Nathan James Van Gambling is a plumbing and heating engineer and lecturer who is also an expert in solar thermal heating systems and energy efficiency and indeed lectures regularly on the subject at industry events such as Low Carbon Homes, as well as producing podcasts. Nathan has a regular presence on Twitter (@betateach) where he discusses these subjects with other heating engineers and solar thermal experts, such as Rob Berridge (@HeatingConsult) and others in the heating industry. For anyone interested in how heating and hot water can be decarbonised and how buildings can be made more energy-efficient, this Twitter discourse surely has got to be a ‘must-read’.
In an in-depth and detailed conversation with Nathan, Robin Whitlock discussed the various benefits of solar thermal systems, how to make energy use and water heating more efficient and why plumbing and heating engineers should be listened to and consulted with far more than they actually are. If we are truly serious about decarbonising heating and hot water, engineers are right there on the ‘front line’, and they should really be brought into play more often.
In Part 1 of this interview, Nathan discussed the potential of solar thermal systems for decarbonising heating and hot water, why conventional gas heating is still very much the main focus within the heating industry, why plumbing and heating engineers on the ground are in a very good position from which to positively influence the transition to renewable heating technologies and the ease with which solar thermal systems and thermal stores could be installed in residential properties.
In Part 2, Nathan goes on to talk about thermal stores in greater detail with regard to how they work, with particular reference to Eric Hawkin’s design of thermal store, which he designed and installed himself and has been operating in his house for the past 19 years, about Eric’s invitation to the Climate Change Committee (CCC) and their enthusiasm for hydrogen. Nathan goes on to talk about how energy intensive heating water actually is and how solar thermal systems with thermal stores could benefit the world’s major coffee chains that currently rely on constantly boiling water in their barista machines.
In the first part of this interview, you mentioned thermal stores and in our conversations on Twitter, you referred to one such thermal store designed and installed by one of your colleagues, Eric Hawkins...
Yes. So I put in one of Eric’s prototypes, Eric’s been involved in the solar thermal industry longer than anyone in the UK. He’s lived out in China for five or six years and been all over the world studying this sort of technology. He’s very, very passionate and I’ll promote him to the end of my days. He’s started a kind of campaign for solar thermal and, basically, his thermal store is extremely simple. It literally is just a store. Everything is a direct connection, so when we say ‘direct’, you can buy a solar thermal ready cylinder, which basically has two coils in it. So if you imagine a cylinder and you cut it open, the water that’s inside that cylinder is the water you’re going to bath in. It’s what we call secondary water. It’s the water that’s coming out of the tap, that’s what’s stored in that cylinder.
You’ve got two coils in it. You’ve got a coil at the bottom, which is connected to your solar thermal, so any hot water that’s produced up on the roof runs around that coil and heats up the water inside the store. The top coil comes from the boiler and heats up the water and that’s the cylinder. Now don’t me wrong, that’s all well and good because it is still utilising some part of the sun’s energy, but a thermal store basically has direct connections – it has the coil connected to the mains water, but I’ll talk about that in a minute, but it’s just a big box of water and the water coming from the solar thermal panel on the roof is exactly the same water that’s in the store, your water that’s going around your radiators is exactly the same water that’s in the store, you might have a wood burner connected, so you can connect loads of heat sources to it. You can connect a heat pump to it, a boiler, a wood burner, so solar thermal at the moment does need another heat source and people say well you still need a gas boiler. Well yes, but I can turn my gas boiler off for 4-6 months of the year. If we had 23 million people in their houses doing that, you imagine the carbon savings! Astronomical. So it doesn’t make sense [the way we do things at the moment] and then they say, “well it’s expensive”, but there’s a payback here, the system I’ve got costs the customer under £3,000. Double-glazed windows take years to payback, and the customer never moans about them.
