Will the grid cope with all our homes becoming all electric?

As we all move away from gas appliances, mainly heating but also cooking, more and more homes will become all electric.

At a personal level we have recently changed to an all electric home replacing our gas boiler with an air source heat pump in a 250 year old semi-detached cottage by the sea in Scotland, but if everyone did that would the electric grid in the streets and towns need considerable expensive upgrading or not?

Clearly there will be different situations whereby homes are supplied by a variety of district heating schemes. These district heating schemes may utilise industrial waste heat or large communal heat pumps using for example geothermal energy in abandoned flooded coal mines. However there will be homes where these schemes may not be possible for different reasons.  

In this post I will assume the related issue of being able to supply enough alternative energy for the average winter months will be achieved. I will also assume that there is adequate additional national/regional energy storage for supply shortages due to weather related issues with our alternate energy sources that will also be developed. However even if we have the regional energy storage we still have to deliver power at peak demand times along the cables to people's homes and this in turn means solutions must be implemented at or within the homes. If we increase our peak demand in line with our additional electricity consumption we will fry these cables regardless of regional or national storage facilities. So as we move to all electric homes we must ensure our peak winter demand does not unduly increase. This is therefore the part of aiming towards net zero that is also in the hands of the home owners or occupiers. We can't just wait for governments or energy suppliers to solve this particular issue, though they can provide help for homeowners to do so by either grants or tariff incentives.

With this electrical network problem in mind I decided to find out how much extra demand on the grid our individual home would need to meet our personal demand in the depths of winter when all gas appliances were removed. Furthermore I wanted to do this in a way that was scalable:- a solution that a large enough percentage of the population could achieve. So a series of steps were taken over the last few years.

Step 1:-

D.I.Y. of basic draught proofing our old cottage with increased loft insulation to the Energy Performance Standards recommendations. 

This was achieved on a very low budget and it's a bit like “picking the low level fruit” that is an important starting point that is easily scalable. (We already had standard double glazing but didn't consider the very expensive external wall insulation)

Step 2:-

The installation of an air source heat pump (to water for radiators).

Link to common myths about heat pumps.

This step obviously increased our grid demand but due to the high efficiency of heat pumps this increase in demand is minimised. Heat pumps generate renewable energy from the outside environment (from air, ground or water) and this means their efficiency can be around 300% or more even in retrofit situations.

This is a big step and the most expensive but can be greatly helped with government grants. This may not be easily 100% scalable but in smaller homes or well insulated houses much cheaper air to air heat pumps may well suffice and can be fitted with less outside space requirements. Also, as we have done, if there is little space for a domestic hot water supply it is well possible to use a heat pump for space heating only and use a smart instantaneous heater for the DHW supply. If you use hot water carefully this can have huge advantages, reducing the cost and space requirements for a heat pump and allowing more homes to install one.

Step 3:-

Being all electric now creates the incentive to now consider load shifting by simply consuming energy at times of low demand.

 However whether or not you have a heat pump this can be a very effective zero cost step that many people can do to different levels.

When we are considering the increase demand on the network to people's homes that will decide if our network will cope, it is clearly the peak demand times in the daily demand cycle which peaks largely at 4 to 7 pm and in particular that peak in mid winter that needs to be addressed. If this is addressed (and also a smaller morning peak around 7 am to 9 am) then as far as the loading of the domestic network is concerned all other times are dealt with. (Note it is the demand power cycle that is relevant when considering the impact on the street network, although it is the supply/demand cycle that has the impact on the energy supply from the nation or region and the resulting tariff costs if smart tariffs are employed.)

The home occupier can reduce the peak demand by small changes in lifestyle:- putting devices such as washing machines over night and changing cooking times or if relevant shower times for example.

Here energy companies are presently incentifying customers to move their times of electric consumption by example from the use of smart tariffs; a great incentive to get a smart meter that can read your consumption every half hour if needed.

Step 4:-

Optimize the use of heating systems....

Link to weather compensation and temperature modulation.

....and in particular heat pumps, by using slow and steady heating incorporating weather compensation for the flow temperature of the water in the radiators or underfloor heating. This not only increases the efficiency of heat pumps but also shifts a lot of the electrical consumption out of peak demand times.

By completing these 4 steps it was likely that our personal electrical consumption was no higher than previously when we had gas heating. Not everyone may be able to achieve this due to restrictions of work or school schedules or building constraints but if some can go one step further then I believe we can collectively reach Net Zero without needing to upgrade the electrical grid to our homes in most situations:-

Step 5:-

Storing energy within the homes and place of the consumers.

Clearly if homes can import more of their energy by importing at low demand times and storing this energy for later use then this will have a major impact of balancing the grid on a daily cycle and further help our grid to cope in an all electric world.

Energy can be stored in hot water tanks for DHW or even by the use of heat batteries that can be used for both DHW and space heating with or without a heat pump. This means that on a daily level we are importing energy when supply exceeds demand but are also minimising demand at peak times. However a home electric battery can also be used to store energy and this has a number of additional major advantages. For this to be more scalable the battery needs only to be large enough to cover perhaps 4 or 5 hrs of evening demand in mid winter and the more of the previous 4 steps to reduce consumption have been taken the easier this will likely be manageable. (We find a 9.5kWh battery more than enough)

The advantages of having a home battery for storage.

A). A home battery can store all your electricity needs, not just heating, to supply energy over peak demand making load shifting not only easier but much more effective. So cooking, lighting, refrigeration and so on can also be eliminated from your import at peak times.

B). The battery can also be used to return energy back to the grid at peak demand times if not used in the home and so your individual demand is going below zero on average during peak times. (Of course unfortunately this will be far easier to do and maximised outwith winter when your own personal demand is smaller)

C). Relating to a different issue the same battery can be used throughout the year working well with solar panels to reduce your overall consumption. It is worth adding here that you may even be able to import energy when prices go zero or even negative and by importing energy when supply well exceeds demand you are playing a small part of incentifying energy companies (or governments?) to carry on creating more renewables.

In conclusion, what have we achieved in our home?

In what may be considered a fairly challenging retrofit home we have moved from gas appliances to an all electric (and more comfortable) home without extensive and very expensive external wall insulation.

Previously our largest rate of importing electricity was typically at peak evening times, but that has reduced to virtually zero in spite of being all electric.

Thus I believe that if we can collectively reach Net Zero with the energy supply then we can do so largely with the existing underground electric network in the streets to our homes. Clearly we don't need the majority of homes to achieve all these steps to balance the grid on a daily basis. There is no point in shifting the present peak time on the grid to zero but merely to even it to a fairly balanced daily level.

Smart tariffs, (in addition to some of the steps I have written here), that reward or penalise consumers will become more common and will be able to achieve this balance.