UK Electricity 2050 Part 1: a demand model

Guest post by Energy Matters’ commentators Alex Terrell and Andy Dawson. Alex Terrell is a business consultant in the area of Vehicle Telematics. He has also consulted in Energy and Manufacturing, and has a degree in Engineering. Andy Dawson is an energy sector systems consultant and former nuclear engineer.

This lengthy post is in three parts and aims to provide greater sophistication to a UK 2050 electricity model than can be achieved using the DECC 2050 calculator. Part 1 (below) presents the demand model. Parts 2 and 3 (to follow) will look at how demand may be met by a high nuclear option and from a renewables option.


There is endless discussion and debate over what the UK’s electricity supply should look like moving forward out to 2050. However, there is less discussion over what demand will be, and how this might vary from day to day and season to season. This article looks at UK electricity demand over the long term – specifically setting a scenario for 2050, which also meets the UK Government’s aim of an 80% reduction in CO2 emissions. Electricity demand in 2050 will vary significantly depending primarily on:

  • The temperature and resultant heating or cooling requirements
  • Whether it is a weekday or weekend

We have created a demand model based on using a number of technology assumptions for 2050, and a high electrification scenario. The demand model has then been matched to UK daily temperature data from the last 20 years to identify how demand could vary on a daily basis in 2050.

Average demand over the course of the year is expected to be 72GW. However, this will vary from a daily average 43 GW (experienced when the temperature is 18 centigrade and it’s a weekend) to 121 GW (experienced when the average temperature is -7C, as it was on 20 Dec 2010).

In cold weather, the largest element of demand is for heating, leading to greater seasonal variation than at present. However, we assume that homes have sufficient thermal mass that demand can be smoothed out over the course of a day, by making small changes to the time of heating. Electric vehicle charging will also help to smooth daily demand and shift demand to weekends.

Two subsequent articles will apply the demand model to historical daily weather patterns from previous years to identify how demand could be met with two extreme supply scenarios:

  • A nuclear power scenario, using some supplemental thermal fuel (gas, diesel, biofuel etc.) backup.
  • A wind and solar scenario, using thermal fuel as backup.

We have not modelled scenarios with higher levels of gas usage and carbon capture and storage – in particular, the technology of steam reforming natural gas (and sequestrating the resultant CO2) could help reduce peak winter demand as people choose to burn hydrogen for heat rather than use electric heating.


This report follows on from an article published earlier by Andy Dawson on Energy Matters examining whether conversion of the UK’s current electricity supply to a completely (or near-completely) decarbonised mix of nuclear and pumped storage is feasible. During the discussion following that article, a number of commenters raised the question of (a) was comprehensive decarbonisation an option by that approach, and (b ) what were credible future demand scenarios mostly arising from use of the DECC “Pathways” models.

DECC introduced its pathways scenarios modelling tool in order to allow anyone to enter their inputs and see the effects, with an aim of reducing emissions by 80%. One of the issues with the “pathways” models is that they’re rather blunt instruments (in that the various supply scenario components are a limited menu), and that it’s far from clear if the underlying models take adequate account of variations in demand; as has been pointed out by many on these pages, both diurnal and seasonal variations in demand mean that simple models based on averages are far too simplistic to make a real contribution to the debate. This led us to the conclusion that the only real option was to build our own, based on realistic (and readily adjustable) assumptions about the scale and shapes of the various elements of overall demand.
Current UK Final Energy consumption is approximately 140 Million tons of oil equivalents, which equates to 1,628 TWh/year. Electricity is just under 20% of this. It is widely accepted that if the UK wishes to make deep cuts in its carbon emissions, then much of the remaining 80% needs to be converted to electricity. Please note that this implies significant investment in the national electricity transmission and distribution systems. We have NOT attempted to model this, as it is an implicit requirement in any decarbonisation scenario.

However, some sectors are likely to be extremely difficult to “electrify”:

  • There do not seem to be any credible technology paths to the decarbonisation of aviation, with the possible exception of biofuels. The weight and aerodynamic implications of cryogenic storage make hydrogen fuelling unlikely, and fully synthetic fuels seem unlikely to be available in volume by 2050 at acceptable prices.
  • While there do seem to be viable options for the decarbonisation of long distance bulk shipping (several small modular reactor (SMR) designs seem to be in the “sweet spot” for large ship engines, and weight/bulk of cryogenic H2 storage appears viable on large vessels), for smaller and mid-sized vessels, achieving a high energy density for the fuel source remains an issue.
  • Long distance road haulage will be problematic. Conventional battery approaches seem unlikely to give an adequate range:payload:recharging time relationship to make for attractive economics. Options could include H2 fuelling (with the fuel derived from methane reformation), or standardised “swappable” batteries – in the absence, however, of an obvious contender technology we’ve assumed the continuation of liquid fuelling.

Whilst biofuels could go a long way to fulfilling the above demands, it is likely that the electricity sector will have to significantly expand, and go well beyond an 80% CO2 reduction target in order to offset emissions from these sectors. This raises a number of questions:

  • At what efficiency can current demand be converted?
  • What is the total of electrical demand?
  • What is the seasonal and daily variation in this demand?
  • How can this demand be met with low carbon technologies?

The 2050 Demand Model

Using the DECC scenarios:

The DECC pathways calculator allows us to make various assumptions and models average energy flows in 2050. We can use this with a “high electrification scenario” to estimate electricity requirements. Figure 1 shows our pathway, alongside the “no change” pathway and the Atkins pathway.

