Peer-to-Peer Energy

This week my son came up with the observation that the world's biggest hotel company does not own any hotels and a company has launched a peer-to-peer delivery service.  In both cases, the common element is the software that links the service provided with the consumer.  The government also announced that it was withdrawing subsidies for new onshore wind farms.  Do these events have anything in common; probably not, but there maybe an idea which is worth exploring.

Subsidies is often difficult to discuss.  The concept is that a government provides an incentive to for someone to do something useful which would otherwise be uneconomic and recovers the cost from the tax payer or the consumer.  The downside of subsidies that they can become subject to the doctrine of unforeseen consequences which are painful to rectify.  An example is agricultural subsidies, after the second world war European governments wanted to stimulate food production and a system of subsidies evolved and people got fed but a few decades later, the system is producing "butter mountains" and "wine lakes" as supply and demand become unbalanced.  This leads to policy reform and farmers have to diversity and buildings that once sheltered cows become holiday homes for economists.  Maybe, a better designed policy could have given agriculture a smoother path.  We all eat, so why can farming be unprofitable.

Supporting sustainable energy is a good thing, part of the support is intended to increase the proportion of energy which is produced from sustainable resources, however, in the author's opinion, the object should be to lower total emissions.  To lower emissions you need a policy which encourages energy management and storage.  Wind energy comes in pulses a few days apart, these pulses are stronger in winter when the sun does not shine brightly and it does not shine at all at night.  My perception is that investment in sustainable sources is driven by the system of FITs and strike prices and that investments in sustainable generating capacity do not displace fossil/nuclear sources.  Incorporating a few kwh of storage into a household's energy economy could become a game changer.  Ignoring seasonal variations, the peak energy demand in most homes is morning and evening, in the morning people are showering and breakfasting and in the evening they are cooking and staring at screens, the peak of solar energy generation is at solar noon.  At present, most of this imbalance is mopped up by gas fired turbines.  The availability of solar power during the day allows them to be throttled back and powered up when the lights go on in the evening.  Maybe with a few kwh of storage per household, you can retire some existing fossil/nuclear capacity by storing wind and solar generated electricity when it is available.  I have not studied this in detail, but I think that it is only Germany which has some support for storage.  The shadow of subsidy cuts raises the fear of job losses in established industries which are painful, could a better policy created a more balanced industry.

Assumptions are always dangerous, but I need to make at least two.  My perception is that people fear rising bills and don't care too much where their energy comes from if their lifestyle remains unchanged.  Without being obsessive and using LED lights we have trimmed our electricity consumption by about 25%.  I am intrigued by the internet-of-things, I may be weird, but I am prepared to share the management of my fridge if I get to share the savings.  Add some storage and there are some interesting ideas to explore.

Roof-top PV is well established and there are a couple of reasonably sized wind turbines withing cycling distance of where I live.  One of these is owned by an opera house, this is not an obvious form of diversification but their land includes an ideal bit of Downland ridge.  Consumers and producers are linked by the grid creating at least a theoretical basis for peer-to-peer energy.  For the concept to work there has to be some economic realism, the price offered by the consumer has to make sense to the producer.  Ideally, green energy would have a premium which would offset subsidies.

Despite having spent much of my life writing software, I'm ashamed to say the my mobile phone skills are poor compared with those of my children.  They run whole chunks of their lives with their phones, objects for which there is only a transient need for are traded on eBay, cheap fares are found on off-peak trains and friendships are maintained across continents.  At present energy is not an obvious addition to this array, but................

London Filth

A year ago I knew little about Victorian rubbish, however, in the course of home renovation I've had some personal contact with it.  Coal was the dominant fuel of the Victorian period and the first part of the 20th century with millions of homes burning it, there was a lot of ash to get rid off, not to mention the manure from the horses which which provided the motive power for much local urban transport.  I've found ash mixed with mortar in walls, as a filler in retaining wall cavities and in the bricks used for internal walls.  So far, no horse dung, but I have found some wooden paving blocks which were intended to minimize the noise of horse's hooves.  I have attempted to recycle some old bricks and hardcore and become aware that there are people seeking out the sites of ash tips.  The most exotic thing I found in my personal stash of the stuff was a broken egg cup, but some people find the lure of finding bottles and pot lids too strong to resist.  Then my son turns up with a book entitled:  "Dirty Old London - The Victorian Fight Against Filth". by Lee Jackson.

