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.

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.

Town Ash

Once I knew little about town ash, then four weeks ago I found that I was the proud owner of quarter of ton of the stuff.  I mentioned this discovery to several people, only to find that ash is deeply rooted in folk memory and I became ashamed of my ignorance.

Back in the 19th century and early 20th, the energy economy was for all practical purposes, coal.  Unlike today where coal is burnt in a relatively small number of locations, most of which are power stations, coal was burnt in small quantities in millions of urban locations.  Just look to the skyline in most English cities and you will see a chimney of some sort.  Most homes had one or more open fires and a range for cooking, all of which were producing ash.  Sometimes ash was separated from other household rubbish and collected separately, sometimes the dustin was the last resting place of all of a household's filth.  Ash as domestic waste lives on, in 2004 the council supplied me with a plastic wheelie bin which is embossed with the slogan "No Hot Ashes".

Finding a use for this stuff was making a virtue of necessity.  My ten sacks of ash had been used to provide support during the construction of  brick wall, one of the faces of which was sloping.  After a century, the ash had become soil and plant life had caused the structure to degrade requiring a rebuild.  Ash had also been used in the mortar and this made it easy to reclaim the bricks, however, they were of poor quality and I opted to use new ones.  The originals were FreeCycled and may now be part of a garden path.  The man who collected them told me that ash was frequently used in Victorian civil engineering as a fill for canal and railway embankments.

What was once Victorian rubbish can now be collectable history and ancient tips are sought out by bottle and pot lid collectors.  On learning this decided to sieve my ash before disposing of it.  Whilst there were no great discoveries other than an almost complete egg cup, several bits of broken clay pipe and fragments of jars as few of which had writing.  The pile of fine ash from this exercise can be used as a soil improver, as there were many many species of plant established in the wall, there may be some truth in this.

A few fragments have various combinations of letters which suggest they are from local companies suggesting that the ash was also local.

As was also used in brick making, having seen a lot of broken bricks recently, I would suggest that bricks with a high ash content are of low quality, but that might just be the result of a small sample.  Ash is also known as "breeze", this has been used in conjunction with cement to to produce a large building block known as a Breeze Block.

Clinker, which is the lumpier bits of ash was often used as a base for concrete used in step, pathways and standing areas:

An allotment holder told me that ash was often dug in allotments where the soil contained a lot of clay, this made it lighter and prevented it from becoming waterlogged.   One use attracts mixed feelings, sometime back a local resident disposed of his ash by spreading it on a rough, steep track that ran by his house, this made walking a lot easier, but, for regular users it required additional shoe cleaning.  As I work from home, my dress code does not require me to have clean shoes, so I was grateful for his efforts.

Finding uses for ash was a form of recycling, in many towns it is normal to separate items that be recycled, e.g. bottle, tins, paper, plastic etc. from material which can only be disposed of in landfill or incinerators.

Postscript - 03-Jan-2015

Recently I was walking around the northern part of Brighton where many roads are build on sloping ground and where retaining walls are common.  One such wall was dark grey with fragments of pottery visible on the surface (I have a bucket full of similar stuff).  I'm guessing that this wall was in part a mixture of town ash and cement:

Why is broken pottery such a common feature of the ground surrounding Victorian and Edwardian buildings?

Storage - A personal survey

Having made frequent references to storage in this blog, I thought it would be good to read around the subject, this post is more or less a list of links to Wikipedia articles.  The list is neither complete or comprehensive.  Whilst randomly clicking around, I was intrigued by the number of references to submarines and electric fork lift trucks.  Whilst these appear to be diverse applications, both make use of stored energy and both have well developed infrastructures to support their operations.  Maybe the starting point of a sustainable energy economy is a submarine, maybe this was the origin the line in the Beatles song which goes "We all live in a yellow submarine".  Storage is the key technology in a sustainable energy economy, generation is the most visible element and attracts most of the attention, but it is storage that bridges the gap between the regular pattern of daily life and the shifting sun and fickle wind.

Traditionally, system efficiency has been principal method used by engineers to assess performance.  Whilst it is not unimportant in storage systems, in the authors opinion it is the unit cost of energy as perceived by the end consumer which is the most important measure.