Figure 1various outputs from the DECC pathways. Ours is available here. Our pathway works out to an average of 72GW. That would be straightforward, but as we know, averages are not the most important thing for an electrical network. DECC’s pathway does not appear to take into account either seasonal and daily demand variations, or weather related supply changes, as demonstrated here.

How will demand vary over the course of the week and over the year?

For this we need to look more closely at the major demands for electricity: Heating, Vehicles, Industry, and commercial. The following assumptions are sanity checked against the DECC Pathways outputs.

We modelled how demand might vary according to temperature, specifically with external daily average temperatures of 30C (extremely hot), 18C (pleasant), 12C (typical), 0C (Cold) and -10C (exceptionally cold – it last happened in 1838 according to the Central England Temperature records). The outcome is shown in Figure 2. We see that whilst the average electrical demand is only 1,721 GWh/day according to the Atkins pathway, and 1,740 GWh/day according to our pathway, the actual demand could vary from 1215 GWh/day to around 3,000 GWh/day in exceptionally cold weather.

The assumptions within the categories for:

  • Heating and Cooling – Homes
  • Commercial
  • Industry
  • Road Transport

are given below.

Figure 2 – Daily electrical demand according to pathway averages (left) and modelled demand according to external temperature.

Heating and Cooling Homes

The DECC pathways calculator makes no breakdown of when the heating is applied. To understand this, we need to identify current heating needs and make some big assumptions regarding heating demand in 2050.

There were 27 million households in the UK in 2010, up from 19 million in 1970. Population growth has been a small driver, but a bigger driver has been a reduction in the number of people per household. We have assumed that this trend will not continue and are assuming 30 million households in 2050. Note, however, that even were growth to continue, shifts in the housing mix – particularly an increasing proportion of apartment dwellers – can largely offset this impact.

In 1970, the overall rate of heat loss from a home was, on average, 376W/°C. Forty years later, it had fallen by almost a quarter to 287W/°C according to UK housing facts, page 54. This means that the average 2010 home needs 287W to maintain a 1 degree temperature differential with the outside. Figure 3 shows how this is made up and how it varies over time.

Figure 3: Average heat loss per dwelling (W/°C). This measure of heat loss says that for an average home, if it is 1°C cooler outside than inside, it needs 287 watts (2010 figure) of heating to maintain a stable temperature. The measure is affected by insulation and ventilation losses.

The spike in 2008 was due to a change in modelling of ventilation losses. If we add this back to the 1970 figure, then the fall is from about 420 W/°C to 287 W/°C, a fall of 32%.

If we assume a geometric trend rate of fall, we arrive at 2050 figure of 196W/°C. This figure is highly significant in establishing energy requirements in 2050. It means that if the average temperature is 0C outside, and 20C inside, the average home will require 94KWh of heat in a day. This is very easy for a new-build house to achieve (UK homes built since 2013 in accordance with building regulations easily surpass this level), but very difficult for a 1980s build house. Simple cavity insulation, double glazing, and increased loft insulation won’t be sufficient – it would probably need external wall insulation, which also has the added advantage of providing a very high thermal mass inside the insulated boundary. More challenging would be changes to ventilation, including heat recovery from exhaust air. It’s doubtful this latter can be achieved with much of the “legacy” housing stock, and hence places a limit on attainable reductions.

The UK has a very low rate of new house building – only about 0.5% of the stock is replaced each year. Nevertheless, by 2050, perhaps 20% of homes will be built to post 2013 standards and that will help to bring the average energy consumption down. However the energy is supplied, the UK needs to improve the energy efficiency of its housing stock – both of existing houses and of new build houses. This is perhaps the only area where there is consensus amongst energy experts and environmental groups. Based on this analysis, we would also recommend favouring improvements that boost the thermal mass of homes, even where this increases the “embedded energy” of the build. Key assumptions for the model include:

  • There are 30 million “homes” – a mix of flats and houses, up from 27 million in 2010.
  • The internal temperature is set at 20C – compared to the current average of 18C. However, this can fall to 19C at 0C external and 17C at -10C external. With better insulated homes, people will want to keep them warmer than they do today.
  • At 0C outside temperature, the average home requires, on a daily basis:

    – 10.5KWh of domestic water heating. This is provided 70% with heat pumps at a COP of 2, 20% from resistance heating, and 10% from solar and district heating.
    – 90KWh of space heating, of which 10KWh comes from lighting and appliances. The remainder is provided 80% with heat pumps at a COP of 3 (a typical house might have two 5KW air source heat pumps), 10% from resistance heating, and 10% from solar and district heating.

  • The average home will have sufficient heat capacity so that unheated, the temperature will fall by no more than 2C over 24 hours (at 0C outside temperature). This requires, for example, 40 cubic metres of concrete or brick in the walls and floors, inside the insulating envelope. This effectively means that heat can be delivered within reason at any time of the day, and used to even out electricity supply.
  • Domestic water requires 3.7KWh of heat per day. In summer, this is mostly provided by solar heating, but in cold weather by a heat pump with a COP of 2 (due to the high temperature differential).
  • Heat pump COP at -10C external temperature falls to an average of 2.5 for space heating and 1.5 for hot water.
  • Other technologies will be deployed to reduce overall heating demand, to reach the average 196W/°C assumption. For example:

– In houses with high levels if air-tightness and heat recovery, a heat-pump can remove heat from the extracted air or waste water. This would allow a considerably higher CoP.
– There may be some elements of inter-seasonal heat storage – perhaps using air conditioning and heat transfer in the summer to store heat in the ground, to improve the winter performance of ground source heat pumps.

