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More Climate Communications

August 2, 2022

Friends, I have been out again in search of inspiration for how to encourage changes that will reduce carbon dioxide emissions.

In this article I am just noting down things that happened and reflecting on the interactions. It seems that there is widespread ignorance and misunderstanding of Climate Change coupled with bewilderment about what will actually make a difference.

These notes are for two quite contrasting days. As usual, a solid 99% of people just passed by. Of those who stopped, there was quite a bit of positivity, but also some bizarrely misinformed opinions.

I am still learning…

Thursday, July 28.

10:58 Set up outside CarpetRIght in Teddington.

11:05 John stopped by with many positive ideas. He suggested I put posters in the library and in the local community noticeboard on Broad Street which I could access through the library. He suggested my board should show the savings to be gleaned from using low carbon energy, such as solar power. John lived locally and his street had a WhatsApp group that could share information. It made me think that maybe the ‘Neighbourhood’ app might be useful.

11:12 When John walked back the other way he held up his fist and said “Viva La Revolution

11:23 A mother and her two children (a boy aged 12 and a girl aged 9) stopped by. She was very supportive but the children were obviously disinterested. I asked her what things I could do to communicate better, and she suggested my box should have more colour on it. The children then suggested there should be graphics showing a healthy earth and a poorly earth. The boy suggested I should use Instagram. The mother said they were going with the children to Bordeaux in France next week, and that they would see some of the evidence of wildfires. 

11:34 Three teenagers walked by and waved. But didn’t stop to talk

11:35 A lady caught my eye and said she was in a rush for work, but wished me good luck.

11:38 Man on a bright yellow Suzuki motorbike stopped at the traffic lights, and caught my eye. He nodded.

11:45 A regular at the Sidra café where I have my morning coffee stopped by. I said I was just trying to find out what people thought, and get out of my Twitter bubble. He told me that “almost everyone will agree with me, but that almost no one knew what to do“. I said that seemed a succinct précis of what people had said

11:48 A gentleman, quite elderly, with a straw hat stopped by and asked me “What’s going on with all this weather then? Are we going to get more of it?”. I said we probably were going to get more of it, one or two days like that every year and then slowly becoming more common. I asked him if he thought there was anything we could do about it, and he told me it was “...all those gases going up in the atmosphere“, a phrase he repeated several times. As he left he said “We’ll just have to see what happens then…“.

11:54 A lady called who works in the theology department at the local University stopped by. “Air-conditioning on the buses and trains” she said “that’s the solution“. She said she was out on the 40 °C day, and that the solution was to wear damp T-shirts and trousers. I suggested that some people might think it immodest for ladies to wear a wet T-shirt but she was unabashed.

12:10 An elegantly-dressed lady pushing her mother in a wheelchair stopped by. She said it wasn’t a popular thing to say but she wasn’t sure that it wasn’t the best thing for people to just destroy themselves, leaving just a few small tribes on Earth, and then people would be forced to live sustainably.

She said that what people want is to know what is the right thing, but something which will influence others. We discussed the idea of a Personal Carbon budget. For example, people could have a lifetime budget of 100 tons of carbon emissions by flying, which they could then sell, or buy from other people. She seemed to like this idea.

Her mother intervened to say that when she was younger, flying was very expensive and so people went by boat, and she had come to England from Canada on a freighter which had just a few cabins for passengers. “Flying was very expensive. Slower is better.” she said.

The lady thought that “Human beings will pay if they have too. Raising the price of things will eliminate frivolous use of things e.g., weekend trips”.

She said that  People are creative” and told me that in Lebanon people had rigged up makeshift solar systems with batteries to get by when there was no mains electricity and that people there cooked collectively. She said this was also done in Morocco and Algeria. 

She told me to look out for the ”The Boy Who Harnessed The Wind” a Netflix film about renewable energy in Africa

12:22 A lady carrying her lunch back to her office spoke as she passed, saying “Thank you for doing this.”, although I am not sure she knew what I was doing!

12:24 A gentleman passing by didn’t stop but looked at me, and raised his eyebrows and said “Alright!”

12:29 Colleagues from NPL passed by, and one person told me that his wife’s sister’s husband (!) had asked them if they had heard about this “Protons for Breakfast” site. So it does seem that news is travelling.

12:42 An ex-colleague from NPL stopped by. He was working on life-cycle impact assessments, and said he had done did a life-cycle assessment of the Audi E Tron (an EV) and that it was worse than petrol cars because of the massive embodied energy in the battery.