This book is well researched but wears its scholarship lightly and is an entertaining story about something that you might not want to contemplate at bedtime.  I'm only a short way into the book, but I now have a better understanding of my own rubble.  Around the middle of the 19th century, there was something which, with some stretch of the imagination, be called a virtuous circle.  At the time London was growing and this growth created  a demand for bricks, this in turn created a demand for ash, thus for a time, household rubbish had some value and its collection could be self financing.  Ash was useful for two reasons, the first because it was cheaper than clay (I'm assuming this) and secondly because it contained some un-burnt fuel which assisted the firing process.  As a personal observation, bricks with a high ash content are generally poor quality and me one wonder about building standards at the time.  Horse dung could be sold to farms and market gardens.  At that time brick making and market gardening were local industries and transport costs would have been reasonable, as London expanded, this ceased to be the case and domestic rubbish became a problem for local government.  Some innovative councils came up with the idea of using domestic rubbish as fuel for electricity generation which was a growth industry in the latter part of the 19th century, this was a nice idea, but coal did the job better.  As an aside, I spent half of  one of my teenage years on floating school on the lower reaches of the Thames, each day,  barges owned by the London County Council passed by on their way to dump rubbish at some point far enough away that it would not be returned with the flood tide.

As part of what I loosely call my day job, I'm messing with a cloud sky model for solar irradiance, part of this involves making an estimate of what the solar irradiance would be if the sky was clear.  Clear sky irradiance is influenced by atmospheric conditions.  Two significant variables are the quantities of aerosols and water vapor in the atmosphere.  Aerosols are fine particles, some are the result of natural processes like sand been blown off deserts in the dry summers and volcanic activity and some are due to human activity such as burning fossil fuels.  A gross over simplification would be, that all else being equal, you feel warmer/hotter under a dry, clean sky than under a dirty damp one.  Whilst attempting to understand some of variance between datasets, I downloaded some material from the NASA Earth Observatory (NEO) and plotted it on Google Earth.  The NEO is a wonderful resource for learning about the environment, it is a good combination of data, explanation and guidance for research.

Treat this plot of Aerosol Optical Depth for June 2011 with caution, the shading scheme is somewhat arbitrary and chosen to accentuate difference within a small sub-set of the data, my code could be buggy and human life is finite.

The aerosol content is higher in the dark squares than in the light ones and London stands out as a high spot.  This plot was an distraction from task in hand, but like the pot lid hunters I could not resist poking around.  In some way, it is a continuation of the story of urban filth.

You would not start form here

There is an international joke which goes something like this: "A sharp dressed man on a horse or car asks a farmer for directions to the big city who replies 'You wouldn't start from here'".  Much the same applies to a sustainable energy economy.

A street gas light (from somewhere posh?)

I recently came across a copy of "Everybody's Pocket Encyclopedia" dated 1891.   Somethings never change and others become irrelevant.  The list of 47 celebrities includes Prince Bismark who unified a number of German states into a single country and gave his name to at least one battleship.  Further down the pages is the actress Lilly Langtry who would have been a gift to today's Celeb magazines.  In the same spirit is a table of the  probability of a woman marrying at a given age and her weight for her height, evidently no such data was available for men.  In contrast there is a somewhat confusing method for estimating sidereal time and local time from longitude which implies the book was carried by people crossing continents (A lot of my family went west to America and East to Australia in the early part of the 20th century).  I'm guessing, but today few people are interested in the correct way to address a bishop.

At the end of the 19th century electricity was coming into general use but gas was a common fuel for lighting and coal provided warmth and the power for industry and transport.  The Encyclopedia's list of economic events is a bit patchy on electricity, for instance there is no reference to Nikola Tesla (who among other things developed the transformer) or to Charles Parson (steam turbines were a good way to turn generators).  However, the it has a few milestones for gas lighting:

• 1780 - The invention of the Argand Burner in Geneva
• 1786 - Lebon's Gas light invented
• 1792 - Murdoch's Gas Lighting Trial
• 1804 - Windor's Gas Patent
• 1807 - Clegg's Gas Works built
• 1813 - Westminster Bridge lit by Gas
• 1815 - Clegg;s Gas meter invented
• 1860 - Hugon's Gas Patent (Gas engine)

These events describe the production, use and commercialization of gas as a fuel.   From 1850, references to electricity become more frequent.  Whilst the displacement of gas lighting started in the latter years of the 19th century, the process did not approach completion until the 1920s, a span of approximately one generation.