In practice, there will also be some wood and oil heating. Wood heating – whether logs or pellets – is becoming increasingly common in Germany as an alternative to gas. We would support the use of wood heating in very cold conditions as it would make energy supply easier. However, if homes have wood burners, people will use them throughout much of the year, which will increase local air pollution and reduce the feed for biofuels. Hence we assume no wood heating in our model.

If homes have heat pumps for the winter, these heat pumps will also be used for cooling in the summer. This is not a problem for the supply system, as demand will still be significantly lower in the summer. Indeed, with ground source heat pumps, some air conditioning could be useful to replenish underground heat.

This model shows that heating and cooling of homes will require 243 GWh on a typical per day, which is not far off from the Atkins DECC pathways model. However, this could shoot up to over 1500 GWh in exceptionally cold weather (around -10C)

Figure 4 – National electrical heating requirements according to external temperatures and average internal temperatures.

As home heating can make up over half of electricity demand on a cold day, the “Average Heat loss per dwelling” figure is critical in assessing the overall heating requirement. We have assumed 196W/C. Figure 5 shows how overall demand varies with this figure:

Figure 5 – How overall demand according to average home insulation levels. Overall demand is shown in GWh/day on the left scale, and this is averaged to GW on the right scale.


Commercial demand was estimated based on 2011 data for electrical and non-electrical demand. It is assumed that this demand is:

  1. Mostly switched to electricity using heat pumps and induction heating
  2. Reduced through efficiency improvements
  3. Increased mostly according to population growth (0.3% pa), or for Catering and Other, according to economic growth.

The results, in GWh per year are shown in Figure 6.

Figure 6 – Annual commercial demand for electricity and other energy, extrapolated from 2011 to 2050 assuming extensive electrification.

The daily demand was then calculated based on temperature, and the results shown in Figure 7. We have introduced some curtailment of at -10C, as at these temperatures many people don’t make it to work and many shops will close.

Figure 7 – Daily demand for electricity from commercial


Industrial demand was calculated in the same way as commercial. Most elements were assumed to grow in line with the Economy (2% pa) rather than population (0.3% pa), with an annual efficiency improvement of 1%.

Figure 8 – Annual demand for electrical and non-electrical power in industry.

A large proportion of the industrial load is in fact for heat, with a large proportion of this being supplied at relatively low temperature; here we’ve again assumed a large shift to heat-pumps and/or utilisation of waste heat from generating facilities. For high temperature processes, we assume the majority supply (c. 80%) is via direct resistive or RF methods. In all cases, we assume a significant residual demand which is not readily electrifiable.

Industrial demand is assumed to be progressively curtailed below 0C. This is partly as employees have trouble getting to work, and partly due to Demand Side Reduction coming into play with heavy users of electricity. As a result, industrial demand is reduced in rare, extreme weather scenarios.

Figure 9 – Daily demand for electricity from commercial


We assumed that by 2050, road transport would be predominantly electric, with private vehicles able to travel several hundred kilometres on a charge. As a baseline, we took 2015 DfT mileage date and assumed modest increases in distance travelled.

We assumed a high degree of electrification for all vehicles except for Heavy Goods Vehicles (on the grounds of the particular challenges of meeting the range/payload challenges with foreseeable battery technologies; in this space we suspect that hydrogen based technologies are likely to prove more viable, with fuel supplied via steam reformation of natural gas, and sequestration of the resultant CO2 waste stream, or from nuclear thermal production). However, the choice of technology makes little impact on our electricity demand model.

We also added an up lift for cold and hot weather to provide heating and cooling respectively, and curtailment of car, motorbike and Light Goods Vehicles in very cold weather.

The average car drives about 300 kilometres in a week, which should be well within the electric range of most cars in 2050 (The Chevrolet Bolt is aiming for 200 miles range in 2017). This will require about 50KWh per week, and charging can take place once or twice per week. We have assumed that:

  • Charging time of day can be partly influenced – users will plug their car in and request that it’s charged by a certain time
  • Vehicles will be more likely to charge over the weekend, when they are less likely to be on the road

(It seems that by 2050, to state that the vehicle drives, rather than is driven for appears increasingly probable!)

Adjusting for Weekends

We assumed some shift in demand between weekends and weekdays, as is currently the case.

Road transport (vehicle charging) and use of home lighting and appliances increase at the weekends. Everything else increases for weekdays.

Figure 10 shows the variation on weekdays and weekends for different temperatures.

Figure 10 – 2050 Weekday (WD) and Weekend (WE) daily electrical demand according to average daily temperature.

Intra-day variations

We assume, with some control over when heating is applied, and when vehicles are charged, demand can be largely flattened out over the day. So for example at zero C, the following illustrates how the 2,548GWh of daily demand could be smoothed to a power supply of approximately 106GW.

Figure 11 – Electricity demand smoothed over the day. Road transport is mostly charged at night. Heating and cooling is adjusted to be counter-cyclical with Industrial demand.

Experience to date shows that consumers are very insensitive to short term, small scale price signals. They will not be able or willing to vary their demand to such a fine level just on the basis of price. So fine tuning demand will need to be done by embedded systems connected to a central demand management algorithm. Examples could be:

  • A user will set their thermostat to 20C. The central system will tell the heating when to operate, allowing the temperature to remain between 19C and 21C. There may be a provision to allow the temperature to drop to 18C in “exceptional circumstances”.
  • Car users will plug their cars in, and tell the car when it is needed next. The system will then choose the optimum time to charge.

