Energy Markets and Net Zero

[neilj]

Friend of mine has recently had instated a 17kw home battery system with solar panels on the roof. On a sunny day he's completely self sufficient and often exports electricity to the grid
On non sunny days he can charge the battery at cheap rate tariffs and use it at the times of the day when energy tariffs are higher

The system isn't cheap, with solar panels fully installed around £15,000, but he's happy with it

The price would come down if such systems had to be built in on all new build properties with appropriate roofs. But the battery system alone would be useful

It isn't the answer on it's own, but it will help

[lens]

Jul 10, 2024 8:47:32 GMT Danny said:

May 12, 2024 12:08:48 GMT lens said:

We've got used to a situation whereby electricity is largely generated from fossil fuels (with energy losses) so it's not surprising a kWh of chemical fuel costs less than a kWh of electricity, so consequently a unit of electricity cists more than a kWh of gas. People have been prepared to pay the extra for the versatility and convenience of electricity, (ever seen a gas powered television?) but we're now moving into a world where it's the opposite way round - the starting point is electricity from such as wind and solar, and if you want to make a chemical fuel such as hydrogen from it, then unit for unit it's electricity that will have the cost advantage.

The bit you are missing is energy storage. What to do when its dark and there is now wind, and if they ever get it together when this coincides with the lull in the tides. Hydrogne is a mechanism to store energy, and its big plus currently is we already have the infrastructure to store it and burn it to generate power.

There is no consensus how to store huge amounts of power. Ideas yes, real world cost effective examples no. We are already wasting wind power and we will be wasting who knows, half the power being generated by the time we have enough to mostly fulfill average load. Thats essentially free electricity at peak renewables times. If its free, then the economics of turning it into hydrogen suddenly change.

Danny - Regarding your second paragraph, this is an argument given by those with vested interests in promoting hydrogen for storage, and you are ignoring the flaw in the argument.

To take advantage of this supposedly "free" electricity, presupposes electrolysis/compression/storage etc plant sitting idle most of the time waiting for such periods. That's a very bad utilisation of plant to have it sitting idle for a large percentage of the time. The cost/kg of the hydrogen will be a function of not just the cost of electricity consumed, but also the equipment to do it.

It also ignores other - and better - ways to even out renewable generation versus demand.

Such ranges from better and more extensive grid connections, to smart pricing. For the former, this helps match demand to areas where generation is more plentiful, and can even be over continents, let alone between countries. For smart pricing, we're already seeing it with tariffs available to give extremely cheap per kWh rates **at times when the power companies** most want to encourage consumption. Which is why home charging of BEVs overnight is so cheap.

And the question has to be asked as to which is most cost effective - build out electrolysis etc plant (only used for short periods when the renewable generation is surplus to electricity demand)......... or simply overbuild extra generation capacity to cater more towards the peaks than just the troughs? Think about it. Think about it together with the (in)efficiencies inherent in the hydrogen round trip, especially when turning it back into electricity at scale is almost certainly likely to be via turbines rather than a fuel cell.

Yes, **some** storage will inevitably be necessary, but grid battery storage is becoming a huge business. There are estimates that for Tesla alone their stationary battery business may overtake their car business soon in terms of revenue generation. That's a stat that even I struggle to come to terms with, and would have dismissed as fantasy only a couple of years ago. (And before anybody says it - no, there are no mineral constraints on such, especially if there is move to sodium based chemistries instead of lithium for such.)

There **MAY** be circumstances where weather systems lead to periods of no wind and little sun for more than a day or so, and yes - such do need to be guarded against. But here's a revolutionary thought - what about just using stored fossil fuels for the relatively rare occasions when such happens!!? Does it really matter if carbon emissions for electricity generation are reduced by 90% or 100%? Especially if the bulk of the time renewable electricity is displacing some energy that currently comes from fossil fuels directly ( eg electric cars not needing petrol, heat pumps reducing gas consumption for home heating.)

The imperatives are to accelerate clean electricity generation (build more wind farms), improve grid connectivity, and encourage consumption via electrical appliances rather than burning fuel (electric cars, heat pumps, and electric cooking etc) All these need to happen in tandem. We need to switch as much as possible of our energy generation and consumption from gas/oil to electricity. In the longer term, green hydrogen may indeed have a significant role to play in displacing dirty hydrogen in industry, but as energy storage - no.

[Danny]

Jul 10, 2024 15:04:32 GMT neilj said:

Friend of mine has recently had instated a 17kw home battery system with solar panels on the roof. On a sunny day he's completely self sufficient and often exports electricity to the grid
On non sunny days he can charge the battery at cheap rate tariffs and use it at the times of the day when energy tariffs are higher

The system isn't cheap, with solar panels fully installed around £15,000, but he's happy with it

The price would come down if such systems had to be built in on all new build properties with appropriate roofs. But the battery system alone would be useful

It isn't the answer on it's own, but it will help

Consider the situation of low usage individuals who might be approaching half their bill currently on standing charge. I dont know the real lifetime expectancy of a panel system, so how long it has to repay the costs? (and the interest on 15,000 currently must be significant too)

[Danny]

Jul 11, 2024 0:25:29 GMT lens said:

To take advantage of this supposedly "free" electricity, presupposes electrolysis/compression/storage etc plant sitting idle most of the time waiting for such periods. That's a very bad utilisation of plant to have it sitting idle for a large percentage of the time. The cost/kg of the hydrogen will be a function of not just the cost of electricity consumed, but also the equipment to do it.

yes. traditionally the way to optimise return from plant is to use it continuously. Hence 24 hour factory manning in shifts. Only, we dont actually do that anyway much of the time. I agree it is a different mindset to plan that equipment will be idle part of the time, but that seems to be what is needed. The point is that its the energy which is expensive, not the plant. Whereas historically we have regarded the energy as free, we just had to extract it from the ground.

