current low but at the expense of high voltage on the upside of the regulator.  When a battery pack is used as a load, the voltages look a little more sensible.  Still some work to do, but the basic design is in place.

The next task is to determine if pulse width modulation can be used to control the load, if so, if so, it may be possible to optimise performance.  Ideally, I want the rotor to start to turn at 4 m/s, but the high torque of a large load may prevent this.  Maybe if the duty cycle is 0 when the turbine starts, it can be increased as the rotational speed increases.  Also, it can be adjusted to take account of low wind speeds.  All that comes after I’ve soldered the bits together.

Doris B - Power Curve(2)

Progress (and more to learn and some bugs to find).  The Arduino captured a one minute time series of the voltage across a 22 ohm resistor attached to the generator’s output terminals whilst it was hand cranked.  The load on the crank varies during a rotation so there are constant variations in speed and this can be seen in the time-series, the flywheel effect of the wind turbine’s rotor will probably have a smoothing effect.  The circuity between generator and the ADC needs to include a zenor diode to provide some protection for the chip, once that’s in place, the DC biasing can be setup sensibly.  However, the time series was good enough to passed through a Fourier Transform routine which allowed the rotational speed to be estimated.

The speed and voltage data can then be combined into a power curve, the variations in power are due to uneven cranking.  The 22 ohm resistor was chosen because I had one in a box somewhere.  To get peak performance from the generator will require matching the impedance of the load to the impedance of the generator.  The planned load is a USB power pack.

Whilst messing with electronics and Fourier transforms has been instructive, so too has hand cranking the generator, clearly the torque required varies with the value of the resistor, with a 10 ohm resistor the torque required almost pulls the generator of its mounting.

So on the next trip to the beach, I’ll take a bag of resistors and see how they effect the ability of wind to turn the rotor.

Doris B - Power Curve(1)

In order to match the rotor to the generator, it is necessary to understand the behaviour of both. The first step is to grab data, starting with the generator because this can be done on the workbench rather than the beach. Much the same solution can be used for both. Currently, the instrumentation is an Arduino Nano which provides analogue to digital conversion (ADC) and a Raspberry Pi for processing. Electricity and electronics were part of my OND but that was a long time ago, so setting up the tests involved a little vexation, but eventually a Python programme managed to capture a sample of the output of the generator.

Two things became apparent, first the output of the generator is complex and not a simple sine wave, Secondly the starting torque increased significantly from the open circuit value when a resistor was placed across the terminals.

The next step is to analyse the data, the plan is to use a Fourier transform to determine the rotational speed and the area under the curve will provide the energy generated, putting the two together will provide a power curve (I hope). The Ardunio is a brilliant tool and may offer a solution to the high starting torque. If pulse width modulation is applied to the load, the turbine can start with no load and as speed increases the load on it is increased, this in turn could provide a means of optimising performance.

Doris B - First outing

 On Wednesday evening I took Doris B up to Green Ridge and assembled it.  The wind speed was  roughly 5 - 7 m/s.  Whilst held aloft, the rotor was 2.5m above the ground, it turned smoothly and quietly, which was pleasing, an earlier version had struggled to turn at 10 m/s, so progress is being made.  The next step is understand the relationship between the rotor and the generator,  The speed of this type or rotor is proportional to the wind speed and it is important that the rotor turns fast enough for the generator to produce a useful output.  On returning home I ordered some bridge rectifiers and  an Arduino Nano.  The first use of these will be to obtain a power curve for the generator.

My favourite place for messing with this stuff is on the beach at Aldrington, when the wind is from the SW there is little turbulence.  Most of the other people are beach fishermen and we occasionally swap observations on the state of the sea.  There was a curious incident at Green Ridge, a dog walker scooped up his spaniel, carried it over to my rucksack and let the dog have a good sniff, then walked off carrying the dog, I said "good evening" politely.

Doris B - Trial Assembly

10-April-2019 - Completed the partial assembly of the Doris B5/6 small vertical axis wind turbine this morning before giving it a trial outing on the Downs later today. 

