[petejh]

Entitled..? Not sure what your problem is with being asked to provide details about a topic that you suggested you know about but hadn't given any details.    Whatever your problem, apologies for asking you for any details. And thanks for the details!

I looked up the national grid's site earlier, it gives a similar overview of the same thing as your link. Including the interconnectors with Ireland and France. grid.iamkate.com

Yesterday's real time electricity demand versus generation for the UK grid.




Plus historical averages that show difference between day/night. That big U-shaped dip in night time demand on the half-hourly chart will be flattening out when the whole country are required to charge their EVs overnight between 10pm - 8am.


For UK solar, you can see on average over the past month it made up 5% of supply. Over the past 12 months solar made up 4% of UK supply. Coal 1.8% and Biomass 4% of average annual UK supply.

If overnight demand is going to increase significantly - which must be true if EVs are to be rolled out in scale and charging them has to take place overnight to avoid the grid falling over during the day - and at least 5% of average UK supply isn't available overnight, then it stands to reason something will need to take up the slack. Increased windfarm roll-out as you say. But on those nights when the wind doesn't blow it might need to be gas, biomass, might be some coal, or might be nuclear. Just something interesting to think about.

[ben]

Yeah, I would expect us to have apps where we can choose what % of charge we're prepared to go to on different days, times etc, plus more variable tariffs for buying/selling elec to the grid (possibly push notifications of price spikes to let you adjust on the fly?), options to set a "needs to be fully charged by this time in the morning" etc... not as fun as moving to Southern France though.

I'm with Bulb and am trialling their beta  EV charging app, it lets you do just that.. state you want an x% charge by say 8am and it delivers that, theoretically as cheaply as possible as they can turn it on/off throughout the night to suit them

[Fultonius]

Pete, iirc the average UK daily drive is 20 miles. Let's take an estimate of 0.24kwh per mile, that means each EV needs 4.8kwh.

Say there are 30m EVs, that's 144MWh (jumped to mega there). Or, 14MW for 10 hours. I.e. 2 big wind turbines. *its early, I've not yet had coffee and something seems instinctively wrong about this... I'll double check later.

An average household uses about 4-6kwh per day.

I was at a talk 2 years ago with the head of future strategy at national grid. She was veery positive about the benefit of EVs for the grid.

Think of it another way, imagine you're off grid. Of course you would use your EV to supply your peak demand. Basically the grid will be getting around 40-50kwh of free battery storage on every household!

It's the long windless cold winter weeks that are the biggest challenge for renewables and storage.

[SamT]

Why have you jumped to Mega Watt Hours??

0.25 kWh * 20 miles * 30 cars = 150 kWh non?

[Fultonius]

Just to be confusing....

Using 0.25 kwh/m was a nice touch - I like that, makes the sums easier...

Ok, so 30 million cars =  150,000,000 kwh or 150 Mwh.

Let's assume for the sake of argument each car would need fully charged in 4 hours, and eveyione has a bi (70kwh) battery):

Each Car   requires 70kwh per day.

Assmuning 30m million EVs, Total UK   2100000000   kwh     (or 2100MWH   per day)
Assume 4 hr charging 525  MW   generation required (ignoring losses etc.)

[Carl]

Say there are 30m EVs, that's 144MWh (jumped to mega there). Or, 14MW for 10 hours. I.e. 2 big wind turbines. *its early, I've not yet had coffee and something seems instinctively wrong about this... I'll double check later.

Off by 1000x I think!
https://www.wolframalpha.com/input/?i=20+miles+*+0.24+kWh%2Fmile+*+30000000

[SamT]

Ahh - 30 million cars - sorry missed that.   

(did wonder why you'd chosen 30 cars - 1 street maybe  )

[SamT]

I think the whole decentralised battery storage network for peak lopping via charging cars is actually a goer.  Heard it talked about in lectures 10 years ago, way before anyone imagined so many EV's would be on the road.

The numbers of cars that are actually on the road at anyone time, compared to those parked up are small, and you only need to borrow a small amount of energy from each parked/charging car to cumulatively provide a large amount of energy for peak lopping.

Same sort of thing can be achieved by turning everyones freezers off for 15 minutes during a peak event.  Nobodies really going to notice but the cumulative effect can be huge.

[Fultonius]

Say there are 30m EVs, that's 144MWh (jumped to mega there). Or, 14MW for 10 hours. I.e. 2 big wind turbines. *its early, I've not yet had coffee and something seems instinctively wrong about this... I'll double check later.

Off by 1000x I think!
https://www.wolframalpha.com/input/?i=20+miles+*+0.24+kWh%2Fmile+*+30000000

   doing maths pre    yes, that's why my "that doesn't seem right" alarm bells were running. It was my jump from KWH to MWH where I divided by 1E6 instead of 1E3.

So.....  aye.... quite a bit more haha!  14.4GW required.

[petejh]

Say there are 30m EVs, that's 144MWh (jumped to mega there). Or, 14MW for 10 hours. I.e. 2 big wind turbines. *its early, I've not yet had coffee and something seems instinctively wrong about this... I'll double check later.