12:52 A lady was walking slowly past with a stick. I caught her eye and commented that it was warm now. She nodded and said “As long as it doesn’t get too warm…

12:58 A man who worked at a local e-bike shop stopped and suggested I should get a giant banner and block the entire road. He said he had heard that the materials mined for batteries involved child labour. I told him I was pretty sure that involved the cobalt and not the lithium and that modern batteries use no cobalt or nickel. 

13:00 An expert in Climate Change science and an ex-colleague from NPL stopped by – remember this is Teddington!. She told me she’d read a book of random facts about climate change, but had had to stop because it was too depressing.

13:15 A lady passed by without stopping but said she had had lots of conversations about climate change with friends. I told her to keep talking.

13:17. E-bike man passed  by again having bought his lunch, and he said that he had seen an article on associated press that morning about fugitive methane

13:26. Stopped

Tuesday, August 2nd.

11:03 I ventured away from Teddington to nearby Hampton Hill and set up outside a parade of shops near a local Tesco.

11:25 Interesting interaction with two air-conditioning servicing engineers who had just emerged from Tesco with their lunch.

The younger one engaged me and said “We’re part of the problem mate”. he said, “We’re 7% of emissions.”.  I said he was also part of the solution. We’re all going to need air-conditioning in the future, and installing heat pumps is going to be a big business. He acknowledged that, but said that the refrigerant was harmful, and the less harmful it was, the worse it was as a refrigerant.

Then his older and fatter colleague came out. He said “I’m not going to get drawn into this because we’ll end up having an argument.” And then he got drawn into it. He said there may be some emissions he said, but there is also a natural cycle. I told him that actually it’s all human emissions.

He then went on about ice ages, and the massive emissions in the Victorian era when there was no global warming. I told him emissions in the Victorian era were low: around 1 billion tonnes of CO2 per year and that now emissions are 36 billion tonnes per year.

He then went on to say “Anyway it’s not us, 72% of emissions come from China”. I pointed out that it wasn’t that high and that the US and China pollute similarly. He wandered off saying “I knew we’d have an argument.”

After that interaction, two people at the bus stop spoke to me and said “Sorry you had to have that, he was like that in Tesco!”. Then they said “Good luck!”

11:35 A man about 60 years of age with long hair approached me and asked me what I was an expert in. I said I was an expert in measurements of temperature and explained how I had made the most accurate temperature measurements ever made. He said he had studied particle physics so I included some slightly more technical details. He told me he was in the film and graphics business but didn’t do much these days, just built websites.

I asked him his take on the climate crisis and he said he wasn’t concerned. He said global warming was 0.2°C, and that NASA had edited the data for specific years. I told him that wasn’t true but he insisted and named the individual years in question. Then he had to get on the bus   

11:41 A young man with a ponytail and some over-ear headphones nodded to me. Then an elderly man with smart grey hair and wearing cool summer shorts said good morning. 

11:51 A black man stopped by and said “He didn’t know what to say because things may get political”. He said first he was from Africa and then changed his mind – he sounded very English to me, like he came from Henley or similar – but he did trade with Africa. He said that the UK was exporting polluting old cars to Africa. I said that was shameful and then I asked what he thought we should do about the climate crisis. 

He said that heating has always been terrible in the UK, and that when he was a child (he said he was 61) he would go out to the library to get warm during the day, and when he was at home they would wear cardigans and pullovers. Now he said his children want to wash a T-shirt then put it in the dryer so they can wear that same day. He thought the price rises that are happening at the moment, although they were very hard on people, might help people value energy more.

He said he couldn’t understand how people in Africa, Nigeria in particular were still using diesel generators so much, when Solar is so cheap. Then he had to go and catch a bus. 

11:59  An elderly man called stopped by, he said it was really warming up. I said yes, but that you had to be something like our age to understand just how different the climate was now to how it was when we were young. He said the government needed to sort it out, and I said I didn’t think the government would be able to sort out their own bedroom, and he laughed and agreed.

I asked him what he thought could be done. He asked me “What could we do?” And I told him that our house in Teddington had been off-grid for a quarter of a year. I said there were things that people could do, but it would take the people who had the money to do them first. He said he was really impressed by news of my house and he would tell his friends. As he left he said good luck to me.

12:35 A lady was just waiting for a bus, but caught my eye and said she hoped I was getting lots of interest. I said I”n fact No, most people just didn’t want to think about it” She said that she had just joined Extinction Rebellion and was waiting to go on the first training course.

13:00  After 25 minutes with no interactions I thought it was time to call it a day.

Domestic Thermal Storage 3: Concrete

July 23, 2022

Friends, this is the third and final article comparing different types of thermal storage.

In previous articles I looked at the humble domestic hot water (DHW) cylinder and the use of a phase-change materials (PCMs) to store heat.

In this article I will look at the use of ‘very big lumps of something very hot‘ as a thermal store.