The objectives of the initial trials are to determine if it rotates in a wind of 5 m/s and does not disintegrate at 10 m/s. If it survives, the next step will be add some instrumentation and to try and figure out how it works. The design is based on some maths, guesswork and wishful thinking. There have been four previous versions, mostly made of Meccano and sawn up bits of plastic pipe, this one is mainly made of wood. This is not a finished design but part of a process of learning how to make small wind turbines for rural and urban environments, hopefully the design will evolve. The objective for this series is an output of 2.5 watts (similar to a standard USB port) at 5 m/s.

The early days of electricity - Diverse decsions and technologies

Public electricity supplies started to evolve in the UK during the 1880s.  Today electricity is a utility accessible by a high proportion of the population, but in its early days it was part of the luxury goods industry, a unit might cost between 4d and 1s 3d (2p to 6p) which is around £1 in today's money.  Its attraction was that it was convenient and clean and therefore perceived as being healthier than the gas lamps that it was to displace over the next half century.  Arc lamps improved the lighting of streets and public spaces and this gave local authorities an interest in the industry.  The industry grew using both public and private capital, and some local authorities proved to be adept in managing the evolution of a new technology.  Street lighting was often managed by the gas committee, because that was how the streets were lit, so decisions about borrowing substantial sums against the rates were being made by men who were often involved in decisions about the lighting of urinals

The caption on this cartoon was Electricity for the Ballroom

Electricity works, especially those supplying DC had to be close to the consumer because of the limitation of the early distribution systems.  This resulted in generating plant being located in unlikely places like London's Carnaby Street: its contribution to the swinging sixties is well remembered but its power station is long forgotten. The search for early power stations often takes one to the posher parts of town.

Most of the early dynamos and alternators were turned by reciprocating steam engines.  The early engines were relatively small and built by companies also known for their traction engines and road rollers such as Robey or Fowler.  Until the development of high speed engines such as those of Willans which facilitated direct coupling, the generators were connected to the engine by a belt drive.  Belts would sometime break, in 1882,  the Mansion House was provided with electricity from a generator installed in the basement, where the belt was driven by a gas engine.  During a dinner the belt broke giving the diners the impression they were being attacked by gunfire.  In 1888, the first turbine driven alternator was installed at the Forth Bank power station, close to the centre of Newcastle.

Large generators were steam driven because steam engines could be built to supply hundreds of horsepower and it was a mature technology. At this time steam engines were almost as common as electric motors are today, they powered mills, railways, ships, sawmills, pumps and anything big which needed turning.  Smaller plant in urban areas often used gas engines.  By 1880, most urban and some rural areas had a gas supply and whilst this was mainly used for lighting, it could also used as fuel for engines such as those made by Crossley.  The attraction of gas engines was that there was no need for a boiler and most could be hand cranked into life when needed.  Judging by the number of adverts for fractional horsepower gas engines in pre-1900 magazines, many modest homes may have generated their own electricity from gas.  Such a system is described in a biography of Magnus Volk, the house in which it was installed is comfortable, but not grand.  Many micro systems incorporated a bank of lead acid accumulators making it unnecessary to run the gas engine continuously.

During 1880s and 90s AC and DC systems competed for supremacy.  The AC system would eventually win because it facilitated transmission over long distances allowing big power stations to be sited away from city centres.  However, DC did have the advantage of being able to use lead acid accumulators for storage.  Then as now, the demand for electricity peaked in the early morning and early evening and if only a few hundred homes were being supplied overnight demand could be met from the accumulators allowing the steam plant to be shut down or the boilers banked up.  Accumulators also provided some back-up in the event of plant problems, for this reason, some consumers perceived DC systems as being more reliable.

In the early days, the demand for electricity was measured in kW rather than MW making it possible to supply rural communities using small plant connected to consumers by wires hung from wooden poles. Some of these used water power, Godalming claims the distinction of having the first public electricity supply, this was from a generator turned by a water wheel in a mill. Reeth in Yorkshire had a similar arrangement.

