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Storing electricity

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We are often told by politicians, especially those who are climate change sceptics, that the big problem with renewable energy sources is they’re intermittent nature. As well as times when all our renewable resources don’t meet the demand there are also times when wind generators stand idle even when wind is available. Would it be feasible to direct surplus solar or wind energy to create hydrogen as a means of storing energy?

In reply to Rog Wilko:

It's one way, though another Dinorwic or batteries are probably more efficient.

In reply to Rog Wilko:

I’ve just noticed there’s another thread which is discussing this possibility. Sorry to duplicate.

 Strachan 24 Oct 2022
In reply to Rog Wilko:

Yes, look up “Power to Gas”. This, and the reverse, as well as other forms of vector coupling and Energy Systems Integration have received a lot of attention from Energy Systems researchers in recent years. One interesting area is producing and storing hydrogen offshore from surplus renewable energy generated in that environment, allowing transport and distribution via ship/tanker (like gas) rather than requiring expensive and complex subsea HVDC power grids. This isn’t my area of expertise, and there are obviously a lot of challenges in efficiency (converting to H2 and then back to electricity) and practicality (not least the production of chlorine has when electrolysing seawater to make hydrogen), but it’s an exciting area. Arguably it is better to use renewable power to produce hydrogen or other combustible fuels for drop-in replacement of gas in difficult-to-electrify applications (some heavy industries, or aviation, for example).

 wercat 24 Oct 2022
In reply to Rog Wilko:

or compressing air on a vast scale?

In reply to Rog Wilko:

Certainly possible. The question is always is it efficient enough to be worth doing over other storage methods. From memory, electrolysis to produce hydrogen is bout 80% efficient, your bigger issue is storing hydrogen as it's a very light molecule and quickly escapes. The other thing you need is some way of turning the hydrogen back into electricity or used some other way. Currently, we don't have that infrastructure.

Another option for storage is pumped hydro wich is also something like 70-80% efficient and has the added benefit of being able to quickly contribute to the grid in times of demand.

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In reply to Andy DB:

> Another option for storage is pumped hydro wich is also something like 70-80% efficient 

?!

 kevin stephens 24 Oct 2022
In reply to Rog Wilko: its not just politicians that tell you that but engineers too. Conversion of electricity to hydrogen is only 65% to 75% efficient, you would lose a similar amount to convert stored hydrogen back to electricity in a fuel cell, or worse if burning the hydrogen in a combined cycle gas turbine/steam turbine generator, so maybe 50% efficiency overall at best, a lot worse than pump storage. That’s not including the large amount of energy that would be needed to compress the hydrogen for storage. Current energy storage options such as pumped storage and batteries are very cost effective for short period fluctuations in demand  over a few hours at most but would be impractical and incredibly expensive to provide cover for a few days’ winter high pressure centred over the UK

On a positive note there’s a lot of scope to increase wind generation in the UK so long as you accept the need to fall back on reduced amount of gas generated electricity on non windy days. Indeed it could be argued that some gas fired generation makes investment in more wind generation financially viable

 elsewhere 24 Oct 2022
In reply to Strachan:

Someone I know who works with the wind turbine companies mentioned generating hydrogen offshore. I don't really understand as cabling to send energy ashore as electricity seems much easier than using pipelines for gas and it's already there for the turbine. Maybe hydrogen stored offshore to generate electricity offshore when renewables lacking. Hence stored energy is sent ashore as electrcity.

 elsewhere 24 Oct 2022
In reply to Andy DB:

I did the tourist visit to Cruachan, it's only 550MW ish and one of only 2 pumped storage locations in UK. Apparently our geography just isn't right - not mountainous enough for our population density.

Post edited at 23:12
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 Strachan 24 Oct 2022
In reply to elsewhere:

As I say, I’m not an expert in this sort of thing but my (potentially flawed) understanding is that there are a few possible advantages:

- storing large quantities of hydrogen represents a significant hazard in terms of explosive potential - better done offshore out of harm’s way.

- connecting offshore renewables to the grid isn’t just a case of running a cable; high voltage direct current (HVDC) infrastructure is needed to effectively and efficiently get the power to the onshore grid, and this is a still-developing, expensive, complex technology (even before you get to connecting individual e.g. turbines in a larger array). The power converters etc required to transfer HVDC to the AC grid also represent a non-trivial challenge/ investment/ complexity.

- converting to hydrogen offshore may be more efficient than incurring the efficiency losses associated with transferring electricity over long-distances first (e.g. to shore).

- a fuel, as opposed to electricity, can be moved and stored by e.g. a ship, which for some use cases has advantages.

in other words, it’s not necessarily about transferring a vector to shore directly, whether by cable or pipeline, but rather about dispensing with that kind of infrastructure altogether. As you say though, having an electrolyser and fuel cell co-located offshore potentially solves the storage issue (albeit with efficiency losses) whilst avoiding the need for costly pipelines.

 LastBoyScout 24 Oct 2022
In reply to Rog Wilko:

I've seen one example of storing electricity as potential energy in hoisting large blocks of concrete - sort of a solid form of pumped storage.

In theory, it's simple, but you need an awful lot of infrastructure to bank any useful amount of power.

The problem with batteries is that there's only so much lithium, cobalt and so on available and it's in demand for electric cars.

 Maggot 25 Oct 2022
In reply to LastBoyScout:

> I've seen one example of storing electricity as potential energy in hoisting a large lard arse Johnson - sort of a solid form of pumped storage.

In reply to elsewhere:

> ... and one of only 2 pumped storage locations in UK. Apparently our geography just isn't right

I can think of Dinorwig 1,700 MW and Ffestiniog 360 MW so there are definitely more that 2 in the UK

 > ...mountainous enough for our population density.

Well it's not great but there are actually loads of places that fit the bill if you consider only the physical geography. I mean just sticking to Snowdonia - Cwm Idwal would be great geography, Cwmorthin too for upper reservoirs. Llyn Llydaw to Llyn Gwynant. We're not short of locations. But the issue is more that a lot of the most suitable places are protected national parks and in locations you really wouldn't want flooded or changed.

One location that has been considered since 20s for hydro is Cwm Croesor. Just up from the village there is a natural constriction in the valley so it's 2/3rds dammed already for a reservoir. Rhyolite is terrible for Dams (note: Teton Dam disaster) but this is shallow enough to be OK if constructed carefully and could be a reservoir of a pumped storage scheme. There would be opposition for obvious reasons (loss of beautiful unspoiled valley and farm land), but the location is on the list of places actually considered, I wouldn't support it though!

Post edited at 06:56
In reply to LastBoyScout:

> I've seen one example of storing electricity as potential energy in hoisting large blocks of concrete - sort of a solid form of pumped storage.