To encourage users to accept the approach (with its “Big Brother” and “loss of control” connotations), there will need to be some financial incentives. These will have to be on an aggregate basis – perhaps an annual reduction on the electricity bill. Some customers will prefer to pay a little bit more to have their own “control”, but enough will accept remote control to flatten demand. It should be noted that several markets attempting Smart Meter rollouts have already seen significant consumer backlash over “loss of control” and privacy issues, resulting in the Netherlands (for example) abandoning plans to make such meters mandatory.

If the demand management systems are off by a few GW, then some pumped storage or battery storage (of the order of 10s of GWh) can be used to even out demand over the day, and nuclear reactors are able to go over or under their nominal power for short periods.

Note also that this does not require the ability to draw power down from EV batteries with all of the complexities inherent in this approach – for example, requiring inverters to take DC output from the batteries into domestic AC supplies.

The Demand Curve

Extrapolating the values derived above, we can estimate a demand curve.

Figure 12 – Demand Curve according to average daily temperature

Matching to the weather

We have identified a weather and day dependent demand. The next question is how much demand this creates, given the potential weather in 2050.

The HadCRUT temperature database for Central England has recorded daily average, minimum and maximum temperatures since 1772. In practice, the average temperatures across the entire United Kingdom are likely to be warmer on extreme cold days than just those in central England. However, central England is near enough to major population centres, so we will err on the side of caution and use this as an average proxy temperature.

We also note that average winter temperatures have been increasing over the last 50 years at a rate of about 0.16 centigrade per decade. However, 2010 recorded 27 freezing days, a sequence of 11 freezing days in succession, and a minimum temperature of -7C.

Figure 13 – Central England: Number of freezing days, longest sequence of freezing days, average winter temperatures, and minimum temperatures over the last 50 years.

For a future energy supply scenario, we therefore think it’s prudent to model demand assuming the temperature profile of the 20 years up to and including 2015. Based on this, we can model the percentage of days when average electricity demand will exceed a certain value.

Figure 14 – A frequency distribution of electricity demand in 2050. The most common level of demand (averaged over the day) is 60GW. Demand always exceeds 43GW. This chart is based on 20 years of daily temperatures (from 1996 to 2015) – more years of data would smooth the red line (number of days).

The supply needs to cater to extreme events. A zoom of the above chart to show the probability of average demand exceeding high levels is shown in Figure 15.

Figure 15 – The percent of days when demand exceeds high levels. The percentage figure (y-axis) has a logarithmic scale.

A temperature of -7C (averaged over 24 hours) would result in a demand of 121GW, and we can expect this approximately once every 20 years. In reality – given the consequences of a supply shortage in cold weather – availability may have to higher than 121GW, though this could be enabled by diesel generators with almost no impact on emissions.

As well as being able to supply this amount for a day, the system needs to sustain a high level of output over a number of consecutive days. Figure 16 shows an example of this.

Figure 16 – Electricity demand over a cold spell, with 11 consecutive days of freezing temperatures leading to demand of over 100GW for that time period. This temperature sequence actually occurred in 2010.

Following articles will show how this demand can be met with:

  • A nuclear powered system, using some supplemental thermal fuel (gas, diesel, biofuel etc) backup.
  • A wind and solar scenario, using thermal fuel as backup.
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48 Responses to UK Electricity 2050 Part 1: a demand model

  1. Joe Public says:

    An excellent & informative appraisal, thanks.

    “The HadCRUT temperature database for Central England has recorded daily average, minimum and maximum temperatures since 1772.”

    It is interesting that HadCRUT is quoted. It seems that increasing CO2 emissions, the minimisation of which is the objective of the whole exercise, refuses to significantly affect the temperature of Central England:

    During that period, our population has increased ~ten-fold.

    • Willem Post says:

      Hi Joe,

      That graph is priceless.

      Based on that graph, the UK did not have to do anything in the past, and highly likely would not have to do anything in the future.

      Did you send the graph to Brussels?

      • Joe Public says:

        I believe it was compiled by “XMetMan”. It was available from his original blog, but he deleted that entire blog.

        He’s since re-created a Blog, but I’ve not located the successor to that influential chart.

    • Wookey says:

      The Hadley centre’s plot of Central England Temp (HadCET) doesn’t look like the one you link:
      Theirs goes up (very noisily) about 1C since about 1880, and notably more than 0.5C since about 1985.

      It’s not immediately clear why the two graphs diverge so much, especially recently.

      • Alex says:

        The graph in the article shows a rise of about 0.16C per decade in winter temperatures. Changing the pivot to include all months:
        increases the rate of warming to 0.2C per decade.

        It is likely that UK winters in 2050 will be warmer on average. But that is not a safe assumption to make when estimating how much heating capacity is needed. Especially as we cannot answer “how cold will the coldest day be, in 2050”.

      • Joe Public says:

        Yes, unfortunately I’ve not located an updated chart.

        Was there a reason you mentioned change from ‘1880’, when Hadley’s chart starts at 1772?

        Intriguing, are the periodic falls in temps during periods of rising CO2; and, the periodic falls and rises in temps during the earlier period of relatively stable CO2.

  2. gweberbv says:

    Please check figures 6 and 7. Two times the same plot.