This brute force technology is implemented in a so-called Zero Emission Boiler (ZEB) from the Tepeo company, and in a behemoth of a storage device akin to a miniature version of the ‘Sand Battery’ that got me started on this, the Warmstone store from the Caldera company.

Zero Emission Boiler (ZEB)

A ZEB thermal store is a device about the size of washing machine that is conceived as replacement for a gas boiler in settings where a heat pump cannot be installed.

It is generally placed wherever the gas boiler was, but being essentially a large lump of concrete, it is extremely heavy – 370 kg – and must be placed only on the ground floor of a house.

Click on the image for a larger version. A ZEB thermal store in an extraordinarily uncluttered kitchen as pictured on the Tepeo website.

The difference between a ZEB and the other thermal storage devices I have described is in the amount of energy which can be stored – a ZEB can store 40 kWh of thermal energy – around 5 times more than a typical DHW cylinder. This is enough thermal energy to not just provide hot water to a house (typically 5 to 10 kWh/day) but also to heat an entire home via its central heating system.

One can imagine a ZEB as being a centralised version of old-fashioned electrical storage heaters. It stores thermal energy by electrically heating a block of ‘high-density concrete’ to an astonishing 800 °C.

At these high temperatures, heat loss is significant, but my estimates suggest that ~150 mm of insulation around a 40 cm cubical block, should limit heat losses to ~ 5.6 kWh/day or around 14%/day.

Extracting thermal energy from a ZEB at 800 °C into water flowing at (say) 50 °C is tricky. Slightly to my surprise, energy cannot be extracted rapidly enough for this to instantly heat water and so it cannot be used to replace a combination boiler. It must still be used with a DHW cylinder as an intermediate store of hot water. However it seems likely to me that Tepeo will solve this problem in the next few years.

Below is a YouTube video  in which Robert Llewelyn discusses the ZEB he has had installed in his own home.


A Warmstone thermal store is something like a miniature version of the ‘Sand Battery‘ that claimed to store heat inter-seasonally. But instead of storing 8 MWh like the ‘sand battery’ – it stores ‘only’ 0.1 MWh or 100 kWh.

It achieves this large capacity by heating a large mass of material – probably concrete of some description – to 500 °C. But it uses vacuum installation to reduce the heat losses to just 4.8 kWh/day – or 5% per day – half the fractional losses of a DHW cylinder or PCM material.

Unsurprisingly the device is large and heavy, weighing 1.8 tonnes and standing 1.8 metres tall with a diameter of 1 metre, so this too large for it to pretend to be a domestic installation. The company imagine it being used in large homes which have outhouses or large gardens.


In the first article I looked at thermal storage in a DHW cylinder. This is the default thermal storage that many people still have in their homes – holding about 8 kWh of thermal energy.

In the second article I looked at Sunamp’s PCM storage which can operate in practice like a DHW cylinder – but is typically less than half the physical size while storing similar amounts of thermal energy.

In this last article I looked at two companies looking to ‘go large’ and store one to two days use of thermal energy for a home. To achieve this they have used large masses of stored material electrically-heated to high temperatures. Surprisingly, despite the large masses and high temperatures, the rate at which water can be heated by these devices is still (currently) limited and so they must both still be used with a DHW cylinder.

All the technologies beyond the basic DHW cylinder all feature computer technology which allows Apps to control the storage and allow integration with smart home controllers – something which is apparently very important, but is an area in which I have absolutely no interest: sorry.

What I learned in writing these articles is the very simple lesson that there is no magic to thermal storage technology. There are no magic materials and there is no magical insulation. To store more energy one simply needs a large mass of material, heated to a high temperature, and kept as well insulated as possible.

Summer Solstice 2022: Solar PV update

June 21, 2022

The Summer Solstice seems like a good a time to take a look at the first half-year of generation from our 12 solar panels and the effect of our Tesla Powerwall battery.

Last year at around this time I wrote that – having been off-grid for 90 days – I felt like I was ‘floating’.  And then just a couple of days later I came back down to Earth after several consecutive days of unseasonably dull weather led to me have to buy some full-price electricity! In mid-summer!

This year we have been off-grid for only 50 days so far and I will discuss the reason for the difference below.

In case you don’t have time to read the article, it’s performing pretty much as expected and very similarly to last year.

Let’s begin.

Solar Generation.

One of the difficulties in communicating data from a solar PV system is its variability. The data obviously change seasonally, but also on daily, weekly and monthly time scales. So I have chosen to present the same data in several ways.

Let’s start with a basic chart showing the average daily generation (in kWh) over the last two years.

Click image for a larger version. Average daily solar generation (kWh) for each month of this year and last year.