Initially, electricity was an urban industry relying on clusters of high income households, some smaller communities were still not connected to a central generating station until well into the interwar period.  It was during this time that many small electric companies were formed, examples include the Steyning Electric Light Company and the Peacehaven Electric Light and Power company.  I've seen photo's of these companies' plant, both show belt driven generators, in both cases it looks like the motive power is coming from an industrial internal combustion engine, but it is not clear if the fuel was oil or gas.  One of the more interesting of these companies is the High Salvington Electric Light Company, this served a small development of houses on the Downs to the north of Worthing. The generator was turned by a wind mill/turbine similar in design to those of West Texas -the electricity was used to charge up accumulators which in turn supplied the consumers.  There was an oil engine back-up for days when the wind did not blow.  Now that utility scale storage, like Tesla's installation in Adelaide is becoming available, High Salvington can claim to be pioneer in the field of sustainable energy.

A random history of energy economics (3) - The life cycle of fuels

Fuels like any other product have life cycles.  The stages of the classic life cycle are growth, maturity and decline.  For some fuels like wood, the length of the cycle is measured in millennia, that of coal looks like it might be centuries and carbide probably decades.

My understanding of acetylene lamps is that they were developed for cars and motorbikes at the very end of the 19th century.  Whilst electric incandescent lamps could be powered by a lead-acid accumulator, they were not bright enough to allow safe driving at speed.  The attraction of acetylene is that it burns at a high temperature and produces a bright light.  The gas was generated by the action of water on calcium carbide, the lamps were so constructed that a reservoir of water dripped on calcium carbide which was then burnt in a lamp with a reflector.  The brightness of the lamp was controlled by adjusting the water flow, as the gas was generated, the carbide turned to slaked lime.  "Carbide" was sold in garages along with petrol and oil during the 1920's, but as automotive electrics improved and effective headlamps which could be controlled by a switch became a standard fitting, carbide lamps were largely displaced by the 1930s.

Kerosene (a.k.a. paraffin) as a domestic fuel had a somewhat longer life cycle, it was used for lighting and cooking in late 19th century.  In the era of solid fuel ranges. it facilitated cooking without first having to light a coal fire, although many found the smell unattractive.  Paraffin heaters were widely used well into 1970s and may people remember the Esso's adaption of "the smoke gets in your eyes" for their TV adverts.  Paraffin heaters were generally displaced by low cost gas central heating in the 1970s.

The same pattern of growth, maturity and decline is apparent in the UK coal consumption.  A spokesman for OPEC once commented that the UK did not run out of coal, they just stopped using it.  In the latter part of the 19th century consumption grew as industry, the railways, gas production and other applications expanded.  It remained constant for approximately half a century until the 1970's.  During this time the economy was growing, but technology was evolving which allowed coal to be used more efficiently.  In 1890, electrical power generation had a thermal efficiency well below 5%, by 1970, this was approaching 40%.  The boilers used in the early power stations operated around 150 psi, by 1945 some were operating at 675 psi, the rising temperatures and pressures resultined in higher operating efficiencies.

In the 1960, natural gas (mostly methane) from the North Started to displace coal as a domestic and industrial fuel.

The displacement of coal by natural gas is apparent in the graph below.  Starting around 1830, many towns acquired as gas works either privately or municipally owned, in the early years the principal use was for lighting, but cooking, heating and industrial use increased.  Between 1900 and 1930, electricity, also generated from coal, displaced gas for lighting.    The availability of North Sea gas bought about the extinction of the coal gas works in less than a decade.

Gas turbine power stations, steadily displace coal fired steam technology, a process which accelerated in the 21st century as concerns over the environmental effects of coal grew.

Relevance for Today

The energy mix is constantly changing, the driving force is technology, over two centuries it has included coal, wind, nuclear (after 50 years is this an old technology) and many evolutions within each one.  There is a lot of evolving technology, offshore wind and electrical storage maybe the key elements.  Several cities are talking about petrol or diesel vehicles and only allowing electrical ones, so more change can be expected.

A Random history of energy economics (2) - The Horse and the Lorry

By 1900 railways were the most important element in Britain's transport infrastructure, but they only provided town-to-town communication.  The distribution of goods within a town was done with men with barrows and horses with carts.  In the rural areas "carriers" moved goods and people around with horse drawn wagons.  Horses were widely used well into the 1930s by which time motor transport was firmly established.