There are plenty of fossils from the age of gas.  My own house has the remains of a network of gas pipes which supplied light fittings and geysers.  All this was installed before the advent of "Part P" regulations and some of the notches in the joists are well positioned.  Skips are a good source of social history, when a Victorian property is "gutted" gas pipes are often part of debris.

Edwardian fossils: The wall has a blanked off pipe showing the location of a gas lamp and the grate was part of the house's zoned heating system.

And my point is.....

The acceptance of a "new" technology which does not have to displace an old one, such as mobile phones, can be quite rapid, however, displacement can be a slower process.  In my view, the key technologies for the large scale adoption of sustainable energy sources are storage and management.  This includes devices such as the Tesla "PowerWall" and the internet of things both of which are recent innovations.  Utility scale wind turbines started appearing in the 1980's, solar PV became a mass market technology after 2000.  The table above spans a period of 80 years, these things take time, but if you were starting from scratch......

A very short social history of plumbing

Also, a personal and possibly inaccurate one.  I started last week hunched up over a toilet with my head between the rafters and ended it sitting on the toilet staring at a pressure gauge.  In the intervening week I had seen a century of plumbing and possibly social history.  The renovation of my house has got to the point where some plumbing needs to be dealt with before I can move on.

Lead Piping

The house was built in 1901, at that time a plumber earned about £2 per week or £100 per year and a "professional" e.g. doctor, vicar or solicitor might have received £400 per year.  This is a ratio of 4:1.  Today, plumbers are professionals and the equivalent ratio is 1:1 or less.  Assuming the relative cost of  materials to be the same, the proportion of a job represented by labor has increased.  I dredged these figures from some long forgotten book, so this theory hangs by a very slender thread.

Iron pipe blocked with rust and limescale

When the house was built all the things that used water were clustered together, albeit over two floors.  The piping was lead, bits of it are still embedded in the plaster.  I have never worked with lead but I'm guessing that it's a difficult material.  Whilst it is soft and malleable, it is thick walled and some form of bending tool would be needed to get it round corners and because it is heavy it may have taken two men to install, one to hold it in position and the other to fasten it.  Jointing would require some skill, too much heat from a blow lamp and the stuff would melt or collapse.  I have welded thin sheet metal and know the frustration of letting the work get too hot and watching a hole appear and then grow large.  So I'm guessing that plumbing in 1901 was slow, heavy and skilled work.

A screwed-up fragment of the Daily Mirror from 1949 with the remains of a Jane cartoon strip

Sometime around 1949, an attempt was made to replace some of the lead plumbing with iron piping.  I found a fragment of a "Jane" cartoon from the Daily Mirror dated 1949 which was probably associated with the installation of back boiler in what was then the kitchen.  From 1932 to 1959, Jane was forever saving the nation and losing her clothes with equal frequency, when I worked in a factory in the 1970s old men remembered her with affection/lust.  Iron is not an ideal material for a domestic hot water system, if for no other reason than it rusts. by 1980, much of this pipework was blocked with limescale and rust.  Unlike lead piping which could be bent into position, iron has to be got round corners with threaded elbows.  This required different skills from those needed for lead.  The pipe had to be cut with a hack saw, then each end of the pipe had to be threaded.  Yet again, I'm guessing, but it was probably the apprentice who did the cutting.  A few times in my life I have had to cut up bar stock for some reason or another and I know it to be hard, dull work.  The man who installed the iron pipe was highly skilled as he got it round brickwork and joists in a way that would be hard to do with copper.  It took me a week to remove this pipework.  I used a hole saw to get out the "hidden" lengths which could not be reached with a hack saw, the trick was to drill the pilot hole through the pipe, then use this to guide a hole saw which was half an inch larger than the pipe.

By 1980, the plumbing consisted of lead piping with repairs for frost damage and blocked iron pipe.  The owner decided that enough was enough and had the house re-plumbed with copper pipes.  This would have been a big job and one which I think was "done to a price".  The best routes had been taken by the iron pipes and it was probably cheaper put in 20 metres of copper pipe to take bath water a distance of 7 metres.  The boiler heated the hot water using a gravity feed system which was none to efficient, but all this was better than the original installation.    I have spectacularly made a mess of plumbing using copper pipe, my biggest mistake being not to practice soldering before I started the main job.  These days before I tackle anything big, I find something small to practice on which will either tell me I'm incompetent or teach me how to do it.  With the forgoing caveat, copper piping is reasonably easy to work with, it cuts easily, the fittings are not expensive and solder joints can be made quickly.  As a novice, I tend to use "Yorkshire" fittings which are more expensive than "end feed" but only require even heating with a gas torch.  No one seems to be using lead or iron pipe any more.

