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All across the Great Western territory => Across the West => Topic started by: SandTEngineer on December 13, 2019, 04:02:32 pm



Title: Aberthaw Power Station
Post by: SandTEngineer on December 13, 2019, 04:02:32 pm
Aberthaw, the last coal fired power station in Wales, ceased production at 1530 today (Friday 13/12/2019) with the likely loss of 170 jobs over the next few months.

End of another era........


Title: Re: Aberthaw Power Station
Post by: broadgage on December 13, 2019, 05:46:43 pm
Poor timing IMHO, I can see the need to reduce carbon emissions by reducing and then eliminating coal burning.
But it might have made more sense to keep the power station operational until the end of this winter for "just in case".

By NEXT winter we should have more renewable capacity, and it is uneconomic to keep aging coal burning plant on standby for years, but a few weeks might have been prudent.

Especially as both reactors at Hunterston B wont be available for this winter.


Title: Re: Aberthaw Power Station
Post by: stuving on December 13, 2019, 07:25:42 pm
Especially as both reactors at Hunterston B wont be available for this winter.

Not to mention the risk of a large drop in French production. So far workers in the electricity and gas industries have been kept out of the brouhaha about pensions, though in the long term the plan is for them to lose their special pension schemes just like the railway workers. Apparently (and I've not found a source of data to check these figures) there is a loss of about 1.5 GW most days, but France is, surprisingly, not consistently a nett exporter these days in any case.


Title: Re: Aberthaw Power Station
Post by: broadgage on December 14, 2019, 09:59:17 am
Agree.
BTW, French electricity production data may be found here;
https://www.gridwatch.templar.co.uk/france/ (https://www.gridwatch.templar.co.uk/france/)


Title: Re: Aberthaw Power Station
Post by: stuving on December 14, 2019, 10:56:53 am
Agree.
BTW, French electricity production data may be found here;
https://www.gridwatch.templar.co.uk/france/ (https://www.gridwatch.templar.co.uk/france/)

I've worked out why the data I had found from RTE were inconsistent (with themselves and that Gridwatch panel) - I was in the bit of the RTE site for energy traders. That deals in energy flow predictions (updated until they become actual and then they disappear), and without links to their real-time data.

There is a link on Gridwatch to RTE's pretty presentation graph (https://www.rte-france.com/en/eco2mix/eco2mix-mix-energetique-en)s, which show that when wind power is "on" RTE exports all day: from zero at their peak demand up to 6 GW. There is also about 6 GW of pumped storage, but with peak-trough of 15-20 GW more is needed.

So there are huge swings, notably when French generation is low for whatever reason. For some that's known (calm, shut-downs, strikes...) but RTE also talk about "the normal operation of the energy market"; I presume that means importing (mostly German windpower) when it's cheaper than what EDF can turn off.


Title: Re: Aberthaw Power Station
Post by: SandTEngineer on December 14, 2019, 12:04:33 pm
According to info elsewhere that now leaves the following UK coal fired power stations:

Drax (what hasn't been converted to biomass)
Fiddler's Ferry
Kilroot
Ratcliffe-on-Soar
West Burton

Fiddler's Ferry next to go in 3 months time.


Title: Re: Aberthaw Power Station
Post by: didcotdean on December 14, 2019, 12:11:33 pm
At this moment, despite UK wind being not far off the peak (~12GW/33%) and ~2.25 GW/6.25% from solar, imports are maxed out on 4 out of the 5 interconnectors (~5.5GW/13%). Still it is giving the gas plant a bit of a rest as it is at only around 50% of capacity.


Title: Re: Aberthaw Power Station
Post by: broadgage on December 14, 2019, 01:12:29 pm
I know someone whom works at a power station that receives extra payments from National Grid for being capable of a "black start"
Most power stations require an external source of electricity to run auxiliary plant before electricity can be produced. This is normally obtained from the transmission system.

A minority of power stations have black start capability whereby they can be started up without any external power.
The basic requirements are the ability to start at least one main generating unit/module within a specified time, and to do this at least three times, in case the grid fails before the plant is running, and once running to accept large step changes in load.
This is usually achieved by diesel engines that start from air bottles or batteries, in order to run essential equipment.

The most recent test of the black start capability was a failure.


Title: Re: Aberthaw Power Station
Post by: stuving on October 16, 2020, 12:12:35 am
At this moment, despite UK wind being not far off the peak (~12GW/33%) and ~2.25 GW/6.25% from solar, imports are maxed out on 4 out of the 5 interconnectors (~5.5GW/13%). Still it is giving the gas plant a bit of a rest as it is at only around 50% of capacity.

Apparently, the latest cross-channel interconnector "launched" today - i.e. it has just started its commissioning. This is IFA-2 (http://ifa2interconnector.com/latest-news/national-grid-s-new-undersea-power-cable-between-britain-and-france-energises-race-to-net-zero/); the oldest link is IFA (for Interconnexion France-Angleterre), and both were built by the two electricity network operators jointly (NG and RTE). This end of it is partly at Solent Airport (was Lee-on-the-Solent, or Daedelaus to its friends) and partly just along the coast at Chilling near Warsash.