Ive seen it suggested that we could use disused coal mine shafts for this, though how many of those still exist I’ve no idea.

 kevin stephens 25 Oct 2022
In reply to Rog Wilko: this and all the other suggestions can only provide SHORT TERM storage of an hour or two, not the long term storage of days and weeks needed to be wholly reliant on renewables

Post edited at 07:43
In reply to CantClimbTom:

What about the clay country around St Austell in Cornwall? Several square miles of open-cast mining pits, the Eden Project being in one. As each of them ceases to be worked, could it not be used as the upper reservoir for pumped storage, perhaps eventually connecting them all (excepting the Eden Project!) as one, with the sea as the lower one?

If memory serves me right, I think the topography of parts of the west coast of Ireland lends itself to this version of pumped storage, using the sea as the lower reservoir, and there are ideas mooted in Denmark, and elsewhere for all I know, of getting pumped storage by exploiting the hydraulic pressure of deep trenches near coastlines. Could we use that bomb filled trench between Scotland and Ireland?

 ianstevens 25 Oct 2022
In reply to CantClimbTom:

> (loss of beautiful unspoiled valley and farm land)

Can't have both.

 Mike-W-99 25 Oct 2022
In reply to CantClimbTom:

> I can think of Dinorwig 1,700 MW and Ffestiniog 360 MW so there are definitely more that 2 in the UK

Foyers & Cruachan.

 mondite 25 Oct 2022
In reply to kevin stephens:

> this and all the other suggestions can only provide SHORT TERM storage of an hour or two, not the long term storage of days and weeks needed to be wholly reliant on renewables

Thermal energy storage is an option there and more flexible on location although not sure about size.

 Jim Lancs 25 Oct 2022
In reply to CantClimbTom:

> I can think of Dinorwig 1,700 MW and Ffestiniog 360 MW so there are definitely more that 2 in the UK

Yes there's four. The two in Wales and the two in Scotland (Foyers & Cruachan ).
 

 jkarran 25 Oct 2022
In reply to Rog Wilko:

> We are often told by politicians, especially those who are climate change sceptics, that the big problem with renewable energy sources is they’re intermittent nature. As well as times when all our renewable resources don’t meet the demand there are also times when wind generators stand idle even when wind is available. Would it be feasible to direct surplus solar or wind energy to create hydrogen as a means of storing energy?

Yes, grid scale H2 production is a front runner for storage. There are lots of ways of storing energy though each with their own strengths and weaknesses, each with their own costs and inefficiencies.

One very interesting scheme I've seen proposed ,which we're fast missing our chance to implement, converts existing large scale coal plants into storage. Reusing their assets: space, turbines generating and cooling infrastructure by replacing the boilers with huge nuclear/renewable heated thermal batteries (insulated silos of crushed basalt). Grid scale storage on the (relatively) cheap, slashes pollution, maintains the employment and communities the coal-power once supported and extends the life of a valuable asset with existing grid connections sized to suit its capacity.

The problem of windmills standing idle rather than displacing gas or topping up storage is an economic one, it will need to be addressed if we're to turn new grid scale storage from a buy low, sell high money making scheme with resilience benefits into a genuine decarbonisation tool.

I still think as electricity supply and use patterns evolve we are probably overstating the need for medium term grid scale storage somewhat, I think a lot of that capacity can be delivered through smart consumption. Currently, most of the electricity we consume is used as it's consumed, that won't be the case in a future of widespread EVs and heatpumps. With those you can retain the functionality while allowing the system some freedom over what it consumes and when. Storage doesn't have to return energy to the grid to be effective so long as there is a lot of it connected and behaving in a desirable manner.

jk

 jkarran 25 Oct 2022
In reply to LastBoyScout:

> I've seen one example of storing electricity as potential energy in hoisting large blocks of concrete - sort of a solid form of pumped storage.

You can do it under water where there is a lot more space and in reverse too with buoyant 'loads'. Options like this seem a decent match in scale for deep-water turbines to increase their utility but they do mess up the economics by adding cost and potentially driving down the energy available to sell at peak prices.

> The problem with batteries is that there's only so much lithium, cobalt and so on available and it's in demand for electric cars.

The EV market will very soon start returning those resources to the market, cars have short hard lives. Most will go in the form of batteries/cells to fixed storage where degraded energy density is less important rather than being more fundamentally recycled to begin with at least.

jk

 jimtitt 25 Oct 2022
In reply to jkarran:

The problem with most solutions are as usual the numbers, you need 40 Dinorwics just to charge the UK's HGV fleet when it goes BEV and they don't want to stop while you fill the ponds up again. In fact they will be using the excess power instead.

In reply to jkarran:

> You can do it under water where there is a lot more space and in reverse too with buoyant 'loads'. Options like this seem a decent match in scale for deep-water turbines to increase their utility but they do mess up the economics by adding cost and potentially driving down the energy available to sell at peak prices.

Doing anything in the sea with moving parts is ridiculously expensive compared to doing the same thing on land. You'd need lots of sheltered water and no land to use instead to even consider it.

 Ciro 25 Oct 2022
In reply to kevin stephens:

> this and all the other suggestions can only provide SHORT TERM storage of an hour or two, not the long term storage of days and weeks needed to be wholly reliant on renewables

Not true - in the North sea we have huge potential storage chambers for hydrogen gas (that we previously took fossil fuels out of). 

If we develop the production capacity, we can create huge reserves of gas and have the pipeline infrastructure already in place to transport it at high volume to the onshore energy generation facilities.

It's a long term solution that could tide us over until the physicists crack fusion.

In reply to Rog Wilko:

I think it's going to be some time before we get to this place of 'excess wind power requiring storage' - UK lowest demand is ~20GW and peak wind generation is ~15GW according to Gridwatch. The interconnectors with Europe will also absorb a couple of GW.

 jkarran 25 Oct 2022
In reply to Toerag:

> Doing anything in the sea with moving parts is ridiculously expensive compared to doing the same thing on land. You'd need lots of sheltered water and no land to use instead to even consider it.

Yet we're filling our costal waters with turbines in addition to all the fossil fuel infrastructure in significant part because we don't like to live around this stuff. If some of it is there already it potentially cuts the cost of the next bit.

As I alluded to earlier, I don't think we'll actually end up with as much grid scale storage as some people assume but the options available are varied.

jk

Post edited at 10:32
 jkarran 25 Oct 2022
In reply to jimtitt:

> The problem with most solutions are as usual the numbers, you need 40 Dinorwics just to charge the UK's HGV fleet when it goes BEV and they don't want to stop while you fill the ponds up again. In fact they will be using the excess power instead.

Obviously the numbers are big but we can't keep ignoring the problem forever.

I think the point you're making somewhat obliquely is that there are some big fixed loads (a fully electrified HGV fleet with its high duty cycle being one of them), that those loads (domestic heating being the other obvious example) will require a lot of storage to get us through longer lulls. Realistically too much. I agree.