So with solar thermal, a house has got a system that produces free hot water in the summer and in the winter it contributes to the space heating as well, because you’re still getting energy from the sun even in the winter. In autumn, thermal stores love the sun’s energy because the sun is lower and so it seems to work quite well in autumn. So it’s completely free, but I suppose that’s what’s happening, people at the higher end of society around the world, are not going to be able to make money from it. We’ve got this ridiculous situation at the moment, where gas boilers are being pushed like mad.
I’ve mentioned this to the EUA. Condensing boilers, smart control, turn the thermostats down, la de da de da, but the seven super majors that are extracting gas out of our planet, in Texas for example, they extract so much gas, from fracking, they don’t know what to do with it. They haven’t got the infrastructure to get it round America quick enough, so they burn the surplus off and burning off every day, the equivalent of the amount of gas that would supply all Texas energy needs, every day [for further information about this, read this 13-page report by the Western Values Project for example]. So I asked some of the gas companies what’s going on with this, and the reply I got focused on various international agreements. I replied “do you really need them?”. These companies are located around the whole world, so on the one hand they are telling us to save energy, but on the other hand, in another country, there they are flaring it off every night. It just does not make sense. No logic in it whatsoever.
You mentioned on Twitter that Eric once invited the government’s Climate Change Committee (CCC) to view his thermal store...
Yes. So Eric has had his thermal system in his house for about 19 years I believe. He’s always made it available if anyone wants to come and see it, sort of like a showroom if you like. I’ve not yet actually gone to see it myself but I am aware that he always allows students to come and have a look at it. So on Twitter about six months ago, it was becoming quite evident that the CCC and the EUA were in discussion with each other on Twitter, over such things as gas boilers and hydrogen and so forth, and I made a comment asking why they don’t visit Eric’s house and see how his solar thermal works. I didn’t hear anything, but what I have heard is that someone’s gone over to Germany and looked at their hydrogen boilers or how they’re developing hydrogen boilers. The CCC don’t seem to be talking about solar thermal at all as far as I can see
[Note: this is not strictly true, please see note at the bottom of this article. Also, literally during the time taken to transcribe this interview, the CCC have graciously accepted Eric Hawkins invitation to inspect his thermal store system in his house and a visit is in the process of being arranged currently].
If you think about it, we have millions and millions of homes now in this country with solar PV panels, that produce a little bit of electric for themselves, which is fine, but a lot of the electric also goes back into the national grid, which the panel owners get a little bit of money for, but of course that is free energy which the grid gets to sell back to us. It’s a fantastic system yes, it’s saving carbon, but a certain amount of profit can be made from that, whereas with solar thermal there is no real profit, at all. Actually, I say that, I’ve always said to local people, and I am going to start nudging my local council on this, you can have a developer come in with say 30 houses with a little district heating system that’s completely working off PVT and thermal, with a great big thermal store that’s running the heat pumps, which are using electricity from the PV in a self-sufficient system, and you’ll get consumers that will move in to those houses, and they won’t mind paying the maintenance charge to the developer that built it. Some people can make money off it, developers could. Maybe it’s time to try and persuade developers to build these schemes with 30-50 houses, and like I say, consumers wouldn’t mind paying the maintenance charge, but essentially, solar thermal is an ‘off-grid’ technology.
You said that the CCC has been over in Germany looking at hydrogen, there seems to be a lot of people talking about hydrogen, and also biogas actually, what potential do those two have do you think?
Biogas is a no-brainer, so if you look at my local brewery, Adnams, and I spoke to the communications guy there about this not so long ago, Adnams is amazing for sustainability. They’ve got an anaerobic digester, so all the waste they produce gets digested down, it produces methane and then use the methane to practice their factories and whatever. However, you’re still burning methane and producing CO2.
[Note: for the environmental impacts of biogas from anaerobic digestion, see, for example, this paper but also see this analysis by biogen – “The methane-rich biogas produced by anaerobic digestion is captured for use in a combined heat and power (CHP) plants to produce electricity and heat. No methane is released to the atmosphere and carbon is saved through the displacement of energy from fossil fuels.”].