It adds another 1 GW to the existing 2 GW of IFA, and 1 GW each for Nedlink (Netherlands) and NEMO (Belgium). But more capacity linking to France is being built, in the form of Eleclink (1 GW via the tunnel), and in planning are FAB Link (1.4 GW via Alderney to Exeter) and AQUIND (2 GW into Portsmouth). AQUIND is currently with the planning inspectors, and was recently in the news for wanting to dig a trench through part of the city for its cables - which, oddly, wasn't popular.


Title: Re: Aberthaw Power Station
Post by: broadgage on October 16, 2020, 05:54:38 am
Such interconnectors give most useful flexibility in case of breakdowns or other out of course events.
They also increase the opportunity to use renewable energy, it is always windy somewhere in Europe.
 Adding Norwegian hydroelectric power to the European energy market is particularly helpful. Norway can export hydropower to us during calm weather, and we can export UK wind power to Norway in windy conditions, thereby reducing the demand for hydropower and leaving more water in dams for future use.

My only reservation is that more interconnectors might become an excuse for not ensuring adequate UK generating capacity. We should in my view aim to export electricity on at least a similar scale to that which we import.
Interconnectors can break, and other nations might suffer shortages that limit exports to the UK.

Electricity demand in the UK has fallen in recent years due to energy saving regulations (most of which were bitterly opposed).

I expect demand to increase in the future for several reasons.
1) A growing population.
2) Increased use of electric transport.
3) A move towards electric heating, particularly in privately rented homes.
4) Mains operated smoke detectors in most new properties, only 1 watt each, but a not quite negligible extra demand of  perhaps 50 million watts in total (10 million homes, 5 smoke detectors in each, 50 million 1 watt loads) 50 Mw is about an extra 0.1% on the peak demand.
5) Future requirements to fit emergency lighting to homes, initially only for vulnerable groups, (1 million homes, 20 watts in each of these homes, another 20 Mw.
6) A warming climate increasing the demand for air conditioning, and also increasing the energy used by existing refrigeration equipment.

And whilst energy saving is commendable, it wont carry on reducing demand indefinitely. Much of the "low hanging fruit" has already been plucked.
Take lighting as an example. Replacing a 60 watt incandescent lamp with a 12 watt CFL saves 48 watts. Replacing the 12 watt CFL with a 6 watt LED saves a useful but rather less impressive 6 watts. Replacing the 6 watt LED with a 3 watt LED (not yet available in the UK) Saves a paltry 3 watts, better than not saving 3 watts but hardly dramatic.
And NO lamp with a light equal to a 60 watt incandescent can EVER use less than about 2 watts, and I suspect that 3 watts might be as good as it will get.



Title: Re: Aberthaw Power Station
Post by: Electric train on October 16, 2020, 09:01:20 pm
Such interconnectors give most useful flexibility in case of breakdowns or other out of course events.
They also increase the opportunity to use renewable energy, it is always windy somewhere in Europe.

The downside to the both the interconnectors and renewables (wind and solar) is the lack of inertia they provide to the Grid. The inertia in the system used to be the spinning mass of the large alternators and turbines, the interconnectors as DC with inverters, the wind turbines use static frequency converters and solar is also DC with inverters

The lack of inertia manifest itself in a number of ways, one is under fault conditions, like the August 2019 event, the 400kV system voltage looses stability for longer before it recovers; the major impact though caused by the lack of inertia is poor power factor, this causes me issues in my day job when we need to parallel two grid supply points and some harmonic issues.

I'm not knocking the interconnectors or renewables, its just our National Grid and all the local Distribution Networks was engineered for large bulk rotating machine generation


Title: Re: Aberthaw Power Station
Post by: onthecushions on October 17, 2020, 11:02:24 am

Perhaps renewable sources need the same as UPS systems used to have; large motor/alternator sets running continuously.

There's a small energy (and cost) penalty but that's just part of the joy of sustainability.
It might even make re-newables more useful/marketable as a consistent energy supply.

OTC


Title: Re: Aberthaw Power Station
Post by: ellendune on October 17, 2020, 12:38:48 pm

Perhaps renewable sources need the same as UPS systems used to have; large motor/alternator sets running continuously.

There's a small energy (and cost) penalty but that's just part of the joy of sustainability.
It might even make re-newables more useful/marketable as a consistent energy supply.

OTC


Other solutions are being found including flywheels in Scotland (https://www.theguardian.com/business/2020/jul/06/giant-flywheel-project-in-scotland-could-prevent-uk-blackouts-energy)


Title: Re: Aberthaw Power Station
Post by: broadgage on October 17, 2020, 02:05:30 pm

The downside to the both the interconnectors and renewables (wind and solar) is the lack of inertia they provide to the Grid. The inertia in the system used to be the spinning mass of the large alternators and turbines, the interconnectors as DC with inverters, the wind turbines use static frequency converters and solar is also DC with inverters

The lack of inertia manifest itself in a number of ways, one is under fault conditions, like the August 2019 event, the 400kV system voltage looses stability for longer before it recovers; the major impact though caused by the lack of inertia is poor power factor, this causes me issues in my day job when we need to parallel two grid supply points and some harmonic issues.