I expect we'll need a significant new round of nuclear builds and a lot of mostly offline gas CCGTs to make it work (whatever they burn, probably fossil gas for many years yet).

jk

 Mike Stretford 25 Oct 2022
In reply to Rog Wilko:

> We are often told by politicians, especially those who are climate change sceptics, that the big problem with renewable energy sources is they’re intermittent nature.

Yep, and they'll tell you that fracking is the answer even though there are more uncertainties over shale gas in the UK than there are over the emerging energy storage technologies.

> Would it be feasible to direct surplus solar or wind energy to create hydrogen as a means of storing energy?

Yes. Economic feasibility will depend on hydrogen>electricity efficiency. The turbine manufacturers are all working on this eg

https://www.nature.com/articles/d42473-020-00545-7

For medium term storgae battery technology looks promising. Form Energy's Iron-air is one to watch.

https://formenergy.com/

There's a pilot liquefied air storage prototype in Carrington, will be interesting to see what efficiencies they get as that will also be good for medium term storage.

We will need to go big with these, and we will need some major grid upgrades.... but going forward it is undoubtedly the best option (renewables and storage). The question is whether we join the pioneering countries on this or end up playing catchup. Given our wealth of renewables we should be with the pioneers.

The fossil fuel lobby will confidently 'predict' what is 'impossible' with storage but is is disingenuous and they know it. They know full well technologies will improve with investment and scale. Obviously a nation that hasn't invested and gets stuck on natural gas while other countries buy up the storage tech is great for fossil fuel companies.

Compared to home heating/HW, decarbonising the grid will be the easy part.... so we better get on with it!

Post edited at 10:44
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In reply to Rog Wilko:

Storing heat which then goes on to generate electricity, is one way. For instance molten salt can store heat from large solar arrays for about 10 hours, which would cover night time hours. Obviously this would only be as reliable as consecutive days of sunshine, such as in desert regions.

I wonder if the power such a plant produces could be used to run desalination complexes, to irrigate and revegetate coastal areas of desert, using the concentrated brine by-product as raw material for the molten salt for heat storage (instead of dumping it back into the ocean and killing off life on the sea bed)?

 artif 25 Oct 2022
In reply to Rog Wilko:

I heard Honda were looking in to using the EV batteries as storage, i.e use them for supply when plugged in during peak loads and charge during low load times. I think there was some usage tracking planned so your EV isn't depleted when needed. 

Pretty sure this could be set up on an individual basis without too much trouble, as supplement to solar/wind power or off grid system

 jimtitt 25 Oct 2022
In reply to jkarran:

> Obviously the numbers are big but we can't keep ignoring the problem forever.

> I think the point you're making somewhat obliquely is that there are some big fixed loads (a fully electrified HGV fleet with its high duty cycle being one of them), that those loads (domestic heating being the other obvious example) will require a lot of storage to get us through longer lulls. Realistically too much. I agree.

> I expect we'll need a significant new round of nuclear builds and a lot of mostly offline gas CCGTs to make it work (whatever they burn, probably fossil gas for many years yet).

> jk

Indeed, to reliably provide the 486TWh/yr for the UK transport industry is going to need a hell of a lot of concrete blocks on cranes or Nissan Leafs hooked up to smart changers, to say nothing about a fair number of windmills.

 jkarran 25 Oct 2022
In reply to jimtitt:

> Indeed, to reliably provide the 486TWh/yr for the UK transport industry is going to need a hell of a lot of concrete blocks on cranes or Nissan Leafs hooked up to smart changers, to say nothing about a fair number of windmills.

Concrete on cranes is a non-starter as you well know.

As for EVs, there will be one hell of a lot of them! There are ~30M cars in the UK, EVs will displace most of those over the next 20 years unless another technology breaks through fast. 70kWH/car nominal capacity is pretty normal currently and only likely to rise as tech improves, that makes 2.1TWH of nominal capacity. It's a big number, more than 230 Dinorwics (9GWh) and that's just the cars assuming batteries don't keep growing and that the cars which die on route to that 30M don't end up in home power-banks. Make even a small fraction of that available through smart consumption or by trading power back to the grid and you have a lot of draw deferrable or energy or available.

I think many more windmills are a given, don't you.

jk

Post edited at 11:38
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 jimtitt 25 Oct 2022
In reply to jkarran:

There's the problem, it will take roughly all the putative 30m cars to charge the transport fleet but if the wind doesn't blow then they all stay still, as does the transport sector after a day.

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 ScraggyGoat 25 Oct 2022
In reply to Mike Stretford:

UK wise the ‘fossil fuel lobby’ are dominantly signed up to the energy transition and getting on with it.  the problem is the government lagging in regulation and CO2 per kg tax rate/sequestration rebate to drive the market. But nevertheless projects are moving apace.

Depleted gas fields are being proposed for repurposing as large scale hydrogen stores interlinked with renewable offshore green hydrogen production and blue hydrogen as required eg with Rough being planned for that purpose as part of the East Coast Cluster. Along with salt caverns for storage onshore adjacent to power plants. & assets being screened for CCUS.

it’s been oil and gas service and engines companies such as GE who developed the first hydrogen-methane blend turbines that can operate at upto 100% wet hydrogen.
 In Europe It’s been traditional gas providers / operators such as European SNAM/Stogit whom have for years used hydrogen and now are progressing to put 10% hydrogen into methane, as mentioned above recreating town gas and resulting in lower domestic and industrial emission’s.

The rate of change in the industry and scale of what’s being proposed and worked towards is very fast.

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 Mike Stretford 25 Oct 2022
In reply to ScraggyGoat:

> UK wise the ‘fossil fuel lobby’ are dominantly signed up to the energy transition and getting on with it.  the problem is the government lagging in regulation and CO2 per kg tax rate/sequestration rebate to drive the market. But nevertheless projects are moving apace.

It's a mixed picture but I think it's pretty clear that 'fossil fuel lobby', means what it says on the tin, companies and their investors, and political supporters who main bushiness is fossil fuels and have no plans to switch at the necessary scale. I didn't mean all companies currently making money out of gas, which seems to be how you interpreted it.

I agree with you on government regulation.

1
 elsewhere 25 Oct 2022
In reply to kevin stephens:

> this and all the other suggestions can only provide SHORT TERM storage of an hour or two, not the long term storage of days and weeks needed to be wholly reliant on renewables

The now exhausted methane gas fields that supplied us for decades should have the capacity to hold enough hydrogen for days and weeks.

Post edited at 12:52
 ScraggyGoat 25 Oct 2022
In reply to Mike Stretford:

BP, Equinor and Total are all involved in major large scale Energy Transition projects in the just the UK….and presumably elsewhere.  Yes they are still continuing their former business.

 jonny taylor 25 Oct 2022
In reply to elsewhere:

> The now exhausted methane gas fields that supplied us for decades should have the capacity to hold enough hydrogen for days and weeks.

