The Death Of Fossil Fuels

[IvanV]

Did you type all that but miss the point that the user wants heat, not electricity? They're not dumb enough to store electricity as heat, turn heat to electricity and then use that electricity to heat.

I made the mistake of assuming that if you are storing heat to use later, you use waste heat to heat it up, not high grade power like electricity. So that means your output heat is always lower than your process heat. The reason for discounting that is because heating up a heat store with electricity seems to be a ridiculously expensive thing to do. And that is clearly what the subsequent discussion has also tended to assume.

But I see the point of the device is for those specific applications that need high grade heat, and so are going to have to use electricity (or hydrogen) to create, once fossil fuel isn't allowed. So an efficient high temperature heat store allows them to generate that heat in advance when the electricity is cheap, the wind is blowing, the sun is shining. So this is a specific niche product for heat-using industrial processes to retime their electricity-to-heat activities to times when electricity is cheap.

So this is a niche product for industry, and thus quite different from the generality of hot rocks storage for general energy storage.

The advantage of having fluids to store heat rather than bricks is that you can have preheat stages where you make use of some of the waste heat coming out of the process. That's why molten salt tends to be the heat store medium of choice, as it can be a fluid in a suitable range of temperatures for a multistage heating up.

[dyqik]

Using the waste heat from high temperature industrial processes for lower temperature processes (including office heating and the like) is an option that would yield net energy savings for the whole plant.

Given the cost of high temperature processes and plants, I'd expect that to either be already in place, or to be expanded really soon, independent of the high temperature heat source, as it's just good economics.

Anyway, I have to go back to trying to keep my receiver systems cold now. My major issue is dumping the 10kW of 35°C heat from our refrigerators at 13,800 ft in very dry 15°C air, in a way that fits under our antennas.

[lpm]

But I see the point of the device is for those specific applications that need high grade heat, and so are going to have to use electricity (or hydrogen) to create, once fossil fuel isn't allowed. So an efficient high temperature heat store allows them to generate that heat in advance when the electricity is cheap, the wind is blowing, the sun is shining. So this is a specific niche product for heat-using industrial processes to retime their electricity-to-heat activities to times when electricity is cheap.

Good on you for figuring it out from first principles, but you could have just read the twitter thread that explained it?

On the more general point, people who've ditched gas and have HPs already use bricks as thermal storage, using either cheap overnight electricity or daytime solar. It's not complicated. Having more thermal mass means cheaper bills. But not at all sure of the CO2 cost-benefit - the CO2 cost of a concrete slab with underfloor heating vs the CO2 saved when importing from the grid.

[Gfamily]

Using the waste heat from high temperature industrial processes for lower temperature processes (including office heating and the like) is an option that would yield net energy savings for the whole plant.

Given the cost of high temperature processes and plants, I'd expect that to either be already in place, or to be expanded really soon, independent of the high temperature heat source, as it's just good economics.

A problem is that high temperature processes are usually conducted (hah!) at some distance from where the waste heat could actually be of use. A couple of decades ago, there were plans for our local coal powered power station to be retrofitted to provide warm water for greenhouses and fish ponds, but the move away from coal means it's basically decommissioned now.

[dyqik]

But I see the point of the device is for those specific applications that need high grade heat, and so are going to have to use electricity (or hydrogen) to create, once fossil fuel isn't allowed. So an efficient high temperature heat store allows them to generate that heat in advance when the electricity is cheap, the wind is blowing, the sun is shining. So this is a specific niche product for heat-using industrial processes to retime their electricity-to-heat activities to times when electricity is cheap.

Good on you for figuring it out from first principles, but you could have just read the twitter thread that explained it?

On the more general point, people who've ditched gas and have HPs already use bricks as thermal storage, using either cheap overnight electricity or daytime solar. It's not complicated. Having more thermal mass means cheaper bills. But not at all sure of the CO2 cost-benefit - the CO2 cost of a concrete slab with underfloor heating vs the CO2 saved when importing from the grid.

That very much depends on the lifetime of the concrete slab. If it's good for a century, then it's probably a win. Also if it includes a significant amount of rubble in the fill under it, which is essentially recycling old concrete/brick.

