The generation elements of a sustainable economy attract more attention than the things that use energy. A couple of acquaintances have installed rooftop PV and this has been the subject of discussion amongst the neighbours with questions like "how much electricity to the generate", "how much money do you make" etc. In contrast, my four LED light bulbs and newly acquired Raspberry Pi attract little or no interest. I am old enough to realise that "do you want to see my LED" is not the best way to start a conversation. In a more general sense, wind farms and solar parks get more column inches in the media than boiler controls and politicians are careful in the choice of language they use to talk about energy consumption.
With a little creativity its possible to determine the perception of any project. My view is that wind and solar sources are complimentary. Wind produces most energy during the winter and solar can be a cheap source of electricity in summer, but both are discontinuous sources and without low cost storage, require an equivalent fossil fuel backup, which means wind and solar capacity has to be matched with a flexible and responsive technology such as gas turbines.
This is an attempt to make the case for focusing on conservation. There are many ways of looking at the numbers, hopefully this one is simple, albeit with some gross over simplifications. Let's start with the assumption that one house in a hundred as rooftop PV and that the installation costs £5,000 and produces 2,500 kwh/year. The owner of the PV panels recovers his/her/its costs from a feed-in tariff. The panels produce most of their output a few hours either side of solar noon during the summer months, not much during the winter and none at night.
Peak demand for electricity is in early evening during the winter months and this can't be met directly by solar generation, at a guess, the peaks are largely met by gas fueled generators.
As the result of some policy as yet undefined, instead of one household investing £5,000, one hundred households each invest £50 in conservation technologies, in some respects this is more of a challenge than installing rooftop PV, For my household selectively replacing four 20 watt CFl's with 5 watt LED has resulted in reducing consumption by about 50 kwh/year . Extrapolating this to 100 households results in savings of 5,000 kwh. More to the point, these savings take place at the time of peak demand, thus reducing the need for fossil fuel capacity.
The more overall demand is reduced, the easier it is to integrate sustainable sources into the energy economy.
Sunday 30 November 2014
Saturday 22 November 2014
Energy - A short family history
I've dipped into history for several posts and after some random research, a pattern seemed to be emerging. I take the view that technology evolves and allows you to break with the past, however, the past delivered you to the present and you need to learn from it. I'm not advocating returning to coal fired ranges for cooking and horses for transport, but I do think that energy management which was once an integral part of daily life could be as effective in achieving sustainability as technology. This very brief history is based on half remembered comments and Sunday mornings spent at car boot sales.
In the context of our family, the history of energy can be summarised in three periods, from approximately 1850 to end of the Great War, the interwar period and the Second World War, then the post war period to the end of the 20th century.
My mothers grandparents or great grandparents "left the land", making some assumptions about age, this must have taken place between 1850 and 1870. It is possible that they worked on the land with horses and heated their homes and cooked their food with wood fires. Apart from the railways, most transport involved a horse in some way or another. You provide a modern vehicle with some form of ID, then press a button and drive off but a horse requires daily maintenance and preparation for a journey. Unlike a car some of the emissions from a horse can be recycled. The wood for fires had to be collected, cut up and dried. Wood is only a good fuel if it is dry, thus if you want a warm winter you need to gather fuel in summer. At the start of the 20th century, my mother's family were settled in a Yorkshire town, still working with horses, but now delivering timber to building sites. The homes were now heated by coal fires and lit with oil lamps and gas mantles. The provision of heating and lighting involved a lot of cleaning for the women of the household, tasks such as black leading the range, cleaning sooty oil lamps and laying fires made them effective saleswomen for the gas and electricity companies in the interwar years. Money and time had to be planned, fires were only lit when someone was in a room, meals had to be planned around the range. The warmth of the range made the kitchen the family centre in many homes. When the war came, the men and horses went and those that returned were not in good shape and that was the end of the family's involvement with horses.
The interwar period was one of change. Coal was still the dominant fuel for industry and transportation. My wife's family were mining engineers and many of mine worked on the railways. My mother;s cousin drove steam trains for the L.N.E.R. He had started as a "boy", then become a fireman, shovelling the coal into the engine's firebox and finally a mainline driver. I only knew him late in life, he felt he had had a good life, but made it clear that it had been a hard one. A fireman's day started well before an engine left the sheds, the first job was to rake out the ashes from the firebox, shovel coal from the tender/coal box and then raise steam, all this is hard physical work which often started at 04:00 or earlier. In addition to maintaining the timetable there were often restrictions on the amount of coal available, it was not unknown to scavenge wood when the opportunity presented itself. Towards the end of his career, electric trains were being introduced and these were popular with many drivers. I had a brief experience of steam winches in 1970 and quickly became aware that it was necessary to have a working knowledge of engineering to maintain and operate them, in contrast electric machines were relatively simple to use.