Hmm, my immediate reaction was to be amazed that this would be at all viable, since the gas field is very much not a sealed storage bladder. It seemed to me that if you inject X amount of hydrogen into it then you don't get back X amount of clean hydrogen later. In fact, given diffusion, mixing, different properties of hydrogen compared to the original (and partially remaining) contents of the reservoir, you might well get back zero.

That drove me to google. Skimming the abstract of this thesis https://era.ed.ac.uk/handle/1842/39250 it sounds like the thinking is it might be viable for long-term storage on a "seasonal" basis, but I imagine you have to fill a significant capacity of the reservoir before it starts to make any sense as an approach (hence presumably the mention of seasonal storage, initial injection for 2 years and allowing to settle, etc)

Interesting stuff...

 Mike Stretford 25 Oct 2022
In reply to ScraggyGoat:

> BP, Equinor and Total are all involved in major large scale Energy Transition projects in the just the UK….and presumably elsewhere.  Yes they are still continuing their former business.

Did you read my last post? Not sure what you are trying to argue with me about.

As I said it's a mix picture. Companies vary in their efforts from pretty transparent PR focused projects to those who are genuinely planing a company wide transition. There are plenty of cases of companies embarking on these project whilst also funding climate change denial, more recently through association membership. I'm not claiming great conspiracies it's just that big corporations have many departments/personnel and not all will be pulling in the same direction. It's also well known that in any big transition some companies will decide their best bet is to profit as much as possible from the old tech in the remaining time. Some may be forced that way by investors.

Do you accept that there is still a 'fossil fuel lobby' who are funded? (and for the 3rd time I'm not directly referring to fossil fuel companies).

 mondite 25 Oct 2022
In reply to AllanMac:

> Storing heat which then goes on to generate electricity, is one way. For instance molten salt can store heat from large solar arrays for about 10 hours, which would cover night time hours.

Depending on how it is designed and how well insulated it is there are some experimental ones remaining efficient for a week or so.

Can also be linked to wind or other renewable sources to charge it up.

For heating rather than general energy there are some areas using concrete or water as a heat storage medium. Charge it up over the summer and then use over the winter.

It is something which seems to work best as a distributed system to heat towns etc.

 elsewhere 25 Oct 2022
In reply to mondite:

I think the Perlan hot water tanks in Rekjavik (fed with waste how water from geothermal electricity generation) fill up with 4 million litres of hot water in the summer for use in winter.

https://hotelklettur.is/en/activities/perlan/

In reply to Rog Wilko:

I’ve burned a lot of hydrogen over the years in IC engines and gas turbines, as well as ‘000s miles in hydrogen fuel cell powered EVs. My guess is that battery tech is an intermediate step to hydrogen infrastructure and usage. 
With the batteries, there are some alternatives to the lithium and other associated technologies which are destined to become depleted. I did a lot of long term vehicle testing with molten sodium type technology which proved itself to be reliable.

The figures (I might have missed them) being discussed in this thread seem to be all renewables plus transient storage. However, if everything progresses as it should, then nuclear SMR should be providing significant base load, which changes the landscape, as would a grown up government investing in connected, useable public transport 

 jkarran 25 Oct 2022
In reply to jimtitt:

I'm not proposing charging trucks (providing long term baseload) from the cars to bridge long winter lulls. Gas and interconnection is likely to be the only practical option there. 

Jk

 wintertree 25 Oct 2022
In reply to paul__in_sheffield:

> then nuclear SMR should be providing significant base load,

Grid scale storage solves the mismatch between fission plants and diurnal cycling about 15-50 times faster/sooner than it solves the intermediacy issues with renewables.

This always seems to get overlooked. “Virtual storage” from smart BEV charging alone would probably be enough for a stable, 100% nuclear grid in a decade or so’s time.  I’m not saying a 100% nuclear grid is desirable, but given the commonality of problem (supply/demand mismatched times) and the much smaller storage needed to solve that for nuclear than for renewables, it’s worth taking stock that soon enough, nuclear won’t have to be limited to baseload.

Post edited at 16:18
 Ram MkiV 25 Oct 2022
In reply to jimtitt:

> ..... the 486TWh/yr for the UK transport industry

Have you got a source for this figure? Seems high...

 Strachan 25 Oct 2022
In reply to Rog Wilko:

Among all the discussion of vehicle to grid technology it is worth mentioning that EV batteries are optimised for weight, and the specific use case, rather than for absolute durability, low cost, resource abundance, etc. Although repurposing old, otherwise disused, EV batteries for grid-scale storage or home storage applications makes good sense (at least in the absence of effective recycling technologies), it is unlikely that most EV owners are going to want their expensive battery undergoing the wear-and-tear (capacity reduction) associated with playing a dynamic role in balancing the grid when the car is not being driven. Unless there are (e.g. financial) incentives for this, it is perhaps not the panacea it first appears.

 jimtitt 25 Oct 2022
In reply to jkarran:

> I'm not proposing charging trucks (providing long term baseload) from the cars to bridge long winter lulls. Gas and interconnection is likely to be the only practical option there. 

> Jk

Then why in my comment regarding Nissan Leafs hooked to smart chargers in a discussion about the transport industries energy requirements did you even mention EV's? It's quite clear that even with the most optimistic uptake of private BEV's they aren't going to provide anything but a small contribution to grid stability let alone provide anything to solve the problem that renewable energy and a storage system is required to provide approximately three times the energy currently supplied by electricity at the moment if a CO2 neutral policy is to be achieved. 

As Wintertree says, it's going to be nuclear power (or import hydrogen from places that can make it cheaply). The options are limited or zero at the moment and foreseeable future.

While some on this thread complain about oil/gas company lobbying (and here in it's Germany nuclear) it's clear there is a "bury your head in the sand" lobby spreading absolute garbage about changing from hydrocarbons to hydrogen, completely ignoring reality but offering no solutions.

 jimtitt 25 Oct 2022
In reply to Ram MkiV:

42.4m tons oil equivalent for 2020 (includes private transport).

And this should give you a clue about the big numbers involved, it isn't kW, MW, GW or TW, energy use is measured in a convenient unit, the Mtoe. The energy in one million tons of oil. Or 11.63 TWh

Post edited at 17:23
 wintertree 25 Oct 2022
In reply to Strachan:

>  it is unlikely that most EV owners are going to want their expensive battery undergoing the wear-and-tear (capacity reduction) associated with playing a dynamic role in balancing the grid when the car is not being driven.

There are two levels to dynamic balancing.

  1. Smart charing - imagine plugging your car in on an evening and saying "I need at least 150 miles range by 8 am", and it's only charged above that if/when supply exceeds demand, and charging during the night is shifted around (on/off or variable charge rate) to use the optimal periods.  No extra battery wear/tear 
  2. Vehicle-to-grid mode - extra battery wear/tear.