[lpm]

But I see the point of the device is for those specific applications that need high grade heat, and so are going to have to use electricity (or hydrogen) to create, once fossil fuel isn't allowed. So an efficient high temperature heat store allows them to generate that heat in advance when the electricity is cheap, the wind is blowing, the sun is shining. So this is a specific niche product for heat-using industrial processes to retime their electricity-to-heat activities to times when electricity is cheap.

Good on you for figuring it out from first principles, but you could have just read the twitter thread that explained it?

On the more general point, people who've ditched gas and have HPs already use bricks as thermal storage, using either cheap overnight electricity or daytime solar. It's not complicated. Having more thermal mass means cheaper bills. But not at all sure of the CO2 cost-benefit - the CO2 cost of a concrete slab with underfloor heating vs the CO2 saved when importing from the grid.

That very much depends on the lifetime of the concrete slab. If it's good for a century, then it's probably a win. Also if it includes a significant amount of rubble in the fill under it, which is essentially recycling old concrete/brick.

But we need to get out of the habit of looking at a 100 years. Heating homes will be zero CO2 in 20.

For example insulation stops having a CO2 reduction purpose. Instead it takes on a storage purpose.

Weird stuff happens when electricity is 100%+ fossil free. We have to switch our thinking. For example, using extra electricity to target CO2 elsewhere, such as in reducing concrete/brick manufacture by lowering insulation/storage levels.

[shpalman]

Using the waste heat from high temperature industrial processes for lower temperature processes (including office heating and the like) is an option that would yield net energy savings for the whole plant.

For example, at the massive Ratcliffe-on-Soar coal-fired power station where some solar panels were installed to "help heat and light the admin block"?

[IvanV]

But I see the point of the device is for those specific applications that need high grade heat, and so are going to have to use electricity (or hydrogen) to create, once fossil fuel isn't allowed. So an efficient high temperature heat store allows them to generate that heat in advance when the electricity is cheap, the wind is blowing, the sun is shining. So this is a specific niche product for heat-using industrial processes to retime their electricity-to-heat activities to times when electricity is cheap.

Good on you for figuring it out from first principles, but you could have just read the twitter thread that explained it?

I had my bovine excrement detector set excessively sensitively for the first read, and needed to return and read it more carefully. We still need always to analyse such things against what we know, because there have been so many proposals in this area that, in the end, just didn't stack up.

[IvanV]

On the more general point, people who've ditched gas and have HPs already use bricks as thermal storage, using either cheap overnight electricity or daytime solar. It's not complicated. Having more thermal mass means cheaper bills. But not at all sure of the CO2 cost-benefit - the CO2 cost of a concrete slab with underfloor heating vs the CO2 saved when importing from the grid.

Electrical storage heating is not something that should be promoted as a main method of heating, even with cheap overnight electricity, given present costs and methods of generating electricity.

But if you have a heat pump, then it makes some sense to create some thermal inertia.

If renewable electricity becomes exceedingly cheap, then things do indeed change. It is not implausible that solar PV can become very cheap, but far from clear it will do or over what timescale. Then electrical storage heating may indeed be more practical, though probably not much help during the dimmest days of the winter. It's not very plausible that wind power will get that cheap.

[Grumble]

As EVM points out in this video (which is about the costs of running a heat pump in winter), why would he use direct heating of water via an immersion heater when he has a heat pump right there? Heating water via a heat pump is less efficient than using it for heating a house, but it’s still about 200% efficient, whereas an immersion heater can never be more than 100%.
Heat pumps can be used for industrial heat, it might make sense to dump excess energy into a heat store (via a heat pump) then use that to feed a second heat pump at another time.
I’ve not listened to the Volts episode yet, just chiming in from the sidelines.

[lpm]

On the more general point, people who've ditched gas and have HPs already use bricks as thermal storage, using either cheap overnight electricity or daytime solar. It's not complicated. Having more thermal mass means cheaper bills. But not at all sure of the CO2 cost-benefit - the CO2 cost of a concrete slab with underfloor heating vs the CO2 saved when importing from the grid.