I came across some figures comparing the cost of coal distribution from depot to customer by 30 cwt truck and a horse and cart in 1931.  The figures seem to relate to an adequately funded and well run coal business.  Two points about the graphs, first they are for 1931 and are not comparable to costs in 2017 and that the original data is in pounds, shillings and pence which was converted decimal pounds for the benefit of Excel.  I have doctored the data a little for the sake of comparability.  In 1931, the price of domestic coal was between £1.50 and £4.50 per ton depending on the grade, local terrain and market conditions.  Anthracite was the premium product whist Bituminous coal was cheaper, also coke from gas works was widely used.

Both the horse and truck were depreciated over four years and  funded by money at 5%, the horse cost £90 and the truck £250.  The cost structures for both modes of transport is broadly similar, the exceptions are higher capital related costs of the truck, the legal requirements for a license and insurance and maintenance.  Food for the horse and fuel for the truck are similar as are the wages of the driver.

The big difference is the level of productivity, the horse shifts 38.5 tons/week, whilst the truck can do 49.5, but the unit costs are similar at around £0.20/ton.  I suspect that there was a lot of variation within the industry.  If only one man was employed to work with the truck, he would have to work harder than the bloke with the horse and cart, the references I have seen to coal sacks at this time suggest there were 1.25 cwt ( very roughly 62kg or very heavy, I struggle with 25kg bags of sand).  This might have been OK for a youngish man shooting coal into a cellar with street access, much less for an older one shifting the bag from the street to coal store in the scullery at the back of the house.


Some random reading suggests that the domestic coal market was split into three sectors.  At the top end would be customers that bought coal in large quantities, say greater than half a ton, possibly belonging to a "coal club"  which spread the cost more or less evenly over the year, trucks would give an advantage to merchants serving this group.  Those serving customers purchasing less than half a ton and paying the current market price might have a cost advantage from the potentially lower costs of the horse and cart.  At the bottom end of the market would be those purchasing small quantities of coal, possibly as little as 7 pounds would pay high prices to men with barrows.

A Random History of Energy Economics (1) - Gas Engines in the Home

Over the past year I've been acquiring a few copies of the "The Model Engineer and Amateur Electrician" at car boot sales.  I now have about 15 examples dating from 1899 to 1919.  Models make up a large part of the content, but there is also an informed debate on technology as it was evolving.  At the bottom of one page is a note that a Frenchman has observed that a platinum wire is heated with an electric current and then placed in a jar of methane continued glow.  I'm guessing that this curiosity was an early version of the catalytic converter found on most modern cars.  There are notes on telephones and wireless telegraphy and a discussion of the ideal way of storing energy to power motor vehicles, electricity is was thought to have potential and compressed air to be a bad idea.  Electric shock treatment must have been fashionable as some advertisers claimed it was better to be shocked by their apparatus than that of a rival company.  With hindsight X-Rays were not something the citizen scientist should be encouraged to mess with.  The classified ads can be intriguing, there is a suggestion that a vicar had a model gunboat to sell and why would someone expect to exchange an accordion for a lathe?

In the diversity of items advertised, three occur frequently, these are gas engines, dynamos and accumulators.

In 1905, electricity was still a luxury product costing may be 4d - 6d per kwh (roughly 50p in today's money) and many urban areas did not have a supplier and remote households had to generate their own electricity if they wanted it.  Gas, however was a mature technology, many gas companies had been established between 1820 and 1850 and most urban areas had a gas works.   In some coastal towns, the coal was supplied by brigs from Newcastle running themselves aground on the beach  and being re-floated after their cargo had been hauled away by horse and cart. The cost of gas might be something like 2s 6d and 3s per 1,000 cubic feet, depending on the nature of the gas this would be roughly 10p/kwh today.

At the turn of the century gas was increasingly being used for heating and cooking, but the principal application was lighting. Whilst gas lighting was better than candles, it could make the air in a room foul, the products of combustion being carbon dioxide, carbon monoxide and water vaoiur plus anything else the gas company could not get rid of.  Gas mantles required cleaning  and lighting, whilst electric lamps were clean and available at the flick of a switch.  Doctors wrote letters extolling the benefit to health of electric lighting.  It's not easy to make a like for like comparison with the cost of gas and electric lighting but it seems that electricity was perceived as being 5 - 10 times more expensive.