Batteries

Batteries are the most familiar form of storage.  A gross over simplification would be to divide them into two categories defined by weight, the heavy lead acid form which has been in use for a century of more and the lightweight varieties such as NiMH (Nickel Metal Hydride), Ni Cd (Nickel Cadmium), LI (Lithium Ion).  Lead Acid accumulators have a long history of use in domestic energy storage providing the energy for lighting, door bells and valve radios.  If operated conservatively they have a long life and can provide a few kwh for domestic use and more than 1,000 kwh for submarines.  If used in vehicles, the result is the milk float, the high energy density of LI batteries makes it possible to design sleek and elegant high performance vehicles such as the Tesla Model S which has LI batteries with capacities of 60 - 85 kwh.  The life of a battery is a function of the way that it is used, high charge and discharge rates will shorten the life of most types of battery, the depth of discharge is also a factor.

Compressed Air

Compressed air motors have long been used to provide power where any form of combustion is undesirable, for example in mines or where atmospheric oxygen is not available.  Compressed air powered many torpedoes in both the First and Second World Wars.  Storage schemes using compressed air range from small pneumatic accumulators to utility scale projects based on underground caverns. Large marine diesel engines often use compressed air for starting.  At the time of writing, it seems that most of the utility scale projects are still at the proposed or planning stage.  Compressed air storage based on underground caverns maybe less visible than the major civil engineering works required for pumped water systems.

Pumped Water Storage

Pumped water storage is a utility scale technology, often based on worked out quarries and large dams.  The system consists two reservoirs, an upper one and a lower one.  The energy to be stored is used to pump water from the lower reservoir to the upper reservoir.  That energy is reclaimed by letting the water flow back to the lower reservoir through turbines which power generators.  Often the machinery is in the form of units which can  work as either motor/pump sets or turbine/generators. Pumped water is currently the most common utility scale storage technology.

Thermal Storage

Thermal storage includes several diverse range of technologies.  At the domestic level it includes night storage heaters, these use off-peak electricity to heat up a mass of bricks or water, as these cool during the day they provide space heating.  Domestic hot water systems often incorporate an insulated tank, this can be heated using off-peak electricity or solar thermal devices in a suitable climate so that hot water is available for an early evening bath.  At the utility scale, heat from large solar concentrators has been used to create a reservoir of molten salt (or similar substance).  The heat stored in this material can then be used to create steam for use in a conventional steam turbine generator.  The Wikipedia article has a link to an article describing a solar basede Seasonal Thermal Storage System in Canada.

Hydrogen

Whilst hydrogen is not a dedicated storage technology as such, it can be produced by sustainable sources, for example by electrolysis from wind generated electricity.  It is a versatile fuel and can be used to generate electricity directly in fuel cells and as fuel for reciprocating engines which are adaptions of those used in automotive applications.  The German Type 212 submarine uses a form of hydrogen fuel cell to achieve better performance and endurance than a conventional diesel electric vessel.  Earlier this year Toyota announced the launch of fuel cell based car.

Flywheels

Flywheels have long been used for storing energy for very short periods of time, for example smoothing out the torque produced by reciprocating internal combustion engines.  It maybe an urban myth, but success of the Citroen 2CV (the famous "tin snail") has been said to be due to a large flywheel which made it well suited to undulating roads of rural France.   Flywheels form the basis for for some recuperative braking systems, these capture a vehicle's kinetic energy as it brakes and then restore it to the drive train on the next acceleration.  This type of system has been used in F1 racing cars.  The flywheel is an attractive energy storage device, it may have a longer life expectancy than chemical based systems.  Despite its apparent simplicity, large systems are heavy, high rotational speed systems which present some design challenges, however, it seems that these are been overcome.

Links

Batteries
Milk Float
Tesla
Compressed Air Storage
Pumped Water Storage
Thermal
Type 212 Submarine
Hydrogen Storage
Hydrogen Fuelled Vehicles
Flywheel Energy Storage
Regenerative Braking

Cars don't do very much

The street I live in is for all practical purposes, the car park of the local railway station.   During the day, the street is home to a flock of thirty to forty cars, at weekends they may roam the parking lots of the town or journey to the outlying supermarkets and once a year they take flight to Cornwall or the Lake District.  Most of the time they do nothing.

I  have often gazed at these vehicles and wondered if things could be different.  The following will not survive any form of analysis or review, but it passed the time.