This chart shows that generation this year is generally a little better than last year, with the exception of last May, which was enchantingly sunny.

Now let’s look at the daily data, and different averages.

Click image for a larger version: you’ll need to do this to see anything! This chart shows the daily generation this year, and the 5-day running average  of generation this year and last year. See the text for details of the other data on the graph.

The graph above is complicated, showing how various quantities (expressed as kWh/day) change versus day of the year.

Primarily it shows daily solar generation as a light green line. Notice the day-to-day variation: even in June, daily generation can fall to 3.8 kW/day even when the average generation is ~15 kWh/day.

Also shown are the 5-day averages of solar generation this year and last year. The 5-day average shows the smoothing effect of the use of a 13.5 kWh battery. When the 5-day average falls below demand, then it’s likely we will need to buy some electricity from the grid. You can see that this happened in mid-summer last year.

Notice that the 5-day averages show peaks and troughs that can last for weeks.

My expectations for the system are shown as a dotted green line (just a simple mathematical guess)  and as yellow monthly data points estimated using a multi-year European database. Generation is broadly in line with expectations.

The graph also shows nominal household demand as two red-dotted lines.

  • The horizontal line (10 kWh/day) corresponds to daily demand throughout the year.
  • The demand peaking in winter represents the electricity used by the heat pump to heat the house. This demand has only been present this winter – previously, heating was supplied by a gas boiler.

So the generation has interesting day-to-day variability, but when the 5-day average exceeds the average demand, then with the aid of the battery, we stand a good chance of being able to be off-grid for a sustained period.

Looking at the graph, the heating demand was still non-zero in April – and this delayed the point at which we were able to go off-grid.

The graph below shows actual (rather than nominal)  domestic use of electricity and the electricity drawn from the grid.

Click image for a larger version: This chart shows the ±7-day averages of the electricity we use in the house for heating and the electricity we draw from the grid. The difference between the two curves is supplied by the solar PV/battery system. Periods when the house has been off-grid are highlighted in red.

Another way of looking at the data.

Plotting day-to-day generation tends to emphasise the variability of the data.

Plotting cumulative generation through the year tends to de-emphasise the variability and highlight the similarity of generation from one year to the next.

The graphs below show cumulative generation versus day-of-the-year for this year and last year. The upper graph shows the whole year and the lower graph the first half of the year only.

Also shown as dotted lines are the MCS suggestion for likely annual generation and an empirical curve based on the MCS figures that I use to guide my expectations.

Click image for a larger version: This chart shows the cumulative generation this year and last year. See the text for details of the other data on the graph. Broadly speaking, the data are very similar.

Click image for a larger version: This chart shows the cumulative generation for the first 6-months of  this year and last year. See the text for details of the other data on the graph. Broadly speaking, the data are very similar. The very dull period in midsummer last June can be seen as a flat portion on the 2021 generation curve.

Remember that year-to-year variability in generation is typically ±5% (link), so that yearly variations of ~200 kWh on an expected generation of 3,780 kWh is quite normal.


Overall, everything is proceeding as expected. The combination of 12 x 340 Watt Q-Cells panels and the 13.5 kWh Tesla Powerwall battery has been astonishing.

  • We save money in summer – because we are off-grid.
  • We save money in spring and autumn because solar PV is still significant.
  • We save money in winter because we can buy cheap-rate electricity and use it during the day.

The reality of running the house – with fridges and freezers and computers and washing machines and air-conditioning and even tumble dryers – solely from the sunshine for several months a year, still warms my heart.

Another reason to stop using gas

March 6, 2022

Friends, many people are considering reducing, or stopping entirely, their use of natural gas for heating and cooking. Perhaps you are one of these people.

It may be that your motivation is because burning this gas is altering the climate of our planet.

Or may be that your motivation is because buying the gas supports murderous and megalomaniacal regimes across the plant.

But perhaps these motivation aren’t quite enough. If so, then please consider this:

  • Cooking with gas is poisoning you and your family

Yes, cooking with gas emits nitrogen oxide (NO) and nitric oxide (NO2) into your kitchen. Collectively these gases are known NOx.

When NOx reaches the membranes of your skin or nose, it quickly forms nitric acid, which irritates the membranes and can cause asthma and sensitise people to other allergens.

If you are concerned about air pollution in cities, then before worrying about vehicle emissions, you should probably first focus your attention on your own home where NOx levels are likely to be very much higher.

Let me explain

Air consists of very roughly 80% nitrogen (N2) and 20% oxygen (O2).

When burning natural gas, methane (CH4), in air, the majority of the combustion products (water (H2O) and carbon dioxide (CO2)) arise from reactions between methane and oxygen.