So that’s basically biogas, and you can have anaerobic digesters producing biogas and you can store it and transport it around, for example to rural areas that are on LPG or oil heating, and all these technologies you can use with solar panels, so you can have a biogas tank in your back garden, but for half of the year it’s not even going to be used, because you’ll be heating your home with solar thermal and in the winter, your biogas and your solar thermal complement each other to contribute to the space heating.
With hydrogen, that’s a different kettle of fish altogether. It’s being put on the pedestal by the boiler industry because it means they can still make boilers. It’s clean, because it doesn’t produce carbon dioxide, it produces water vapour. However, to get hydrogen, and of course we need lots and lots of it, and it would be quite an easy swap as you just need to change over a few bits and pieces to burn hydrogen, there are two ways of producing it. One of them is electrolysis [using renewable energy], which is good in the sense that you are not using methane. Although I am not an expert, as far as I know, they haven’t managed to solve this yet. It’s extremely expensive and it might even be energy intensive. The other way they are doing it is via steam methane reformation. So you get your methane, turn it into hydrogen, but of course you are left over with carbon dioxide.
What they’re talking about is using carbon, capture and storage (CCS). To me, that makes no sense, because you are actually creating another problem. You’re going to have all this mass of carbon and you’re going to be thinking about putting it into salt mines and underground, and it’s untested, there is not really a lot of research on it, but the research that does come about it will be carried out by the energy industry. That means it will generate a whole new industry. CCS will be a multi-billion dollar industry in its own right in the future. So they will still be selling gas, still selling boilers and will have created a new industry. At some point in the future, I can just see the headlines saying that we’ve now run out of methane, which we need to produce the hydrogen and that then generates a whole new fracking industry, so that makes no sense either. It’s a bit of a strange one. I think hydrogen could be the answer if it was produced using electrolysis, but it is definitely not the answer via steam methane reformation.
I want to amplify the voices of the engineers. Many of them are not even worried about climate change, but the good thing is that they are good at finding solutions. That is what they like doing. They are natural problem solvers, so it’s “what is going to make something more energy efficient, well it’s this, this and this”. They will go and work it out – with theory and practical application. The HHIC have seen how influential engineers have become by chatting on social media and so forth and so they started up something called Installers First, which is supposed to give the engineers a voice. There was then some discussion about heat pumps, and some people thought that heat pumps are new technology. I had to point out that heat pumps are not new. Most offices in London will have heat pumps. A lot of offices now will have something called split frame coils, so they will not only keep you cool in the summer, they will also push heat into the room during the winter.
Another interesting thing you mentioned is this whole thing about energy being wasted by the coffee houses, such as Starbucks and Costa and so on. Could you say a bit more about that?
That comes basically down to the fact that the way we live has changed drastically over the course of the past two generations. When I was young, me and my brother would come home and have a bath on a Saturday and flannel wash the rest of the week. But now some people are having several showers a day – a morning shower, then a shower after a gym session or something, and I also think we have a problem with the way we wash our hands. You have millions and millions of hot taps being turned on daily, every hour, just in the UK. There is absolutely no reason to use hot water on your hands whatsoever [interestingly, a 2005 study published in the Journal of Occupational and Environmental Medicine found that hot water has no clear benefits over cold water for removing germs] and in fact you would scald yourself if you tried.
Now in society, especially in western society, we are addicted to hot beverages. We drink 95 million cups of coffee per day in the UK, and 165 million cups of tea. A lot of them are drunk in these coffee shops. Coffee shops are amazing in one sense, we’ve had them since the 1600s with people gathering in them disseminating information, but we’ve now got to the stage where coffee houses everywhere are constantly boiling water. It’s a little different to a home, because you don’t have to worry about space heating, but you can easily just have a thermal store, containing just the water that is in your solar thermal panels, in the header, the tubes don’t now have water in them, on the roof and the thermal store is therefore constantly getting heated and the mains water that is going into the barista coffee machine, it goes into the thermal store through a coil, picking up the heat that is in that store and then going into the barista machine. Because the water is a very high specific heat capacity, even if you only raise the temperature by 10 degrees, you’ve made a massive change in how much energy you need for it to boil. If you imagine the hundreds of thousands of coffee shops all over Europe, if they were preheating their water with solar thermal, that would be a massive energy saving, and obviously also a massive saving in carbon emissions. Starbucks [and other coffee chains] would still make a huge profit.
