Firing: Stoves, Ranges, and Economical Management of Fuel

This post is chapter XIV of 1894 edition of "The Handbook of Household Management and Cookery" by W.B. Tegetmeier.  As I have another similar work, I'm guessing that that there were quite a few variations on this theme.  The book was compiled at the request of the London School Board for the education of girls.  This places it firmly in the 19th century, a time when big cities like London were developing the infrastructure of education, public health and energy.  It is not "dumbed down", I chose it because it is a discussion of energy and economics that might not take place today.

91. The fuel used for cooking our food and warming our dwellings is usually coal or coke; in some parts wood or peat is employed, and occasionally coal gas.

92. The heat produced during the burning of fuel is given out when the carbon of the fuel unites with the oxygen of the air, and carbonic acid gas is produced, as it is by the breathing of men and animals. This poisonous gas usually passes up the chimney with some unburned carbon which forms the smoke.

 When charcoal is burnt, the carbonic acid is produced without smoke, and therefore it is often used in stoves without chimneys, and the carbonic acid escaping into rooms is frequently the cause of fatal accidents.  All stoves without flues or chimneys to carry off the carbonic acid are dangerous, and many persons have been poisoned by their having been used.

93. The heat produced by the burning of any kind of fuel makes the air in and around the fire much lighter, and it rises rapidly over the fire, usually passing up the chimney. More than nine-tenths of the heat of a common grate passes up the chimney in this manner, and is wasted. If the grate is constructed of thick solid metal, this conducts away a large quantity of the heat so that it is impossible to keep in a very small fire in an iron range, whereas a mere handful of fuel can be kept alight in a grate lined with fire brick or fire-clay which does not cool the burning fuel in the same manner metal does. Part of the heat produced is thrown out by the fire, and passes into the room. In ordinary grates the amount of heat passing off in this manner is very much lessened by the thick bars which are frequently placed in the front of the grate.

94. Ordinary fire-grates are most extravagant modes of using fuel, and are not employed by the people of any other nation. Not only is a good deal of the heat carried away up the chimney, and by the conducting power of the iron, but the shape of the grate and the bars also prevents much being thrown out into the room.

95. An ordinary grate may, however, be made more economical. If it be lined with bricks, tiles, or fire-clay, and the open bars underneath be closed, either by fire-clay or a piece of tin plate, the air will have to enter in front where the fire will be brightest, and no heat will be thrown down into the ash pit.

96. Cooking ranges with an oven on one side are very useful in a small family. If well constructed they will bake bread, meat, and pies or puddings very perfectly.

Even when there is a low fire the oven can be used for stewing, and slow cooking can be done on the top much better than over a common fire.

A boiler by the side is not so important as an oven, Boilers are liable to get filled with the deposit or rock from the water; and if they are of cast iron, they are apt to crack. As an example of a good cheap open range, the following may be taken; it has a fire-clay back to prevent the heat passing away where it is not required, a good sized oven with the door to let down in front, and a boiler. Grates of this kind are now made by many manufacturers, and are sold at a low price.

97. Cooking stoves are much more convenient and economical in use than ranges. They are used by almost all persons in America, and are now very largely employed in this country. A very good pattern is shown in the engraving.   It has an open fire which can be used for broiling and toasting. This fire is quite under control and can be raised or lowered in a few minutes by opening or closing the doors  so as to cause a strong current of air to pass through  the burning fuel or over it as required.  The size shown will bake a joint as large as a leg of mutton or two tins of bread admirably.

The cooking vessels can be put down on the fire or placed on the hot iron top and shifted to receive as much heat as required.

The stove can also be used as a hot place for preserving or stewing.  The open fire is cheerful and the stove is a good heating stove as well as cooking stove.  An large boiler placed on top will furnish an unlimited supply of hot water.  placed in front of an open fire-place these stoves require about six feet of iron pipe to be placed up the chimney. Being perfectly movable they can be carried by the owner from one house to another and placed in front of any fire-place. They are sold by Smith and Welstood, Ludgate Circus.

98. Gas-stoves. Gas when employed as ordinary fuel is exceedingly expensive, being at least five or six times as dear as coal. When the gas is burned inside the oven in which meat is to be baked the vapour arising from the burnt gas renders the meat sodden and unpleasant, and quite different from the meat cooked in an ordinary oven or before the open fire.

Gas can however be used as an occasional source of heat with great economy as it is instantly lighted and put out ; there is no waste of fuel or loss of time.  The best small gas stoves are those that can be placed on a table and burn the gas mixed with air, when it produces a pale blue flame which does not smoke any vessel placed within it.  These stoves are particularly useful in heating a kettle of water in the summer time or when there are no fires in the house.