Copper pipe with insulation

My skills not being adequate to run copper along the path used by the iron pipe, I investigated "plastic" plumbing.  What limited experience and training I have is with metal, but I was told by several merchants, that this stuff is the future and it was only the "old" blokes that won't use it, so I decided to give it a go.  It's more expensive than copper, but allowing for the need for supports every half metre or less, it is very quick to work with and has a 50 year guarantee (I am an  "old bloke", so I may not be able validate that).  I would not have pressure tested a copper pipe, but I did with the plastic and it held 20 psi for 15 minutes, what pressure drop there was, was probably due to the attachment of the pressure gauge which might have been a bit flaky.  The job was more like running cables than plumbing.  This takes me back to my starting point, if labour is expensive, then productivity becomes important and this seems to be the driving force behind the enthusiasm for plastic plumbing.

Plastic plumbing (before making good the plaster)

At the time of writing, I have yet to connect the pipework to tanks and taps, what I'm hoping for is a much lower heat loss as the water moves from the hot water cylinder to the taps.

Images added after original post

This lead tee join supplied the bathroom with water from the main

Small Things

Some time back a journalist friend got to visit a nuclear facility, he not only came back with some good stories but got to wear a hard hat.  For whatever reason, for the past couple of years I've become my own builder and have been renovating my house.  The project has got to the stage where not much more can be done until the plumbing has been dealt with.

It seems that the current system is at least the third version.  The house was build in 1901 with an

extensive network of gas pipes which supplied mantles around the house and geysers in the bathroom and scullery.  A geyser is not a bad solution to the hot water problem, it heats water where it is going to be used, thus if you want 20 liters of bathwater, that's all you pay for.  I suspect that the original device discharged it's combustion products into the bathroom as there is not evidence of a vent to the outside world.    The current concern would be risk of carbon monoxide poisoning but the original inhabitants probably appreciated a warm bathroom.

Around 1950 someone thought that central heating was worth a try.  I'm guessing that the original solid fuel range was replaced by some coal burning object.  The geyser was dispensed with and bathroom was supplied with hot water from a tank in the kitchen via iron pipes.  If this arrangement bought any benefits they were short lived because rust and calcium deposits soon obstructed the flow of hot bath water.  Whilst the choice of pipe material was less than ideal (was there an alternative at the time?), it was installed with great skill along the shortest possible route.

By 1980, the house must have been inhabited by cold, unwashed people.  Someone decided enough was enough and installed a gas fired central heating system with copper pipes.  At that time energy was cheap and labor expensive.  The logical pipe routes were taken up by thick iron pipes, the alternative route from boiler to bathroom required a run of 50 meters of 3/4 inch pipe. which required approximately 15 liters to fill.  To get enough warm water to fill the basin for a shave or make-up removal resulted in running about 25 liters of hot water.  The hot water cylinder has a capacity of 100 liters and is heated by a 20 kw gas boiler (approx. cost: £2000) .  To summarize, the most energy efficient/environmental friendly way of shaving or doing the washing up is to boil a kettle (approx. cost: £20).

The big project is to reduce the pipe run from 50 meters to 10 meters.  Will it make a big difference?  Probably not but it will make a small one, both gas and water consumption should be reduced, maybe by 3 - 5 kwh/day and 25 liters/day respectively.  However, scale these saving up to a million homes (the UK has more than 20 million of them) and the reduction might be significant.  A plant producing 5,000,000 kwh is the type of place where you have to wear a hard hat.

Taking the temperature

In recent years I have become interested in the relationship between weather data and the potential output of wind and solar devices.  Today there are a variety of reporting mechanisms which provide regular and reliable data including automated weather stations, offshore buoys, satellites and the internet of things to which many small weather stations are connected.  All this stuff gets dumped into databases and is an incredible resource.