There are no electric vehicles parked in the street, but there are two or three hybrids.  I'm not convinced by hybrids, my understanding is that they attain a high level of fuel efficiency by using an electric motor and battery to optimise the usage of a petrol engine.  This is achieved at the expense of weight and complexity, if I were to consider buying a new car I would opt for something small and light with a simple but efficient drive train or something electric if it cost the same.  Hybrids and electric vehicles have batteries and that's what makes them interesting.

A short walk to the north takes you to a couple of oddly sited charging points for electric vehicles.  If these were located closer to the station an owner of an electric vehicle could leave it to charge during the day.

A short stroll to east takes you to a park which on a clear day gives you a distant view of the location of a planned offshore wind farm.  I am an enthusiast for wind and solar energy, but I perceive them as weather dependent sources which stall with clouds and calm which require some form of buffer storage to even out the gaps between supply and demand.

In many homes, the commuter is away all day at work and children are at school so apart from an over enthusiastic robotic vacuum cleaners, domestic electricity consumption is relatively low during the day. It is in the evening that the home wakes up, lights go on, meals are cooked and hair is straightened.

In an integrated world, the car has found something to do when otherwise it would be idle, during the day it has been harvesting electricity from an offshore wind farm, in the evening when it arrives home some of that energy is used to meet its owner's domestic needs.  The technology used to get solar panels to feed into the grid, is the same as that needed to use energy stored in the car's battery.  In this scenario one battery is contributing to the domestic energy economy and transport.

Its not difficult to pick holes in this scheme and one bit which does need some innovation is the tariff under which this would operate.  Ideally this should take account of the sustainable energy use and offer an incentive maximise its use.  There is potential conflict with HMRC, petrol and diesel are heavily taxed, whilst electricity for automotive use is not.

Footnote

This post was originally published in 2014, since then the Rampion wind farm has been completed and the use of the two charging points referred to above has increased.  When they were first installed, they were rarely used, I've passed by them a few times recently and more often then not at least one vehicle is connected.

Under the floorboards

For sometime I've been renovating my house, mainly to avoid doing things I need to do, like finish software, write etc. etc., so I wave my neighbours off in the morning as they commute to the codeface with a cheery wave of my trowel.  I don't hold with the view that the past is a guide to the future, but I think that if you don't know where you are coming from, you don't know where you are going.  Poking around under floorboards to remove defective piping and demolishing some decaying brickwork has provided some insights into energy use and sustainability, and oddly, the smoking habits of workmen over the past 100 years.

The remains of a clay pipe from 1901 and an empty packet of "woodies" from the 1940s or 50s.

I've recovered a few fragments of clay pipes, including a couple of bowls, pictures of Victorian builders often have a couple of blokes posing with a pipe.  A couple of butts smoked so far down that the smoker probably burnt his fingers could date from the 1920s or 30s.  Around 1950, the then owner rewired the house (partly because the previous wiring had started a fire), the electricians smoked filter tipped "Woodies" (introduced in 1948) and some unidentifiable brands, possibly including Craven A.  There are a lot of butts, many people smoked in the 1940s and 1950s, many, like my mother, acquired the habit during World War Two when long term health issues came a long way second to short term survival.  The dark world world between the rafters was next visited during the 1980s when central heating was installed and the house rewired, a few filter tips may have been dropped during this time.

An egg cup salvaged from quater of a ton of town ash that was used to support an angled wall, the same filth also yielded the remains of a marmalade pot.

The original 1901 builders seem to have used "Town Ash" as a filler to support sloping brickwork during construction and possibly to make mortar in places, maybe, because they thought they could get away with it.  They did, its taken them a 100 years for them to be found out.  Town Ash is just the stuff raked out of open fires and cooking ranges.  Having just removed quarter of a ton of the stuff, I would suggest that a late Victorian breakfast consisted of a boiled egg, toast and marmalade followed by a pipe of tobacco.  I'm trying to decide if ten bags of damp, black stuff are history or rubbish that has waited a century to be disposed of.

Whilst I have not found any, I have heard stories of builders using slag from Roman Iron works in the Weald.  The Roman connection may be fanciful, but the Wealden Iron industry was producing waste for several hundred years until iron production moved north as coal displaced charcoal as fuel.

It was possible that this pipe was installed in 1949 and was decommissioned in the mid-1980's, so this blockage accumulated over a 30 year period..  A fragile and smelly fragment of the Daily Mirror with a section of the Jane cartoon strip dated December 1949 was found close to this section.

