The Future of Power Generation in Great Britain

[Cobnapint]

PushedDover said:

Cobnapint said:

But we've closed most of our generating capacity down and replaced it with mostly unreliable wind.
It's been done to death on here.

Done to death by yourself does not give it validity fyi

Not saying it does.

Doesn't mean it's not true though.

[ianrb]

Evanivitch said:

PushedDover said:

At a generation level it is irrelevant ?

How’s that gas from Russia working out

The biggest issue switching from Russian gas was replacing pipelines infrastructure with LPG and regasification facilities. Seems to be going quite well since.

It's LNG. Different stuff.

[tamore]

i can't get my head around the energy market. mostly LNG being toasted to make energy at the moment with a fairly low wind across the UK, but wholesale cost is £3.00 MWh!

[Mikey G]

tamore said:

i can't get my head around the energy market. mostly LNG being toasted to make energy at the moment with a fairly low wind across the UK, but wholesale cost is £3.00 MWh!

Looks like an oversupply at the moment as the frequency is quite over 50Hz, could be due to a slight increase in expected wind output despite it being rather low at the moment.

[tamore]

don't really know how it works. how big is an average gas/peaker plant? how long does it take to bring up from standby/ wind down when on?

[dvs_dave]

Condi said:

There is a different thread for this, but HS2 is considerably cheaper and faster than upgrading our existing lines, and adds a lot of capacity. Think of it like a bypass for trains. Faster/longer distance trains will go on HS2, hugely increasing the capacity for slower, more local and goods trains on the congested areas outside London and the Midlands.


Anyway, heat pumps. I tend to agree that the government have jumped a bit "all in" on them, but for a well insulated new build they do work well. The problem comes retrofitting to older homes and they don't work so well, especially at "house scale". At small scale they work better - an air con unit will do heating too at reasonable effectiveness.

Like everything, there is a time and a place for them, but the Telegraph article simply dismisses all heat pumps as the wrong solution, which isn't true. The best idea would be to try and insulate older properties, but the schemes which did exist years ago no longer do exist. Equally landlords should be forced to upgrade their properties, while the government are trying to get there, there are a lot of exemptions in the existing rules.

Heat pumps are a no brainer for new builds, but more of a challenge to retrofit into old stock for various reasons already discussed without changing the entire system for ductless splits, or bigger radiators, etc. Although hybrid/dual fuel systems are a common solution in other markets and the best of worlds. Not sure why such solutions aren’t being pitched as whilst not zero emissions, way way less emissions as gas is only needed for top-up/backup heat outside of the optimum operating ranges of the heat pump, which isn’t actually all the often in the UK.

If combined with a heat store (aka a large hot water tank), then they can work off peak and store the heat to be used during peak times. Pretty much the same principle as the old storage heaters from yesteryear.

Edited by dvs_dave on Sunday 19th March 19:53

[Evanivitch]

tamore said:

don't really know how it works. how big is an average gas/peaker plant? how long does it take to bring up from standby/ wind down when on?

STOR sites are about 20MW typically.

[PushedDover]

Evanivitch said:

PushedDover said:

At a generation level it is irrelevant ?

How’s that gas from Russia working out

The biggest issue switching from Russian gas was replacing pipelines infrastructure with LPG and regasification facilities. Seems to be going quite well since.

And the price?

[Mikey G]

PushedDover said:

And the price?

I have generally skipped over your tit for tat exchanges so far, but maybe if you do a little research yourself you will see that current gas prices have fallen to a 20 month low last seen during the late summer of 2021 before the war kicked off, which would suggest supply issues have been reduced to a level that the market has stabilised over the last couple of months.

[xeny]

Mikey G said:

I have generally skipped over your tit for tat exchanges so far, but maybe if you do a little research yourself you will see that current gas prices have fallen to a 20 month low last seen during the late summer of 2021 before the war kicked off, which would suggest supply issues have been reduced to a level that the market has stabilised over the last couple of months.

I've not done a detailed analysis, but how much of that is due to a pleasantly mild winter and some pretty large scale industrial demand destruction in Europe, which is not great from an economic perspective.

[Condi]

Mikey G said:

I have generally skipped over your tit for tat exchanges so far, but maybe if you do a little research yourself you will see that current gas prices have fallen to a 20 month low last seen during the late summer of 2021 before the war kicked off, which would suggest supply issues have been reduced to a level that the market has stabilised over the last couple of months.

Or the demand has been destroyed by a combination of industry turning off, domestic heating being turned down, and an unusually mild winter?

Supply is still a massive issue, hence the high prices for next winter, but we have been "lucky" this winter. I don't really agree we've been lucky, because industry turning off is not good, but maybe better to say we've coped well with some help from the weather.

Europe is gradually building up LNG import capacity, but its not going to replace Russian gas like for like and of course there is only so much LNG supply the world is fighting over, whereas a lot of Russian production only had one market.

[Condi]

tamore said:

i can't get my head around the energy market. mostly LNG being toasted to make energy at the moment with a fairly low wind across the UK, but wholesale cost is £3.00 MWh!