    With regard to electrification of space heating it should be obvious that it will never work in the way presented here. A good portion of the power plant fleet would have to sit around idle and wait for some quite cold days on which heating demand will skyrocket.

    This inflated electricity demand is due to the combination of increased heat demand plus the reduced efficiency of air-based heat pumps. This could be mitigated a bit when assuming heat pumps with underground sources. However, they are not possible everywhere and can easily double the price of the heat pump system.

    To me it seems reasonable to keep some gas-based backup heating systems in the buildings instead of back-up power plants (e. g. above a given heating demand for a reference outside temperature buildings are required to keep backup heating system that can be switched on by the grid operator). This is probably cheaper and also more efficient – in particular when air-based heat pumps are considered which are simply shitty on the few days with very low outside temperatures.

    • Alex says:

      Thank you for reading this. Figure 6 (annual figure) and Figure 7 (daily figure) are different. Did we miss something else?

      In reality, I doubt we can get rid of gas “back up” by 2050 – too much insulation needed, too many heat pumps, too much generating capacity. But it should be the target. We did mention wood burning, which is very popular in Germany.

      Parts 2 and 3 will quantify the issue of idle capacity.

      • gweberbv says:


        I do not think that it is a reasonable target to have 100% electric heating. Like it is a questionable target to reach 100% renewables (unless you have huge hydro ressources).
        Such analysis will always tell you that the cost are prohibitiv. Or you have to make unrealistic assumptions. Because the last – maybe – 20% are very hard to achieve.

        In particular, using an air-based heat pump in a situation where the COP is around or even less than 2 AND electricity is produced mainly by burning gas is just a stupid idea. It would be much more economic to directly burn the gas where the heat is needed with an efficiency of something like 90% (and no need to transport huge amounts of electricity). Of course not in all buildings but in those that have the highest heating demand.

        I think you should add gas-based backup heating systems to your model. Those will be mandatory in not so well isolated buildings that rely on air-based heat pumps. So, for maybe 50% of the building stock you will have a cut-off for electricity demand for heating at an outside temperature of maybe -5 degree.

        • Alex says:

          You raise some good points.

          I think it’s reasonable to target 100% electric heating. Whether it can be achieved by 2050 is the big question – it’s certainly a stretch target, and there are two linked goals: (1) Demand side – installing heat pumps and insulating, and (2) supply side – which will be covered in parts 2 and 3.

          “In particular, using an air-based heat pump in a situation where the COP is around or even less than 2 AND electricity is produced mainly by burning gas is just a stupid idea.”

          Even at a CoP of 2, it’s energetically better to use a heat pump than a boiler. However, we looked at ways of trying to reduce peak demand. Our thinking was that heat pumps are not ideal for domestic hot water, as the CoP is low. Could you use gas for hot water and heat pumps for heating? Yes, but then you have two bits of infrastructure which is going to cost more. Once a house converts to heat pumps, it should use them for space heating and hot water, and dump the gas boiler.

          More likely will be that some, older building stay on gas for all their heating needs.

          There is a mention in the article of steam methane reforming – and it might be possible to use hydrogen for peak heating, and store the CO2. That’s an approach I’m currently exploring. I think it needs nuclear heat from MSRs to be truly viable, and if you have MSRs, why would you want gas heating?

          • OpenSourceElectricity says:

            COP for domestic hot water – especially if the water stored at elevated temperature is _not_ the drinkable water, as it should be done with heat pump systems, is well above 2 for mostt time of the year , so uning gas for this purpose will not save any CO2 emission, or general energy consumption.
            Most of the year temperatures are above -15°C, and even above -0°C.

          • Alex says:

            We used these values:
            Manufacturer claims are generally much higher, but to date real work implementations have been lower, so hopefully that will improve.

            I think your key point is a home user will be reluctant to invest in gas heating of domestic hot water, just because the CoP is poor for a few days of the year.

          • gweberbv says:


            the low COP for warm water is basicly a remnant from the design that is usually used in combination with fuel-based heating system. There you heat the drinkable water in a tank to something like 60 degree Celisus (you don’t want to get much lower because of bacteria growth in warm water) and later you mix this hot water with cold water you end up at a usable temperature of slightly below 40 degree Celsius.

            With a heat pump reaching 60 degree is expensive/inefficient. But in the end you need only 40 degree anyways. So, the way to go – as already mentioned by OpenSourceElectricity – is to heat a big tank to a temperature slightly above 40 degree and then use this water to heat the drinking water via a heat exchanger.

            But I think this is an side issue in the context of your analysis. The elephant in the room is the skyrocketing electricity demand due to space heating.

  3. Joe Public says:

    Complementing @gweberby’s comment about attempting to electrify the heating demand, it should be realised that the UK’s maximum heating demand is ~350GW vs current maximum electricity demand of ~58GW.

    See chart of national half hourly heat demand (red) for 2010 and actual half hourly national electricity demand (grey) in section 58:

    Report to the Secretary of State for Business, Energy and Industrial Strategy from the Parliamentary Advisory Group on Carbon Capture and Storage (CCS)
    September 2016

    In addition, it is noted

    If the demand management systems are off by a few GW, then some pumped storage or battery storage (of the order of 10s of GWh) can be used to even out demand over the day, ….

    The UK’s 4x Pumped Storage facilities have a total capacity of approx 28.7 GWh, enough to supply the current UK demand on a winter’s day for about ….. 40 minutes. Add the heating load, and that duration shrinks to ~10 minutes.

    Compare that with our gas storage capacity.