The text was produced by photographing the pages with my phone and using OneDrive's extract text feature.  Whilst I have read it through, any errors are mine not the original author's.

Simulation and Sustainability (15) - Think differently

In the second half of last year I wrote a short and simplistic simulation in Python designed to explore ways in which a typical household could increase its consumption of wind and solar energy by the including storage in it's energy economy.  Several scenarios where explored and written up as posts as part of this blog, this one is some thoughts on the project. The link at the bottom of the page points to the original posts.

The concept is simple, a household has, say, 10 kwh of electrical storage and by some yet-to-exist technology which gives it the ability to "buy" electricity from a variety of suppliers.  It makes use of  sustainable energy  when it is available and if there is a surplus stores it for use when the sun does not shine (i.e. at night) or when the wind does not blow.   It first checks to see if any solar energy is available on a local grid and if none is available it sees what wind farms can offer and finally when the storage is exhausted, falls back on conventionally generated supplies.

As with many simulations, there are a lot of assumptions and arbitrary rules, so the conclusions suggest a direction of travel rather than precise estimates of how such a system might behave.  Renewable currently account for roughly 15% of the electricity consumed in the UK, by incorporating storage into a home's energy system, an individual house might increase this to 50 - 80%.

Whilst wind and solar generation are critical technologies in a sustainable energy economy they are both weather dependent sources and require either storage or a  backup in the form of gas fuelled power stations to bridge the gap between intermittent supply and regular demand.  The pattern of investment that seems to be emerging is that offshore wind farms are incremental to conventional capacity and this raises the question: "Is it possible to displace some fossil/nuclear capacity by increasing the use of energy storage".

When I first started thinking about a simulation to explore this idea I had in mind the lead-acid battery packs used by fork lift trucks, however, since then products like Tesla's PowerWall have become available and these have the advantage of being packaged as consumer products.  As electric vehicles become more common, the profile of electrical energy storage will become more familiar.  It also raises the possibility of using the family car as part of the household energy supply.  For example, most cars do very little, often sitting around car parks at the end of the commute, if during that time, the car is charging itself on wind or solar generated electricity, it might return home with a surplus which can be used to light the home and cook the evening meal (I appreciate there might be some complexities in this scenario).

The current electricity supply model has evolved on two assumptions:

• That supply and demand can only be synchronized by adjusting the output of generators
• There is no limit to consumption

If these constraints are relaxed, alternatives forms development emerge.  Storage helps with the first item and the second is a challenge.  People do not buy energy, they purchase the benefits it provides.  One example of a technology which delivers this is LED lighting.  A decade ago our home was lit with incandescent bulbs and it consumed 20 kwh/day, now with LEDs we are down to 4 kwh/day and we can still see to read.

The potential to re-apply investment in energy infrastructure is illustrated by a hypothetical nuclear power station.  Say it costs  £20 billion and several years to build a 2,000 MW unit.  If the average home consumes 4,500 kwh/year, this imaginary project with a load factor of 90% can supply approximately 3.6 million homes.   This very simplistic calculation suggests that one power station represents an investment of £5.5k/household.  This is similar to the cost of a 10 kwh storage unit.

Sustainable energy sources are unlikely to fully replace conventional ones but there is scope to investigate some alternatives.

This link provides a description and pointers to related posts:

• Doris - A thought experiment in progress

Messing with model wind turbines

If there is a theme to these posts, it is learning about sustainable energy.  Staring at a wind farm or an array of solar panels can be instructive, but some personal experience is always useful, even with the limitations imposed by small models.  These two models were made with materials which were lying around where were a length of drain pipe, some plywood offcuts and a random selection of Meccano.  If I ever repeat this exercise, I would opt for a lighter construction and a small alternator as a load.  An attempt at making a dynamometer was not wholly successful.

Wind in urban and rural areas is often turbulent and gusty with frequent changes of direction.  There are a few small horizontal wind turbines in our area, the only ones which give the impression of running continuously when the wind is blowing are those mounted on tall masts.  One of the attraction of vertical axis turbines is that the can adapt to frequent changes in wind direction without having to "hunt" for the wind, another is they are quite simple machines.  Many Savonius turbines used in the Caribbean to drive irrigation pumps are just a 40 gallon oil drum which has cut in two along and welded back together.  I am not fully convinced that rotating machinery has a place in the urban environment, however, the Savonius design  has some inherent speed limitation.  For these reasons I opted to mess with vertical axis designs.