Whilst gas had been used for cooking and many homes used electricity, either from a power station or from lead acid accumulators before the outbreak of war in 1914, it was in the 1920s that these things started to become accessible to a large part of the population. These changed the nature of the household energy economy and improved the life of women. Coal remained the dominant fuel for heating, but cooking an lighting now involved flicking a switch rather than shovelling and cleaning. Initially, electricity was just used for lighting, but new uses were soon found, in our family vacuum cleaners were popular, followed closely by electric irons.
Increasing numbers of young men bought motor cycles, some realising that a woman wearing a skirt would not ride pillion attached a side car and a few raffish fellows acquired three wheeled cars driven by a vee twin mounted on the front. As the second world war approached, some of the better off members of the family had acquired a small car. Even amongst the non-technical members of that generation there was basic familiarity with the petrol engine acquired out of necessity, most knew the mantra of compression, spark and petrol. Cars at that time were equipped with starting handles which provided an opportunity for showing off and frequent humiliation. This maybe an urban myth, but it was widely held that a woman's stocking could be used as a temporary fix for a broken fan belt, this was not a good chat up line, not least because stockings were expensive. The efficiency of petrol engines was not high, my perception is that the cost of production (and thus selling price) was more important than efficiency, 30 miles per gallon seemed to be the expectation. Many engines of that period had side valves and were made of cast iron.
Domestic energy consumption steadily increased during the interwar period, probably the rate of increase was slowed by the depression of the late 20s and early 30s. Unit prices also started to fall. The graph below shows the electricity consumption of one family from 1926 to 1948.
Typical consumption was between 500 and 700 kwh/year, today, the average consumption of a modern household is around 3,500 kwh. The austerity imposed by the second world war is clearly visible in the graph which shows annual consumption falling to less than 400 kwh.
The first decade of the post war period was a continuation trends established in the pre war era, there was full employment and a demand for consumer goods and the electricity to power them, some pundits were advocating the merits of an all-electric home with none of the mess of coal fires.
The term "dash-for-gas" gets regular outings, but it is a good description of the energy sector towards the end of the 60s and early 70's when the discovery of large gas reserves in the Southern North Sea and the subsequent displacement of "town gas" which was manufactured from coal. For the most part this change of fuel required only minor modifications to appliances, however somebody made a pledge that all appliances would be adapted and every so often the papers would feature a story about an unlikely object being fueled by North Sea Gas, fridges and radios attracted a lot of attention. For most households, the advent of gas central heating heralded a new age. The coal and ash buckets were replaced by an electrical/mechanical timer which ensured that the house was warm when the family woke up and there was bath water in the evening and it was cheap. By the end of the 70's gas had displaced coal as a fuel for domestic heating. This was not a bad thing, but the next generation grew up when energy management was delegated to a time switch and at a time when for many people (but not all) the percentage of household income spent on gas and electricity was falling as wages generally increased.
At the start of this century, energy prices have risen and there are concerns about the environmental impact of fossil fuel consumption. It's an exaggeration to say that many households have found this difficult to cope with because of timer switches and thermostats located in drafty halls, but its a reasonable hypothesis that these contribute to high energy bills. There are some signs of change, predictably, the smart phone is part of this and there are some systems which allow heating systems to be controlled remotely and portable thermostats. The benefits of these systems may be that they encourage energy management.
The interwar period was one of change. Coal was still the dominant fuel for industry and transportation. My wife's family were mining engineers and many of mine worked on the railways. My mother;s cousin drove steam trains for the L.N.E.R. He had started as a "boy", then become a fireman, shovelling the coal into the engine's firebox and finally a mainline driver. I only knew him late in life, he felt he had had a good life, but made it clear that it had been a hard one. A fireman's day started well before an engine left the sheds, the first job was to rake out the ashes from the firebox, shovel coal from the tender/coal box and then raise steam, all this is hard physical work which often started at 04:00 or earlier. In addition to maintaining the timetable there were often restrictions on the amount of coal available, it was not unknown to scavenge wood when the opportunity presented itself. Towards the end of his career, electric trains were being introduced and these were popular with many drivers. I had a brief experience of steam winches in 1970 and quickly became aware that it was necessary to have a working knowledge of engineering to maintain and operate them, in contrast electric machines were relatively simple to use.