Electrical storage heating is not something that should be promoted as a main method of heating, even with cheap overnight electricity, given present costs and methods of generating electricity.

But if you have a heat pump, then it makes some sense to create some thermal inertia.

If renewable electricity becomes exceedingly cheap, then things do indeed change. It is not implausible that solar PV can become very cheap, but far from clear it will do or over what timescale. Then electrical storage heating may indeed be more practical, though probably not much help during the dimmest days of the winter. It's not very plausible that wind power will get that cheap.

You're not quite getting it, because you keep using present tense. "Given present costs and methods" is the wrong place to start. As a result you are continually talking about different things to the rest of us.

We know how to make loads of CO2-free electricity, the remaining problem is how to store surpluses to cover ordinary lulls and super lulls. The point is that things have dual purpose, so using them in dual ways. Bricks make walls, they also store electricity. Water washes humans, also stores electricity. Cars take us from A to B, also store electricity. It's not all about paying for batteries in the grid and compressed air and hydrogen, when we already own things and can use them.

There are people who already have the nearly full set (EV + solar + home battery + hot water cylinder + heat pump + other generation assets, don't yet have EV back to the grid as that's not ready yet). They are showing how it will work. In 2023. There's no need for speculation because they are solving the equations with simple white board calcs. It's a simple extrapolation of what EVM is doing now to what we'll all do in 2033 or 2043. There's a bunch of YouTuber's like him showing their maths and experimenting with when they fill the battery, and if they use HP or an Eddi to heat water from PV, and what time in the morning their storage runs out on cold days requiring grid import, and what curves and set backs optimise HPs.

And above all they've got surplus solar in summer - thanks to trying to cover as much winter HP use as possible - so are trying to manage poor export prices against home/car usage.

[lpm]

As EVM points out in this video (which is about the costs of running a heat pump in winter), why would he use direct heating of water via an immersion heater when he has a heat pump right there? Heating water via a heat pump is less efficient than using it for heating a house, but it’s still about 200% efficient, whereas an immersion heater can never be more than 100%.

I did the maths and decided not to bother with HP for hot water, just went straight to immersion. Mainly because I won't get a HP for 2-5 years, once the gas boiler needs replacing and hopefully there are more (and better) installers. It's only averaging 5.4 kWh per day, which is 65p. Halving that cost with a HP would only save £118 pa, and the individual circumstances of my house meant no chance of payback from a complex install. Plus I now have the option of A2A solutions which could be a significantly cheaper install.

EVM is fine-tuning rather than shifting the dial, because for most of the year he will be exporting solar at low rates and halving the solar usage won't be more than a few pence saving a day. Efficiency disappears as a concern during solar surplus, i.e. most months of the year, which is hard to intuitively grasp during our current 2023 obsession with efficiency.

[dyqik]

On the more general point, people who've ditched gas and have HPs already use bricks as thermal storage, using either cheap overnight electricity or daytime solar. It's not complicated. Having more thermal mass means cheaper bills. But not at all sure of the CO2 cost-benefit - the CO2 cost of a concrete slab with underfloor heating vs the CO2 saved when importing from the grid.

Electrical storage heating is not something that should be promoted as a main method of heating, even with cheap overnight electricity, given present costs and methods of generating electricity.

But if you have a heat pump, then it makes some sense to create some thermal inertia.

If renewable electricity becomes exceedingly cheap, then things do indeed change. It is not implausible that solar PV can become very cheap, but far from clear it will do or over what timescale. Then electrical storage heating may indeed be more practical, though probably not much help during the dimmest days of the winter. It's not very plausible that wind power will get that cheap.

You're not quite getting it, because you keep using present tense. "Given present costs and methods" is the wrong place to start. As a result you are continually talking about different things to the rest of us.

We know how to make loads of CO2-free electricity, the remaining problem is how to store surpluses to cover ordinary lulls and super lulls. The point is that things have dual purpose, so using them in dual ways. Bricks make walls, they also store electricity. Water washes humans, also stores electricity. Cars take us from A to B, also store electricity. It's not all about paying for batteries in the grid and compressed air and hydrogen, when we already own things and can use them.