Both can have a fiscal reward for the person charging the car, but only the second needs a reward high enough to counteract additional wear and tear.

 wintertree 25 Oct 2022
In reply to jimtitt:

>  It's quite clear that even with the most optimistic uptake of private BEV's they aren't going to provide anything but a small contribution to grid stability

Why do you say that?  There are half a million BEVs in the UK now.  That's about 30 GWh of storage (they could run the whole country for an hour if correctly hooked up, equivalent to about 3 Denorwic's of stored energy.  Shame the roll out was dumb, not smart) and about 1.5 GW of instantaneous demand if all charging at once.  Being able to smartly and responsively shed even a quarter of that load is massive in terms of grid stability.  Some suppliers like Octopus are giving customers good incentives to get smart charging.  

Can you give a rational basis why you think smart charging of BEVs couldn't evolve in to a major component of grid stability?   

Beyond what's happening right now with smart charging, BEV (including plug-in hybrid) sales are now 0.4 m / year, so it's let's say pessimistic to assume 4m BEVs on the roads in a decade.  That'll be about 320 GWh of stored energy (or 35 denorwics worth).  Let's hope the V2G stuff goes ahead so some small fraction of it is accessible as supply as well as most of the charging being demand amenable to shifting.

> While some on this thread complain about oil/gas company lobbying (and here in it's Germany nuclear) it's clear there is a "bury your head in the sand" lobby spreading absolute garbage about changing from hydrocarbons to hydrogen, completely ignoring reality but offering no solutions.

There are solutions other than hydrogen.  Aluminium ion batteries for example.  The issues with potential lithium availability at global scales go away, and every other part of BEVs are already so awesome in terms of performance that ICE and power starved fuel cell vehicles are like something from the Stone Age.  Battery <> Grid technology already exists at scale, and that's transformed (power density, cost, mineral resource availability) by a move to aluminium chemistry.

I know some people have a habit of knocking the progress in the battery R&D pipeline, but I suggest that's because they have their heads firmly in the sand about the decade-deep nature of the pipeline.  Its input is being stuffed with concepts and demonstrators faster than ever, and they continue to work through the pipeline delivering regular improvements to batteries.  It would be foolish, naive and uniformed to pretend that the outputs are going to suddenly crash to a halt

There are unsolved challenges to going all-in on hydrogen, and there are unsolved challenges to getting Aluminium ion batteries in to commercial use.  There are far more fields interested in advancing the battery technology so there's a lot more synergy in development.  

 Mike Stretford 25 Oct 2022
In reply to jimtitt

> While some on this thread complain about oil/gas company lobbying (and here in it's Germany nuclear) it's clear there is a "bury your head in the sand" lobby spreading absolute garbage about changing from hydrocarbons to hydrogen, completely ignoring reality but offering no solutions.

You make a reasonable point abut EVs and I'd add heat pumps to that. IMO the way forward would be to almost decarbonise the grid first without huge changes to home heating or transport, which require more localised, 'small' changes to infrastructure. I realise that hasn't been policy, EVs have been promoted as some green panacea, but it's not too late to change tact. Obviously the grid would need to be expanded later on but we'd have the experience.

Your comments about concrete blocks and cranes, rather than the more promising technologies do suggest you aren't entirely objective on this.

Post edited at 18:22
 jimtitt 25 Oct 2022
In reply to wintertree:

> >   There are half a million BEVs in the UK now.  That's about 30 GWh of storage (they could run the whole country for an hour if correctly hooked up, equivalent to about 3 Denorwic's of stored energy.  Shame the roll out was dumb, not smart) and about 1.5 GW of instantaneous demand if all charging at once.  Being able to smartly and responsively shed even a quarter of that load is massive in terms of grid stability.  Some suppliers like Octopus are giving customers good incentives to get smart charging.  

> Can you give a rational basis why you think smart charging of BEVs couldn't evolve in to a major component of grid stability?   

> Beyond what's happening right now with smart charging, BEV (including plug-in hybrid) sales are now 0.4 m / year, so it's let's say pessimistic to assume 4m BEVs on the roads in a decade.  That'll be about 320 GWh of stored energy (or 35 denorwics worth).

Exactly, they aren't hooked up and to be a significant contribution it is nescessary they are all connected, fully charged to a system that doesn't exist 24/7 with an ownership that is prepared to forego the use of their vehicle until an unknown time in the future. Put simply, I'll charge my truck to deliver your spuds and your weekend in the Peak is cancelled. Grid stability short-term is one issue, providing a reliable energy source to suit transport demands is another. 

2
 JCurrie 25 Oct 2022
In reply to the thread:

Lots of interesting stuff being discussed but no mention of flywheels. Is this because they are a non starter? I’d have thought they might have a role to play in storage. Yes, lots of them would be needed but a simple technology that wouldn’t necessarily need rare materials. Or is it me being simple?

 Siward 25 Oct 2022
In reply to mondite:

Yes, as per my link above I'm on the verge of filling my shed up with sand and putting some solar panels on top  

 Giffer 25 Oct 2022
In reply to Rog Wilko:

An interesting fact, but the UK already can meet 100% of it's electricity power requirements with the existing offshore wind turbines we have.  Great on days when the wind blows, not so great when it doesn't.  So without storage, there is little point in adding much more capacity as the limiting factor right now is the wind.

If we are discounting fossil fuel, then nuclear or tidal is probably the only viable options in short/medium term to give reliable power until a suitably way of storing power is devised.  But whatever solution we come up with, get used to paying a lot more for your electricity since without storage we need to maintain 100% duplicate back up capacity for those days when the wind doesn't blow.

 kevin stephens 25 Oct 2022
In reply to Giffer: I’m not sure on your figures. It’s quite windy at the moment but the UK’s only getting 20% of its electricity needs from wind

https://gridwatch.co.uk/

A well sited wind turbine will produce an average of around 1/3 of their maximum rated capacity , which is still a great return on investment making it worthwhile to install a lot more

Post edited at 20:43
 mondite 25 Oct 2022
In reply to JCurrie:

> Lots of interesting stuff being discussed but no mention of flywheels. Is this because they are a non starter?

They are being experimented with but mostly for short term demands since think they have limitations on size/storage capability. Main use currently seems to be for balancing demand/providing immediate power whilst other systems are spun up.

 jimtitt 25 Oct 2022
In reply to Rog Wilko:

The German answer (apart from going into hydrogen in a big way) is simple and is in operation. We send excess wind energy down a wire and use Norways hydro system as pumped storage.

 Strachan 25 Oct 2022
In reply to wintertree:

I don’t dispute the role that smart charging can have in demand management, but demand side response is not the same as grid-scale storage, which is what was being discussed upthread.
 