    Existing (2016) gas storage facilities ~51.15TWh

    Withdrawal capacity ~1.926 TWh/DAY Duration up to 67 days (Rough)

    On the day of peak supply in (relatively mild) winter 2015/16, gas storage provided its highest supply of the winter at 1.078 TWh

    On 4x days in (relatively mild) winter 2015/16 demand exceeded 3.675GWh

    Even in the winter, extract from storage makes up only a small proportion of GB’s total supplies. Most is from linepack.

    • Alex says:

      Of course heating is the big issue, and the total amount of heat needed is the big uncertainty, which Figure 5 tries to encapsulate. That comes down to the heat needs of individual homes.

      We’ve then tried to flatten demand, to – at 0C – an average of 106GW – flat over 24 hours. If the algorithms are off by 5GW for 10 hours, that’s an error of 50GWh, which could be made up with pumped storage – even current pumped storage plus Coire Glas (planned 30GWh, and 600MW – so for this purpose would need to quadruple power).

      That would be to flatten demand for nuclear. Matching demand to renewables with storage is of course an order of magnitude harder.

  4. Jonathan Madden says:

    Thank you for this analysis. I look forward to the next instalments.

    The UK, along with other developed nations, has outsourced production of many goods to Asia, India and China in particular. As well as reducing costs this has the apparent benefit of lowering energy use and emissions, at the expense of raising them elsewhere in countries which do not impose financial tariffs on CO2. The quantity of emissions thus displaced is hard to estimate but may well equal or exceed the reductions made within the UK.

    Your forecast of lower 2050 industrial emissions than today suggests that the sources of manufactured goods will remain roughly the same going forward and that significant repatriation of factory capacity will not occur.

    A gradual shift to air sourced heat pumps for domestic heating/cooling will reduce gas and oil usage, assuming electricity generation relies increasingly less on fossil hydrocarbons. Given their efficiency, especially in a well insulated building, and comparative simplicity I would consider it a priority to fit new housing with heat pumps in favour of gas boilers. (But heat pumps don’t do the hot water.) There is also the matter of fan noise from the external unit, which may be a limiting factor for high density housing. I think that ground source heat pumps will remain a fairly niche application because of cost.

    To a much more minor extent, Britain has a stock of housing that is ‘listed’, and managed in England by English Heritage. There are some 400,000 listed buildings in England, many of which are thermally inefficient. Owing to the difficulty and cost of obtaining listed building consent to make changes to the exterior (for Grade 2) and also the interior for Grades 2* and 1 it appears likely that many of these will remain proportionally higher consumers of energy than their unlisted equivalents. For example it is not easy even to replace windows in a Grade 2 building, but absolutely no problem for the building to fall into dilapidation! But again, this will not have very much impact in the bigger picture, less than 4% of domestic heating perhaps.

    • Alex Terrell says:

      Thanks for comments Jonathan.

      We can’t really do much about imports from China and elsewhere, other than try and bring them back. The model assumes that industrial demand rises with growth (2% pa) for:
      – High Temp Processes
      – Low Temp Processes
      – Drying and separation
      – Elec. Motors
      – Compressed Air
      – Other
      and population (1% pa) for:
      – Lighting
      – Refrigeration
      – Space Heating
      Then a 1% pa efficiency gain is superimposed.

      You are absolutely right about listed buildings. The only thing I can say is that they still fit into the “average” and we have assumed that average improvements continue at the same “geometric” rate – about 32% heating reduction in 40 years (slightly offset by homes being 2C warmer).

      • Jonathan Madden says:

        Thank you for your reply, Alex.

        I suppose we could as a nation, from a somewhat cynical standpoint, actually increase offshore production going forward and push the transition to becoming a service and high-tech economy to a conclusion of mininal local manufacturing, and greatly reduced industrial emissions.

        1% pa population rise implies ca. 640,000 pa at today’s figure. That would become 800,000 pa in 2050, with a projected population of 80m. However should there be a change in immigration policy towards tighter controls this would imply reduced inward migration of people of working age and, by implication, lower, or at least deferred, demand for new houses. High rise apartment blocks, if well designed, can dramatically reduce heat demand and this is the primary focus of new builds in, e.g. Russia.

        Regarding space heating, I have noticed, maybe subjectively, that I tend to feel ‘colder’ at home in winter as comared to warmer seasons, despite the temperature being the same. I put this down to relative humidity being lower, increasing my perspiration: cold winter air with low humidity outside retains the same absolute water vapour content when it enters the building. I wonder if there is some simple way of raising humidity indoors so that one can be warmer without raising the temperature?

    • gweberbv says:

      Jonathan Madden,

      if a ground source for a heat pump ism expensive or not depends entirely on your investment horizon. The lifetime of the ground source is a few decades at least and over this time it will increase the average COP of the heating system by a least 1. Over this time, it will in most cases pay back even large investments. But very few people will care about heating efficiency over the next 50 years.
      Therefore government should step in and subsidize the installation of heat pumps based on ground sources. (The transition to heat pumps needs to be subsidized anyway because relying on the existing gas infrastructure is much cheaper on a timescale on 10 or 20 years. So there is little incentive for the owners of buildings to change their heating systems.)

      • Jonathan Madden says:


        I suppose a ground source heat pump would count as a home improvement and add to the value. Part of the problem in Britain is that gas at, say, 3p/kwh compares with 10p/kwh for electricity, which removes much of the COP gain for heat pumps. It’ll take a significant rise in the gas/elec price ratio to encourage capital investment in heat pumps.