There are people who already have the nearly full set (EV + solar + home battery + hot water cylinder + heat pump + other generation assets, don't yet have EV back to the grid as that's not ready yet). They are showing how it will work. In 2023. There's no need for speculation because they are solving the equations with simple white board calcs. It's a simple extrapolation of what EVM is doing now to what we'll all do in 2033 or 2043. There's a bunch of YouTuber's like him showing their maths and experimenting with when they fill the battery, and if they use HP or an Eddi to heat water from PV, and what time in the morning their storage runs out on cold days requiring grid import, and what curves and set backs optimise HPs.

And above all they've got surplus solar in summer - thanks to trying to cover as much winter HP use as possible - so are trying to manage poor export prices against home/car usage.

One thing to add is that a lot of the optimization going on now is basically hacking the price structures that are currently in place with most people not doing that.

Those price structures will change over time, but some elements of then are fixed - e.g. higher solar output in the day, higher heating and electric usage during daylight and evening hours.

[IvanV]

You're not quite getting it, because you keep using present tense. "Given present costs and methods" is the wrong place to start. As a result you are continually talking about different things to the rest of us.

We know how to make loads of CO2-free electricity, the remaining problem is how to store surpluses to cover ordinary lulls and super lulls. The point is that things have dual purpose, so using them in dual ways. Bricks make walls, they also store electricity. Water washes humans, also stores electricity. Cars take us from A to B, also store electricity. It's not all about paying for batteries in the grid and compressed air and hydrogen, when we already own things and can use them.

There are people who already have the nearly full set (EV + solar + home battery + hot water cylinder + heat pump + other generation assets, don't yet have EV back to the grid as that's not ready yet). They are showing how it will work. In 2023. There's no need for speculation because they are solving the equations with simple white board calcs. It's a simple extrapolation of what EVM is doing now to what we'll all do in 2033 or 2043. There's a bunch of YouTuber's like him showing their maths and experimenting with when they fill the battery, and if they use HP or an Eddi to heat water from PV, and what time in the morning their storage runs out on cold days requiring grid import, and what curves and set backs optimise HPs.

And above all they've got surplus solar in summer - thanks to trying to cover as much winter HP use as possible - so are trying to manage poor export prices against home/car usage.

What I am particularly concerned to avoid is working with costs and methods that are implausible, and also distinguish the possible from the likely with those that are not implausible. The key question is, what are things likely to cost? What it costs now, what we can do now, is at least a starting point to ground that. It will be cheaper, but how much cheaper? What can we reasonably expect to be able to do? That has huge effect on what is an efficient strategy.

The present government has devised its strategies with the assumption that various things will exist at large scale before long - carbon capture and storage, large scale use of hydrogen - but it is increasingly clear they will not. That's the kind of mistake you risk making if you fail to ground things in realistic costs and methods.

We know how to make loads of CO2-free electricity, but the key point is what is cost-effective? I dream of a world where the CO2-free electricity can be so cheap that we can use it wastefully. And I can devise a not-implausible scenario where it comes to pass - ie PV becoming very cheap. But we cannot rely on it coming true. We need to work with plausible future costs and methods. In high probability scenarios, we cannot be very wasteful of low-CO2 electricity, and will not be massively overbuilt in it, by 2050.

Your third paragraph, unfortunately, does not present a way forward for the majority of us. There are issues that it is far from clear are easy to solve, or will get so much cheaper that it ceases to be a problem, for the majority. What I have italicised in your second paragraph added very little. So, bricks are cheap. So what? Many things are cheap. I pointed out that using them in electrical storage heaters in present technology is not attractive. What they become attractive to be used for depends upon cost, both the energetic and the civil engineering aspects.

[lpm]

But you're not distinguishing build costs from running costs.

TopBadger had solar on his roof. The big costs are history. Every marginal kWh he now gets is not just cheap, it's free. As you know, it's the marginal that counts not the average.

You also don't seem to realise HPs run 24/7, with only a small set back at night. Energy usage is a function of outside temperature, not inside temperature. Literally it's the outside thermometer that's the controller. Imagine the HP is ticking along at electrical consumption of X but then the outside temperature drops from 10 C to 0 C. And that coincides with a lull.