Off by 1000x I think!
https://www.wolframalpha.com/input/?i=20+miles+*+0.24+kWh%2Fmile+*+30000000

Come on a sense check would show a couple of turbines are not going to be able to charge 30 million EVs overnight! But that's what this is useful for right, to get a feel for what's lacking and what's going to need to happen about it.

Also.. The concept of an average drive only being 20 miles is just that - a concept, not a useful baseline to plan generation capacity for dealing with real life EV-recharging behaviour. Ask yourself if you'd happily always drive around in your car with only 20 miles in the tank? That's on the light. Hardly anyone is happy doing that all the time, people like to feel they have some buffer for the unexpected.
The same attitude to refuelling can be seen with batteries. Look to your phone or laptop - the reality is that when people's phone battery gets a bit low they put it on charge. When the laptop isn't in use it's often plugged in. It's also also why people buy groceries for more than the next 4 hours consumption. Just one toilet roll..?

Clearly behaviours and attitudes to personal transport are going to have to change. I love the ideas and possibilities the transition opens up - decentralised battery storage feeding back to grid for one. But refuelling of cars/vans/trucks via electricity generation shouldn't be based on theoretical minimums that will never be the case in reality. What happened to over-engineering?!

Perhaps if you doubled the theoretical minimum required charge to 40 miles that would reflect something closer to the reality of people's charging behaviour. Lots of overnight generation required...

[nik at work]

Not sure I follow you there Pete. If the average distance a vehicle travels per day is 20 miles then it make no odds whether that 20 miles is charging the battery from 0 mile range to 20 miles range or from max range minus 20 miles to max range? Once the “buffer” is loaded in (I.e. the first full charge) then all subsequent charges will be simply replacing what was used the previous day, which on average will be 20 miles per EV (I’m assuming that the 20 miles figure has a reasonable basis, and accept your point re: a bit of over engineering). Have I misunderstood your point?

[SamT]

Also Pete.. any networked storage type system is not going to borrow or discharge your batteries below a certain point.. say 80% full.   So nobody is going to wake up in the morning to a flat car battery/low range.

[petejh]

* Instinctive answer would be a 10-15% of full charge automatic cut-off. Cut-offs can work both ways right.

Exactly. I already said this ^


Nik, yeah that would seem to make sense. It's still currently a huge overnight energy demand just at 20 miles worth of charge, as shown.

Also the generation requirement might/probably will drop with battery tech improving for EVs and for other large-scale battery storage schemes.

[andy_e]

I wrote out a long post about energy transition technologies, energy storage etc., but it didn't seem to actually post, so I'll precis it again here...

Renewables isn't just solar and wind, which have intermittent supply, but also emerging technologies like tidal current power. Excess energy generated during sunny or windy periods also has huge potential for storage that is not yet being realised, as compressed air, green hydrogen, pumped hydro, mineshaft gravitational, and others I forget. District heating schemes storing excess energy as heat in shallow geothermal and abandoned mines will also reduce the electricity demanded for heating. Even ignoring nuclear, interconnectors provide potential to boost renewables supply by connecting grids that experience different weather patterns, so if the UK or Irish offshore wind is having a bad night, then perhaps the Baltic offshore wind may be generating an excess that we can buy. So the whole problem of "it's not sunny at night" isn't really a problem from a supply point of view.

However, the energy transition and technology isn't going to solve the climate crisis without societal change as well. The point about people travelling less and or taking public transport, which was dismissed in a privileged manner, is actually important. The ludicrous situation in the UK is that public transport is overpriced and inefficient. It should not be cheaper and faster to drive somewhere than take the train or bus. Things are slightly better in mainland Europe, where train travel is largely quick, comfortable, and an absolute joy. Public transport is just one of the myriad ways that more efficient transit networks and a reduced reliance on EVs will reduce the electricity demand that the projected numbers on this thread are based on. There also needs to be a shift in attitudes towards active and assisted active transport. E-Scooters, E-bikes and the like are going to be hugely important in travel within cities (e.g. commuting), and place a far lower demand on electricity supply and, importantly, pollutnats from tyres, space taken by parking, and congestion, within city centres.

[remus]

While I agree with your overall point I think it's worth noting that the below all come with big caveats. Tidal power has proven to be very hard to do on any sort of scale and large scale energy storage has also proven to be very tricky so far (e.g. green hydrogen has huge energy losses, pumped hydro is too dependant on geography, mineshaft gravitational storage is a complete non-starter when you do the energy density sums).

Renewables isn't just solar and wind, which have intermittent supply, but also emerging technologies like tidal current power. Excess energy generated during sunny or windy periods also has huge potential for storage that is not yet being realised, as compressed air, green hydrogen, pumped hydro, mineshaft gravitational, and others I forget. District heating schemes storing excess energy as heat in shallow geothermal and abandoned mines will also reduce the electricity demanded for heating.