        Ironing out diurnal heating demand variation can be achieved, as mentioned, with thermal mass placed within the building insulation. In my case, for example, I have about 30t of masonry ‘indoors’ and this permits me to turn off the heating overnight, or for 8-hour periods, and only experience a 3C drop. But one can’t easily retrofit heat accumulating material, leaving many homes with low thermal mass and more continuous heat requirements.

        • Alex says:

          “Part of the problem in Britain is that gas at, say, 3p/kwh compares with 10p/kwh for electricity, which removes much of the COP gain for heat pumps.”

          Just looked at and (ignoring fixed charges):
          Gas: 4.1p
          Electricity day: 18.7p
          Electricity night: 6.8p

          If I lived in the UK, I’d buy a air to air heat pump, and run it at night – but still keep the gas boiler for day heating and hot water. However, I live in Germany where it’s:
          Electricity: 30 cents
          Gas: 5 cents
          So, heat pumps don’t work out at all here. Maybe if I could run it off my solar panels, but I tend to need the heat when they’re not delivering much electricity.

          Air to air heat pumps are cheap – about £1,000 for a 5KW unit, so cheaper than a gas system. However, they don’t heat water. That adds to cost (and lowers the CoP), but also means you can store your heat in a thermal tank. The big gain is if you can get rid of gas entirely.

          • Joe Public says:

            Hi Alex

            The big gain is if you can get rid of gas entirely.

            I don’t know the relative situation in Germany, but GB gas demand is significantly higher than power demand. In 2015 GB gas demand was 880TWh vs ~334TWh for power demand; and, only 20% of the gas demand was by gas fired power stations.

            Then there’s the ‘minor’ issue of the total inability to store much ‘electricity’ cheaply.

          • OpenSourceElectricity says:

            Where do you pay 30ct/kWh for electricity? Ipay 24ct including taxes. Since the gas heating also needs electricity, Heat pumps and gas are about equal here today if heat distribution fits to heat pump use. If costs for gas (base price for gas , chimney sweep etc) can be removed at all heat pumps are cheaper, or if a part of the power comes from PV.
            With a heat distribution which needs high temperatures, heat puumps are more expensive. it needs a detailed calculation today it is not a nobrainer in one or the other direction here.

          • Alex says:

            Typical price here

            Maybe 25 cents / KWh is a more accurate price as the fixed cost is still there, whether you use a heat pump or not. However, if you can get rid of the gas, you can also get rid of the fixed price.

            It still means there’s no realisable path for Germany to move from gas heating to heat pumps.

        • Alex says:

          “But one can’t easily retrofit heat accumulating material, leaving many homes with low thermal mass and more continuous heat requirements.”

          A common insulation method is to fit external insulation around the existing building, and a new render. This is expensive, but is the best way to deal with pre-1980s houses. It results in about 80 tons of masonry inside a highly insulating envelope. That is ideal.

          New builds are often wood and foam. Excellent insulation, but poor thermal mass. We’d prefer concrete inside foam, as shown here: – though I think they need more polystyrene outside and less inside.

          Of course, that doesn’t help old houses which can’t be externally insulated. In Germany, they’d knock them down and build proper houses. In the UK, people prefer old dilapidated buildings.

          • steve says:

            You hit the nail on the head re people preferring old buildings in the UK. We have an awful lot of them, wheras in some continental areas the massive number of victorian houses were not built or were demolished with some help from the RAF. The numbers of old poorly insulated houses is the elephant in the room that HMG avoids addressing. In England alone there were 22.2m dwellings in 2008. Only 12% are post 1990, when insulation standards started to increase. These standards have only come anywhere near enough post 2000. 21% are pre 1919 and 95% are traditional masonry and timber.For older houses CO2 emissions are 2x those of post 1990. Energy use has continued to increase since 1950 and now the estimate for 2050 is 55% of total.

            I do not agree that having a large thermal mass saves energy. In my case, I have a victorian terrace with 3 storeys and if I turn the heating off at night the temperature falls 3 deg C- but then it takes 8 hours to warm up again, with the boiler running continuously. I have improved the comfort and reheating time by DIY internal wall insulation, which reduced heat loss by a factor of 8 and has only 12mm plasterboard to heat up. The party walls and partitions stay warm and the house warms up in an hour.

            The problem with older houses is that it is impossible to fix 150mm of foam insulation to the external wall and maintain the facades in narrow streets. Also the roofs may have to be extended. Room sizes are already inadequate and 150mm or more internal foam insulation is also unwelcome. The government has chosen to increase standards for new housing to a point where building is expensive or impractical, and encourage the easy measures, such as thicker loft insulation and better boilers. However the major problem is wall and suspended floor insulation. Draughts up chimneys and around doors also tend to be ignored. Wall insulation is not listed in the high cost measures in the government paper below.

            It is possible to fit foilbacked plasterboard with a cavity to cross battens with a multifoil quilt and a wall lined with foil and increase insulation by a factor of 8 over a solid 225mm masonry wall. This is inexpensive- but illegal. Regulations require a higher standard and the UK and Germany boffins do not recognise multifoils. They only count as the same thickness of fibreglass. Having built in an extension with a multifoil and 100mm fibreglass, I find that the room stays warm with no radiator at all. I have only had to fit one to keep the inspector happy. No wonder the Greendeal is a failure, as owners are forced to use an approved contractor and the cost can be up to £10k for a small house, with associated loss of space.