Is anybody actually talking to the coffee industry about this?
As far as I am aware, only me via a few Tweets here and there. As far as I know, no-one is talking about it. It’s one of the biggest problems we’ve got, and people are not aware of it. Obviously people are very aware about their cars and the pollutants from them, but people are not aware of just how much energy it takes to heat up water, because we’re so used to heating it up now. We never used to be. With my Dad’s generation is was a pot on the stove and that was it really. Now, we just heat it up all the time.
There seems to be almost a culture change needed...
As I mentioned, I am optimistic because of young people, who I think hold the key in many ways, and I’ve worked with them in further education. I think the younger generation have a lot of power, that they probably don’t realise, especially with coding. You’ve got situations now in which young people are walking into banks and asking them what they invest in, and as soon as they hear the answers they are walking back out saying “Nah you’re not for me”, because they can command large sums of money. They have so much power, and so you usually find that young people are much more egalitarian, I think.
Individually, what can we do? That’s a tough one. You can’t really tell people to drink less coffee or not have a shower, so it has to be done in a lot more holistic way, but I am optimistic. A wild idea I had is that in the future, we could have smart clothing that is keeping your body warm, monitoring your body temperature and even monitoring room temperature. The only reason we heat buildings, apart from preventing them from going mouldy and ventilation, is to keep comfortable. We’ve done that for millennia by wearing other animals skins, that would keep the heat in. As I say, the heating industry is a very new industry. It was only in the 1950s that we adopted this concept of central heating.
[Note: When Nathan said during this interview that the CCC does not seem to be talking about solar thermal, it is indeed the case that there is not even one mention, anywhere, by the CCC in their Net Zero Report 2019.
Furthermore, it seems that the Solar Trade Association (STA) has had difficulty getting the CCC to consider solar as a whole, let alone thermal. In February 2014, this led to an official comment from the STA expressing surprise and concern at the CCC’s omission of solar technologies from their report on the UK housing stock. According to a spokesperson from the STA, via personal email communication, solar thermal has not enjoyed the prominence that other decentralised energy generating technologies have, partly because solar thermal is still considered expensive to deploy.
The STA has previously cited examples of successful schemes in its Leading Lights report and also devoted its entire Solar Thermal Now report to the subject two years ago. It also remains very enthusiastic about the technology and continues to investigate the technology in greater depth, particularly with regard to water intensive outputs such as breweries and swimming pools and also in relation to district heating schemes with the STA’s work in this area being led by its solar heat working group chaired by Dr Richard Hall.
When asked on Twitter about the CCC's apparent silence with regard to solar thermal, Chris Stark, the CCC’s Chief Exec, replied stating that the CCC has considered solar thermal but that it doesn’t feature strongly in it’s outlook for heat, mostly because the CCC considers the technology to be quite niche and on the grounds of cost.
Dr Richard Hall, of the previously mentioned STA solar heat working group, replied in this same Twitter conversation that: “A bit like wind and solar power, the costs of solar thermal comes down significantly when it is used at large-scales. Denmark is a great example where they have over 1GW of solar thermal connected to their heat networks”.
Chris Stark also responded that the CCC is tasked with finding good national strategies that are cost effective, which means that solar thermal doesn’t stand out as a major component.
However, some really good news is that Jenny Hill and other representatives from the CCC buildings team have accepted Eric Hawkins invitation to come and inspect his thermal store system and a visit is now being discussed currently.
This highly interesting debate about the potential role of solar thermal continues on Twitter for anyone who is keen to find out more about the subject.]