One of the hardest jobs has been the removal of some iron piping, my guess is that this was installed around 1950 because of man's deep seated desire for hot bath water.  Iron was probably used for lack of anything better, but its not an ideal material for domestic plumbing, where the pipe had to be cut  to remove it, the bore can been seen to be constricted by a mix of limescale and rust.

1920's wiring, see text for description.  It was possible that this cabling was used for lighting and lead sheathed cable for power sockets.  The wood channelling is unusual.

It is the three generations of electrical wiring that are relevant to this blog.  The house was built in 1901 without an electricity supply, my guess is that this was installed in the early 1920s.  Only the ground floor was served with lighting and power sockets.  The wires are tinned copper and sheathed in rubber over which there is a fabric outer layer.  The live and neutral wires are separated in wooden conduits.  In the 1930s the cabling was extended to upper floor where the wires are the same, but the conduit is black painted metal tubing with clamps for elbows and tees.  Around 1950, the electrical wiring caused a serious fire.  The damage was repaired and the house rewired.  This cable is like modern "twin and earth" (T&E?), but made of different materials, the outer insulation could be polythene (a guess) the conductors are sheathed in rubber.  This survived until the 1980's when it too was replaced, this time by PVC T&E.

Cross section of lead covered cable, thought to have been installed around 1930, the cross section of the conductors appears to be larger than modern T&E cabling and the earth smaller.

When the house was built, it could probably consume about 10 - 50 kwh/day mostly in the form of coal for cooking and heating and some gas and rape seed oil for lighting.  There is a natural limit to coal consumption which is imposed by the capacity to shovel it and dispose of the ash.  With the advent of electricity this, this able to add another 5 to 20 kwh/day from incandescent lighting and electric fires.  Central heating lifted the energy absorbing capacity to well over 100 kwh/day.  For most of the 20th century energy prices were falling, if only as a proportion of household income, as prices fell consumption increased.  In the 21st Century energy prices are rising, but the legacy systems where were created during the era of cheap energy remain, making it difficult to cut consumption without the risk of chilblains.

Cabling from the 1950.  The outer sheath appears to be polythene(?) and the insulators around the cable appear to be rubber.

Climate and Sustainability

The the oil and gas industry has, within very broad limits an idea of the resources available to it.  Whilst it is possible to drown in a sea of numbers, it can be summarised as there always being  enough to fuel the next generation, say 30 - 50 years of supply, albeit with an uneven geographic distribution.  When I first became interested in wind and solar energy I simply wanted to know something about the energy resources of my back yard in the south of England.  This can be summarised as no potential for wind technology because my house is located in an suburban valley and sheltered from the prevailing wind, solar could make a contribution during the summer months, but not much during the winter.  Storage would help deal with the short term uncertainty of the weather, but not with seasonal variation.  As a result, I tend to favour buying energy from large scale sustainable sources rather than attempting to generate it myself.  This started me wondering about a framework for evaluating wind and solar energy.  Treat this post with caution, it evolved over a few cups of coffee and time spent looking at weather reports at  randomly selected locations around the world.

One starting point was climate and terrain (defined in such a way to include offshore areas).  I like to see the world in numbers like average wind speed, solar irradiance, the attenuating effect of clouds and likewise measures, but the potential for wind and solar devices in a given location can be felt on the face.  This might be summarised as "If you can wear a hat without fear of loss, it might not be a good place to put a wind turbine" and "If you don't need sunscreen, you might not need solar panels".

Economics has to be part of the scheme.  The volume of oil and gas reserves is related to price, if the price is low reserves which are in geologically complex areas or in harsh environments will not be economically recoverable, when the price rises, such reserves can be included in the resources available.  The same logic applies to sustainable resources, for example average wind speeds are higher offshore due in part to lower surface friction, but the cost of working offshore is significantly higher than onshore.  I am intrigued by the concept of airborne wind turbines which operate in the smooth air above the planetary boundary layer, but I guess the technology and economics are a challenge.  A similar logic can be applied to solar devices, the effects of seasonality can be offset by installing more panels, however, the system cost will increase.