It also ignores other - and better - ways to even out renewable generation versus demand. Such ranges from better and more extensive grid connections, to smart pricing.

Its a national scandal the last government failed to ensure the grid kept base with distribution needs. A very expensive mistake they have not been blamed sufficiently for. Smart pricing was invented maybe in the 60s what with surplus overnight nuclear power. The smart meter installation program is significantly a failure, the first genertaion of meters have had to all be replaced again and we have now hit consumer resistance from those who arent interested. Its getting to the point they cant replace the failed ones as fast as they are installing new ones. In the 60s the idea was storage heaters, warmed at night to heat during the day. Dont hear much about that currently, the idea seems to be to power heat pumps at the time the heat is needed, so demand will be 24 hours but mostly during the day. The one plan to use night power seems to be to charge cars, but there are multiple problems including them still being a minority of vehicles and the impossibility of charging most of them overnight as things stand in infrastructure terms. We seems to have a growing sector of power demand for powering computers, which obviously is either 24 hours or when people are awake.

And the question has to be asked as to which is most cost effective - build out electrolysis etc plant (only used for short periods when the renewable generation is surplus to electricity demand).........

The goal will be to over install renewables generating capacity so that max capacity is well in excess peak demand. at least double i would think, maybe a lot more. The question is how storgae costs compare to the cost of surplus generators. Either way we will have surplus plant lying idle. We ALREADY have wind generators deliberately turned off because we cannot use the electricity.

Think about it together with the (in)efficiencies inherent in the hydrogen round trip, especially when turning it back into electricity at scale is almost certainly likely to be via turbines rather than a fuel cell.

I have, and i have inadequate information to determine the optimum solution. Massively inadequate information, but the best solution will be significant surplus generating capacity together with surplus storage capacity mostly being unused. Dont forget, whatever way you store energy we will not be using the techology much, maybe most, of the time. Whatever system will have this same problem of idle plant.

Yes, **some** storage will inevitably be necessary, but grid battery storage is becoming a huge business.

So why havnt we intalled some and stopped wasting the wind power we are currently throwing away? Maybe it isnt actually ready yet?

There **MAY** be circumstances where weather systems lead to periods of no wind and little sun for more than a day or so, and yes - such do need to be guarded against. But here's a revolutionary thought - what about just using stored fossil fuels for the relatively rare occasions when such happens!!?

i have repeatedly said this is a better idea than building new nuclear. Disturbing you think it revolutionary. Of course, hydrogen is largely interchangeable as a fuel with natural gas. The same plant to burn fossil gas can use generated hydrgen.

The imperatives are to accelerate clean electricity generation (build more wind farms), improve grid connectivity, and encourage consumption via electrical appliances rather than burning fuel (electric cars, heat pumps, and electric cooking etc) All these need to happen in tandem.

hence my recent comments that currently electric vehicles are not saving carbon emissions, because we have not installed renewables plant sufficient to power them but instead are burning extra fossil in power stations.

[lens]

Jul 17, 2024 9:05:51 GMT Danny said:

Jul 11, 2024 0:25:29 GMT lens said:

To take advantage of this supposedly "free" electricity, presupposes electrolysis/compression/storage etc plant sitting idle most of the time waiting for such periods. That's a very bad utilisation of plant to have it sitting idle for a large percentage of the time. The cost/kg of the hydrogen will be a function of not just the cost of electricity consumed, but also the equipment to do it.

yes. traditionally the way to optimise return from plant is to use it continuously. Hence 24 hour factory manning in shifts. Only, we dont actually do that anyway much of the time. I agree it is a different mindset to plan that equipment will be idle part of the time, but that seems to be what is needed. The point is that its the energy which is expensive, not the plant. Whereas historically we have regarded the energy as free, we just had to extract it from the ground.

Danny - Just keep digging. If you think you're making the case for hydrogen as energy storage - you're not! "It's the energy that's expensive, not the plant"!?  Oh come on! In the case of wind the energy is (literally!) "as free as the wind" - it's the plant to convert it into electricity which is expensive. Same with solar, and (arguably) as you say with fossil fuels - it's the mines/drilling and production rigs with refining that costs the money.

And Danny - we *DO* have 24 hour manning in some factories, precisely to make most possible use of capital plant in such. (Even if labour cost/hour is more overnight). Obviously you've never worked in such as a car factory, but just as a single example: en.wikipedia.org/wiki/Nissan_Motor_Manufacturing_UK:

"Employees at NMUK work a standard 39-hour week. While Office staff work on a fixed day shift basis, manufacturing staff work alternating morning and evening shifts. Morning shifts run from 7 am to 3:18 pm. Evening shifts run from approximately 4:35 pm to 12:53 am. Shift times can vary depending on requirements. When required, overtime is worked, although it balanced out during the year with planned downtime.[citation needed]

A 3-shift system has been introduced at times of high demand, meaning that the factory is active 24 hours a day. "

Perhaps simplistically, the production cost of finished goods is a function of the costs of raw materials, labour **and plant**. Most suitable manning will vary from case to case, but to say "we need a different mindset" is just silly. Many factories do work best with a 9-5 day - others are more efficient working close to 24/7.

In this case, does it really have to be spelt out? Cost/kg of green hydrogen will be a function of electricity cost **AND** plant utilisation. I hope in the future there is a future for green hydrogen, in displacing dirty hydrogen that industry needs, but it won't magically be cheap because it will be only produced with "free" electricity that would otherwise not be used. (And any such hydrogen that is made is far more suited to industry than energy storage anyway.)

