Another GW of wind power approved in the UK

Capt'n Midnight

http://www.bbc.co.uk/news/uk-england-norfolk-18735802

Two large wind farms off the Norfolk coast have been approved by the government.
...
Race Bank, which will be developed by Centrica, and Dudgeon, created by Warwick Energy, will produce a combined total of more than 1GW of energy.

Macha

Capt'n Midnight wrote: »

http://www.bbc.co.uk/news/uk-england-norfolk-18735802

Good to see. Also good to see them refusing some projects on environmental grounds.

Shame they're changing their market rules to subsidise nuclear and cut renewables support.

pljudge321

Anyone else get pissed off when you read stuff like this or is it just me being pedantic.

Provide enough power for 730,000 homes, the Department of Energy and Climate Change (DECC) said.

produce a combined total of more than 1GW of energy.

Do you have a link for how the new market rules in Britain will work Macha?

Macha

pljudge321 wrote: »

Anyone else get pissed off when you read stuff like this or is it just me being pedantic.

Yup - journalist clearly isn't familiar with energy statistics.

pljudge321 wrote: »

Do you have a link for how the new market rules in Britain will work Macha?

This gives an overview. The bill itself is here:

http://www.decc.gov.uk/en/content/cms/legislation/energybill2012/energybill2012.aspx

Chloe Pink

pljudge321 wrote: »

Anyone else get pissed off when you read stuff like this or is it just me being pedantic.

I do on the basis that the installed capacity and power/energy generated are very different; power/energy generated is about a quarter of the installed capacity.
Race Bank will have up to 580MW of installed capacity and Dudgeon up to 560MW of installed capacity; total installed capacity of up to 1140MW.
Now divide by 4 (assuming a load factor of 25%) to get the energy/power output - 285MW

Macha

Chloe Pink wrote: »

I do on the basis that the installed capacity and power/energy generated are very different; power/energy generated is about a quarter of the installed capacity.
Race Bank will have up to 580MW of installed capacity and Dudgeon up to 560MW of installed capacity; total installed capacity of up to 1140MW.
Now divide by 4 (assuming a load factor of 25%) to get the energy/power output - 285MW

Actually, I think pljudge321 was talking about people not understanding that energy generation is measured in MWh.

Chloe Pink

Macha wrote: »

Actually, I think pljudge321 was talking about people not understanding that energy generation is measured in MWh.

A fair point too but to treat the installed capacity as the output (in any unit of measure) without applying the load factor is completely misleading.

Macha

Chloe Pink wrote: »

A fair point too but to treat the installed capacity as the output (in any unit of measure) without applying the load factor is completely misleading.

Well nor is that how you calculate the predicted output of a wind turbine. You at least have to specify the amount of time.

In this case to consider the housing figure, you take the installed capacity (1140MW), multiply it by the amount of hours in a year (= 9,986,400MWh), multiply by a very conservative load factor for offshore wind, ie 0.25 (= 2,496,600 MWh) and divide by the average amount of electricity used in a house per year, ie 3,300kWh. The result is 756,545 households, even higher than the 730,000 cited in the household.

Fossil fuel and nuclear plants capacity is quoted as equivalent generation all the time without a squeak about load factors or average annual running times in the respective market.

Capt'n Midnight

Chloe Pink wrote: »

A fair point too but to treat the installed capacity as the output (in any unit of measure) without applying the load factor is completely misleading.

Broken record time

Everyone who cares knows that power stations don't run 24/7, and in the case of wind turbines the capacity is the nameplate capacity.

I defy you to find someone who actually thinks windmills produce power when the wind isn't blowing !


Not sure if they will be on line before or after the UK - Norway interconnector.

Chloe Pink

Capt'n Midnight,
From a 1000MW new power station we could expect it to output over the year to about 90% of its installed capacity.
From 1000MW of new wind turbines we could expect them to output over the year to about 25% of their installed capacity.
I think it is reasonable to be clear on this point if only to assist those who are new to the world of power generation and don't know this and I think it is disingenuous not to be clear about it.