Fractional horsepower gas engine/dynamo sets provided a source of electricity where a public supply was not available and possibly a means of getting a supply at a lower cost.  At the time of writing, I'm still attempting to identify a property which had such an installation.  At a guess, a common configuration would be to have the machinery in a shed where it was used to charge accumulators which were in turn connected to the lighting circuits in the main house.  Voltages seem to have been in the range 4 - 12 volts and accumulators could be relative large, say more than 50 AH.

After 1900, the public electricity supply expanded rapidly, but in most places this was AC, whilst the use of DC in the home decreased, cars and motorbikes created a new demand and low voltage dynamos were used to charge automotive batteries.  Early radio sets also needed a DC supply.

The magazine has several references to water engines, for owners of landscapes which were suitable for the construction of small dams and there a few mentions of "hot air" engines, I take this to mean "Stirling" engines, but so far no description of the workings of these devices.

Art and Energy

The Brighton Museum is staging an exhibition of the work of John Constable which he produced whilst living in the town from 1824 to 1828.  I went because it's a form and period of painting I'm attracted to.  The space is quite low key and does not shout "great art" making it possible to appreciate the pictures for what they are, sensitive and imaginative depictions of Brighton and the surrounding countryside at the start of it's period of expansion.

What I did not expect was an insight into the energy economy of the town before the arrival of the railways.  There are several pictures of beached collier brigs.  After 1840 most Brighton and Hove's coal supply was came from the harbour at Shoreham by rail, but before that a lot of it was landed on the beach and taken to buyers in the town by horse and cart.

The collier brigs were two masted vessels of 100 - 300 tons with a length of between 70 and 90 feet and a small crew, maybe 6 - 10 men.  They mostly worked out of the Tyne taking a cargo of coal outward and returning home in ballast.  Some vessels also carried passengers between the North and London, before the railways this might have been preferable to several days in a coach travelling along rutted roads, at least in fine weather.  Navigational equipment was probably the master's experience and a compass.

At coastal towns like Brighton and Hove which did not have port facilities, the brig was run on to the beach and the cargo unloaded into horse drawn carts using local labour.  When the vessel was empty she was re-floated on the rising tide.  The price realised for the cargo would have depended on the season, the weather and before 1815 the trade could be disrupted by French privateers, this threat may have been used to hike the price.

Coal landed on the beach within the parish boundaries was subject to coal tax.  This explains the location of the Brighton Gas works (1819) just beyond the eastern parish boundary at Black Rock and the Hove Gas works (1825) which is at the extreme west of the town.  These works were located to avoid the coal tax.  Coal tax was abolished around 1870 and was not a factor in the location of electricity generating plant.  From 1820 to 1880 gas was used for street lighting and in  the posher town houses.  After the establishment of electric light companies in Brighton and Hove, gas lighting was displaced, initially by arc lamps, then by incandescent bulbs.

At the turn of the century the demand for coal in Brighton and Hove had greatly expanded.  In 1928 there were four railway goods yards, each of which acted as a base for coal merchants, some of these operated nationally, others were local family businesses.  Going west to east, the goods yards were located at Sackville/New Town Road (Hove), Holland Road (Hove), Cheapside (Brighton) and Kemp Town (Brighton).  With the exception of Cheapside which is close to the main Brighton station, these yards are now industrial estates doing amongst other things, serving the local building trade.

By the 1880s, the railway's coal distribution network was evolving at the same time as the market for coal for electricity generation emerging.  Brighton's first power stations were close to North Road and supplied from the Cheapside yard.  Hove's was at Holland road where it may have had it's own siding for coal deliveries.  At the end of the 19th century, the demand for electricity was growing and city centre locations for industrial plant was neither desirable or practical.    Brighton built a new power station at Shoreham harbour, close to the gas works which had already located, both the gas and electricity works were now supplied directly from the sea by steam engined colliers.

Industry attracts fewer artists and poets than traditional landscapes, seascapes and portraits, but there is one reference in John Masefield's "Cargoes" which is relevant.  I suspect generations of English teachers have hoped to inspire a love of words and rhythm with this, the last verse is:

    Dirty British coaster with a salt-caked smoke stack,
    Butting through the Channel in the mad March days,
    With a cargo of Tyne coal,
    Road-rails, pig-lead,
    Firewood, iron-ware, and cheap tin trays.