Expectations affect how wind and solar systems are perceived.  I guess these can be summarised with three scenarios.  The first is grid-tied systems where wind an solar power is fed into the grid when it is available causing fossil fuel sources to be run down, when the wind stops blowing and clouds cover the sky, these are bought back on stream.  Off-grid systems rely sustainable sources, probably with storage and some form of fossil fuel backup.  It might seem a pointless distinction, but I would add "starting over" solutions as separate category.  I suggest that starting an energy economy from scratch might evolve some interesting solutions, possibly related to conservation, storage and management.  Along with expectation, goes realism, few people want wind powered railways and schools, hospitals and similar infrastructure need a lot or reliable power, but that still leaves a lot which could be configured not to.

Climate is largely determined by latitude and recorded in weather reports.  The Koppen schema has five top level categories and more than 20 sub categories, however, the relationship between sustainable energy sources and climate can be illustrated by just two diverse classifications.

Hot deserts (Koppen group B), e.g. parts of Arizona, which are within 30 degrees of the equator have relatively minor seasonal variation in clear sky solar irradiance, when clouds appear they are often high in the atmosphere and where they cause less attenuation than water laden low cloud.  Average non-storm wind speeds are relatively low.  This type of climate makes it possible, in conjunction with some storage capacity (if only because the sun does not shine at night) to maintain a more or less constant load from solar sources, onshore wind is less attractive.

Poleward of the hot deserts are the temperate maritime areas (Koppen group C).  Beyond 40 degrees of latitude, sun-earth geometry ensures that solar irradiance will be season, for example, in the south of England, the clear sky solar irradiance is something like 1 - 2 kwh/m2/day in winter and around 6 - 8 kwh/m2/day.  The clear sky irradiance is attenuated by clouds, in summer these are often intermittent layers of cumulus, in winter they can be dense stratus. which can reduce the solar irradiance to less than 1 kwh/m2/day.  Except for small loads, e.g. some traffic signs, off-grid solar systems are not viable in this climate.  In part, due to the proximity to the coast, average wind speeds on exposed locations such as ridges and hilltops can exceed 5 m/s.  Wind too is subject to seasonality it is stronger in winter when the dominant weather is fronts from the Atlantic, but even then, there can be intervals when the prevailing weather is high pressure over Europe resulting in still, clear air.  In general, wind becomes more reliable as an energy source with increasing latitude.

Wind Power - A view from 1910

I learned about "Windmills and wind motors" by F.E. Powell from a list of publications in an old magazine, the book was originally published in the US in 1910.  A scanned version is available in the internet archive of the American Libraries, a not-for-profit organisation to whom I would like to say thank you.  Increasingly, my reading material is coming from either the internet or car boot sales, I appreciate that my reading choices  are not constrained by the need to search for bits of paper, although that is something I enjoy doing.  A link to the book can be found at the end of this post.

Mr. Powell is an enthusiast for his subject, but unlike many enthusiasts for the technology, he understands that wind is a non-continuous form of energy which requires storage (banks of accumulators) in order to meet a continuous demand.  He is also quite restrained in his reference wind speed which is 16 miles per hour which is approximately 7 metres/second.  This amount of wind occurs frequently in many locations, this is in contrast to many modern wind turbines which are rated at 15 metres/second, a speed which occurs less frequently.  Chapter 6 is entitled "The production of electricity by wind power" and is a good discussion of the problems which need to be solved.  As the book was written well before the electronic age, control functions are implemented using mechanical or electro-mechanical devices which makes you appreciate the capability and availability of devices like mosfets, comparators and even computers.

The book appears to be intended for model or amateur engineers and as chapter 5 describes the construction of a machine with a rotor diameter of 10 feet (approx. 3 metres), fairly serious ones.  I admit to reading the descriptions of constructions fairly quickly, but I liked the method rotor hub construction in chapter 4 which consists almost entirely of wood and which could be made using only hand tools:

Many of the components do require access to a reasonably equipped workshop and an ability to use lathes and engage in pattern making.  This book was written at a time of rapid development of engineering and production processes and the artisan type skills needed would have been more widespread than they are today.  Model engineering magazines and related material turn up frequently at car boot sales.

I was originally drawn to this book in the search for technological history.  Wind power was a mainstream technology in the 19th century, although it was being challenged and displaced by steam towards the end.  wind was used for pumping water both for irrigation and drainage, grinding corn and working saw mills and sailing ships so there must have been a considerable knowledge of both the machinery and of wind as an energy source.  Wind powered electricity generation is clearly not a new idea and one which has been evolving for more than a century and that the Danish government was supporting research into the potential right at the start of the 20th century.

Link to scanned version of complete book:

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