You'll then see what I mean by insulation being electrical storage. The bricks of the house are electrical storage. A house with poor storage drops from 20 C to 18 C quickly, so its HP calls for extra grid electricity over and above X early. The next door house cools more slowly so only needs the extra electricity a couple of hours later.

Then add dynamic electricity prices to the mix. Storing, via the route of delaying consumption, becomes valuable.

You seem to be thinking of ancient 20th C Economy 7 storage heaters, which shows how you are struggling to think in the world of 2050.

[Grumble]

As EVM points out in this video (which is about the costs of running a heat pump in winter), why would he use direct heating of water via an immersion heater when he has a heat pump right there? Heating water via a heat pump is less efficient than using it for heating a house, but it’s still about 200% efficient, whereas an immersion heater can never be more than 100%.

I did the maths and decided not to bother with HP for hot water, just went straight to immersion. Mainly because I won't get a HP for 2-5 years, once the gas boiler needs replacing and hopefully there are more (and better) installers. It's only averaging 5.4 kWh per day, which is 65p. Halving that cost with a HP would only save £118 pa, and the individual circumstances of my house meant no chance of payback from a complex install. Plus I now have the option of A2A solutions which could be a significantly cheaper install.

EVM is fine-tuning rather than shifting the dial, because for most of the year he will be exporting solar at low rates and halving the solar usage won't be more than a few pence saving a day. Efficiency disappears as a concern during solar surplus, i.e. most months of the year, which is hard to intuitively grasp during our current 2023 obsession with efficiency.

He didn’t get a HP for hot water though, it’s just a side benefit. If we’re talking about saving excess electricity as heat then using a HP makes sense.

[Millennie Al]

I dream of a world where the CO2-free electricity can be so cheap that we can use it wastefully.

sounds like

It is not too much to expect that our children will enjoy in their homes electrical energy too cheap to meter,

[bjn]

These things are not the same. We now have the reality of negative prices for electricity due to an abundance of renewable generation. The other was marketing b.llsh.t.

[IvanV]

But you're not distinguishing build costs from running costs.

TopBadger had solar on his roof. The big costs are history. Every marginal kWh he now gets is not just cheap, it's free. As you know, it's the marginal that counts not the average.

You also don't seem to realise HPs run 24/7, with only a small set back at night. Energy usage is a function of outside temperature, not inside temperature. Literally it's the outside thermometer that's the controller. Imagine the HP is ticking along at electrical consumption of X but then the outside temperature drops from 10 C to 0 C. And that coincides with a lull.

You'll then see what I mean by insulation being electrical storage. The bricks of the house are electrical storage. A house with poor storage drops from 20 C to 18 C quickly, so its HP calls for extra grid electricity over and above X early. The next door house cools more slowly so only needs the extra electricity a couple of hours later.

Then add dynamic electricity prices to the mix. Storing, via the route of delaying consumption, becomes valuable.

You seem to be thinking of ancient 20th C Economy 7 storage heaters, which shows how you are struggling to think in the world of 2050.

The big costs matter before you incur them. Most of us are in the situation of being before we incur them. That is the massive impediment to achieving your vision. For many of us, the costs are too large to be imaginable. The govt is yet to register how much support people need for this in our massively unsuitable housing stock, and we are installing HPs more slowly than nearly all our peers in Europe, a lot more slowly. Though Germany, among major/wealthy EU countries, is almost as bad.

The big costs are putting HPs in peoples houses, and building all the wind turbines and solar PV. People are going to get antsy about building them when there are so many of them that lots of their load is shed, or sold to people who buy spill units very cheaply for their application that depends on access to very cheap electricity.

How wonderful it is once you have your HP system installed. You can think about tweaking and managing it, like using your HP to heat up some bricks. A rich person's problem. I'm looking at the big problem, not the little tweak.

The original case you cited from Twitter literally involved someone heating up bricks with electricity. That is why I mentioned electric storage heaters. Because they were doing precisely that. Once someone starts heating up bricks with electricity, my immediate reaction is, that's crap. Hence my first post on this. Later I worked out that it made sense in that niche case.

