Consumer Premesis Thermal Storage

In the UK, domestic heating accounted for ~70% of the domestic power consumed in 2020 [1]. Less than 5% of this heat was produced by electricity in 2020, but this needs to change…

For gas-dependent countries, the move to renewable energy sources often implies electrification of heating. At scale this presents some challenges to electrical power generators and distributors, especially if the common-mode demand issue of heating are not mitigated by time-shifting electricity consumption as adoption of electic heating increases. Meeting these challenges will require investment in the grid infrastructure, but mitigation with flexible consumption also plays an important role in peak load shifting as well as minimising curtailment during low loads.

It should be noted first that heat pumps provide a very effective solution to electrification of heat and should be used whenever possible with average efficiencies of well over 300% becoming increasingly achievable. A well designed heat pump installation can provide sufficient capacity to heat some less well insulated properties, often without requiring major central heating upgrades and should be considered with the help of reputable installers. One of the few drawbacks of the most efficient heat pumpts is that their lower operating temperatures have limitations in hjow much energy can be easily stored. This means “common mode” electricity consumption is more likely to be at peak times and when carbon intensity and grid loading is at its highest. This can also lead to conflicts with consumer’s adoption of ToU tariffs that benefit users with EVs or other storage enabled facilities. However there are new thermal storage technologies that can provide sufficient thermal storage for at least hot water applications of heat pumps.

So there are some hard-trade-offs to decide when choosing an alternaitve to gas heating, but advances in buildings regulations, electricity distribution policies and standardised technologies can drive consumers to invest in electrified heating. e.g.

  • Building regulations disallowing gas boilers in new builds (e.g. 20XX!!!).
  • Air and ground source heat pumps are increasingly economic alternatives to gas and oil fired space heating with subsidies and diminishing price differentials between gas and electricity.
  • Smarter time of use (ToU) tariffs that incentivise using the cheapest and usually greenest energy. Dynamic ToU tariffs that track the sporadic, but predictable availability of low carbon, low cost renewables.
  • Demand-side response mechanisms and aggregation can potentially be passed on to consumers or heating product suppliers.

In cases such as smaller dwellings or those with large amounts of solar PV or limited budgets the adoption of directly heated thermal storage can be an attractive and effective choice for in reducing energy costs and carbon emissions of electric heating. Nearly all homes can support a water cylinder or other thermal storage product of some capacity, which could provide either or both hot water and space heating depending on the size of property. The relative ease with which thermal storage can be obtained for most homes in the UK, for example, provides a very large potential energy sink that surpasses any currently available grid-scale energy storage or vehicle-to-grid feed-in from EVs over the next 8 years and is one of the cheapest investments available.

The potential energy impact of even current levels of domestic thermal storage in hot water cylinders is both immense and technically practical. Using the example of the UK’s 28 million homes the following potential impact on demand flexibility could be made with relatively small investment:

Selecting a new type of heating system to invest in can be a difficult decision when overall running cost benefits are hard to predict. However there are some (often ignored) facts that should be taken into account when choosing an appropriate alternative heating system:

  • Running costs of time-shifted direct electrical heating can approach those of air-source heat pumps when the cost differential of peak and off-peak energy costs are accounted for.
  • Solar and other off-grid microgeneration is an increasingly attractive investment, particularly if energy can be consumed within the home before it is fed-back into the grid. Solar diverters also need to be smart to provide the comfort and capacity required to mimise running costs.

Commercial Factors

Consumer Premises Thermal Storage is unfortunatey in somewhat of a commercial vacuum. Though storage is popular with solar enthusiasts there are significant commercial barriers and promotional problems with the concept, particularly for aqueous varieties:

  • Will your plumber recommend electric heating when your gas boiler needs replacing?
  • Which OEMs will invest in high termperature water safety components and cylinder designs?
  • Will Dynamic ToU tarrif costs stabalise, become more regulated or attract better support from the government?

We have a developed an open source thermal storage cost and capacity calculator here to help work out some of the costs and comparisons for different thermal storage options, tariffs and other heating options. (Warning it requires a fair amount of knowledge to paramterise for a particular home, currently, but watch thsi space while launch a new version with some more user-friendly ways of setting it up)

inx develop thermal storage and heating system controllers that optimise energy consumption, cost and carbon emissions. We provide this service to OEMs to help them make products run greener and save their customers money. The optimiser optimiser can combine dynamic ToU tariffs (such as Octopus Agile) with micro-generated solar PV and optimise any form of energy storage. See the inx page for more details and to drop us a line if you have a product you can make greener with smarter technology.    

[1] Space and water heating in terms of equivalent tonnes of oil identified in table P6 of ECUK2021-Primary Energy Tables.