The role of Vehicle-to-Grid in GB
According to the National Grid ESO GB will increasingly depend on Vehicle-to-Grid (V2G) technology to help to counter the variability of renewable sources (primarily wind) when generating electricity by providing storage.
The details of how the figures we discuss here are arrived at are included in the FES 2021 data workbook. They assume a maximum V2G take-up of 45% of households by 2050.
The most recent release of ESO’s Future Energy Scenarios (FES 2021) includes a maximum V2G capacity of 19.5GW and a maximum V2G storage capacity of 139.5GWh. These are part of the Leading the Way scenario.
How useful would this amount of storage be?
Taking w/c 28 March 2022 as an example, wind had a poor week and frequently contributed little to the GB grid, as shown in the chart.
On the first day alone the deficit was over 700GWh.
In 2022 these huge deficits were dealt with by nuclear, gas and coal sources, together with interconnector imports and other sources including hydro and biomass. In that week the lights stayed on in GB.
How would this look in 2050?
Let's project that week’s wind and weather forward to 2050. What would the performance look like?
Wind capacity should have increased by a factor of 5, but demand will have approximately doubled (both according to Leading the Way). Take a look at the updated chart.
On the first day the deficit has now grown to around 1400GWh, which is 10 times the total V2G storage capacity projected for 2050.
V2G storage would have inadequate power to supply all of the deficit even for the duration of Monday morning. If all of its power were available it could provide almost half of the deficit for about 6 or 7 hours, then it would be exhausted.
If nuclear is still available - and allowing for the continued contributions of hydro and other minor sources - the lights would stay on until lunchtime.
If other sources are available – e.g. other storage and interconnectors - then the lights may be kept on for a few more hours, but currently projected quantities for these alternative supplies would not last for long.
And once the V2G users' batteries have given up their alloted amount, how long before they can be recharged when GB is in the grip of an extended wind lull, or even a sequence of extended wind lulls?
Would V2G happen like this anyway?
Given current and ongoing improvements to weather forecasting, if a forecast for low winds is made, how likely is it that significant numbers of V2G users would willingly commit a significant proportion of the energy stored in their EV batteries to grid use?
Wouldn’t V2G users be looking at the forecasts and thinking about getting to work for the rest of the week or taking a trip at the weekend?
Would available financial benefits be preferred to the ability to use vehicles?
Wouldn’t V2G be useful anyway, even if it’s only a small part of a solution?
It’s not only being presented as part of the solution. It’s being presented as most or all of the solution to dealing with the variability of renewable energy in GB.
The danger is that too much is being expected of it. Many are suggesting that it's the solution to the problem of variable sources.
But in reality it couldn’t help GB much at all.
What to do instead?
The use of variable and uncontrollable sources requires reliable backup sources.
Many other sources such as interconnectors are outside GB control, so can only be alternative uncontrollable (essentially variable) resources. Sometimes they will be available, sometimes thay won't. Look at our use of imports over the last year or two to see how that availability varies.
One reliable source would be dedicated storage. But to be reliable the amount required needs to be calculated in an adequate way. That has not been done yet.
Reliable sources also need to be paid for and put in place. That has not been done yet either.
Let’s take a look at what others have said in support of V2G either generally or specifically in relation to GB.
Some seem convinced that 100% take-up is possible.
That would be interesting in GB, given that out of about 32 million cars there are almost 12 million where the keeper has no private off-road charging location.
V2G would be a challenge if you were sharing a public charging location.
Could all the sharers do V2G at the same time?
How would that work?