One key difference here is that effective demand management can reduce the impact of EV charging on the grid, but doesn’t ultimately confer a net positive effect (similar to how demand management alone can, by definition, never get us to Net Zero). By contrast, vehicle to grid technology, by allowing the EV to actively feed energy back into the grid as required (in a manner more akin to a prosumer, rather than a consumer) can make a net positive contribution to decarbonisation, by removing the need for fossil energy in the periods of low renewables output. Demand management can smooth out the peaks but ultimately it can’t fill in the troughs in the way V2G, at least in principle, can.

 henwardian 26 Oct 2022
In reply to Strachan:

> Arguably it is better to use renewable power to produce hydrogen or other combustible fuels for drop-in replacement of gas in difficult-to-electrify applications (some heavy industries, or aviation, for example).

Yup, hydrogen goes well with aviation...

https://upload.wikimedia.org/wikipedia/commons/1/1c/Hindenburg_disaster.jpg

In reply to henwardian:

> Yup, hydrogen goes well with aviation...

Not exactly comparing like with like!
For me the biggest problem with hydrogen is containing it, H2 is a very small molecule and a very buoyant gas. If it can find a way to escape it will do.

 kevin stephens 26 Oct 2022
In reply to Strachan:

> Arguably it is better to use renewable power to produce hydrogen or other combustible fuels for drop-in replacement of gas in difficult-to-electrify applications (some heavy industries, or aviation, for example).

Hydrogen isn’t quite a drop in replacement for natural gas, it contains a lot less energy per cubic metre. Many companies buying industrial steam boilers or co generation engines now can specify them to be “hydrogen ready”. But the energy capacity will be reduced by 2/3 so they would have to leave sufficient footprint to accommodate two more boilers or engines, not to mention budget if and when the hydrogen economy and infrastructure arrives.

the prospect of blending a little hydrogen into existing natural gas networks is a lot easier and more likely, but it won’t make that much of a contribution to net zero 

 Strachan 26 Oct 2022
In reply to henwardian:

I’m not suggesting anyone use hydrogen-filled (note not fuelled) airships, or even hydrogen gas as an aviation fuel, but catalytic approaches to converting green hydrogen to sustainable hydrocarbon fuels using renewable carbon sources doesn’t seem so daft. The energy density of batteries is not going to get us anywhere near long-haul electric flight any time soon, and hydrogen gas, whilst light, needs heavy tanks to achieve the required density (putting alternative possible storage technologies, solvents, etc as aside), to compress it to sufficiently small size to be used for aviation. Not that kerosene is completely non-combustible in itself of course.

 Strachan 26 Oct 2022
In reply to kevin stephens:

You’re quite right, ‘drop-in’ was a poor word choice. But relatively speaking the modifications of processes and facilities may be slightly less drastic if converting e.g. steelmaking to H2 than if electrifying it.

 jimtitt 26 Oct 2022
In reply to Ridge:

> Not exactly comparing like with like!

> For me the biggest problem with hydrogen is containing it, H2 is a very small molecule and a very buoyant gas. If it can find a way to escape it will do.

Makes you wonder how industry copes with the 100m+ tons they produce every year.

 jimtitt 26 Oct 2022
In reply to kevin stephens:

> Hydrogen isn’t quite a drop in replacement for natural gas, it contains a lot less energy per cubic metre. Many companies buying industrial steam boilers or co generation engines now can specify them to be “hydrogen ready”. But the energy capacity will be reduced by 2/3 so they would have to leave sufficient footprint to accommodate two more boilers or engines, not to mention budget if and when the hydrogen economy and infrastructure arrives.

> the prospect of blending a little hydrogen into existing natural gas networks is a lot easier and more likely, but it won’t make that much of a contribution to net zero 

Err, rubbish. All they do is change the burner jet to allow more gas to flow in. The main alterations to existing domestic boilers are to change the flame detector to a UV one and possibly alter the condensate drain.

 henwardian 26 Oct 2022
In reply to Ridge and Strachan:

I think you may have taken my post a _little_ too seriously...

 jkarran 26 Oct 2022
In reply to jimtitt:

If you read back I clearly stated I think we need new nuclear.

I am not proposing feeding significant energy back from cars to the grid but instead having them (and systems like heat pump heating) consume smarter to help handle short-medium term supply demand mismatches. I think cars which interact with domestic solar to act as power banks for the home sharing a fraction of their capacity probably will emerge if electricity prices stay silly. 

I'm mostly ignoring the issue of needing more electrical power in the long run because the solution is blindingly obvious, as it always has been: we build more generating capacity or we reduce demand or some mix thereof. It's almost unrelated to the shorter term storage options I was discussing.

Personally I think new nuclear any time soon is a pipe dream so we'll end up with a lot of gas ccgts largely stood idle to complement the continued growth of renewables. 

Jk

 kevin stephens 26 Oct 2022
In reply to jimtitt:

Not rubbish at all Jim, I've discussed this with a number of manufacturers of industrial steam boilers where the limiting factor is size of combustion chamber etc and design flow rate of combustion product gases.  You may remember your basic combustion engineering where the key parameters for effective combustion are Time, Temperature and Turbulence, Time being the critical factor that determines residence time in the combustion chamber restricting volumetric gas flow rates 

Post edited at 10:20
 jimtitt 26 Oct 2022
In reply to kevin stephens:

That may be so for some industrial steam generators which are continously running but for small domestic hot water systems which are the vast majority the changeover is simple. At it's simplest one runs a longer burn time.

 wintertree 26 Oct 2022
In reply to Strachan:

Sorry, what started as a short reply ended up pretty long and rambling as I started to actually engage the brain.

> I don’t dispute the role that smart charging can have in demand management, but demand side response is not the same as grid-scale storage, which is what was being discussed upthread

If talked myself round to the view that smart deferred charging is pretty equivalent to vehicle-to-grid supply.  Both have the same capacity - the fraction of a car's battery the owner is willing to make available for smart shifting.  Intuitively it feels like V2G is more potent, but I'm not sure intuition is doing us well here; both have the same limiting factor.

> Demand management can smooth out the peaks but ultimately it can’t fill in the troughs in the way V2G, at least in principle, can.

It does't need to fill in the troughs if it can lop the top of the next peak instead of drawing power during the trough.  A trough in supply is only a problem if you can't create a matching trough in demand.  By deferring vehicle charging you can create that demand trough.  Same net effect.

As we shift to more electrically driven, flexible demand sinks like BEVs and heat pumps, that becomes more significant.  

> By contrast, vehicle to grid technology, by allowing the EV to actively feed energy back into the grid as required (in a manner more akin to a prosumer, rather than a consumer) can make a net positive contribution to decarbonisation, by removing the need for fossil energy in the periods of low renewables output

Eventually; right now it can be shown conceptually that battery systems time-shift the CCGT component of our mix as there's always some CCGT; shift renewable power one way in time and the CCGT is shifted the other, and some energy sacrificed to bidirectional inverter/charger/battery losses.

If/once we get to a system where the time-averaged renewable output is enough to not need any CCGT infill, then that changes and BEVs can make that critical difference; even then it doesn't need to be by back-feed.  