The nitrogen molecules – despite making up the bulk of the air – are relatively inert. But they are not completely inert.

At the high temperatures – approaching 2000 °C – of a methane flame, the nitrogen and oxygen molecules dissociate into atomic nitrogen and oxygen and in this state they react to form oxides of nitrogen, primarily NO.

This NO then converts to NO2 over a time frame that depends on what else is in the atmosphere. Thus even when the amount of NOx is constant, the fractions of NO and NO2 are likely to change over time.

When methane combustion takes place in a boiler, none of the combustion products enter your home.

But when you cook with gas, the combustion products are all vented directly into your home. Including the NO and NO2 i.e indoor NOx pollution.

Is this really a problem?

I don’t know for sure, but I suspect it must be.

Whereas professional kitchens frequently have strong extraction over open burners and ovens, domestic kitchens often do not. And where extraction is present, it is often not used, and when it is used, it only covers burners and not ovens.

Concentrations of NOx are difficult to measure for several reasons.

Firstly a meter to measure NO2 costs thousands of pounds versus a hundred pounds or so for a CO2 meter, and so there are very few reported measurements in kitchens.

And secondly, the ratio of NO to NO2 is generally not well-known in any particular circumstance.

Consequently using measurements of NO2 to estimate NOx will always give an underestimate of the NOx level.

One measurement in kitchens is in this article.  It shows measurements of NO2 during an evening of cooking in one US household. I have reproduced the figure below.

Click on figure for a larger version. While cooking with gas in this US household, NO2 levels rose to almost 300 ppb. This figure is modified from the linked article.

In the UK exposure limits for NO2 are an annual average exposure to 40 μg/m^3 with less than 18 exposures per year to peaks above 200 μg/m^3 averaged over 1 hour.

So it looks like the occupants of this household are being exposed to very high levels of NO2. But the  NO levels close to the cooker are likely to be even higher.

My Measurements and Calculations

I wondered if the measurements above were plausible. The peak did not have the shape I would have expected: it seems to fall very rapidly suggesting there was strong airflow through the house.

Unfortunately, I can’t measure NO or NO2 directly but I routinely monitor CO2 in the central part of the house, well away from the oven and hob. Nonetheless I regularly see the CO2 levels rise to over 1000 ppm during cooking. For this article I also took measurements with the detector at roughly head height next to the hob.

Click on figure for a larger version. The location of the CO2 meter relative to the hob for the  measurements in red in the graph below.

The graph below shows the CO2 data.

  • For the detector near the hob, the burner was on for 15 minutes and the CO2 levels rose immediately.
  • For the detector in the neighbouring room, the burner was on for 17 minutes and there was a delay of many minutes before CO2 levels began to rise.

Click on figure for a larger version. The rise in carbon dioxide concentration above background resulting from a single gas burner on teh hob. The measurements in black were measured several metres away in a different room. The measurements in red were measure at head height above the hob..

What is clear from both these measurements is that CO2 concentrations of at least 500 ppm above background are likely to be commonplace in all the rooms in homes which use gas hobs, ovens or grills.

I wondered if the ratio of production of NO to CO2 might occur at a fixed ratio. If so, that would allow me to use measurements of CO2 concentration to estimate likely levels of NO.

I wasn’t quite sure how to do this but an old friend suggested using the free and excellent GasEq software to calculate the likely combustion products and their relative concentrations.

Using the methane combustion in air example, I calculated the ratio of the NO in the exhaust gases to CO2. Then from measuring the CO2 rise due to combustion, I could estimate the NO concentration in the house.

Click on figure for a larger version. Logarithmic graph showing estimates of the NO concentration in parts per billion (ppm) assuming 500 ppm CO2 concentration from combustion and 400 ppm CO2 background concentration i.e. a measured CO2 concentration of around 900 ppm. See text for further details.

At first I was shocked. The calculation suggested that NO levels of several thousand ppm were likely. But this was based on two assumptions: that the gas flame was adiabatic and stoichiometric. What wonderful words.

  • Adiabatic means that no heat is lost from the flame and so the products would be at their maximum possible temperature, approximately 2225 K. However in a domestic gas burner, heat will be lost to both the burner itself, and saucepans which typically only reach 250 °C. So I repeated the calculation for lower temperatures.
  • Stoichiometric means that exactly the right amount of oxygen was mixed with the methane so that all of the methane and oxygen reacted.
    • If the gas mixture has excess methane (a so-called fuel-rich mixture) then less oxygen will be available to react with the nitrogen, and NO production will be reduced.
    • Similarly If the gas mixture does not quite enough methane (a so-called fuel-lean mixture) then some un-reacted oxygen will be available to react with the nitrogen, and NO production will be increased.