The imbalance price might be £3, but the wholesale cost won't be. One day I will endeavour to explain again, but as I'm currently abroad it won't be today.

[PushedDover]

Mikey G said:

I have generally skipped over your tit for tat exchanges so far, but maybe if you do a little research yourself you will see that current gas prices have fallen to a 20 month low last seen during the late summer of 2021 before the war kicked off, which would suggest supply issues have been reduced to a level that the market has stabilised over the last couple of months.

Thanks for the pointers on research.
Seems to check out fine

[phumy]

Evanivitch said:

tamore said:

don't really know how it works. how big is an average gas/peaker plant? how long does it take to bring up from standby/ wind down when on?

STOR sites are about 20MW typically.

STOR (gas) sites can be on line, synchronised and up to full output with around 3 to 4 mins and there are literally hundreds of these small sites located all over the country.

A CCGT could be up to near full capacity within 1.5 to 2 hours, depending on how long it has been shutdown, a hot start (less than 8 hrs shutdown) youre looking at around 90 mins, if its been shut down for a week then up to 4 hours to full output. Im talking about a 750MW to 850MW site.

Edited by phumy on Monday 20th March 05:47

[djc206]

phumy said:

STOR (gas) sites can be on line, synchronised and up to full output with around 3 to 4 mins and there are literally hundreds of these small sites located all over the country.

A CCGT could be up to near full capacity within 1.5 to 2 hours, depending on how long it has been shutdown, a hot start (less than 8 hrs shutdown) youre looking at around 90 mins, if its been shut down for a week then up to 4 hours to full output. Im talking about a 750MW to 850MW site.

Edited by phumy on Monday 20th March 05:47

Interesting thanks. When you say up to full capacity in 4 hours what sort of capacity curve, if that’s a thing would a CCGT plant follow after a cold start? ie is it like a car where you get most of the power not long after a cold start you just can’t wring it’s neck fully until warmed up or is a very slow build up to that ~800MW

[Mikey G]

Condi said:

Mikey G said:

I have generally skipped over your tit for tat exchanges so far, but maybe if you do a little research yourself you will see that current gas prices have fallen to a 20 month low last seen during the late summer of 2021 before the war kicked off, which would suggest supply issues have been reduced to a level that the market has stabilised over the last couple of months.

Or the demand has been destroyed by a combination of industry turning off, domestic heating being turned down, and an unusually mild winter?

Supply is still a massive issue, hence the high prices for next winter, but we have been "lucky" this winter. I don't really agree we've been lucky, because industry turning off is not good, but maybe better to say we've coped well with some help from the weather.

Europe is gradually building up LNG import capacity, but its not going to replace Russian gas like for like and of course there is only so much LNG supply the world is fighting over, whereas a lot of Russian production only had one market.

I would like to think we are going to be a little more prepared for next winter than we were for this one. IIRC wasnt the stats that only 5% of our gas was Russian before the conflict?
I noticed Rough is being topped up again currently, was 28% last time I looked. According to this site it looks like its from our very own gas fields https://terravolt.co.uk/uk-gas-visual/ Maybe they are making the most of current lower prices to top up storage. But I guess they wont want to overdo it as the price will just collapse if another mild winter happens next year and we'll get all the tears from the energy companies about lack of profits.

[Talksteer]

djc206 said:

phumy said:

STOR (gas) sites can be on line, synchronised and up to full output with around 3 to 4 mins and there are literally hundreds of these small sites located all over the country.

A CCGT could be up to near full capacity within 1.5 to 2 hours, depending on how long it has been shutdown, a hot start (less than 8 hrs shutdown) youre looking at around 90 mins, if its been shut down for a week then up to 4 hours to full output. Im talking about a 750MW to 850MW site.

Edited by phumy on Monday 20th March 05:47

Interesting thanks. When you say up to full capacity in 4 hours what sort of capacity curve, if that’s a thing would a CCGT plant follow after a cold start? ie is it like a car where you get most of the power not long after a cold start you just can’t wring it’s neck fully until warmed up or is a very slow build up to that ~800MW

The GT gets up to temperature really fast it's the steam turbine or more specifically the steam generator which suits in the gas turbine exhaust which takes time to get to capacity.

Curve is basically nothing for a decent amount of time as the GT warms up on idle. Then about 25% as the GT operates are part throttle and synchronizes, then a flat spot which the steam system builds steam, then a linear ramp up to about 80-90% and a slower ramp for the last 10%.

[Talksteer]

xeny said:

Ivan stewart said:

Why ?? If you used intermittent renewable energy to produce hydrogen at source ,it’s easy to store so you have power ready to use day and night And I would think cheaper to transport than electricity ..

round trip efficiency is terrible, it leaks like a *** as it is so small so not that easy to store, and if we have an entirely electric energy sector, the storage capacity needed would be huge, far greater than we are failing to provision for natural gas when it only makes up a small fraction of the sector.

If you run expensive capital equipment in an intermittent manner then it's products become expensive just due to capacity factor. You then also add an element of wear and tear to the kit as you switch it on and off or up and down.