Jul 17, 2024 9:05:51 GMT Danny said:

Jul 11, 2024 0:25:29 GMT lens said:

It also ignores other - and better - ways to even out renewable generation versus demand. Such ranges from better and more extensive grid connections, to smart pricing.

Its a national scandal the last government failed to ensure the grid kept base with distribution needs. A very expensive mistake they have not been blamed sufficiently for. Smart pricing was invented maybe in the 60s what with surplus overnight nuclear power. The smart meter installation program is significantly a failure, the first genertaion of meters have had to all be replaced again and we have now hit consumer resistance from those who arent interested. Its getting to the point they cant replace the failed ones as fast as they are installing new ones. In the 60s the idea was storage heaters, warmed at night to heat during the day. Dont hear much about that currently, the idea seems to be to power heat pumps at the time the heat is needed, so demand will be 24 hours but mostly during the day. The one plan to use night power seems to be to charge cars, but there are multiple problems including them still being a minority of vehicles and the impossibility of charging most of them overnight as things stand in infrastructure terms. We seems to have a growing sector of power demand for powering computers, which obviously is either 24 hours or when people are awake.

Well, where to start? Firstly, the smart meter program now reaches over 2/3 of all UK households - hardly "a failure", even if admittedly some first generation meters had problems. It's also important to note that a large reason for their introduction is to allow automated meter reading without a man having to knock on your door - they aren't just there to provide tariff flexibility.

As for the highlighted section, then what "multiple problems"? Apart from Rome not being built in a day? Why is there "an impossibility of charging most EVs overnight"? Because it's not true. Last figures I heard were that about 80% of EV charging DOES happen overnight, and there's plenty of scope for that to remain more or less the case with ramping up the numbers. It'll actually help the grid by evening day/night load - the capacity is there. And I'm increasingly hearing of friends having home battery systems fitted to further benefit from cheap overnight electricity.

Heat pumps. No Danny - demand will *NOT* be "mostly during the day". For home use they will typically go on in the early hours of the morning to warm the house for when people start to get up - and go off maybe 9am as they go to work and school. Then they will come on again maybe around 5pm to warm the house for people's return, and go off again around midnight. Oh! Exactly how many people have their gas central heating timer set at the moment. (And maybe be on in the small hours to warm the hot water tank?)

Jul 17, 2024 9:05:51 GMT Danny said:

Jul 11, 2024 0:25:29 GMT lens said:

The imperatives are to accelerate clean electricity generation (build more wind farms), improve grid connectivity, and encourage consumption via electrical appliances rather than burning fuel (electric cars, heat pumps, and electric cooking etc) All these need to happen in tandem.

hence my recent comments that currently electric vehicles are not saving carbon emissions, because we have not installed renewables plant sufficient to power them but instead are burning extra fossil in power stations.

Danny - do you ever actually read what other people write? Do you ever stop to consider if you may be wrong? In this case you have half a point, but it's just not helpful. I could just as well argue that it's not charging electric vehicles that is via fossil fuelled generated electricity - it's all the lighting that is powered by such, the green electricity goes to electric vehicles! (Quite apart from which, it's more efficient to burn the fossil fuel centrally and power the car electrically, giving possibilities for regenerative braking.)

Just as accurate - if equally unhelpful. I could also argue that there's little point in building out any more green generation - what's the point if there are no BEVs or heat pumps to use it? (Or grid to transport it?) But they would be as stupid as your argument. The way forward is to increase generation, grid capacity and electrical appliances such as BEVs all in tandem.

But I'll put to you again the question I did before. (And which I don't think you ever answered?) If not a move to BEVs, then what? Stay as we are? All motor vehicles to remain burning diesel or petrol and emitting exhaust pollutants? And if not that, then do please tell us your alternative?

[neilj]

lens
'Danny - do you ever actually read what other people write? Do you ever stop to consider if you may be wrong?'

Sir, Sir, I know the answer to these two questions, is it no and no 😀

[lens]

Jul 18, 2024 5:57:01 GMT neilj said:

lens
'Danny - do you ever actually read what other people write? Do you ever stop to consider if you may be wrong?'

Sir, Sir, I know the answer to these two questions, is it no and no 😀

I thought the absolute peach was Danny's reply to you saying "I don't know the real lifetime expectancy of a panel system, so how long it has to repay the costs?" Yet still he feels able to argue an opinion in the face of others who DO know (rough) answers to that and many other questions!

But let's see if he can manage to give a succinct answer (a few words maybe?) to the simple question posed to him....... (if not BEVs going forward, Danny..... then what do you propose?)

[leftieliberal]

New Scientist article on energy storage options (via web archive to avoid paywall).

[lens]

Jul 21, 2024 18:15:04 GMT leftieliberal said:

New Scientist article on energy storage options (via web archive to avoid paywall).

Hmmm. I'm a bit surprised to find that in New Scientist, and Roger Harrabin is a journalist - not a scientist.

The principle of much of what he describes has been known for a while - and mostly the schemes are found to be not viable when they are gone into in depth. At least in other than niche cases.

The idea of weights, pulleys and mineshafts is just a case in point, and it's worth reading cleantechnica.com/2024/06/10/gravity-storage-101-or-why-pumped-hydro-is-the-only-remotely-real-gravity-storage/ for some of the maths behind it. Gravity storage is certainly scientifically feasible, but as the CleanTechnica article says, the only realistic sensible form is pumped hydro. It's worth quoting here the basics of WHY the weights/mineshafts plan doesn't really stack up. If you can't be bothered to read it all, just look at the last (highlighted) paragraph. I can't fault his basic calculations:


"Let’s pretend we can find a kilometer-deep mine shaft that’s abandoned and hasn’t filled with water up to 30 meters below ground level. Oh, wait, we can’t find something like that because ground water? Ignore reality for a minute.