So I repeated calculations for a range of stoichimetries (±5% and ±10% from ideal) and a range of temperatures, extending down to more than 200 °C below the adiabatic flame temperature.

My conclusion from this calculation is that even with very conservative assumptions, when CO2 levels from combustion rise 500 ppm above background, the levels of NO in the air is likely to be several hundred ppb. Eventually some fraction of this NO will convert to NO2 and yield NO2 levels well-above safe exposure levels.

Of course without direct measurements, I don’t know this for sure, but I am surprised that this issue is not discussed more.


My conclusion is simple. Based on measurements of CO2 concentration in my own home, and calculations of the likely ratio of NO to CO2, I think that NOx exposure in UK households with open gas hobs, ovens, and grills is likely to routinely exceed exposure guidelines.

For people standing over a hob, or people routinely working in a domestic kitchen, exposure levels could easily be dramatically higher.

If anyone has problems with asthma or is concerned about their own – or their children’s exposure to air pollution – then it is likely that the best thing people can do is to stop using gas for cooking, and to instead use microwaves, electric ovens and induction hobs.

This archaic ‘burning’ technology is funding Putin’s war machine, changing the Earth’s climate. AND polluting my home!

Personally, I just can’t wait to get rid of this gas hob as soon as possible.

Talk on 2nd February in Twickenham

January 31, 2022

Friends, if you live in West London, and have nothing better to do on Wednesday 2nd February at 7:30 p.m., then you might like to consider coming to hear me talk.

I’ll be talking about the steps I have taken to reduce household carbon dioxide emissions, and suggesting first steps that anyone interested might take.

The talk is in a room above a pub in Twickenham (Google Maps Link)

The Royal Oak,
13, Richmond Road,
TW1 3AB.

This is located opposite a Shell Petrol Station and York House.

I have been trying very hard to keep the talk as short as possible to allow more time for… talking i.e. actual conversations.


If you would like to come along, please e-mail the Richmond and Twickenham Friends of the Earth at


If you aren’t able to come, but have a question which you would like answered, please just drop me a line at .


Happy Christmas and Best Wishes for 2022

December 18, 2021

Click image for a larger version

Friends, it’s the end of the year and there is still so much to write about. But for the next couple of weeks, it won’t be me doing the writing.

I feel the need for a break and so I will be hunkering down in Podesta Towers and dreaming of spring sunshine on my solar panels.

My aim is to stay warm, catch up on some other projects, and try to avoid catching Omicron!

I wish you all the best for the Christmas Season and a splendidly low-carbon 2022.

Journey from the Centre of the Sun

August 15, 2021

Click image for a larger version. Some of the stages in the energy conversions and transfers that allows me to have hot water in the mornings without any carbon dioxide emissions. Simple heh?

Friends, just the other day I wrote about how my heat pump produced hot water each day.

The way in which the heat pump extracts heat from the air is ingenious in the extreme.

But as I reflected on it, I realised that this ingenuity occurred in the middle of a long series of energy transformations taking – very roughly – 170,000 years.

Please allow me to explain.

#1 Where does the energy come from?

The source of nearly* all the energy humans exploit on Earth is sunlight.

Using sunlight and carbon dioxide plants produce oxygen (thank you) and carbohydrates. This so-called ‘photosynthesis‘ captures energy from the sunlight in the form of re-arranged chemical bonds within carbohydrate molecules.

When we use animals for work – horsepower and ox-power – the energy the animals use is derived from the carbohydrate molecules in their food.

When we burn plants – primarily wood – for heat, the energy released is from the reverse of the reaction that created the carbohydrate molecules. And so, the carbon dioxide which was captured when the plant grew, is released. But since burned wood is generally only a few decades old – burning plants can be (almost) neutral in the production of carbon dioxide.

Fossil fuels are all derived from plants, and the energy of the captured sunlight has been ‘distilled’ over thousands of years by a variety of physical processes into coal, oil and gas. Unfortunately, burning fossil fuels also releases carbon dioxide, but not carbon dioxide that was recently captured. It releases carbon dioxide that was captured eons ago.

Burning fossil fuels is still the main way in which we make electricity – so electrical energy is in some sense the energy of ancient sunlight. How charming.

#2 Where does the energy of sunlight come from?

That the Sun is hot has been obvious to all humans since the dawn of time.

But the source of its immense heat was a mystery until just about 100 years ago when it was suggested that hydrogen nuclei (a.k.a. protons) might ‘fuse’ together to make helium nuclei, and release energy.

Segueing past a few decades of research and speculation, we now know for sure that nuclear fusion deep within the Sun is indeed the source of the energy that makes the Sun hot.