            And so the 88% of housing remains with the main elements of the structure uninsulated, while with much higher bills are on the way- and the smart grid is looking more and more like a decchead’s dream.

          • Alex says:

            Having a large thermal mass does not save energy. It just allows you to time the delivery of the energy. As I’ve found out, it’s a pain if you go away for a week’s skiing, and the house is 11C when you get back, and takes 2 days to reheat. That is what we have the wood stove to help with – and also as insurance in case gas or electricity gets cut off. Wood stoves are ideal for this, but we wouldn’t want them to be used too much.

            UK housing is a pain as you say, with a replacement rate of 0.5% per year or so. That still means though by 2050, 20% of homes will have been built to post 2013 Part L building regs. Overall, we’ve assumed the same gradual improvement, which still adds up to quite a lot by 2050.

            Figure 5 illustrates what will happen if we don’t hit, or exceed, the 196W/C/Home target.

          • steve says:

            In MacKay’s SEWTHA he finds that in, high density urban housing, both air and ground heat pumps do not work as well as elsewhere. They are cooling too little air and soil. I do not have my copy with me to give refs. This is relevant to much of British older terraced housing and flats.

          • Alex says:

            If I recall right – Mackay demonstrated that a city area will freeze the ground if everyone uses GSHP. The solutions to that would be to:
            1. Improve insulation, so less heat is taken.
            2. Run a bit of air con in summer
            3. Run ambient air through the ground in the summer. This starts to take on inter-seasonal heat transfer concepts – so for example, you could run water under a black asphalt street and into the borehole, to warm the ground to a modest 20C, so that the heat pumps work much better in winter.

            Air source heat pumps need some separation from the neighbours wall. Siting may be a problem in old terrace rows.

            If only we could knock these down and build something decent ….

          • steve says:

            Also a good source-

          • steve says:

            I went to stay in Tavistock last weekend, when the weather was cold and a lot of the green welly squad had lit up their wood burners. My greeny son asked what the smell was as he has an allergy and avoids polluted cities. There were far more particulates and NOX in the air than in Oxford St.

          • gweberbv says:


            I would expect that a building from 1960 is not better than one from 1860. In Germany it will be most probably even of less quality because of after-war shortages. Only after the first oil crisis governments and people start thinking about energy efficiency.

            It is not true that you cannot preserve the ‘look’ of a house when you cover the walls with insulation. This is the building I am working in:
            This is what it was looking about 10 years ago:
            In the meantime it got about 15 cm of insulation. But you really have to take a close look to notice the difference.

          • steve says:

            gwe. You are right about some 1960s houses being worse than old ones. From 1920s to 1960s they were built with double brick or dense block cavity construction with twisted steel ties. the cavities are always draughty and the insulation worse than a solid 22cm wall.

            The insulated building you show is a large detached block with a big roof overhang. In the UK big blocks of flats and schools have been insulated successfully too. However, small houses in narrow street with small roof overhangs, and drains beside the wall are more difficult.
            Also, the owner has to pay £10k+ and will not see a payback in a very long time. If I decide to insulate the back of my house, I will have to pay the council for planning and building regulation approval, costing another pile in order to have some ignorant …. tell me what I have to do.Are building inspectors as big a pain in Germany?

  5. OpenSourceElectricity says:

    You could also use more modern equipment for heating, e.g. a heat distribution which works with 30/27°C and a warm water system which works with 45 °C in storage and a heat exchanger to heat up the drinkable water while flowing threw.
    Both bring up the COP, to about 3 for -10°/30°:, and for warm water to 2,3 (-10°/45°C)
    Well designed heat distribution systems + warm water equipment are crucial for using heat pumps efficient.

  6. Euan Mearns says:

    Alex / Andy,

    I guess Figures 14 and 15 caught my attention. If I read correctly about 6% of days have average daily demand >100GW meaning that we need 20 GW on standby to be used for only 6% of the time.

    How does this compare with current?

    I think the problem lies in electrification of heating. Today we use a store in the form of nat gas and when its cold draw down storage more quickly. Our boilers / furnaces run more for heating as the mercury plunges.

    And how does peak daily demand relate to mean daily demand. maybe you answer that in the post?

    • Alex says:

      This is the same pareto anaylsis applied to 4 years of gridwatch data, 2012 to 2015.

      On the one hand, this looks a lot easier. However, this is based on daily averages – and today there is no attempt to smooth demand over the day – other than economy 7.

      I’ll try it with the 5 minute intervals from gridwatch – but it’s 480,000 rows.

      You are absolutely correct that heating is the problem. At a guess, there are 30 million 20KW gas and oil boilers, providing a heating capacity of 600GW. But most of these only run 20% of the time even on very cold days.

    • Alex says:

      Here is the graph with a new green line added, which is based on 5 minute intervals.
      6% of the time, average daily demand exceeds 47.5GW.

      The current and future daily averages, max, min, stdev, and CoV are shown here:
      (this table is planned for part 3. Note this is 2015 only, which is somewhat lower than 2012-2015).

  7. Andy B says:

    Shouldn’t Figure 2 be GWh on the y axis? Pesky units always catching me out!!

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  11. Iain says:


    One point neglected is that space heating demand increases substantially with windspeed, due to air changes – draughts.

    The use of wind generated electricity could balance the supply/demand.

    • Alex says:

      Would that be the case with properly insulated homes – as we’re expecting in 2050?

      Building sealing and mechanical heat recovery are very cost effective forms of insulation and mean that space heating demand won’t vary with wind speed.

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