Mine shafts have a diameter of 5 to 20 meters. Let’s pretend we have a huge 20-meter mine shaft that’s a kilometer deep and not full of water. Okay, how big a load of sand can we put on an elevator in a 20-meter diameter shaft? Let’s assume we can put it in a big bin 10 meters tall. So that’s 20 meters in diameter and 10 meters tall of sand. That’s a lot. For Americans, that’s 66 feet across and 33 feet tall.

The volume of a cylinder that size is 3,142 cubic meters. By the way, calculating that is taught in 8th Grade. We’ve advanced all the way to 13-year-old children in basic schools in our math and physics.

Sand has a density of about 1,600 kilograms per cubic meter. That’s about 5,000 tons of sand. Hmmm. Do we have winches that can lift 5,000 tons? Errr. No. That’s almost exactly ten times bigger than massive winches for deepwater construction. Okay, let’s pare that back. Maybe 1,000 tons of sand? Cut the depth to two meters instead? Sure. Let’s do that math, once again, for this fictional, huge, water-free, deep mine shaft, one of which might exist in the world.

1,000,000 kilograms * 9.8 m/s^2 * 1000 meters = about 1,360 kWh. That’s 1.4 MWh.

That isn’t very impressive. A kilometer-deep shaft with a massive elevator full of two meters of sand worked by a couple of the biggest winches ever built and it’s only as much as a third of a Tesla Megapack that is 29 feet long and 8.5 feet tall."


Of course, if you own the rights to a big disused mine, and you can smell grants earmarked for green energy storage R&D, you may prefer not to think along such lines or worry about the cost of keeping water pumped out.......

Regarding the New Scientist article again, then it also states ".....these mega-batteries have drawbacks, not least that they typically depend upon rare, expensive metals. Some of these, such as cobalt, are mined in awful conditions that raise serious human rights concerns." Oh dear. So no battery storage then? Except it isn't true. Not now anyway.

Lithium batteries may use cobalt and nickel where energy density is of prime importance - but that's not so for grid storage! And Tesla at least use lithium iron phosphate (LFP) chemistries for their Megapacks.https://www.utilitydive.com/news/tesla-shifts-battery-chemistry-for-utility-scale-storage-megawall/600315/

[lens]

Incidentally, further to the above, the New Scientist article refers to "Gravitricty’s demonstrator rig in Scotland lifts and lowers two 25-tonne weights" - together with a photo of a pretty large looking rig. Just for fun, it was worth doing the calculation to estimate roughly how much energy it would store. (Go on, have a guess!?)

They don't give a height, but on an assumption of 25 metres from top to bottom I estimate this structure would store up to............. about 3.5kWh. Wow. Just wow.

[leftieliberal]

Jul 21, 2024 23:12:49 GMT lens said:

Incidentally, further to the above, the New Scientist article refers to "Gravitricty’s demonstrator rig in Scotland lifts and lowers two 25-tonne weights" - together with a photo of a pretty large looking rig. Just for fun, it was worth doing the calculation to estimate roughly how much energy it would store. (Go on, have a guess!?)

They don't give a height, but on an assumption of 25 metres from top to bottom I estimate this structure would store up to............. about 3.5kWh. Wow. Just wow.

What you are missing, perhaps because you didn't bother to read the article properly instead of picking on the first example you could ridicule, are quotes like this:

Heat storage technology remains in its infancy and its affordability and efficiency is a slippery, contested matter. Yet we are also starting to get preliminary numbers on its costs. In a 2020 report, the International Renewable Energy Agency (IRENA) calculated the cost of TES using molten salt at around $22 to $26 per kilowatt-hour, whereas using hot bricks was $10 to $15 per kWh, depending on the scale and design. These costs are much lower than green hydrogen storage, which the US Department of Energy estimates at up to $50 per kilowatt-hour, largely because the infrastructure needed is so involved.

Pumped hydro is fine where the topography is suitable, which in practice means in Scotland (where virtually all the UK's existing hydro plants are) so it's not much good for demand in South-East England because you have to add the cost of strengthening the electricity grid to cope with the North-South flows. 

Sometimes you are as bad as Danny.

[lens]

Jul 22, 2024 10:20:32 GMT leftieliberal said:

Jul 21, 2024 23:12:49 GMT lens said:

Incidentally, further to the above, the New Scientist article refers to "Gravitricty’s demonstrator rig in Scotland lifts and lowers two 25-tonne weights" - together with a photo of a pretty large looking rig. Just for fun, it was worth doing the calculation to estimate roughly how much energy it would store. (Go on, have a guess!?)

They don't give a height, but on an assumption of 25 metres from top to bottom I estimate this structure would store up to............. about 3.5kWh. Wow. Just wow.😉

What you are missing, perhaps because you didn't bother to read the article properly instead of picking on the first example you could ridicule, are quotes like this:

Heat storage technology remains in its infancy and its affordability and efficiency is a slippery, contested matter. Yet we are also starting to get preliminary numbers on its costs. In a 2020 report, the International Renewable Energy Agency (IRENA) calculated the cost of TES using molten salt at around $22 to $26 per kilowatt-hour, whereas using hot bricks was $10 to $15 per kWh, depending on the scale and design. These costs are much lower than green hydrogen storage, which the US Department of Energy estimates at up to $50 per kilowatt-hour, largely because the infrastructure needed is so involved.

Pumped hydro is fine where the topography is suitable, which in practice means in Scotland (where virtually all the UK's existing hydro plants are) so it's not much good for demand in South-East England because you have to add the cost of strengthening the electricity grid to cope with the North-South flows. 

Sometimes you are as bad as Danny.

Ooooh, nasty! 😉 Please say you didn't mean that!