[andy_e]

Yep, fair enough, but like all emergent technologies things will improve. Hydrogen is an interesting point as it depends entirely on its use as to how efficient it is as an energy store/fuel. Using hydrogen for heating/cooking/vehicle fuel is not good at all, but using stored hydrogen in industrial applications, especially close to the point of storage, gives far better returns.

Pumped hydro is far less dependent on location than you may think, as pumped hydro within abandoned mine infrastructure is simple and relatively cheap, and calculations that were done as part of a postdoc I was involved in shows significant potential capacity in the UK in areas like South Wales, east of the Peak, Yorkshire, Tyne-Tees, and the Central Belt. Pumped hydro can also be combined with minewater thermal energy storage, which is nice! Pumped hydro is also possible in specially-created caverns, but this proves far more expensive.

[SamT]

The whole mineshaft thing comes up regularly on UKcaving and is always debunked dispelled.

Always looks like a potential on paper, but the realities of finding viable shafts/sites rules the vast majority out.

[andy_e]

Interesting, debunked/dispelled by whom? There are proven schemes in the Netherlands, Glasgow, and the National Coal Mining Museum.

[petejh]

The whole mineshaft thing comes up regularly on UKcaving and is always debunked dispelled.

Always looks like a potential on paper, but the realities of finding viable shafts/sites rules the vast majority out.

The gravity storage in mineshafts idea was covered in one of the episodes on the 39 ways to save the planet programme, here: https://www.bbc.co.uk/programmes/m000z1k0

It sounded like the UK would be minor local-scale stuff. They were talking about schemes under construction in Poland on a much larger scale.

Gravitricity (the company on the 39 ways programme) website mentions them scoping out S.African mines: https://gravitricity.com/

[remus]

The whole mineshaft thing comes up regularly on UKcaving and is always debunked dispelled.

Always looks like a potential on paper, but the realities of finding viable shafts/sites rules the vast majority out.

The gravity storage in mineshafts idea was covered in one of the episodes on the 39 ways to save the planet programme, here: https://www.bbc.co.uk/programmes/m000z1k0

It sounded like the UK would be minor local-scale stuff. They were talking about schemes under construction in Poland on a much larger scale.

Gravitricity (the company on the 39 ways programme) website mentions them scoping out S.African mines: https://gravitricity.com/

I haven't listened to the podcast, but the numbers on their website are pretty unconvincing. They mention

"A wider portfolio of future commercial sites has also been developed, which confirms significant potential for over 10,000MWh of energy storage capacity to be deployed globally in existing shafts alone." https://gravitricity.com/projects/

Which means they're predicting a total global capacity of 10GWh...which is about the same as Dinorwig. Maybe there's some niche use cases but it's not gonna solve energy storage on the kind of scale that's required.

[petejh]

Yep the podcast said pretty much the same, local small scale use. Interesting idea though, and might lead to other interesting ideas.

[SamT]

Interesting, debunked/dispelled by whom? There are proven schemes in the Netherlands, Glasgow, and the National Coal Mining Museum.

That's heat pump tech using warm water from flooded mines, which is ace.. I was referring to the whole dropping heavy weights down shafts at peak grid events.

Basic fag packet calcs plus a knowledge of 'actually suitable' sites usually concludes that the potential is minuscule.  Mainly because a lot of the mines are now flooded.. which is where the heat pumps come in!!

[andy_e]

Ah! Fair enough. At scale as a single solution then yes they're not great. but as part of a wider energy storage network then they can be valuable local assets. Gravitricity are at some stage of connstructing one in Leith, which will be interesting to see how it goes.

[teestub]

Was interested to see that the demand for electricity in the country had reduced substantially over the last decade, as another factor to throw into the generation requirement calcs. I’d never really considered this with growing population etc.
https://www.statista.com/statistics/323381/total-demand-for-electricity-in-the-united-kingdom-uk/

[Fultonius]

Say there are 30m EVs, that's 144MWh (jumped to mega there). Or, 14MW for 10 hours. I.e. 2 big wind turbines. *its early, I've not yet had coffee and something seems instinctively wrong about this... I'll double check later.

Off by 1000x I think!
https://www.wolframalpha.com/input/?i=20+miles+*+0.24+kWh%2Fmile+*+30000000

Come on a sense check would show a couple of turbines are not going to be able to charge 30 million EVs overnight! But that's what this is useful for right, to get a feel for what's lacking and what's going to need to happen about it.

I know, I know. I was busy walking to the shop to pick up stuff for breakfast, typing on my phone and doing it in my head pre-coffee. Notwithstanding....I can't believe I actually typed that.    If you ask my other half I'm very smart:stupid!

The little bit of my brain say "wait a fuckin minute here" was evidently still asleep.

Also.. The concept of an average drive only being 20 miles is just that - a concept, not a useful baseline to plan generation capacity for dealing with real life EV-recharging behaviour

Others have already commented, but this wasn't what I was intending to mean. 20 miles a day is the current average, not a concept. So that's still the average amount needing topped up per day. We currently have way more capacity than we would need if our demand was better spread. Yes, making use of the solar by charging during the day is ideal, but 2-way charging and shaving the peaks is clearly the way to go.