Macha, indeed, my apologies I should have referred to the output 'over a year'.
The load factor for a new power station is about 90% i.e. close to the installed capacity which probably explains why it is little mentioned.

Capt'n Midnight

Chloe Pink wrote: »

Capt'n Midnight,
From a 1000MW new power station we could expect it to output over the year to about 90% of its installed capacity.
From 1000MW of new wind turbines we could expect them to output over the year to about 25% of their installed capacity.

Really ?

90% uptime yes ( excluding unplanned stuff)
average continuous operation at 90% not a chance for most stations because there just isn't the demand for that much electricity.

25% ?? UK offshore windfarms have 32-36% capacity
https://en.wikipedia.org/wiki/List_of_offshore_wind_farms_in_the_Irish_Sea



Again anyone with half a brain can figure out that wind turbines produce no power when there is no wind, even if general media science/technology journalists are generally pretty bad

Chloe Pink

Capt'n Midnight wrote: »

90% uptime yes ( excluding unplanned stuff) average continuous operation at 90% not a chance for most stations because there just isn't the demand for that much electricity.

Yes but they can if needs be and surely the point of power stations providing baseload is that they are in continuos operation.[/QUOTE]

Capt'n Midnight wrote: »

25% ?? UK offshore windfarms have 32-36% capacity

One of the advantages of offshore as UK onshore is often less than 25%
Load factors for 2003 to 2010 for UK onshore and offshore are at this link:
http://www.ref.org.uk/publications/217-low-wind-power-output-2010
The average for the UK is about 26.5% for the years 2003 to 2010.
The average for Ireland is 32.3% for the years 2002 to 2009.

Capt'n Midnight wrote: »

Again anyone with half a brain can figure out that wind turbines produce no power when there is no wind, even if general media science/technology journalists are generally pretty bad

And that's exactly the point and the problem; for many their only comprehension of wind power generation will be through journalists and as some of them haven't quite grasped the point then I think it's fair enough to highlight it.
It's not just that wind turbines produce no power when there is no wind; it's that they produce no power when the wind blows too much, too little or not at all.

Macha

Chloe Pink wrote: »

Macha, indeed, my apologies I should have referred to the output 'over a year'.
The load factor for a new power station is about 90% i.e. close to the installed capacity which probably explains why it is little mentioned.

You don't need to apologise but actually the technology with the highest load factor is geothermal, not fossil or nuclear.

Chloe Pink wrote: »

One of the advantages of offshore as UK onshore is often less than 25%
Load factors for 2003 to 2010 for UK onshore and offshore are at this link:
http://www.ref.org.uk/publications/217-low-wind-power-output-2010
The average for the UK is about 26.5% for the years 2003 to 2010.
The average for Ireland is 32.3% for the years 2002 to 2009.

So you're happy to look at 'new power plants' but want to only look at old wind technology? Apples and oranges to some extent. The 2011 Digest of
UK Energy Statistics states that load factors for various technologies were as follows:
-CCGT: 60.6%
-Nuclear: 59.4%
-Conventional thermal (ie FF): 35.1
-onshore wind: 21.7
-offshore wind: 30.5

So in reality offshore wind and conventional thermal are showing very similar load factors.

Chloe Pink wrote: »

And that's exactly the point and the problem; for many their only comprehension of wind power generation will be through journalists and as some of them haven't quite grasped the point then I think it's fair enough to highlight it.

I think the bigger issue is the inability of some of them to think outside the current energy market model of baseload.

Chloe Pink wrote: »

It's not just that wind turbines produce no power when there is no wind; it's that they produce no power when the wind blows too much, too little or not at all.

[mod]For the umpteenth time, stop dragging any thread to do with renewables down this line of argument. If nothing else it is getting incredibly boring.[/mod]

pljudge321

Macha wrote: »

I think the bigger issue is the inability of some of them to think outside the current energy market model of baseload.