If a consumer can afford to have their vehicle battery partially discharged to the grid, they can afford to have it under-charged from the grid; both clearly need a way for the user to specify their minimum charge level required. 

If you think of a renewable heavy grid has having peaks and troughs, conceptually smart under-charging is shifting energy back in time (*) from a peak to an earlier trough, and V2G is shifting energy forwards in time from a peak to a later trough.  The amount of energy that can be shifted is defined by the battery (common to both modes) and by the inverter/charger (not going to differ wildly in power levels)

Once the system is established, it doesn't really matter which way the energy is shifted in time.   The more I think about it, the more V2G starts to feel superfluous, if there's capacity for it to make a difference, the same difference can be made by smart deferred charging.  I can see two symmetry breakers; one is that V2G can respond to the actual renewable power state where-as reduced charging depends on the accuracy of the future forecast renewable power levels (favouring V2G) and there are worse efficiency losses and worse battery wear and tear costs in V2G (favouring smart under charging).

A key point is that heat pumps don't have an equivalent V2G mode, so accurate forecasting of renewable peaks and troughs is critical to using them in a demand-deferral mode to fit a renewable heavy grid.

The forecast point is kind of critical - where V2G really comes in to its own is "digital inertia" - the ability to provide a sudden and massive supply of power in response to a dropping grid frequency, allowing unforcast (indeed, unforcastable) events such as the sudden failure/disconenct of a big source of power to be handled without unplanned load shedding, and reducing the risk of a cascade failure (been a few of those in well developed power grids in the last decade...).  Smart load shedding of chargers and heat pumps would be a massive step here, but then V2G adds even more capability.  Battery capacity limits don't really come in to play here, as this only needs to reduce demand and/or add supply for a few seconds to minutes to give time for other existing, slower grid-scale responses to kick in. 

  • Currently I think there's an opposing effect with grid tied solar-PV, where the EREC standards require them to disconnect from the grid outside of a narrow frequency band, so that if we start to get a big grid frequency drop during the daytime, several GW of solar power is going to suddenly drop offline and push things over the edge...  That probably needs some re-thinking as grid tied solar rises... 

(*) like borrowing money from a bank against your coming pay packet, here the battery is the bank. 

Post edited at 11:27
 Mike Stretford 26 Oct 2022
In reply to kevin stephens:

> I’m not sure on your figures. It’s quite windy at the moment but the UK’s only getting 20% of its electricity needs from wind

> A well sited wind turbine will produce an average of around 1/3 of their maximum rated capacity , which is still a great return on investment making it worthwhile to install a lot more

 46% at the time of posting!

We also waste a lot of wind due to curtailment, so the potential figure could be much higher...... which brings us back to storage!

Edit: With the planned offshore wind project we will regularly be producing surplus in ~5 years. Storage tech is evolving so right to hold off but now getting close to the point where we need to chose a handful of the technologies and upscale them.

Edit edit: 54% from wind and solar!

Post edited at 11:24
 elsewhere 26 Oct 2022
In reply to wintertree:

> If a consumer can afford to have their vehicle battery partially discharged to the grid, they can afford to have it under-charged from the grid; both clearly need a way for the user to specify their minimum charge level required. 

Fleet operators rather than consumers for early adoption as they have very predictable requirements such as these hundred buses/vans need to cover 15,000 miles tomorrow just like yesterday and the day before. They won't be needed for a climbing trip or to visit granny at the weekend.

Likely to be on the road during the day but increasingly available for V2G after 9-5 working hours and after evening commute to cover evening peak demand.

Solar must cut off when frequency drops, that's a bizarre sounding regulatory setup.

Post edited at 11:44
 kevin stephens 26 Oct 2022
In reply to jimtitt:

Of course, I was responding to a post which specifically referred to using hydrogen as a channel for surplus energy to be used in INDUSTRIAL applications

 kevin stephens 26 Oct 2022
In reply to Mike Stretford:

At the moment any surplus of electricity would be sold to Europe via the cross-channel interconnectors, which are also used to import surplus French nuclear electricity when their demand is low on less windy days.  This is a lot cheaper and more efficient than storage

Post edited at 12:08
1
 magma 26 Oct 2022
 kevin stephens 26 Oct 2022
In reply to magma:

Are you just posting that because you have a vested interest?

 Mike Stretford 26 Oct 2022
In reply to kevin stephens:

> At the moment any surplus of electricity would be sold to Europe via the cross-channel interconnectors, 

It isn't

https://renewablesnow.com/news/uk-wind-curtailment-cost-in-past-two-years-put-at-gbp-806m-787668/#:~:text=The%20cost%20of%20curtailment%2C%20however,carbon%20dioxide%20(CO2)%20emissions.

> which are also used to import surplus French nuclear electricity when their demand is low on less windy days.  This is a lot cheaper and more efficient than storage

The cross channel interconnectors do have limited capacity and we can't rely on France having surplus when we need it. Storage is required hence big investment and loads of R&D in the sector.

 magma 26 Oct 2022
In reply to kevin stephens:

not at all- although i had an interest when i studied geophysics.

looks to be a lot of potential given more funding (but that's what they said about CCS..)

In reply to jimtitt:

Delusional!

UK Busses and HGVs in 2018 (last "normal" year) was around 8Mt of diesel, which is around 80 twh/yr (note this is including the highly inefficient diesel combustion process...). Or 12-13Mt for LGV, HGV and Busses combined. It would only be around 35 twh/yr if they were fully electrified.

Sources:  https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1094351/DUKES_2022_Chapter_3.pdf

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/812622/Road_fuel_consumption_and_the_UK_motor_vehicle_fleet.pdf

UK wind fleet provides around 75 twh/yr at present, expected to increase to 166 twh/yr in 2030 for offshore alone.

I suspect Hydrogen, or H2Elec hybrid may be the way to go for HGVs etc. Who knows, not my area.

Each HGV is around 260 kw when running flat out, so let's make a big assumption that all trucks run 50% of the time, but the flow is "continuous" (i.e. every day the same number of trucks are running, and they're all filling up with "energy" spread even throughout the day.

260kw per truck, at 21% load* = 54kw average (or 1316 kwh/day)

Apparently there are 540,000 HGVs on the road, so:

29 GW power required to keep them running. That's going to be a tough nut to crack....

*21% comes from an average of 400km per day, 71km/h when driving.

What's your solution?

 jimtitt 26 Oct 2022
In reply to Alasdair Fulton:

Transport includes mopeds, scooters, cars, busses, vans, HGV's, air, rail, sea and anything else that uses energy to move something or someone.

Post edited at 14:16
 jimtitt 26 Oct 2022
In reply to wintertree:

Indeed, the forecasting is going to more resemble astrology than anything else.

Using BEV's to begin fill the troughs in supply depends on a succesful social experiment since the users have to a) allow it, b)be fully charged and c) be connected to a smart charger at the relevant point in time.