Whilst gas had been used for cooking and many homes used electricity, either from a power station or from lead acid accumulators before the outbreak of war in 1914, it was in the 1920s that these things started to become accessible to a large part of the population. These changed the nature of the household energy economy and improved the life of women. Coal remained the dominant fuel for heating, but cooking an lighting now involved flicking a switch rather than shovelling and cleaning. Initially, electricity was just used for lighting, but new uses were soon found, in our family vacuum cleaners were popular, followed closely by electric irons.
Increasing numbers of young men bought motor cycles, some realising that a woman wearing a skirt would not ride pillion attached a side car and a few raffish fellows acquired three wheeled cars driven by a vee twin mounted on the front. As the second world war approached, some of the better off members of the family had acquired a small car. Even amongst the non-technical members of that generation there was basic familiarity with the petrol engine acquired out of necessity, most knew the mantra of compression, spark and petrol. Cars at that time were equipped with starting handles which provided an opportunity for showing off and frequent humiliation. This maybe an urban myth, but it was widely held that a woman's stocking could be used as a temporary fix for a broken fan belt, this was not a good chat up line, not least because stockings were expensive. The efficiency of petrol engines was not high, my perception is that the cost of production (and thus selling price) was more important than efficiency, 30 miles per gallon seemed to be the expectation. Many engines of that period had side valves and were made of cast iron.
Domestic energy consumption steadily increased during the interwar period, probably the rate of increase was slowed by the depression of the late 20s and early 30s. Unit prices also started to fall. The graph below shows the electricity consumption of one family from 1926 to 1948.
Typical consumption was between 500 and 700 kwh/year, today, the average consumption of a modern household is around 3,500 kwh. The austerity imposed by the second world war is clearly visible in the graph which shows annual consumption falling to less than 400 kwh.
The first decade of the post war period was a continuation trends established in the pre war era, there was full employment and a demand for consumer goods and the electricity to power them, some pundits were advocating the merits of an all-electric home with none of the mess of coal fires.
The term "dash-for-gas" gets regular outings, but it is a good description of the energy sector towards the end of the 60s and early 70's when the discovery of large gas reserves in the Southern North Sea and the subsequent displacement of "town gas" which was manufactured from coal. For the most part this change of fuel required only minor modifications to appliances, however somebody made a pledge that all appliances would be adapted and every so often the papers would feature a story about an unlikely object being fueled by North Sea Gas, fridges and radios attracted a lot of attention. For most households, the advent of gas central heating heralded a new age. The coal and ash buckets were replaced by an electrical/mechanical timer which ensured that the house was warm when the family woke up and there was bath water in the evening and it was cheap. By the end of the 70's gas had displaced coal as a fuel for domestic heating. This was not a bad thing, but the next generation grew up when energy management was delegated to a time switch and at a time when for many people (but not all) the percentage of household income spent on gas and electricity was falling as wages generally increased.
At the start of this century, energy prices have risen and there are concerns about the environmental impact of fossil fuel consumption. It's an exaggeration to say that many households have found this difficult to cope with because of timer switches and thermostats located in drafty halls, but its a reasonable hypothesis that these contribute to high energy bills. There are some signs of change, predictably, the smart phone is part of this and there are some systems which allow heating systems to be controlled remotely and portable thermostats. The benefits of these systems may be that they encourage energy management.
Sunday 9 November 2014
Soil and Satellites
Recently I've started exploring satellite data, mainly to learn about the distribution of clouds. The NASA Earth Observation site (NEO) is a great resource learning about the atmosphere, solar insolation, land cover and much else (there is a link at the bottom of the page). The site has a large number of thematic world maps with various time and space resolutions. In addition, the data behind the maps can be downloaded making it possible to extract data for a specified tile containing data for an area of interest.
For a couple of years I have been collecting soil temperatures in my back yard, I thought it would be interesting to compare surface temperatures as measured by the Terra and Aqua satellites with my observations for 2013. The results are shown in the graph below.
Whilst there is reasonable agreement between the two datasets, it is not a like-for-like comparison. The most obvious difference is that the NEO data comes from a sophisticated spacecraft with massive scientific backup. My data is derived from a hole in the ground which is protected by an empty dog food tin. The satellite data is an "average" for a 0.1 by 0.1 degree tile (very approx. 10 by 10 km), the one which contains my back yard contains a wide range of surfaces including urban, agriculture and woodland. The satellite builds up a picture of the Earth's surface from a series of scans rather than constant monitoring and only collects some types of data on clear days.