In the case of hydrogen production it is likely that you would actually have batteries to keep it running through daily demand fluctuation.

I've yet to see a usage for intermittent power where the capital kit is cheap and tolerant of frequent start-ups.

The biggest demand management options are likely to be vehicle batteries and heat storage.

[phumy]

Talksteer said:

djc206 said:

phumy said:

STOR (gas) sites can be on line, synchronised and up to full output with around 3 to 4 mins and there are literally hundreds of these small sites located all over the country.

A CCGT could be up to near full capacity within 1.5 to 2 hours, depending on how long it has been shutdown, a hot start (less than 8 hrs shutdown) youre looking at around 90 mins, if its been shut down for a week then up to 4 hours to full output. Im talking about a 750MW to 850MW site.

Edited by phumy on Monday 20th March 05:47

Interesting thanks. When you say up to full capacity in 4 hours what sort of capacity curve, if that’s a thing would a CCGT plant follow after a cold start? ie is it like a car where you get most of the power not long after a cold start you just can’t wring it’s neck fully until warmed up or is a very slow build up to that ~800MW

The GT gets up to temperature really fast it's the steam turbine or more specifically the steam generator which suits in the gas turbine exhaust which takes time to get to capacity.

Curve is basically nothing for a decent amount of time as the GT warms up on idle. Then about 25% as the GT operates are part throttle and synchronizes, then a flat spot which the steam system builds steam, then a linear ramp up to about 80-90% and a slower ramp for the last 10%.

The Gas Turbine, once started can get up to temperature fast (they dont warm up at idle) however once up to 3000rpm and synchronised with the grid, the exhaust gasses must follow a prescribed temperature increase which is basically driven by the differential of the exhaust gas temperature and the HRSG (Heat Recovery Steam Generator, basically a boiler) first row of superheater tubes, these are the first ones to get hit by the exhaust gas. Once the GT is synched with the grid it will slowly start to increase the exhaust gas temperatures so that there is always less than 50 degC differential between the gas outlet and the metal temperature of the tubes. The exhaust gas temperature at this time is held around 350DegC, this is due to thermal expansion of the tubes, its not good to expand/heat them too fast, same as a cast iron exhaust manifold in your car. Once the temp of the tubes is around 300 the GT is normally around 50-60MW then can be released to increase load to its max, usually around 250MW.

After around 10 mins of running the first one, the second GT can be started, in the UK this is to not exceed the stack emissions within 1 hour, if you started both at the same time the emissions would normally hit and go over the stations allowable limit. So, second one starts and has to go through the same heat exhaust/tube expansion issues until it gets to 50-60MW then that can be released. All this time the HRSGs are producing steam and is sending all this steam to the steam turbine condenser via two bypass valves, bypassing the actual tubine blades. There is then a waiting period, not too long as there has to be the correct temperature, correct pressure and the correct steam conductivity, once all these three parameters are all in spec then the turbine throttle valves can be slowly opened, whilst closing the bypass valves transferring the steam to run up the steam turbine to 3000rpm (synchronising speed). Whilst the steam turbine is getting synced to the grid the GTs are increasing the exhaust temperatures to produce more steam to drive the steam turbine but theyre not increasing electrical load.

The steam turbine is also increased in load by introducing more steam, however, it is constrained by thermal expansion of the blades and can only increase load at certain ramp rates and these are determined by differential expansion between the different rotor stages of the steam turbine and also the metal temperatures of the casings, once these expansions are ok then the turbine can go up to full load, the GTs will now be flat out. Youre then at full load.

You probably know that the ambient temperature affects Gas Turbines quite a bit, cold weather and the load rises by up to 30MW to 40MW difference between winter and summer. Rainy day will also affect the output as will a hot afternoon. During a very cold day, say around 3DegC the gas turbine will bleed off hot are from the 3rd or 4th stage of the compressor and return it to its own inlet to stop ice forming in the air intake, GT blades do not do ice, they can break, so on the very cold days load is actually reduced due to warm air bleeding back to the intake.

Sorry if this has wandered off from the thread but i thought some might be interested in how a CCGT is started, its not quite a simple as that but its the main nuts and bolts of how it works, its a one person operation and the automation helps enormously. Obvioulsy lots can go wrong on start up and things sometimes do but the plant has a system that will put it into a "safe" mode until you can sort out what the issue is.

STOR gas engines are just a big V16 or V20 ICE (MTM German, or Rolls Royce) that have been converted to run on Natural Gas and will start up from an automated signal from National Grid, once a signal is receved to start, it will go to its normal start sequence and will be up to speed within less than a minute, (these engines use a sump heater and a cylinder jacket warming system) so thermal expansion is not normally an issue. Once theyre up to synch speed they need to run the auto synch which will take around a minute, once thats synched its just a case of ramping up the load, usually 1.5 to 2 mins and its then up to full load, these stations normally would have 8 to 10 engines under one roof, so theyre pushing out 16MW to 20MW per station, these are dotted all over the country.

Edited by phumy on Tuesday 21st March 08:37

[djc206]

Very interesting, thanks both