I've always been troubled by the "salt caked smoke stack", maybe I'm too literal, but the verse does invoke the rhythm of a reciprocating steam engine.

Footnote

I wrote this quickly from memory without checking the facts, please feel free to offer corrections.

The price of house coal

The starting point for this post was some old family accounts which extended, with gaps from the 1920s to the 1940s.  This was augmented by some figures found in the online version of Hansard.  Some local history material provided a human dimension to the numbers.

The graphs should be treated with caution as they are random in both time and location.  House coal can be priced in several ways, my family always discussed it in terms of cost per hundredweight (112 pounds or very roughly 50 kg).  In 1835 it became compulsory to sell coal by weight rather than volume, before that there are references to "chaldrons", this was a volumetric measure which might account for 0.5 - to 1.5 tons.

The economics of coal consumption are complex, at £10/cwt, the energy cost is around 2p/kwh which is lower than for gas or electricity.  However, the "benefit" derived from a kg of coal depends on the efficiency of the device in which it is burnt.  When used in a cooking range, a lot of energy is used just warming up a large lump of iron before the thing is warm enough to boil a kettle for tea.  Early ranges were not insulated, which made them inefficient cooking devices, but a desirable source of warmth in the kitchen, modern solid fuel range cookers are well insulated which minimizes heat loss.  In England, houses were heated with open fires which have a very low efficiency (10 - 20%?) with most of the heat going up the chimney.  From limited research, it seems that the French prefer stoves which use coal more efficiently.

During the 20th century, the overall trend in the "real" price of coal was upwards.  At the end of the 1960s coal began to compete with "North Sea Gas" in the domestic fuel market.  Gas was both cheaper and more convenient than coal and coal's share of the market started to decline.  By the end of the century, coal had become a "niche" product and costs rose as the economies of scale that had been possible faded away.

The retail price of coal has always been subject to wide variations and fluctuations.  In 1795 it was feared that France would invade England and for a time the price of coal was around 55 shillings per chaldron, this would be more than £50/cwt in today's money.  Households purchase coal for the heat it produces when burnt, premium grade Welsh Steam Coal might have a calorific value of more than 30 MJ/kg whilst that of lower grade fuel might be half that. Some of the variation in the price shown on the graphs is due to variation in the grade of coal.

Apart from events in the wider economy, the price of coal was determined by who you were and where you were.  A well-off, well managed household would buy several tons for delivery in large loads during the summer when they would benefit from lower prices.  At the other end of the scale, those on low incomes might have had to buy coal by the stone (14 lb) or lesser quantity and paid a high unit price (there is an analogy here with today's pre-payment meters).   Some coal merchants operated "coal clubs" which allowed fuel costs  to be evenly spread over the year.

Transport was a significant part of the cost of distributing coal from the mines to the consumer, by the late 19th century coal merchants were often clustered around railway goods yards.  The coal merchant was responsible for unloading the trucks, if this was not done within an agreed period, say, three days, the buyer was charged demurrage until the wagon was empty.  In the early part of the century it was not unknown for captains of collier brigs from the Tyne to run their vessels on to the beaches of seaside towns if they thought they could get a better price for their cargo than they would get at a port a few miles down the coast.  If the cargo was discharged at a port, then the buyer would have the cost of transport to the point of use.  There was always a risk that they could be stranded for several days until favourable weather and tide allowed them to re-float.

A wide variety of enterprises were active in the local coal markets, some companies operated across regions, some were local businesses, maybe just a father and son working together with a horse and cart and below them were the barrow boys.  Our family favoured the Co-Op, probably to get the "divi".

A coalman's job was hard and dirty, often it was delivered to the consumer in sacks containing one and a quarter hundredweight (roughly 60 kg).  Large houses would have purpose built coal stores and some town houses had coal cellars which extended under the pavement which could be filled through a hole normally covered by an iron cover.  The difficult ones were small terraces where the coal had to be carried through the house to the scullery, a task which had to completed without upsetting the housewife.

The early days of electricity in Hove (3)

As with previous posts in this series, this one is work in progress and subject to corrections and revisions.