The environment deep within the Sun is extraordinary, with a temperature of roughly 15 million degrees Celsius.

The hot dense gas emits electromagnetic radiation – γ-rays, X-rays, ultra violet and visible light – in all directions. The nuclei and electrons in the Sun are a plasma – which is opaque to radiation. So the radiation is constantly absorbed, causing local heating, and then being re-emitted by the nuclei and electrons in the various layers of the Sun.

Because the Sun is so vast and so opaque – it takes roughly 170,000 years for the energy to travel from the core of the Sun to the surface of the Sun. Just so you know it was not a typo: I did indeed say 170,000 years.

Eventually the energy reaches the outer layers of the Sun which are at a tepid 5,500 °C (ish). The glow of this hot plasma sends visible light out in all directions and after roughly 8 minutes, a tiny fraction of it reaches Earth.

#3 My hot water: a summary

Click image for a larger version. Some of the stages in the energy conversions and transfers that allows me to have hot water in the mornings without any carbon dioxide emissions. Simple heh?

So where does the energy that heats my hot water come from? The letters in the bullet points below refer to the diagram above.

  • Nuclear fusion (A) around 170,000 years ago created energy from the fusion of hydrogen nuclei that were themselves created in the primordial ‘big bang’.
  • This energy travelled through the Sun’s layers as a variety of forms of electromagnetic radiation – γ-rays, X-rays, ultra violet and visible light – until it reached the outer layers when the radiation could travel uninterrupted into space (A, B).
  • A tiny tiny fraction of this radiation was intercepted by solar panels on my roof, which converted some of the visible light into an electrical current (B, C, D).
  • This electrical energy was stored in a battery by electrically forcing ions of lithium metal (shown in the figure as red dots) to cluster together against their desire to diffuse away from one another (E).
  • This energy was then released at night by allowing ions of lithium metal to diffuse away from one another (F), forcing electrons around an external inverter circuit that created AC currents to power a motor in a compressor (G) and electronics which ran the heat pump.
  • The heat pump then chilled a refrigerant (G) that extracted heat from molecules in the air that had also been heated by sunlight over the preceding few days.
  • This energy was transferred as heat to water flowing in a circuit through the heat pump (G).
  • And then this energy was further transferred as heat to fresh water in a hot water tank (H).

And then finally (I) a few hours later, this energy was transferred to the outer layers in my face and hands where transient receptor proteins in thermoreceptors in my skin sent signals to my brain that caused me to realise the water coming from the tap into the sink was ‘just right’.

Simple heh?

* Nearly?

Humans do exploit one source of energy which did not originate in the fusion of nuclei within the Sun: nuclear power.

Nuclear power exploits energy released by splitting the nuclei of heavy atoms that were created – as I understand it – during the last few destructive moments of a previous generation of stars.

These elements – uranium primarily – were then deposited on the primordial Earth as it formed at the same time as the Sun was ‘born’.


COVID 19: What have we learned? Nothing.

June 4, 2021

Click for a larger image. Logarithmic graph showing positive cases, hospital admissions and deaths since the start of the pandemic. The blue arrows show the dates of ‘opening’ events. See text for further details. The red dotted line shows cases doubling every 15 days as they did in September 2020.

Friends, so here we are, 4th June 2021, and I am reluctantly concluding that – as they did last summer – the government are about to screw things up.

The graph at the head of the page shows casesadmissions and deaths throughout the pandemic.

The situation now is strikingly similar to July last year, except that the growth rate of cases is more similar to September last year.

The statistics for admissions and deaths represent ‘ground truth’ – but when the situation is changing rapidly they lag the spread of the virus by several weeks

So to assess the spread we should look at cases. And with the best part of 1 million tests a day, mostly in asymptomatic people, we should have a reasonably good track on what is happening.

In my previous blog (s), I suggested we should not care about:

  • the absolute number of cases,
  • the population prevalence of cases,
  • or even the rate of change of cases.

What mattered was:

  • Is there the potential for the pandemic to expand into the general population and kill hundreds of thousands of people?

Last summer the answer was definitely ‘Yes’.

This summer I previously thought the answer was probably ‘No’.

Now I think that in fact the virus has run away from us – spreading through schools – and has the potential to reach to the general unvaccinated population.

And although it I don’t think it can kill ‘hundreds of thousands’, it could easily kill ‘thousands‘ and cause serious illness in many more.


First of all, please let me me warn you about statistics which state the fraction of the ‘adult’ population which have been vaccinated. Adulthood is not relevant.

It seems that unvaccinated and previously uninfected people can catch COVID and spread it, no matter how young, even if their symptoms are not strong.

As I write: 59% of the entire population, including practically all of the most vulnerable groups have received a first dose of the vaccine. Vaccination is reaching an additional 8% of the population per month.

