Notes on Demand Side Response
Increased electrification due to, for example, EV Charging and the transition from gas for central heating, will result in the requirement for an increase in the total supply of electric power but also in “bottlenecks” in the transmission system due to capacity limitation of existing infrastructure e.g. transmission cables at all levels, transformers and substations.
Stability of the electrical supply system requires that the supply and demand of power are maintained in balance. Achievement of the required balance between supply and demand can be greatly assisted by controlling the demand side to shift the timing of the demand for energy to level out the peaks and troughs of demand (shaving off the peaks and filling in the valleys).
2. Demand Side Response
Reduction of CO2 Emissions
At the busiest periods of peak demand, the additional generation that is the most carbon-intensive has to be put into use. By shifting demand to off-peak periods, the peak demands during the busiest and highest carbon intensity periods can be reduced, which limits the strain on the overall generation and distribution systems. Demand is shifted to make the best use of low carbon intensity generation, such as wind power through the night. The difference in carbon intensity between peak and off-peak periods can be 80-200g/kWh. This can result in a significant reduction of overall CO2 emissions.
On average, a house consumes 10kWh per day. If 3 kWh of power demand can be shifted from the peak hours to off-peak hours, this would result in an annual shift of 1100 kWh.
This would reduce a household’s carbon emissions by 88 – 220kg annually. If an average household could reduce emissions by 200g per year and 10 million households did the same, this would reduce 2 million tonnes of CO2 annually.
Reduction of cost of electricity to consumers
If a household is on a dual-rate tariff, such as Economy 7, and assuming a peak tariff of 43p/kWh and off-peak tariff of 25p/kWh, then this would result in savings for the average household of £198 in a year.
If a household has an EV tariff, with even lower off-peak tariffs, savings of more than £300 per year can be realised. Over 10 million households, this would result in savings of £3 billion in energy costs.
How to Shift Demand
Typical household appliance electricity usage:
Electric heater/stove: 1.5 kW - 4 kW per unit
EV charger: 3 kW - 7 kW per unit
Laptop charger: 30 - 90 W per unit
TV: 50 - 300 W per unit
Washing machine: 1 kW - 3 kW per unit
Dishwasher: 1 kW - 3 kW per unit
Depending on how long each appliance is in use, energy savings can be made by shifting the time of use from daytime to nighttime.
This could be done manually or using “smart” appliances. Many current appliances on the market do not have the “smart” features that allow control over the time of use.
Existing “Smart Meters” are not really smart as they do not take any control actions and only possess the ability to measure, record and transmit data about power/energy usage without physically attending to and recording meter readings.
However, control can be achieved by controlling the access to electric power using “smart plugs” or “smart circuit breakers”, which will be controlled by the AllGreen App currently under development.
It may not be convenient to shift the time of use of all appliances in the household. In this case, demand shift can be achieved using battery storage. The battery can be charged up during the off-peak time and power appliances during peak times.