The advantage of models is that they can be moved around on a bicycle and tried in various locations.  Despite mounting the Savonius model on a 5 metre pole, it never turned continuously in my back yard whatever the wind was doing elsewhere, that was a useful lesson.  About 7km to the west of where I live is a small airfield where the remains of some of the Second World War defences are accessible.  The roof of a pillbox which had been build on an embankment is about 10m higher then the surrounding flat terrain, here the Savonius model spun freely and smoothly.  The wind there is both smooth and steady.  In contrast, performance on the upper level of multi-story car parks in the city centre was disappointing, the turbine would spin during gusts, then stay sullenly stationary for at least 30 seconds before starting up again.  Performance on jetties along the sea front was good if the wind was blowing of the sea and poor if it was coming from the land.  I did not investigate too closely, but the wind at the top of cliffs appeared to be complex, I may have formed a different opinion if the turbine had been on mast rather than at head height.  It is important to be careful in public places.

I had no desire to draw attention to myself, but with the exception of a large Alsatian called Trooper I was allowed to engage in this bizarre activity without interference.

I had been intrigued by the Darrius design of turbine, however, the model refused to do anything useful, which with hindsight is probably a good thing.  The most probable cause was poor construction which did not allow for setting an appropriate angle of incidence on the vertical blades.  An afternoon spent figuring out the aerodynamics of this type of machine was useful.

Whilst this design looks simple, the aerodynamics and resulting stresses are complex, had the thing worked, it would have probably shaken itself to bits.  I'm not certain of my facts, but I think that this design is capable of over-speeding under no-load conditions.

I became somewhat more absorbed in this project than I intended and when time permits I want to build another Savonius model.  If I proceed with a second attempt, the design will incorporate a small alternator to act as a load and provide some indication of output.  The first attempt used a fluid clutch attached to a torsion spring, this was a good illustration of the rule which says "if it looks complicated, it's probably wrong".  Secondly, the rotor would consist of three segments each 120 degrees apart, this would smooth the output torque and prevent the rotor getting "stuck".  Most of the time the Savonius was self-starting, but occasionally act like a weather vane until given a sharp prod with a finger.  I have seen some beautiful picture of Savonius turbines where rotor is a spiral which suggests the possibility of making a turbine into a garden feature.

Both models are being dismantled for firewood and the recovery of the Meccano bits.

Economics, LED Lighting and Sustainability

Economics and sustainability do not sit comfortably together.  Fossil fuels are convenient and after more than a century of development the devices which consume them are reasonably efficient and in some respects cheap.

Things that are tagged as "sustainable" or "green" often have a premium either paid directly by the owner or indirectly by a third party in the form of a subsidy.  Ideally, sustainable technologies should deliver the same benefits for the same cost as traditional technologies.

My experience with LED lighting suggests that it meets these criteria.  I bought my first LED lamp approximately 4 years ago and it did not win the hearts and minds of my family.  I'm guessing but I think it produced 50 - 60 lumens per watt which was only a modest improvement on CFLs which lit the house, however, the real problem was the fact that the light came from a surface rather than a sphere, thus the diffuse light reflected from ceilings was lost.  About two years later, some small LED globes started appearing with an output of around 400 lumens and maybe an efficiency of 60 - 70 lumens/watt.  These worked well and some 10 watt CFLs were replaced with 5 watt LEDs.  Recently, the "right" product appeared in the form of a globe lamp with an output of around 900 lumens and an efficiency of 90 - 100 lumens/watt.  We are now replacing 20 watt CFLs with 10 watt LEDs.

The benefits of moving from CFL to LED appears in the electricity bill, we currently consume about 1,500 kwh/year making the bill, excluding standing charges, roughly £250/year.  I extracted the graph above from my account on the energy suppliers website.  It needs treating with caution as I'm not sure it compares like-with-like.  I'm guessing that the "similar house" means one in the same postcode area and that the "efficient house" is the lower quartile for that postcode area, so all the graph tells you that our home uses electricity than our neighbours, possibly because we have LED lighting.

Let's take this experience to some illogical conclusions.   Say, an investment of £250 in LED lighting reduces a home's electricity consumption by 200 kwh/year most of the reduction taking place in winter when the demand for energy is highest.  Compare this with a hypothetical rooftop PV installation costing, maybe, £5,000 which produces 2,000 kwh/year mostly during the day in summer when the demand for energy is lowest.  Which technology gives the best environmental outturn?

3D Data and the Dipstick

One way of working with data which has a spatial or geographic context is to figure out a way of plotting it on Google Earth.  Apart from the provision of maps, Google Earth takes care of all the maths needed to display 3D data which can reduce the task  to generating a .kml file with the data to be displayed.

Whilst techniques such as correlation are useful, displaying two or more variables graphically can provide an insight into data which might not be obvious on a graph or from a table of numbers.  Recently, I have had to look at some atmospheric data obtained from GFS (see note below), in addition to latitude and longitude, some elements of this have a vertical component defined by the pressure level (e.g. 900 mb).  The example below shows relative humidity around noon for a randomly selected day in June 2015.