[IvanV]

I dream of a world where the CO2-free electricity can be so cheap that we can use it wastefully.

sounds like

It is not too much to expect that our children will enjoy in their homes electrical energy too cheap to meter,

The latter makes it sound like something that probably will happen. Whereas a dream can be a complete fantasy.

But, like modern mobile phone technology would be a dream to someone 100 years ago, it isn't necessarily a fantasy and there is a chink through which it might just happen. But we should not depend on it or plan for it or assume it will happen.

There is some possibility that PV can become very cheap. A Moore's Law can apply to that technology. Then it becomes possible to massively overbuild it. It is useful enough we will install it even if you only needed it very intermittently, like your car that doesn't move 23 hours per day, and other things you have that you use very intermittently.

[lpm]

But you're not distinguishing build costs from running costs.

TopBadger had solar on his roof. The big costs are history. Every marginal kWh he now gets is not just cheap, it's free. As you know, it's the marginal that counts not the average.

You also don't seem to realise HPs run 24/7, with only a small set back at night. Energy usage is a function of outside temperature, not inside temperature. Literally it's the outside thermometer that's the controller. Imagine the HP is ticking along at electrical consumption of X but then the outside temperature drops from 10 C to 0 C. And that coincides with a lull.

You'll then see what I mean by insulation being electrical storage. The bricks of the house are electrical storage. A house with poor storage drops from 20 C to 18 C quickly, so its HP calls for extra grid electricity over and above X early. The next door house cools more slowly so only needs the extra electricity a couple of hours later.

Then add dynamic electricity prices to the mix. Storing, via the route of delaying consumption, becomes valuable.

You seem to be thinking of ancient 20th C Economy 7 storage heaters, which shows how you are struggling to think in the world of 2050.

The big costs matter before you incur them. Most of us are in the situation of being before we incur them. That is the massive impediment to achieving your vision. For many of us, the costs are too large to be imaginable. The govt is yet to register how much support people need for this in our massively unsuitable housing stock, and we are installing HPs more slowly than nearly all our peers in Europe, a lot more slowly. Though Germany, among major/wealthy EU countries, is almost as bad.

The big costs are putting HPs in peoples houses, and building all the wind turbines and solar PV. People are going to get antsy about building them when there are so many of them that lots of their load is shed, or sold to people who buy spill units very cheaply for their application that depends on access to very cheap electricity.

How wonderful it is once you have your HP system installed. You can think about tweaking and managing it, like using your HP to heat up some bricks. A rich person's problem. I'm looking at the big problem, not the little tweak.

The original case you cited from Twitter literally involved someone heating up bricks with electricity. That is why I mentioned electric storage heaters. Because they were doing precisely that. Once someone starts heating up bricks with electricity, my immediate reaction is, that's crap. Hence my first post on this. Later I worked out that it made sense in that niche case.

I bet some of our ancestors were saying "Hypocausts? Do you realise how much they cost to install?"

In my lifetime there was the switch to central heating, at high cost and far bigger disruption to home owners, in a much poorer UK than today's. I remember it happening. We weren't allowed to have bare feet and wore shoes indoors because the floorboards were lifted and there were nails everywhere. I remember my dad trying to figure out what we could do with the old coal cellar. The UK went from 20% to 80% central heating in 20 years.

There will have been a bunch of people on Facebook back then moaning that the costs of central heating "are too large to be imaginable".

The average UK house price is £294,000. £8k install cost is 2.7% of that. I wonder how much central heating cost to install in the 70s, relative to incomes and house prices. My parents did it when we moved house and presumably the cost was factored into the mortgage. The house probably cost ten bob and the central heating a tanner.

A £294,000 mortgage costs £1,412 per month at 4.9%. An extra £8k would be £1,459. Extra £47 per month, £564 a year.

Does a heat pump save £564 a year relative to a gas boiler? No it doesn't. In EVM's video he had £104 a year saving (at standard March 2023 energy prices), plus another £102 to be had for saving on the gas standing charge. Hence a lot of the tweaking to squeeze out extra payback.