No, I did read it fully, and yes heat storage via bricks or salt may have viability in some cases - which is why I didn't mention that at all - and certainly not negatively.

But to the best of my knowledge "gravity storage" first came up well over ten years ago. And has gone nowhere in any real sense. (Except for hoovering up grants for trial projects.) Which is why it's so depressing after all this time to see it given such uncritical attention in New Scientist, when basic simple maths shows up the problems. And the CleanTechnica article I linked to is solely talking (and debunking) "gravity storage" suggestions - no mention of heat storage.

But if you can point out a flaw in my maths - and Gravitricity's project will store far more energy than I believe - then point it out, and I'll happily retract.

No, pumped hydro won't be suitable for many areas for the reasons you say, but the CleanTechnica article is referring to global cases in general, and basic principles - gravity (hydro) storage is feasible *in areas where suitable*, other (gravity) suggestions just aren't, ever.

[leftieliberal]

Jul 22, 2024 12:22:24 GMT lens said:

Jul 22, 2024 10:20:32 GMT leftieliberal said:

Sometimes you are as bad as Danny.

Ooooh, nasty! 😉 Please say you didn't mean that!

No, I did read it fully, and yes heat storage via bricks or salt may have viability in some cases - which is why I didn't mention that at all - and certainly not negatively.

But to the best of my knowledge "gravity storage" first came up well over ten years ago. And has gone nowhere in any real sense. (Except for hoovering up grants for trial projects.) Which is why it's so depressing after all this time to see it given such uncritical attention in New Scientist, when basic simple maths shows up the problems. And the CleanTechnica article I linked to is solely talking (and debunking) "gravity storage" suggestions - no mention of heat storage.

But if you can point out a flaw in my maths - and Gravitricity's project will store far more energy than I believe - then point it out, and I'll happily retract.

No, pumped hydro won't be suitable for many areas for the reasons you say, but the CleanTechnica article is referring to global cases in general, and basic principles - gravity (hydro) storage is feasible *in areas where suitable*, other (gravity) suggestions just aren't, ever.

You also need to understand that pumped hydro doesn't supply electricity instantaneously. In operation the impellers need to be spun up before the water hits them and it takes time (I have seen figures of 10s of seconds quoted) for the water stream from top reservoir to provide a stable flow. So if something, say, took out one of the interconnectors, pumped hydro would not be fast enough to cope. We do need quite low capacity but fast-acting sources and gravity storage, along with flywheels and batteries can supply that. In the old days the inertia of the turbines acted like flywheels, but apart from nuclear power stations, non fossil fuel sources of electricity are low inertia.

And incidentally, Roger Harrabin, who you deprecate as "a journalist - not a scientist" is a Honorary Fellow of St Catherine's College, Cambridge (where he got his degree) and was the person for whom the BBC created the role of Environmental Analyst in 2004. I think that I would trust his reporting more than a self-appointed "expert" like you. Just because you can find a blog post that agrees with your views doesn't make it right. That CleanTechnica blog post only considers the steady-state situation and you completely missed the fact that he does not mention slew rates at all. 

[lens]

Jul 24, 2024 11:08:12 GMT leftieliberal said:

Jul 22, 2024 12:22:24 GMT lens said:

Ooooh, nasty! 😉 Please say you didn't mean that!

No, I did read it fully, and yes heat storage via bricks or salt may have viability in some cases - which is why I didn't mention that at all - and certainly not negatively.

But to the best of my knowledge "gravity storage" first came up well over ten years ago. And has gone nowhere in any real sense. (Except for hoovering up grants for trial projects.) Which is why it's so depressing after all this time to see it given such uncritical attention in New Scientist, when basic simple maths shows up the problems. And the CleanTechnica article I linked to is solely talking (and debunking) "gravity storage" suggestions - no mention of heat storage.

But if you can point out a flaw in my maths - and Gravitricity's project will store far more energy than I believe - then point it out, and I'll happily retract.

No, pumped hydro won't be suitable for many areas for the reasons you say, but the CleanTechnica article is referring to global cases in general, and basic principles - gravity (hydro) storage is feasible *in areas where suitable*, other (gravity) suggestions just aren't, ever.

You also need to understand that pumped hydro doesn't supply electricity instantaneously. In operation the impellers need to be spun up before the water hits them and it takes time (I have seen figures of 10s of seconds quoted) for the water stream from top reservoir to provide a stable flow. So if something, say, took out one of the interconnectors, pumped hydro would not be fast enough to cope. We do need quite low capacity but fast-acting sources and gravity storage, along with flywheels and batteries can supply that. In the old days the inertia of the turbines acted like flywheels, but apart from nuclear power stations, non fossil fuel sources of electricity are low inertia.

And incidentally, Roger Harrabin, who you deprecate as "a journalist - not a scientist" is a Honorary Fellow of St Catherine's College, Cambridge (where he got his degree) and was the person for whom the BBC created the role of Environmental Analyst in 2004. I think that I would trust his reporting more than a self-appointed "expert" like you. Just because you can find a blog post that agrees with your views doesn't make it right. That CleanTechnica blog post only considers the steady-state situation and you completely missed the fact that he does not mention slew rates at all. 

Roger Harrabin describes himself after that article as a "freelance journalist", so I don't think my description is to "deprecate" him?

As for "Just because you can find a blog post that agrees with your views doesn't make it right", then now who is deprecating a source!? Michael Barnard is not just some random internet blogger, but Chief Strategist for TFIE. He's a consultant on major projects, and to get an idea of the scale and who he is adviser to, try tfie.io/ .  I don't particularly like Michael Barnards style of writing, but I've never been able to fault him for factual accuracy. You don't need to do much googling to find many other references to gravity storage going back over 10 years, and the problem comes up over and over.