Together with the 10% – 20% (roughly) of the population who have had the disease, we are close to herd immunity. This would be relevant if the virus were spreading randomly through the population. But it isn’t.

The virus appears to be spreading amongst exactly the fraction of the population who have not been vaccinated. This is an inevitable consequence of our choice to vaccinate the elderly first. And as social restrictions have eased, viral spread is barely hindered by social distancing.

There are three problems with this.

#1: More Death 

If we consider the population of people who could be infected to be the roughly 20 million people under 30: then with a fatality ratio of 0.01% this corresponds to a summer with a further 2000 dead people under 30. If we are lucky the number might be only a few hundred.

To me, these wholly preventable deaths seem like those who died in WW1 after the armistice: more tragic somehow than the previous 129,000 deaths.

This does not take account of the fact that vaccinated people are not invulnerable – merely less vulnerable.

#2: More Illness

Without further interventions, the current case rate appears to be growing at the same rate it did in schools last September. Cases are doubling roughly every 15 days. By the end of June they will exceed 10,000 per day and approach 40,000 per day at the end of the school term.

Aside from the deaths, this corresponds to a lot more illness – some of it chronic ‘Long COVID’.

#3: Rolling the variant dice

The larger the pool of infected people, the more chance the virus has to mutate and find variants which might escape the vaccine, or – heaven forbid – take a more dangerous form.

As far as I understand, nobody knows why elderly people are more vulnerable to COVID-19. But imagine a hypothetical COVID-21 which was more deadly to children? Is that an experiment we really want to conduct?


The latest outbreaks have not been contained locally– yet another failure of Track, Trace, and Isolate.

The vaccination program means that unlike last summer, we are unlikely to face a wave of a further 80,000 dead people.

But I am expecting a further wave of wholly unnecessary deaths – I just don’t know how large a wave to expect.

I did write out a list of recommendations for what we should do about this situation. But having edited it, and reflected on it, I realised that the recommendations were all obvious, but that writing them down was pointless, because the Government just doesn’t care!

Stay safe.




The Cat Sat on the Mat

March 14, 2021

While walking though Teddington the other day I saw tender sight which brought a smile to my eyes.

A man was mending his very old car – an Austin Maxi – and had tools and components laid out around the car.

And just by the car was a small mat on which his cat was very contentedly sat.

I commented to him that it was very considerate of him to put down a mat for the cat.

He smiled.

Then he told me that the mat was there to cover a drain so that he didn’t accidentally lose any parts. And the cat was sitting there opportunistically rather than by invitation.


Correlation does not imply causation

It had seemed so obvious that the man had placed the mat down for the cat. I had immediately intuited his state of mind and fondness for his cat.

In order to have fully appreciated what was happening, I would have needed to:

  • Imagine into being a drain – for which I had no evidence – it was completely covered.
  • And then understand that it would be sensible to cover the drain if working near it – a mat would be ideal.
  • And finally understand that cats will sit on mats unbidden.

And so I was reminded that even the simplest and most apparently obvious things are sometimes not what they seem.


See also these links suggested by astute commenter Dave Burton

In the bleak midwinter

January 19, 2021

So here we are in the bleak mid-winter – the place that everyone with External Wall Insulation loves to be.

As I remain-at-home-to-protect-the-NHS-and-save-lives I have spent a great deal of time staring at the following graph which shows the impact of the triple-glazing and External Wall Insulation.

Click for a larger vsrsion. Plotted in blue against the left-hand axis, the average daily consumption of gas (kWh per day) This is shown against the left-hand axis. Plotted in green against the right -hand axis is the average difference of the outside temperature from 19 °C (°C).

The graph shows two quantities plotted versus the number of days since the start of 2019.

  • In blue, I have plotted the average daily consumption of gas (kWh per day)
    • This is shown against the left-hand axis
  • In green, I have plotted the average difference of the outside temperature from 19 °C (°C)
    • This is shown against the right-hand axis

The dotted red line shows the weather now (circled in green) is colder than it was at this time two years ago.

However the amount of gas (circled in blue) that I am using to maintain the temperature of the house is now about half what was then: just over 50 kWh per day now versus just over 100 kWh per day then.

The carbon dioxide emissions associated with heating the house look set to be about 1.25 tonnes this winter – still a terrible figure – but much lower than 3 tonnes emitted in the winter of 2018/2019.

To go further we need to ditch the gas boiler and switch to a heat pump. Hopefully we will achieve this in the summer and then we can reasonably hope that next winter we will lower the carbon dioxide emissions associated with heating the house to about 0.4 tonnes – just 13% of what it was in 2018/2019.



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