For lack of a better name, this graphic device has been called a dipstick.  In terms of kml, each dipstick is a series of linestrings, the colour of which is determined by the value of the data value.  In this example, the colour scheme has been taken from ColorBrewer.  A vertical exaggeration of 5.0 has been applied, some experimentation is needed to find a value which is appropriated for the data and the geographic scope.

I'm far from being an expert on weather data, but my understanding is that clouds form when the relative humidity is high, this example suggests clear skies over the south east of England with low to medium cloud to the north.

GFS is the Global Forecast System, extensive datasets from which are made available by NOAA.  I would like to express my appreciation as these are a valuable learning resource.

I believe this representation to be original, any plagiarism is unintentional.

Water Metering - A brief (and personal) history

The great thing about the internet is that you can find a large lump of iron whilst walking the dog and an hour later history unfolds.  I found this object whilst following my dog into some bushes to prevent him doing something regrettable.

It is probably a water meter which was made by Glenfield and Kennedy in Kilmarnock, the location suggests that it might have been installed around 1910 (a guess).  It seems that water passing through the device causes a reciprocating motion of a piston in a cylinder, a mechanism records the number of oscilations and this is scaled to indicate the cumulative water flow.  At a guess the maximum flow rate was not high (the piping seems to be 1/2 inch internal diameter) and there would have been a noticable pressure drop across the meter.  Maybe the occupants of the building were not too keen on bathing.

A few years back, the water company moved us onto a metered supply in place of a fixed tariff.  The meter appears to use a small turbine and does not appear to drop the pressure of restrict the flow rate.

When it was announced that water meters were going to be installed, there were two reactions, the first was that bills were going to increase and secondly that a restriction on consumption was an infringement of liberty.  Our own bill fell, this may not have been the case if all our children were still living at home, also we only use rain water on the garden.  The second one has faded, but is a recurring theme.

Whilst I am interested in sustainability, I am not convinced that price and enforced constraint are effective tools for managing consumption.  In theory, increasing resource prices should reduce consumption, however, the energy is inelastic, which is an economist's way of saying that a big increase in price does not result in a big drop in consumption. Those on low incomes resent high prices (children have to be washed and petrol may be needed to get to work) and those on high ones don't care.  To complicate matters, the business model of energy companies is based on selling more product, although there seems to be increasing competition for market share.  Changing this is a big challenge, one possibility is to move to a system which is based on the benefits of water, energy etc. rather than the volume supplied.

Historic Windmill Sites

When I first became interested in sustainable energy it seemed that it was a data-rich industry, whilst good quality meteorological data is available in long time series, a lot of it comes from aerodromes which are flat, unobstructed spaces.  Solar devices are relatively independent of terrain, however, the output of wind turbines is determined by terrain.  Within a few kilometers of where I live, the wind speed can vary between 0 and 10 m/s according to location, where the terrain ranges from seafront, urban areas, exposed ridges and sheltered valleys.  Whilst industrial scale wind turbines for electricity generation are a relatively recent development, the wind was a significant source of energy in the 19th Century for milling and pumping applications.  There were approximately 20 windmill sites within what is now the Brighton and Hove city limits with several more within a few kilometers.  It is interesting to look at the location of these mills in the context of terrain.

The graphic below was mainly compiled from two sources:

• Timothy Carder's excellent "The Encyclopedia of Brighton" which was published in 1990 by East Sussex County Libraries.
• SRTM 1 arc second elevation data.  The 1 arc second data became available in 2014, prior to that only 3 arc second data was available for areas outside the US.  I very much appreciate this data being available.

The shading is relative and based on one of the ColorBrewer schemes with linear interpolation between the intervals, this is a convenient way of working with continuous data.

The graphic clearly shows that the favored location for windmills was either on the coast or along the chalk ridges that extend southwards from the Downs, only one appears to be located in a sheltered location.  Siting a windmill or turbine requires access to land, thus available locations may not always by the optimum ones.  The Google Earth screenshot below illustrates the competing uses for land.  In this case, the contours were generated using the SRTM 3 arc second data set.

Post mills are relatively portable, the machinery is mounted in a wooden structure which rotates around a post, a picture in a local museum shows one being moved on a sled drawn by oxen.  During their lifetimes five mills were moved to new sites either in one piece or in separate loads.  I have not studied the history of milling in the town, but I'm guessing that the early mills were built in the late 18th century to serve Brighton's growing population, however, as the demand for building land grew, the mills were displaced.  The screenshot shows the change of location of four mills, a fifth Preston Mill moved several miles to the north to Clayton where it is still in existence and has been restored and is now a listed building known as "Jill".  Towards the end of the 19th century the windmills came under the combined pressure of demand of building land and competition from steam and motor mills and their numbers dwindled.