Gas or electric?

[StephenOak]

My understanding of the issue here is that reactor design hasnt really moved on, and still produce lots of waste.

No, nuclear has never produced much waste. The total amount the UK has produced to date would fit into a few large 'sheds' on the sort you see on an industrial estate.

I know there are a number of programmes globally looking to address this with safer, low waste reactor designs.

Both conventional ones that 'burn' more fuel and things like LFTR that are different in principle.

The price of batteries dropped by 87% in 2010-2020, they dropped 13% last year.

Any sources for that?

Also, Lithium is cheap.

You can make anything look cheap by comparing it to the right other object. Part of the reason there is a lot of research into other technologies is because lithium is so expensive.

For short term peaks you have the incredibly expensive, polluting peaker plants that can spin up in minutes rather than hours or days like the big cheap gas plants.

Once again, I have no idea what you mean. Some peaking plants are OOGT and are less efficient but are not polluting. I have never heard of a CCGT plant that takes more than a few minutes to start and maybe half an hour to get up to maximum efficiency. I have no idea why you think they take days to start.

Short term stability isn't going to be an issue for much longer.

Goody. A problem that we never used to have and was only introduced by adding loads of expensive unreliables to the grid is going to be solved at even more expense.

And the reason they're used at the moment is to make money, Hornsdale has done better than it was predicted for both it's investors and the SA public.

Utter nonsense. IF SA had a reliable grid there would be need for Hornsdale. And it has been so successful only because the grid in SA has been so unreliable.

apparently we've got around a GW of installed grid batteries

Which basically amount to zero when compared to the size of the grid.

that's a decent 320MW/640MWh one though.

You seem to have written 'decent' when you meant 'miniscule'. Batteries can possibly be a useful, albeit very minor, part of balancing the grid, but I get a bit irritated when people talk about how big they are are refer to them as grid-scale when they are so relatively small. UK electricity consumption is c. 850GWh/day.

BTW,

Responding to "[Batteries have] already undercut the business case for peaked plants entirely as they're too expensive and slow to make sense." I said

Really? Any numbers to back that up?

Responding to "The advantage [of LAES] is that you can keep that power for a long time at minimal cost." I said

How does that compare to storing the equivalent amount of energy as natural gas?

 

[IT Minion]

Any sources for that?

https://about.bnef.com/blog/battery...ps-up-with-market-average-at-156-kwh-in-2019/

But I was wrong, that was only 2010-2019. Any thoughts?

You can make anything look cheap by comparing it to the right other object. Part of the reason there is a lot of research into other technologies is because lithium is so expensive.

You're thinking of Cobalt. Or maybe nickel. Graphite is an alternative but that's still lab based and not generally available now.

Once again, I have no idea what you mean. Some peaking plants are OOGT and are less efficient but are not polluting.

Less efficient is more polluting.

You seem to have written 'decent' when you meant 'miniscule'. Batteries can possibly be a useful, albeit very minor, part of balancing the grid, but I get a bit irritated when people talk about how big they are are refer to them as grid-scale when they are so relatively small. UK electricity consumption is c. 850GWh/day.

Well we're getting you closer to possibly embracing modern systems, so I guess that's a start.

BTW,

Responding to "[Batteries have] already undercut the business case for peaked plants entirely as they're too expensive and slow to make sense." I said

https://www.ge.com/power/transform/...cles.2018.oct.storage-threat-to-peaker-plants

Responding to "The advantage [of LAES] is that you can keep that power for a long time at minimal cost." I said

Yeah, not a clue, how much does it cost to store Gas in grid volumes?

I have never heard of a CCGT plant that takes more than a few minutes to start and maybe half an hour to get up to maximum efficiency. I have no idea why you think they take days to start.

Any examples or statistics to back that up? My understanding is that cold starts are slow, but CCGT can ramp up or down within 60-100% load in around half an hour or so, roughly. And doing so costs more for operational and maintenance costs.

 

[StephenOak]

Thanks for the links, I'll look at them later on.

You're thinking of Cobalt. Or maybe nickel. Graphite is an alternative but that's still lab based and not generally available now.

I'm not thinking of anything in particular. There are lots of different ideas being investigated. Lithium batteries are expensive, at scale they are very expensive. The UK battery you linked to y/day is £200 million (IIRC), which is a lot for such a small facility.

To provide a significant grid-scale battery backup you are talking about 100s of £billions. So something that performs a bit less well in other areas but is cheaper would be attractive.

And of course these are lab based. Lithium batteries were lab based once, and it was 10 years before they were available and another 10 years before they were common & cheap enough for mass use. Everything has to start somewhere, you are touting the benefits of LAES but (AFAIUI) that there is not one of them in the country and we don't have real-world figures on construction & running costs or efficiency. Maybe the first half a dozen of these will all be dogs until a decent design / setting will be derived.

Less efficient is more polluting.

Only if you use an odd definition of polluting.

Well we're getting you closer to possibly embracing modern systems, so I guess that's a start.

Modern does not always mean good.

Yeah, not a clue, how much does it cost to store Gas in grid volumes?