I'm not knocking the interconnectors or renewables, its just our National Grid and all the local Distribution Networks was engineered for large bulk rotating machine generation

Yes, could not have put it better myself.
But in fact the position is worse than suggested above, generation connected via static inverters, and imports also connected via static inverters do suffer from lack of inertia as described above.

Also, an increasing percentage of the electrical load these days consists of switched mode power supplies*. These often work correctly down to 85 or 90 volts.
Suppose that some transient fault or failure briefly reduces the nominal 230 volt supply to 115 volts. Back in the old days, most loads would use less current at this temporarily reduced voltage, this helped the system to recover from the fault.
These days, the load current will roughly double at the reduced voltage, this increased current will tend to further reduce the voltage, and in extreme cases might lead to a total failure.
During the 1970s power shortages, as well as rota power cuts, voltage reductions were imposed to reduce the load. This works less well today as all those switched mode* power supplies will draw constant watts at the reduced voltage.

*electronic lighting ballasts, electric vehicle chargers, most consumer electronics, variable speed motor drives, and modern electric trains/trams, are all examples of switched mode power supplies.


Title: Re: Aberthaw Power Station
Post by: broadgage on October 17, 2020, 02:33:49 pm

Perhaps renewable sources need the same as UPS systems used to have; large motor/alternator sets running continuously.

There's a small energy (and cost) penalty but that's just part of the joy of sustainability.
It might even make re-newables more useful/marketable as a consistent energy supply.

OTC


Other solutions are being found including flywheels in Scotland (https://www.theguardian.com/business/2020/jul/06/giant-flywheel-project-in-scotland-could-prevent-uk-blackouts-energy)

Flywheels cant store enough energy to compensate for calm weather and limited power availability.
They are however very helpful by adding inertia and thereby promoting stability, I expect more schemes similar to the one in the above link.


Title: Re: Aberthaw Power Station
Post by: mjones on October 17, 2020, 02:43:30 pm
Some of the more unusual  methods  being proposed to store surplus renewable  energy should help in that respect,  for example as liquified air that would drive a turbine and heavy weights pulled up and down mine shafts  by motor/generators.  However other methods like hydrogen electrolysis and large  flow batteries will have the problem you describe.


Title: Re: Aberthaw Power Station
Post by: stuving on October 17, 2020, 04:01:51 pm

Perhaps renewable sources need the same as UPS systems used to have; large motor/alternator sets running continuously.

There's a small energy (and cost) penalty but that's just part of the joy of sustainability.
It might even make re-newables more useful/marketable as a consistent energy supply.

OTC


Other solutions are being found including flywheels in Scotland (https://www.theguardian.com/business/2020/jul/06/giant-flywheel-project-in-scotland-could-prevent-uk-blackouts-energy)

Flywheels cant store enough energy to compensate for calm weather and limited power availability.
They are however very helpful by adding inertia and thereby promoting stability, I expect more schemes similar to the one in the above link.

You don't need to - this contract was one of five signed by NG-ESO in January. They are paying for a service (presently called synchronous compensation), ?328M over six years. It is up to the contractors to find the capital cost. Together they profide 12.5 GWs of inertia - the grid had 300 not long ago, now has 100-200 depending on the connected plant mix (which is seasonal) and will soon be below 100 some of the time. So this is only a part of the solution.

In addition to that Statkraft one, there is another new one in Wales and three using existing things as flywheels. On is a turbine at Cruachan, operated by Drax. Uniper are using two old power station turbines at Killingholme, and building two new SCs at Grain. Triton are providing this service at Indian Queens (near St Dennis)  - of which they say this:
Quote
Indian Queens Power Station is an OCGT (Open Cycle Gas Turbine) power station located in Cornwall. The station has an output capacity of 140 MW providing voltage support to the UK electricity market as part of an ancillary services contract with National Grid.

The turbine drives an air cooled generator through an SSS (Synchro Self Shifting) clutch which allows the plant to operate as a synchronous compensator when required. The power plant operates at peak times when power demand is high.   

Synchronous compensators (a big flywheeel and a synchronous motor) are not at all new, but big ones have become rare. Most of the work has gone into "static" systems, based on BESS*. The trick is similar to regeneration in a train - make the DC/AC converter work in both directions, and add software. I found a research project (SP's Phoenix) description from 2017 in which a plan to repurpose a closed power station was rejected as "of extremely high risk", in favour of building a new one. That is now an experimental hybrid (70M flywheel + 70 MW static), to look at the different effects of the two and how to link them.

Virtual inertia was included in the "Enhanced Frequency Control Capability" project for NG-ESO, which is reporting this year. But it's a slippery term - real inertia feeds power in or out immediately and proportionally as the phase angle (or RoCoF - rate of change of frequency) departs from its stable point. That reduces the RoCoF, but the methods EFCC ended up with don't - they intervene after a second or so (and non-linearly) to yank the system frequency back into line. I suspect that for those with power systems attached to the grid that can be an important difference.

*BESS - battery energy storage systems, or what were called batteries



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