Moving the supply peaks into the troughs is difficult, moving the troughs easier by simply not supplying power when the consumer wants it but when it is available, naturally the problem being what happens after a couple of days.

Using BEV's as a source to make the grid robust is more likely but one would like to see some accurate modelling before we dump our emergency generation capacity and spinning reserve. We need a guarantee that enough capacity is available at all times and it's hard to see that without an enormous oversupply. A 1MW diesel (or gas/hydrogen) generator is cheap and just sits there until it's needed. 

 kevin stephens 26 Oct 2022
In reply to jimtitt:

There are already market mechanisms to facilitate / incentivize this through the capacity market, STOR, frequency reponse etc.  However use of diesel generators for this purpose is now much more difficult due to tighter NOx emission limits under the Medium Combustion Plant Directive

 jimtitt 26 Oct 2022
In reply to kevin stephens:

I thought you guys had left the EU?

We actually got a healthy grant for installing a 1MW plant in our bio-gas system as part of the new grid stability plan in Germany as we conform to the MCPD requirements and the start-up is under 8s, exactly why since the area has plenty of hydro it's hard to tell. It hasn't actually started since it was installed but maybe when our local nuclear power plant eventually goes off stream it will burst into life.

One off-the-wall idea we discussed over some beers was reverting to an old idea of PTO drive generators, every farmer has a collection of Euro 6 tractors just sitting around and the modern software would allow remote starting, an interesting concept for sure!

 wintertree 26 Oct 2022
In reply to elsewhere:

> Solar must cut off when frequency drops, that's a bizarre sounding regulatory setup.

I agree. I went back to read G98 and I was talking out of my a*se. See section 9 below - they’re expected to remain online through quite a wide frequency band althoigh they’re not expected to deal with very rapid excursions.  Dunces hat for me.

https://www.energynetworks.org/industry-hub/resource-library/erec-g98-requirements-for-connection-of-fully-type-tested-micro-generators.pdf

 kevin stephens 26 Oct 2022
In reply to jimtitt:

At the moment we are keeping and adopting emissions regulations such as the MCPD, also ESOS (Energy Saving Opportunity Scheme - mandatory energy audits) which is the UK's implementation of the European Energy Efficiency Directive.  Also we now have the UK ETS which seems to be proving more expensive than the EU ETS. Not sure how much of this will remain under our new Govt.  I'm working in Ireland this week so firmly under the jackboot of EU (common sense) regulations.

Post edited at 17:40
In reply to Rog Wilko:

Maybe this is half baked and left field, but pumped storage... Why do we (or at least me until 5 minutes ago) only think of mountains... with a mountain Llyn/tarn/loch up top and a big valley lake at the bottom?

These are located far from the biggest population centres like Greater London or Midlands conurbation etc so a bad choice of feature. I get it that the mountain lakes provide a height difference and so potential energy, but why not a lake at ground level and some re-engineered mine workings. Snowdon colliery in Kent as just one example has shafts 977m deep, the Midlands is hardly short of old deep mines. Pump them out (store energy) and flood them (generate). There would be a continuous drain on resource to pump so this is not 100% efficient and understood some hefty engineering is needed to concrete reinforce large sections so you don't wash out and destroy them, but isn't that comparable or better than hollowing out mountains?

We've got lots and lots of deep mines sitting flooded and derelict and no shortage of water in those parts. Just an idle thought as another option...

Post edited at 21:48
 elsewhere 27 Oct 2022
In reply to CantClimbTom:

That's an interesting idea. One issue is that the water you pump out is likely to be too polluted to just discharge into a river.

https://www.gov.uk/government/news/coal-authority-upgrades-vital-mine-water-treatment-scheme-in-scotland

Although the water is warm so there is geothermal potential.

Https://www.bbc.com/future/article/20210706-how-flooded-coal-mines-could-heat-homes

 jkarran 27 Oct 2022
In reply to CantClimbTom:

> Maybe this is half baked and left field, but pumped storage... Why do we (or at least me until 5 minutes ago) only think of mountains... These are located far from the biggest population centres like Greater London or Midlands conurbation etc so a bad choice of feature.

Cross country electricity transmission is efficient and the infrastructure exists (even if it may need upgrade to connect a particular project.

> I get it that the mountain lakes provide a height difference and so potential energy, but why not a lake at ground level and some re-engineered mine workings. Snowdon colliery in Kent as just one example has shafts 977m deep, the Midlands is hardly short of old deep mines. Pump them out (store energy) and flood them (generate). There would be a continuous drain on resource to pump so this is not 100% efficient and understood some hefty engineering is needed to concrete reinforce large sections so you don't wash out and destroy them, but isn't that comparable or better than hollowing out mountains?

You're not going to pull water nearly a kilometre up, it needs to be pushed which implies 'hollowing a mountain out' anyway for want of a better description to install the plant. I don't think reinforcing/lining an abandoned deep mine is viable so you would expect accelerated erosion of remaining support pillars/timbering. See somewhere like Fairburn Ings and the surrounding moonscape for a vision of what a collapsing coal seam does to a landscape, it looks like Messines on steroids (with ducks). That is not going to go down well in the shires.

Deep mines as seasonal thermal stores with added geothermal input is being seriously looked at but low grade heat isn't easy to use or convert. I believe there have been plans developed to build solid-mass gravity batteries in some of the deeper coal pit shafts. I suspect technology will have got ahead of that now, probably more cost effective to just install chemical batteries at the surface.

jk

Post edited at 09:37
 jkarran 27 Oct 2022
In reply to Alasdair Fulton:

> 260kw per truck, at 21% load* = 54kw average (or 1316 kwh/day)

That 260kW is peak/rated power, right? A quick sum suggests something more like 175kW for a cruising truck (Cd=1, Crr=0.01, A=8sqm, M=44T, V=25m/s) and that's picking worse case drag coefficient figures.

> What's your solution?

There's scope to improve the efficiency of the vehicles and the economy they lubricate. That said, transport is energy intensive, ultimately we are just going to have to generate enough power for our needs and desires.

jk

 jimtitt 27 Oct 2022
In reply to jkarran:

Water has the fundamental problem that it isn't very heavy, it's cheap but you need a lot of it or get it a long way up.

The solution from Heindl Energy is to cut a cylinder of rock and use this as the weight in a hydraulic accumulator with a recieving pond next door. So this 250m diameter cylinder of rock slowly rises into the sky then sinks, be worth watching!

That one might be a bit of a problem with the Nimbys so Gravity Power are using a weight as the piston in a shaft which is filled with water and sealed. The water is just pumped below the piston to raise then released again to generate. There's a MW one under construction about an hour from me, might be worth a trip to look at it.

 Forest Dump 27 Oct 2022
In reply to jkarran:

There's work going on in the Bridgend / Maesteg area looking at the viability of using old mine works as a heat source for a district heat system 


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