As for my being a self-appointed "expert" - then you have no idea who or what my background is. So why jump to insults? I actually find it quite laughable. Shall we stick to physics, maths and facts, regardless of who is saying what?

I'm quite happy to let the facts speak for themselves. The formula for potential energy of a weight raised to a height is quite clearly and simply given by mass x gravity x height. Working out the maximum possible potential energy that could be stored by any gravity system couldn't be simpler. Doesn't need an expert. And for a 50 tonne weight raised and lowered 25 metres is about 3.5kWh - before efficiency losses. Facts are facts. If you think that's wrong  - regardless of where it's coming from - then please point out the mistake. (The figure was so low I thought I must have got a decimal point wrong at first. Maybe it is? - but show me where?)

A bit more research shows Gravitricity's project is talking about a 530 metre drop at the Pyhäsalmi mine. So we're a bit closer to real numbers. Assume 100 tonnes (for which you need a pretty big winch) and it gives us 100,000 x 9.81 x 530/3,600,000 kWh. Just under 145kWh. Before efficiency losses. About the size of the batteries from 2 large BEVs. Can you give me any criteria for grounds that make you think the project is going to be remotely viable compared to simply using a Li-Ion battery?

[EDIT Yes, re pumped hydro, such may not come on to supply instantly - but (in places like Dinorwic) it's already been fulfilling a very valuable role for decades. It's most positive feature is an amount of energy that such a mineshaft and weight system could only dream about - from memory over 1.5GWh, and I believe it is capable of a couple of hundred MW for about 5 hours. For more instantaneous response then battery is indeed better. Even if Gravitricitys gravity storage was to be built, then whilst it may meet response speed criteria, then what on earth would make it preferable to battery nowadays?]

[leftieliberal]

Jul 24, 2024 15:44:51 GMT lens said:

Jul 24, 2024 11:08:12 GMT leftieliberal said:

[EDIT Yes, re pumped hydro, such may not come on to supply instantly - but (in places like Dinorwic) it's already been fulfilling a very valuable role for decades. It's most positive feature is an amount of energy that such a mineshaft and weight system could only dream about - from memory over 1.5GWh, and I believe it is capable of a couple of hundred MW for about 5 hours. For more instantaneous response then battery is indeed better. Even if Gravitricitys gravity storage was to be built, then whilst it may meet response speed criteria, then what on earth would make it preferable to battery nowadays?]

Dinorwig (note spelling) was built back at a time when there was much more inertia in the electricity generating system as I already pointed out above but which you ignored. At that time, the tens of seconds it took to come up to full power didn't matter, but it does now. You are only looking at capacity not response time. And Li-ion batteries aren't a silver bullet; no-one has quantified the fire risk arising from rapidly discharging grid-scale batteries yet and there are plenty of examples of fires during the charging of small Li-ion batteries (internal resistance generates heat during both processes).

As I have pointed out before there are almost no sites that have ever been proposed for hydro-electric pumped storage in the UK outside of Scotland and pumped storage should use existing hydro-electric sites because flooding of valleys generates methane, which is a more powerful greenhouse gas than carbon dioxide.

Getting back to gravity trains, their chief value is in places where there are mountains but little rainfall, like the South-Western states of the USA. Here is a real example from 2018 www.bbc.co.uk/news/av/technology-44549962
(actually I think it is a pretty ugly approach, although it illustrates the principle of having marshalling yards at two different heights and a track between them. A better approach would be to clamp the wagons on to a continuous cable (just like gondolas in ski resorts) which gets rid of the limitation on gradient. That your Michael Barnard hasn't understood this, some six years after it appeared on TV, shows that he is more interested in dissing alternative approaches than genuinely pointing out their strengths and weaknesses.

[lens]

Jul 25, 2024 11:07:47 GMT leftieliberal said:

Jul 24, 2024 15:44:51 GMT lens said:

[EDIT Yes, re pumped hydro, such may not come on to supply instantly - but (in places like Dinorwic) it's already been fulfilling a very valuable role for decades. It's most positive feature is an amount of energy that such a mineshaft and weight system could only dream about - from memory over 1.5GWh, and I believe it is capable of a couple of hundred MW for about 5 hours. For more instantaneous response then battery is indeed better. Even if Gravitricitys gravity storage was to be built, then whilst it may meet response speed criteria, then what on earth would make it preferable to battery nowadays?]

Getting back to gravity trains, their chief value is in places where there are mountains but little rainfall, like the South-Western states of the USA. Here is a real example from 2018 www.bbc.co.uk/news/av/technology-44549962
(actually I think it is a pretty ugly approach, although it illustrates the principle of having marshalling yards at two different heights and a track between them. A better approach would be to clamp the wagons on to a continuous cable (just like gondolas in ski resorts) which gets rid of the limitation on gradient. That your Michael Barnard hasn't understood this, some six years after it appeared on TV, shows that he is more interested in dissing alternative approaches than genuinely pointing out their strengths and weaknesses.

But that's not a "real example"!! Not a proper working, commercial one, anyway. It's an early R&D prototype from 6 years ago, and the ARES website shows no updates to their "News" section for nearly 4 years! (I wonder why?) You can see various fancy renders of what they propose (which keep changing) see the "skierpage" link below  - but no real progress. I'm surprised you haven't mentioned "Energy Vault" as well. They did at least have a large gravity structure in Switzerland, you can even see photographs at en.wikipedia.org/wiki/Energy_Vault . And they went public via a SPAC in 2022. So success for gravity storage at last!? Errr, no. The shares are only worth about 10% of the original value, though the company are still a going concern. But their latest projects seem to have been largely battery grid storage ( eg investors.energyvault.com/news/press-releases/news-details/2024/Energy-Vault-Announces-Supply-of-B-Vault-Energy-Storage-System-and-Start-Commercial-Operations-of-100MW200MWh-Jupiter-Power-Battery-Energy-Storage-System-at-St.-Gall/default.aspx ) even if they don't seem to have fully given up on the idea of gravity.