In the early seventies I had a brief career as a merchant seaman, by general agreement, this was not a good choice and a decade later I was working as a computer programmer where I was only a minor hazard to those around me.   However, the experience did give me an appreciation of conditions offshore where the wind can be smooth and steady and then become violent in a storm.  Offshore installations have to be built to withstand extreme conditions,

One of the more agreeable jobs on the morning eight to twelve watch was taking the sea temperature before the weather report was sent (in morse code) just before noon.  An alternative was chipping and scraping which was not agreeable.  This task was not without risk.  The ship was moving at around 14 knots and the drill was to throw a bucket on the end of a line ahead of the ship where with luck it might end up just below where you were standing and then haul it back onboard and poke it with a thermometer.  If you were not quick, the bucket went aft and became a small sea anchor.  The biggest risk was losing the bucket in which case one would have to explain to the bosun the loss a valuable item of equipment and request/steal a replacement.  A related problem was staying calm whilst spectators expected you to loose the bucket.   It was good practice to tie the shipboard end of the line to a railing, this cut down the loss of buckets but at the risk of getting fingers trapped between rope and railing.  In a calm sea it was not too difficult to stay dry, but if the ship was rolling and the bucket was full on arrival, there was a chance of a wet boiler suit.

I think that current practice for measuring sea water temperature is to have a sensor on a cooling water intake which takes the fun out the process at the expense of better data.  If the weather conditions where such that risk of bucket loss was high, then no data was collected.

This experience taught me to be both respectful and cautious of environmental data

Clear Sky Fraction

I live in a temperate maritime climate (i.e. the south coast of England) where clouds in various forms are frequently present in the sky.  Some simple experiments using a very small solar panel suggested that clouds have a significant effect on the performance of solar devices.  On a clear summer day, the global horizontal irradiance (GHI) at noon can be close to 1000 watts/ms, a few days later when the sky is overcast this can fall to less than 200 watts/m2.  In winter, the higher frequency of occurrence of clouds further increases the overall attenuating effect.  Also, the nature of the irradiance changes, under a clear sky the diffuse fraction might be around 15% with, under an overcast cloud sky, the diffuse fraction rises to 100% and there is no direct beam irradiance.  I wanted to quantify the attenuating effect of clouds one possibility is a statistic called the clear sky fraction (CSF).

This work has not been reviewed and should be treated with caution.

CSF is defined as the ratio of observed GHI under a cloud sky, to the estimated GHI under a clear sky (i.e.if the clouds were not present in the sky).

Unlike wind whose velocity can be more-or-less over several hours, solar irradiance is constantly changing, it is close to zero at sunrise and sunset and at a maximum around solar noon.  This makes it desirable to use a ratio which is independent of Sun-Earth geometry. The principal input for models of solar irradiance is air mass (AM) which is a ratio describing the amount of atmosphere the Sun's rays most pass before reaching the Earth's surface.  At solar noon close to the equator, the value of air mass is close to 1, whilst it is approximately 15 around sunrise and sunset in the temperate latitudes during the summer.  Based on observations in the south east of england, the author suggests that the "economic" range of air mass values is in the range 1 to 6.  At an air mass values of 6, the zenith angle is approx. 75 degrees (corresponding to an altitude of 15 degrees).  Depending on the terrain, when the sun is low in the sky, the shadow of hills, trees, buildings etc. effect the irradiance up a flat surface.  Experience suggests that within the range 1 to 6, CSF is more of less independent of air mass.

Horizontal irradiance was chosen because of the importance of diffuse irradiance under a cloud sky. Under a thick overcast sky there is no direct beam element to the irradiance which is all diffuse and is evenly distributed around the hemisphere of the sky.  Whilst it would be more convenient to consider a sloping surface (which is the normal way of mounding most solar devices), this would not account

 for all the diffuse irradiance.  Also, GHI is the most commonly collected form of solar irradiance data.

A problem in calculating CSF is the choice of method for estimating the clear sky irradiance.  There are two options.  The simplest is to use some form of model, many of these use atmospheric data such as water column and aerosol optical density and if this data is available, are capable of producing good estimates of direct and diffuse irradiance, the downside of these models is that detailed atmospheric data may not be available for the location where the observations are being made.  An alternative is to use observations of clear sky irradiance at the chosen location and the correlate thises with air mass.  Either approach has a degree of uncertainty associated with it.  not least of which is that whilst the reflection and absorption of clouds will be the dominant atmospheric effect, others such as moisture content will also have an impact.

I am currently messing with cloud sky models of irradiance which are based on CSF.