But that's with current subsidised energy prices where the green levies are charged on electricity instead of fossil fuels and everything is out of whack. Gas wholesale prices are actually double marginal renewable prices. Flip by a third, 10.3p gas becomes 13.7p, 34p electricity becomes 25p. EVM would now be saving £576. And obviously that's just the start, once gas and electricity reach parity everyone's desperately trying to find a HP installer. Houses for sale without a HP will suffer the same penalty that houses without central heating did by the 1980s. US evidence shows houses with HPs already command a price premium.

It feels like HPs are a rich person's problem right now, same as installing central heating used to be. But the new housing stock comes in, people move house and have an upgrade budget, boilers break down and replacement happens.

And of course the UK is one of the worst countries for this transition due to government incompetence. Norway has already hit >60% HPs. The transition starts with the cold countries, because that's where savings are bigger, then migrates across to mild countries.

[IvanV]

I bet some of our ancestors were saying "Hypocausts? Do you realise how much they cost to install?"

The average UK house price is £294,000. £8k install cost is 2.7% of that.

Only the super-rich had hypocausts. The 99% from the stone age to the industrial revolution spent about 70% of their income on food, and that food was mostly just bread, because a lot else was unaffordable to them. There's some interesting info on Roman Britain period prices and wages in the St Albans/Verulamium museum. I found it rather shocking.

GCH was not some requirement you had to do. It was done because it was attractive to people. Incomes rose rapidly after WW2, people eventually got a lot better off and wanted to be warm. 1950s cold housing was no longer acceptable, even in the social renting sector. GCH was much the most economic way of heating houses where there was piped gas. Like lighting with the invention of light bulbs and electricity, which made good lighting a mass application rather than a privilege of the rich, so GCH turned being warm from a privilege of the rich to a mass application. Though in the lower cost housing sector, you'll find plenty of cases where cheapskate developers put storage heaters in, because they didn't care about their tenants' running costs. My sister lives in such a building. Even today.

£8k is what it costs to install an actual heat pump, assuming that the house is suitably insulated and the radiator plumbing is suitable. That's the best case scenario. People with the best case scenario are easier to persuade to do it.

The problem is that a huge amount of the housing stock is not like that. Take my house, frinstance. Built in 1938 with solid walls. When I bought it in 2000, the walls were so cold, that condensation routinely formed on some of the walls, especially inside or behind cupboards, leading to extensive wet rot in the floorboards. I had to replace the floorboards, and solve the cause of the problem. Fortunately, having a smaller number of larger rooms than many similarly sized properties, it was feasible for me to dryline the walls on the inside with 50mm insulation, cover with plasterboard, redecorate. External cladding was not practical due to insufficient roof overhang. Most British houses have insufficient roof overhang. That action alone cost more than £8k in 2000 - given that it necessarily included redecorating every external wall. Of course I had to pay much else, the woodwork replacement, and woodworm and rot treatments. I had a new roof put on in 2007 as part of a roof conversion, and that is insulated to 2007 standards, an action which also cost more than £8k in 2007. (I now don't have a loft.) The house became warmer with that better roof, but still isn't sufficiently insulated for heat pump heating. I was able to do a back-of-the-envelope and I reckon I'm about D to E on the efficiency scale, which isn't good enough for a heat pump. Short of knocking it down and starting again, it's quite difficult to work out what would be good enough and not end up costing a real fortune. At some point when the house needs a redecorate, maybe we rip off the old insulation/plasterboard and try again with modern materials/methods. Maybe we go for 100mm. There are some locations where that will be difficult, like in the bathroom where the shower and toilet are installed against exterior walls, behind where kitchen cabinets and sink are installed against exterior walls.

Heat pumps work best with underfloor heating. Retrofitting underfloor heating is a project in itself, excluding the heat pump, of considerably more than £8k in most houses. Maybe my house wouldn't be good enough without further installing underfloor heating. The back half of the house has concrete flooring. The kitchen-diner concrete floor is tiled with high quality floor tiles I assumed would last my life.

The average age of the housing stock in Britain is about 65 years or something. Many houses are small, have small rooms, and what I did in terms of dry-lining is difficult for them, and in my case wasn't even enough.

