This idea has been around for a while, and it's interesting to see it coming to fruition. Many, many years ago at uni we studied combined heat and power units (CHP), essentially boilers that would generate heat and electricity. The concept being that reducing the load on the electricity grid and generating power in-home would significantly change how we produce electricity in the UK.
Currently the power grid is (and has to be) designed to meet peak requirements, the example that was given while I was at uni (c30 years ago!) was that during half time in the FA cup final, everyone watching (c20million back in the day) would suddenly boil the kettle generating a huge peak load. Now things have changed and my kids hardly ever watch linear TV, I guess this scenario has changed, but the concept still stands!
Even just regular day to day use creates significant peaks, for example when it gets dark we all turn lights on, and typically domestic power usage is lower during the day with people being out at work. All this means that electricity usage is very uneven, meaning power grids have to be provisioned for way above the average load.
The chart below show average household demand (kW) across an average household in summer and winter. You can clearly see that there is a peak in the morning (around 8am) and another extended peak in the evening between 5-9pm. These peaks are 3x or 4x the usage compared to when most of us are sleeping (midnight to 6am)
Average UK household electricity demand against time of day for weekdays and weekends in mid-July and mid-January, as synthesised by the CREST Demand Model. No solar PV. Demands averaged over 5 weekdays and 2 weekends in each season, for 15,000 households. Data from - www.researchgate.net
What Vehicle to grid technology has the potential to offer is to smooth those peaks and troughs. Imagine that overnight or during the working day (domestic quieter periods) the grid charges EV's, and then in the evening we plug our cars in the power our houses, and then recharge during typical sleeping hours. Then our EV's become large portable batteries, helping smooth out peak loads.
This Yahoo article ( Link ) notes :
"A typical electric car can store between 70 and 80 kilowatt hours (kWh) of electricity, while a home typically uses about 15 to 20kWh per day"
This technology can also be extended covering power failures, although technology and legislation need to catch-up first before we can take advantage of this.
So if we can reduce the UK peak load, this means we need fewer power stations, which hopefully means more renewables, less reliance on energy importing, and lower greenhouse gas emissions.
Octopus should be commended on this initiative and hopefully it will extend to more EV manufacturers shortly.