As I mess with this, I realise I am working backwards.  The story starts with an Act of Parliament of 1890 whose objective was to provide electric lighting in Hove, this was to implemented by the Hove Commissioners (what we now call the council), who formed an "electric light committee".  This first met on Saturday, 26-Apr-1890.

At the meeting on Thursday, 11-Dec-1890 a plan was beginning to form.  It was resolved that the best course of action would be to negotiate with a responsible company to erect buildings and plant and to lay mains in order to supply electricity as required.  It seems that they had considered three options, a) the council would take on the construction and operation of the facility which would be financed by a mortgage on the rates, b) the council would provide the plant and get a contractor to operate it and c) get a private company to finance, build and operate, this being the preferred option.  It was felt that this project was not appropriate for a town council.  The first step was to find a suitably qualified electrical engineer to prepare specifications and advise on terms and conditions of a contract with a company as proposed.

Mr. R.E. Crompton was selected for the task at a meeting on 2-Jan-1891.  This was a logical choice, Mr. Crompton had a proven ability with both arc and incandescent lighting and his company Crompton and Co. was a major manufacturer and contractor.

These deliberations were going on against a backdrop of international and local evolutions in the electricity supply industry.  This was the time of the "battle of the currants".  On one side was low voltage DC generation and distribution, in very crude terms there was direct connection between the consumer's appliances and the dynamos at the power station.  These systems worked well for small communities clustered around the power station.  It was opposed by promoters of high voltage AC systems.  In these the AC generated at the power station is stepped up to a high voltage for transmission and stepped down again for distribution to the consumer, the key component is the transformer.  Ultimately, the high voltage AC systems were to triumph.  At the local level the neighbouring Brighton and Hove Electric Light company was seeking to expand.  At this time Brighton had established an electricity supply four years earlier and had experience with both AC and DC systems.

Mr. Crompton drew up his report and this was considered and this was considered on several occasions and on 8-Jun-1891 a decision was made to adopt the low voltage DC option.  It is clear from the minutes that they had discussed the AC alternative, but Mr. Compton recommended the DC route because Hove was a compact borough and there would be no problems with transmission.  It was pointed out that several London boroughs had adopted this solution as had parts of New York and Berlin.  Mr. Compton's report  effectively became basis of the specification which against which bids would be invited and a prospectus for potential shareholders.

The suggested site was bounded on the west by Holland Road with 135 feet of frontage on what is now Davigdor Road.  To the north was a railway goods yard which was home to several coal merchants.  The plan was to have a siding laid so that coal could be delivered by rail.

The plant in the power station was intended to be implemented in phases.  When complete, the main elements were to be:

• 5 Lancashire boilers rated at 160 p.s.i
• 3 250 HP Willans dynamo sets
• 3 100 HP Willans dynamo sets
• 1 120 cell lead acid accumulator capable of supplying 600 amps for a short period.

Dividing the generating capacity between 100 and 250 HP units suggests that demand was expected to vary during the day.

The plant may have been arranged like this:

The site may have been long and thin making it necessary to use the space efficiently.

The costs for the initial phase with two boilers, three dynamo sets and an accumulator were estimated to be:

• Plant: £8,297
• Buildings: £3,000
• Mains: £12.844
• Total: £24,141

The cost of the complete scheme was around £50,000.

The public street lighting commitment was for 14 ornamental lampstands along the sea front, each with a 10 amp arc lamp mounted 26 feet above the street which was rated at 2,000 candlepower, the total running costs for 2186 hours were estimated to be £280/year.  Even in 1890, Hove was a sizeable town, so this was not a serious attempt to displace gas lighting.  It seems that the principal objective was to sell electricity to commercial and domestic consumers.  The electricity for these lights was to be supplied at half price, or 4d/unit, the retail price being 8d/unit (more than £1 in today's money).

The report reads like it has been written to promote a scheme, it suggests that after seven years, 400 houses would be supplied with electricity and profits could be £5,000/year.  It is not unknown for prospectuses to over estimate demand, however, in this case, it was an underestimate, after two years of operation, 200 households were connected.

