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 2022 data workbook.
The most recent release of ESO’s Future Energy Scenarios (FES 2022) includes a maximum V2G capacity of 19.7GW and a maximum V2G storage capacity of 140.4GWh. These are part of the Leading the Way scenario. They assume a maximum V2G take-up of 45% of households by 2050.
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 about 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.
And once the V2G users' batteries have given up their allotted 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?
To be clear, it is not the National Grid ESO's intention that V2G should be used for longer term storage, so in this case there would be no intention that V2G would solve the supply deficit in the longer term, but it's very important to appreciate the scale of what V2G can do in comparison with GB's likely future supply shortages.
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?
With the current limited implementation and scale of V2G in GB surely we cannot be certain of what consumer behaviour will be in these situations?
Wouldn’t V2G be useful anyway, even if it’s only a small part of a solution?
It's clear from the above that V2G can contribute something, but it’s not only being presented as part of the solution by some.
The danger is that too much is being expected of it. Some are suggesting that it's the solution to most or even all of the problem of the variability of renewable sources in GB.
In reality V2G could help as short term storage, but in the medium to long term it couldn’t help GB much, if 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 they won't.
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?