And Michael Barnard most certainly **DID** understand about alternative gravity storage schemes to mineshaft/Gravitricity! Try reading the link I gave again. As just a (very short) extract: "Let’s start with the various rail-based gravity storage solutions. I’m fairly familiar with heavy freight rail and know that they have to play by the rules just like everyone else.
Steel wheels on steel rails means that heavy trains require less than 2% grades, ......... There are funicular railroads that go up steeper pitches, but they have vastly less mass because the strain on the cables gets so high that they snap........." And so on. I've already said I don't like his style of writing, but if you want yet another opinion (easier to read), try www.skierpage.com/blog/2022/08/eco-latest-gravity-energy-storage/ which details why the claims from both ARES and Energy Vault should be taken with a huge pinch of salt. Again, I can't fault anything factual in that.

But perhaps one fact about the physics of gravity storage of energy - certainly versus battery - should bring the physics into sharp focus. How much potential energy can be stored in a one tonne mass suspended about 2 metres off the floor, or put another way, the energy in what size battery would you need to make that 2 metre lift? The (theoretical) answer works out to be roughly 2 AA cells.......

It may have been one thing when "Click" made their report on ARES about 6 years ago, (Hornsdale was only first connected late in 2017, so a time when grid battery storage was in its infancy, and worth exploring all possibilities), but it's a very different story now, with the amount of grid battery storage being successfully installed all over. I'll say again - Can you give me any criteria for grounds that make you think a battery gravity project is going to be remotely viable compared to simply using a comparable sized Li-Ion battery?

[leftieliberal]

Jul 25, 2024 19:18:04 GMT lens said:

Jul 25, 2024 11:07:47 GMT leftieliberal said:

Getting back to gravity trains, their chief value is in places where there are mountains but little rainfall, like the South-Western states of the USA. Here is a real example from 2018 www.bbc.co.uk/news/av/technology-44549962
(actually I think it is a pretty ugly approach, although it illustrates the principle of having marshalling yards at two different heights and a track between them. A better approach would be to clamp the wagons on to a continuous cable (just like gondolas in ski resorts) which gets rid of the limitation on gradient. That your Michael Barnard hasn't understood this, some six years after it appeared on TV, shows that he is more interested in dissing alternative approaches than genuinely pointing out their strengths and weaknesses.

And Michael Barnard most certainly **DID** understand about alternative gravity storage schemes to mineshaft/Gravitricity! Try reading the link I gave again. As just a (very short) extract: "Let’s start with the various rail-based gravity storage solutions. I’m fairly familiar with heavy freight rail and know that they have to play by the rules just like everyone else.

So you really think this is a meaningful representation of a "gravity train" (taken from Michael Barnard's blog post)?

 
He could have at least used a real example instead of faking it with ChatGPT! It is quite typical of his entire approach that he emphasises the weaknesses in other storage methods, but ignores the weaknesses of pumped hydro.

And you still haven't addressed my point about the time delay in pumped hydro, or the lack of inertia in renewable energy sources.

[John Chanin]

Jul 22, 2024 12:22:24 GMT lens said:

Jul 22, 2024 10:20:32 GMT leftieliberal said:

What you are missing, perhaps because you didn't bother to read the article properly instead of picking on the first example you could ridicule, are quotes like this:

Heat storage technology remains in its infancy and its affordability and efficiency is a slippery, contested matter. Yet we are also starting to get preliminary numbers on its costs. In a 2020 report, the International Renewable Energy Agency (IRENA) calculated the cost of TES using molten salt at around $22 to $26 per kilowatt-hour, whereas using hot bricks was $10 to $15 per kWh, depending on the scale and design. These costs are much lower than green hydrogen storage, which the US Department of Energy estimates at up to $50 per kilowatt-hour, largely because the infrastructure needed is so involved.

Pumped hydro is fine where the topography is suitable, which in practice means in Scotland (where virtually all the UK's existing hydro plants are) so it's not much good for demand in South-East England because you have to add the cost of strengthening the electricity grid to cope with the North-South flows. 

Sometimes you are as bad as Danny.

Ooooh, nasty! 😉 Please say you didn't mean that!

No, I did read it fully, and yes heat storage via bricks or salt may have viability in some cases - which is why I didn't mention that at all - and certainly not negatively.

But to the best of my knowledge "gravity storage" first came up well over ten years ago. And has gone nowhere in any real sense. (Except for hoovering up grants for trial projects.) Which is why it's so depressing after all this time to see it given such uncritical attention in New Scientist, when basic simple maths shows up the problems. And the CleanTechnica article I linked to is solely talking (and debunking) "gravity storage" suggestions - no mention of heat storage.

But if you can point out a flaw in my maths - and Gravitricity's project will store far more energy than I believe - then point it out, and I'll happily retract.

No, pumped hydro won't be suitable for many areas for the reasons you say, but the CleanTechnica article is referring to global cases in general, and basic principles - gravity (hydro) storage is feasible *in areas where suitable*, other (gravity) suggestions just aren't, ever.

The New Scientist article was looking in general at possible energy storage options other than batteries, of which the gravity storage was just one, and hardly ramped, merely reported.  In general pilot studies on these various possibilities are plainly a good idea.  One of them may prove to be practical and scalable, and we do need energy storage of more than a few hours if we are to rely on renewables.  

The main thing I took from the article, was that there is an over emphasis on electricity generation as much energy is used directly as heat, and can therefore be stored as heat.  And that the constant ramping of hydrogen is corporate propaganda - there is little role for hydrogen, green or otherwise.