My hole in the ground was located to avoid the mains water supply and be accessible when when crops a growing, this could be described as a random suburban setting. The temperature readings are usually collected around sunset on Sundays. Soil temperature varies considerably during the day and night, the extremes take place when the sky is clear. In summer the noon temperature can reach 30 deg. C, and in winter under a clear night sky, it can fall well below zero. The graph below shows the variation during a spring day. The thermal turbulence is greatest at the surface (measurements taken at 0.1m). The temperature at 1.0m approximates to the average at 0.1m.
For a couple of years I have been collecting soil temperatures in my back yard, I thought it would be interesting to compare surface temperatures as measured by the Terra and Aqua satellites with my observations for 2013. The results are shown in the graph below.
My hole in the ground was located to avoid the mains water supply and be accessible when when crops a growing, this could be described as a random suburban setting. The temperature readings are usually collected around sunset on Sundays. Soil temperature varies considerably during the day and night, the extremes take place when the sky is clear. In summer the noon temperature can reach 30 deg. C, and in winter under a clear night sky, it can fall well below zero. The graph below shows the variation during a spring day. The thermal turbulence is greatest at the surface (measurements taken at 0.1m). The temperature at 1.0m approximates to the average at 0.1m.
The relationship between surface and air temperature is complex, I have yet to investigate this but it seems that the average soil temp approximates to the average air temperature, however the variations in surface soil temperature are greater than those of the air above.
Reference:
Saturday 1 November 2014
My daughter and the energy monster
You wait a lifetime for a reference to draft excluders then two come along in a single week. To be strictly correct, my daughters use of a discarded pair of tights is a temporary fix for a broken roof window.
The second was in an ad for an energy company, in which two cute children make an energy monster out of old tights and newspaper and save the family lots of money and blocking up gaps under doors. I am not wholly convinced by this scheme, its a nice thing to do, but I doubt that it will be visible on the energy bills of a home with central heating. However, it does make a connection between energy management and home economics.
When houses were heated with coal fires drafts were a problem, in order to burn, a coal fire sucks in cold air from between gaps under doors, badly fitting window and from under the floor and some place that no one ever managed to find. In this situation draft excluders did make a difference. They turn up a car boot sales where they often resemble the discarded limb of a diseased pantomime horse. they may be stuffed with vintage stockings, historic newspaper or just something old and disgusting.
I should be writing a paper, working on software, but I am renovating my house. Whilst its easy to lounge around thinking great thoughts, its also good to contemplate why one's feet are cold. On a winter's evening we draw the curtains, and turn the central heating on for an hour or so and then light a fire in the living room for warmth during the evening. The previous owner installed the radiators in such a way that curtains masked them off from the room. As 100 years of interior decorating is scraped off the walls, one task is to replace and relocate the radiators such that they approximately four inches from the wall. Thus when the curtains are drawn, they form a barrier between the radiator and the window rather than a union.
The second was in an ad for an energy company, in which two cute children make an energy monster out of old tights and newspaper and save the family lots of money and blocking up gaps under doors. I am not wholly convinced by this scheme, its a nice thing to do, but I doubt that it will be visible on the energy bills of a home with central heating. However, it does make a connection between energy management and home economics.
When houses were heated with coal fires drafts were a problem, in order to burn, a coal fire sucks in cold air from between gaps under doors, badly fitting window and from under the floor and some place that no one ever managed to find. In this situation draft excluders did make a difference. They turn up a car boot sales where they often resemble the discarded limb of a diseased pantomime horse. they may be stuffed with vintage stockings, historic newspaper or just something old and disgusting.
I should be writing a paper, working on software, but I am renovating my house. Whilst its easy to lounge around thinking great thoughts, its also good to contemplate why one's feet are cold. On a winter's evening we draw the curtains, and turn the central heating on for an hour or so and then light a fire in the living room for warmth during the evening. The previous owner installed the radiators in such a way that curtains masked them off from the room. As 100 years of interior decorating is scraped off the walls, one task is to replace and relocate the radiators such that they approximately four inches from the wall. Thus when the curtains are drawn, they form a barrier between the radiator and the window rather than a union.
I won't know how effective this has been until the coming winter departs. As part of a major overhaul, its not difficult to add this task to the list, it might not be so attractive as an isolated project. The more I mess with domestic energy, sustainability, the more convince I am becoming that a lot of small things add up to something worthwhile, so maybe I was wrong to dismiss the energy monster.
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