The minutes of the Electric Light committee meeting on 3-Sep-1891 stated that the text of an invitation to bid for the project had been drafted and an agreement to purchase the Holland Road site had been produced together with an application to borrow £1,400.

On 27-Oct-1891, proposals were received from:

• The Electric Power and Storage Company
• The Brush Electrical Engineering Company
• Crompton and Company
• The Brighton and Hove Electrical Lighting Company

A few days later, a bid from the Planet Electrical Engineering Company was received, as this had been submitted on time, but delivered late, it was considered.

Only the bid from Crompton and Company was considered to meet the requirements of the commissioners and on 11-Feb-1892, a deed of transfer of the undertaking to Compton and Company was approved.

Energy Alternatives

The electricity industry took shape in the 1880s.  Initially, it was a "luxury" product consumed by high income households.  Large establishments might have had their own generating plant, but rapid growth in the demand for electricity started when companies were formed to supply consumers from a local power station.  Either by choice or circumstance, many of these companies became owned by local councils, with a little stretch of the imagination, they could be described as being owned and controlled by the community they served.  By the start of the 20th century demand for electricity had grown and the original small power stations with reciprocating steam engines located in residential areas were too small and inefficient to meet the demand, these were displaced by large steam turbine plants located close to a coal supply such as a port, railway depot or even the mine itself.  This became the model used by the industry for a century and it worked well, energy will never be cheap, but its rare to flick a light switch and have nothing happen.  Big nuclear power stations fit into this model.

There are big differences between the late 19th and early 21 centuries, for political and environmental reasons it is desirable to reduce dependency on fossil fuels and many people are uncomfortable with nuclear power.  However, the technologies available make it possible to consider alternatives to the big generator model, for the foreseeable future big power stations will have a role, but it may be possible to stem their growth and possibly even displace some of them.

These comments are based on personal observations, but they may have some wider relevance:

• Energy consumption can be reduced without a drop in living standards.  In our case, we have steadily migrating to LED lighting, 20 watt compact fluorescent lights have are being replaced by 10 watt or smaller LEDs.  As appliances have died of old age, energy consumption has a factor in deciding on the replacement.  The old washing machine consumed 1.5 to 2.0 kwh/wash, the new one typically uses 0.25 to 0.70 kwh.  There maybe environmental benefits, but our electricity bill is £23/month and falling.
• Storage is a potential game changer in the way the industry works.  Demand for electricity peaks in the early evening when families are home cooking, staring at a screen or doing homework, at present supply and distribution is set up to meet the peaks and troughs of daily life, if every house had even a small amount of storage, maybe as little as 2kwh, it could be possible to run the generators under constant load with each household having a time slot for charging its batteries.  Grocery deliveries have made us familiar with delivery time slots, doing the same thing for electricity is not such a big step.  Back to economics, there is the potential for buying electricity at off-peak rates (7p instead of 15p/kwh), so there is some potential upside for the consumer.  Storage also helps integrate energy from wind farms in to the energy economy.
• Back in 1900, if you wanted to generate your own electricity the main options were steam or gas engines, water wheels were an option for those living near a river and wind generation was still being explored.  Even under an cloudy English sky, solar panels can make a contribution.  At present, the economics of home generation are geared towards getting a return-on-investment, however, in conjunction with storage, there is the potential to displace some gas fuelled generating capacity.  Peak demand is in the evening when the sun does not shine bright, if energy generated during the day can be stored for use in the evening, then the load on the grid can be smoothed.  This requires some creative economics.  Some rough calculations suggest that our house's grid dependency would be decreased by two solar panel mounted somewhere other than on the roof.
• Cars and vans contain reliable combined heat and power systems, a 2kw alternator provides electricity some of which is stored in the battery and waste heat from the cooling system is used to keep the cabin warm.  Extracting the appropriate components and packaging them as a consumer product might produce something costing less than £1,000, such an installation could produce heat and power during the winter months. These could be gas fuelled.  In the context of a car, this is established technology.  One of the incentives for the development of petrol and diesel engines was the limitation on consumption of town gas.  Any loss in efficiency in electrical generation could be compensated for by the use of waste heat.

Some of this stuff is fanciful and no doubt others could expand the list but the point is there are alternatives to big power station model.