No idea either. You are the one who said that LAES was 'minimal cost'. If it costs 5% of lithium batteries it looks good. If that figure is actually 100 times what gas would cost it doesn't looks anything like as good.

Any examples or statistics to back that up? My understanding is that cold starts are slow, but CCGT can ramp up or down within 60-100% load in around half an hour or so, roughly. And doing so costs more for operational and maintenance costs.

Nothing specific I can link to, but I have read about CCGT systems starting very rapidly (5 minutes?) but taking longer (15-30 minutes?) to get up to maximum efficiency. That sounds reasonable as they are gas turbines and they start up pretty quick. The core of the system is the same whether the GT is powering a jet, a ship or a generator.

You said that plants take "hours or days" to start, but have yet to supply anything to support that. I could believe a large, simple CCGT (probably older & intended for baseload generation) taking an hour or two for the steam part to get fully get up to temperature, and the gas part being restricted during that time. But the gas part will be generating during that time. But 'hours' (implying maybe double figures) or 'days' really does not sound right.

 

[mikeey84]

Nothing specific I can link to, but I have read about CCGT systems starting very rapidly (5 minutes?) but taking longer (15-30 minutes?) to get up to maximum efficiency. That sounds reasonable as they are gas turbines and they start up pretty quick. The core of the system is the same whether the GT is powering a jet, a ship or a generator.

You said that plants take "hours or days" to start, but have yet to supply anything to support that. I could believe a large, simple CCGT (probably older & intended for baseload generation) taking an hour or two for the steam part to get fully get up to temperature, and the gas part being restricted during that time. But the gas part will be generating during that time. But 'hours' (implying maybe double figures) or 'days' really does not sound righ

Seems you are looking at 2.5 hours from cold or 45 minutes for a hot start, although this is for full capacity

https://etn.global/wp-content/uploa...reduction_for_Combined_Cycle_Power_Plants.pdf

 

[StephenOak]

Seems you are looking at 2.5 hours from cold or 45 minutes for a hot start, although this is for full capacity

Which is broadly in line with what I said. Bear in mind that the document goes on to talk about requirements for plants to be running quicker and methods of achieving that.

Still nothing like "hours or days" to start up.

 

[JP_]

A bit late to this, but if your 30s bungalow is anything like mine (solid walls, drafty timber floor) then I'd put more money into insulation - 10cm between floor joists, 5cm kingspan on the walls, top up loft insulation. Then heating the house will be a lot easier and cheaper - we don't need the heating on at night, no matter how cold it gets outside - heating being off 8 hours a night is a big saving.

I'd always go for gas boiler with thermostats on the radiators - easier to reduce heating in rooms not used so much, and turn up when needed. That will save more (probably) than a complex electrical system.

 

[IT Minion]

Which is broadly in line with what I said. Bear in mind that the document goes on to talk about requirements for plants to be running quicker and methods of achieving that.

Still nothing like "hours or days" to start up.

It is exactly hours, but I'll admit days probably doesn't apply to gas, and I must have been thinking of coal or even more old school systems.

 

[mikeey84]

I've got a question- I'm no engineer as some of my posts may prove!

How does a heat pump achieve 400% efficiency? How does it provide 4 x as much heat from the same amount of power than an electrical heater?

Or have I got the wrong end of the stick?

 

[Captain Nemesis]

Only if you use an odd definition of polluting.

Emitting greenhouse gases.

Less efficient = more fossil fuel burned for the same amount of power generated.

 

[Captain Nemesis]

(certainly AFAIUI) the wood chip at Drax is from mature (100 year old?) trees and they will not be replaced much if at all before the end of this century.

Friend of mine lives near a farm growing bamboo for Drax.

 

[IT Minion]

I've got a question- I'm no engineer as some of my posts may prove!

How does a heat pump achieve 400% efficiency? How does it provide 4 x as much heat from the same amount of power than an electrical heater?

Or have I got the wrong end of the stick?

Normal electric heaters generate heat by making a bit of metal very hot. It converts electricity into energy and it's 100% efficient, 1W of electrical power gives 1Ws worth of heat..

Heat pumps are different, instead of heating an element up they collect heat from the surrounding area. It turns out that they can collect more heat than they would generate by just heating up some metal. So instead of using 1W of power to make the equivalent heat, it uses 1 W of power to collect 4Ws of heat.

 

[mikeey84]

Normal electric heaters generate heat by making a bit of metal very hot. It converts electricity into energy and it's 100% efficient, 1W of electrical power gives 1Ws worth of heat..

Heat pumps are different, instead of heating an element up they collect heat from the surrounding area. It turns out that they can collect more heat than they would generate by just heating up some metal. So instead of using 1W of power to make the equivalent heat, it uses 1 W of power to collect 4Ws of heat.

Perfect explanation. Thanks very much

 

[Captain Nemesis]

it uses 1 W of power to collect 4Ws of heat.

Including of course using 1W of power to collect 4W of heat from inside the house and put it outside.

 

[IT Minion]

Including of course using 1W of power to collect 4W of heat from inside the house and put it outside.

An Aircon unit does that. It's the same principle (obviously) but running in the opposite direction. Some heatpumps can work in reverse, some can't.

 

[Captain Nemesis]

Why buy one that cant