[lens]

Jul 26, 2024 11:56:46 GMT leftieliberal said:

Jul 25, 2024 19:18:04 GMT lens said:

And Michael Barnard most certainly **DID** understand about alternative gravity storage schemes to mineshaft/Gravitricity! Try reading the link I gave again. As just a (very short) extract: "Let’s start with the various rail-based gravity storage solutions. I’m fairly familiar with heavy freight rail and know that they have to play by the rules just like everyone else.

So you really think this is a meaningful representation of a "gravity train" (taken from Michael Barnard's blog post)?

View Attachment 
He could have at least used a real example instead of faking it with ChatGPT!

No, neither I, Michael Barnard, nor (AFAIK) anyone thinks it's "meaningful" in the sense of being realistic. I've already said I don't particularly like the style of his writing, but (in CleanTechnica at least) a ChatGPT headline image is part of his trademark. Take it or leave it. On the whole, comments seem to indicate his images go down well.

But regardless of writing style, I can't fault his factual accuracy, not the general validity of his opinions. It's refreshing to see articles written by someone who speaks their mind and voices their opinions rather than just uncritically parroting press releases.

Jul 26, 2024 11:56:46 GMT leftieliberal said:

It is quite typical of his entire approach that he emphasises the weaknesses in other storage methods, but ignores the weaknesses of pumped hydro.

And you still haven't addressed my point about the time delay in pumped hydro, or the lack of inertia in renewable energy sources.

No - he doesn't "ignore the weaknesses of pumped hydro". Again, read more carefully. If you detect him being positive about such, it's because in spite of issues (response time, availability of suitable site etc) it's in relation to other forms of gravity storage. Look at the physics and maths and pumped hydro *can* be feasible - most of the others just aren't. Certainly not viably, anyway. Pumped hydro's plus is being able to store huge quantities of energy. Schemes able to output several hundred megawatts for around 5 hours.

Regarding inertia, then my apologies as I missed out a paragraph from the previous reply. Yes, moving away from big and heavy spinning turbines means less physical inertia that can be called upon in the event of a sudden supply surge or a generator dropping off-line. But it's been thought about, and already acted upon. As example: www.energy-storage.news/upgrade-at-tesla-battery-project-demonstrates-feasibility-of-once-in-a-century-energy-transformation-for-australia/


"As the amount of variable renewable energy from wind and solar on the grid increases, so too does the need for inertia to keep the network stable. Traditionally, the large rotating mass of thermal power generators such as coal has delivered this inertia as a sort of byproduct to their normal operation.



Today, advanced inverter technologies – known as grid-forming inverters – can do this instead.



In a February 2022 blog for this site, Blair Reynolds of inverter manufacturer SMA explained how it works, with grid-forming inverters providing a sort of “synthetic inertia” to mimic the way synchronous rotating generators like fossil fuel plants generate the AC grid waveform at a common frequency at which the grid operates reliably."



Moving forward, can we not envisage a relatively small battery storage working with a large pumped hydro scheme? The former to provide the inertia you correctly talk about - the latter to provide a larger quantity of energy storage?

[lens]

Jul 26, 2024 12:25:46 GMT John Chanin said:

Jul 22, 2024 12:22:24 GMT lens said:

But to the best of my knowledge "gravity storage" first came up well over ten years ago. And has gone nowhere in any real sense. (Except for hoovering up grants for trial projects.) Which is why it's so depressing after all this time to see it given such uncritical attention in New Scientist, when basic simple maths shows up the problems. .............

The New Scientist article was looking in general at possible energy storage options other than batteries, of which the gravity storage was just one, and hardly ramped, merely reported.  In general pilot studies on these various possibilities are plainly a good idea.  One of them may prove to be practical and scalable, and we do need energy storage of more than a few hours if we are to rely on renewables.  

In general and in principle, yes, I agree. But it's a question of timing. What you say would have been perfectly valid for Gravitricity and others ten or more years ago. Now they have been proven **NOT** to be practical and scalable - even if the company refuses to give up. The pilot studies *were* a good idea, not *are*! I've been given more details about the Gravitricity demonstrator rig - namely that it used 50 tonne of weights, but with a height differential of only 15 metres. Put the actual numbers through the formula and it gives a (maximum) energy storage of only slightly over 2kWh!! For a 15 metre tower and 50 tonnes of weight! They didn't even really need to build the tower to know that, it was evident from basic physics theory over 10 years ago.

It's like writing an article in the past about the possibilities and future of television by mechanical means. Write that in the early 1930's and fine - perfectly valid. Write it in around 1937 and it's a very different story. The Baird experiments were one thing in the 1920's - worth trying various technologies as "pilot studies" - but by the mid-30's it was becoming blatantly obvious that the future of television wasn't going to be mechanical. Post 1936 and the BBC Alexandra Palace trial there was no doubt in virtually anybody's mind - possibly even including Baird himself.

(And on a complete tangent for anybody who may be interested in such technology, a good reference to the Baird studios at Crystal Palace at www.tvstudiohistory.co.uk/independent-tv-studios/crystal-palace-john-logie-bairds-independent-studio-centre/ )

[leftieliberal]

A tour of the now-operational Kirk Hill wind farm, narrated by the Project Manager. He discusses some of the things you have to think about as a civil engineer when project-managing the construction of an onshore wind farm.

[leftieliberal]

Interview with Fintan Slye, the new head of NESO (what used to be called National Grid ESO) on what we will need to do to achieve clean electricity by 2030. It's good to read a common-sense statement on the challenges instead of politicians' platitudes. And no, it won't be easy, in fact he puts it near the limit of what is possible.