"Heat pumps is easy" is, I'm sorry, cloudcuckooland. They are only easy in ideal cases, which is only a minority of real cases.

There are various serious reports available on these issues, looking at the distribution of houses and likely costs for different situations. I have cited references to them in the past on this forum, so I won't repeat them. IIRc, a few years a common conclusion was that the average installation cost, including associated works to make it acceptable, would be something like £25k. That covers cases where you only have to spend £8k, and many other cases where you have to spend a lot more than £25k. And that is not the cost of doing it today, rather that is a predicted future cost when there are lots of installers well experienced in doing the work, it would be routine work not a special, and the materials would be mass produced. And then there's all the people who live in apartment blocks, where you need an overall solution for the block, not a flat-by-flat approach.

[Woodchopper]

Ivan is correct.

Heat pumps work well in a properly insulated home. But they're not going to cut it if not. Their maximum power output is much less than a gas central heating boiler. So to get the efficiency savings and a warm home people need to keep the heat pumps on for longer and ensure that they waste as little of the heat as possible.

Insulating old homes is expensive.

[lpm]

Ivan is not correct.

That was pure fossil fuel industry propaganda. Of course heat pumps work in badly insulated homes! Why wouldn't they? If gas can make a house warm, so can electricity. This is just basic physics. How absurd to think electricity can't make things hot!

The only homes where heat pumps won't work are where there's not the physical space. There's space in the UKs stock of semi and detached houses. For dense apartments district heating would be better anyway. For some flats 1:1 electricity heating is sufficient.

It's straightforward. There will be zero fossil gas. H2 is silly. District heating is limited. The rest is all electricity. Most of that is HP for efficiency.

[IvanV]

That was pure fossil fuel industry propaganda. Of course heat pumps work in badly insulated homes! Why wouldn't they? If gas can make a house warm, so can electricity. This is just basic physics. How absurd to think electricity can't make things hot!

I suggest you go search for the studies, some of which I have referenced on previous occasions, and see if you can find the fossil fuel industry propaganda operating through them.

When you say "how absurd to think electricity can't make things hot", well it can certainly it can by electrical resistive heating. But the point is to use a small amount of electricity via a heat pump. The limitation there is the temperature of the water that comes out. You can make the water out of the heat pump hotter with the electricity by electrical resistive heating, or else with a second heat pump, at additional cost...

The limitation of a heat pump is that the temperature of the water it can produce is lower than GCH. If you have a badly insulated property, you can oversize your gas boiler quite easily, and run it at 80C rather than the usually recommended efficient level of 60C. But your heat pump will be running at 50-55C. It can be oversized, but you can't turn up the temperature of the water. Low temperature water can heat badly insulated homes if you have larger radiators. Or maybe that underfloor heating. Which are costly to retrofit.

I was annoyed enough to go and have a look for the latest studies.

This study, based on actually installing heat pumps in a "representative sample" of 750 properties, found an average installation cost of £15,000, including additional measures, in the properties selected to have heat pumps fitted. But there was a lot of triage to get to the 750 properties. About 10 times that number started the process. At the point when a design was created, about 40%-50% were rejected as "unsuitable for heat pumps". As it says in the intro "Suitability of the wider UK housing stock for heat pumps should therefore not be inferred based on this data."
https://es.catapult.org.uk/report/elect ... ll-report/ (will have to fill in a registration form to get the free report instantly)

So what we learn is that actual realistic installs cost £15,000, when you reject the some 40% to 50% of homes that are not suitable according to that. Which, sadly, is consistent with what I was saying. It is interesting to look at the reasons for rejection. Space constraints, noise issues, insufficient heat capacity of available heat pumps in the market, excessive adaptation costs of the property...

Energy Systems Catapult, a government-funded industry research body, and the consultants they used to conduct this study, are all fossil fuel propaganda, doubtless you will tell me. I don't doubt there are fossil fuel shills emitting anti-heat pump propaganda, and you will doubtless find it places like the Daily Gauleiter. But I think the people doing this kind of government-funded really want heat pumps to be cheap and feasible and are doing their best to show they are. Please supply evidence if you disagree.