Can you clarify what you mean by this? Baseloaded plants are required to maintain power system stability.

Also this load factor argument is ridiculous.

Macha

pljudge321 wrote: »

Can you clarify what you mean by this? Baseloaded plants are required to maintain power system stability.

Also this load factor argument is ridiculous.

In the current system, baseload plants are kept running as much as possible and variable forms of generation are obliged to fit in around them. With this model, it's easy to view variability as the problem and curtailment becomes a big issue (which, yes, makes the load factor argument somewhat pointless).

With a higher share of variable generation on the system, the system starts to move towards a more flexible model where we have more liquidity in the form of intra-day markets, cross-border balancing markets and ancillary services or system services markets. In this sort of set-up, the inflexibility and the slow ramp up rates of baseload technology because the problem.

It's a threatening concept to the old established utilities so of course they oppose it.

pljudge321

Macha wrote: »

With a higher share of variable generation on the system, the system starts to move towards a more flexible model where we have more liquidity in the form of intra-day markets, cross-border balancing markets and ancillary services or system services markets. In this sort of set-up, the inflexibility and the slow ramp up rates of baseload technology because the problem.

Well the baseloaded plants are the main source of inertia, spinning reserve, secondary reserve, and voltage support on the system. They need to be on or the system will just collapse in the event of a frequency event. And when they are on its generally going more efficient for them to run at close to their peak output. This is why our C02 intensity goes up when the wind reaches over a GW or so because thermal plants that can't be shut down for stability reasons have to run at a less efficient set point.

Macha

pljudge321 wrote: »

Well the baseloaded plants are the main source of inertia, spinning reserve, secondary reserve, and voltage support on the system. They need to be on or the system will just collapse in the event of a frequency event. And when they are on its generally going more efficient for them to run at close to their peak output. This is why our C02 intensity goes up when the wind reaches over a GW or so because thermal plants that can't be shut down for stability reasons have to run at a less efficient set point.

It is often said that renewables don't have natural intertia but it can be emulated through controls. Using system frequency as a variable in the controller means that you can mimic a power response. It's quite possible that the whole frequency load methodology will have to be reconsidered.

If overall emissions from the sector come down as more renewables are integrated, the CO2 intensity indicator is not my primary concern.

pljudge321

Macha wrote: »

It is often said that renewables don't have natural intertia but it can be emulated through controls. Using system frequency as a variable in the controller means that you can mimic a power response. It's quite possible that the whole frequency load methodology will have to be reconsidered.

If overall emissions come down as more renewables are integrated, the CO2 intensity indicator is not my primary concern.

You can't emulate inertia, the new GE turbines have a frequency response but its nowhere on the timescale needed in the event of a large disturbance. Its acts as more secondary reserve rather than spinning reserve which is what is needed at the ms timeframe.

I was just including the CO2 intensity as an example.

Macha

pljudge321 wrote: »

You can't emulate inertia, the new GE turbines have a frequency response but its nowhere on the timescale needed in the event of a large disturbance. Its acts as more secondary reserve rather than spinning reserve which is what is needed at the ms timeframe.

But you can also have spinning reserve on the grid separately through storage.

Here is an example:

http://www.a123systems.com/ca93980e-389a-40c6-86f9-b869feabe908/media-room-2011-press-releases-detail.htm

pljudge321

Macha wrote: »

But you can also have spinning reserve on the grid separately through storage.

Here is an example:

http://www.a123systems.com/ca93980e-389a-40c6-86f9-b869feabe908/media-room-2011-press-releases-detail.htm

Try scale it up to the GW size without making it ridiculously expensive. Also that'll be inverter interfaced so it will suffer from the same issues as the wind turbines.

Macha

pljudge321 wrote: »

Also that'll be inverter interfaced so it will suffer from the same issues as the wind turbines.

How so?

Chloe Pink

Macha wrote: »

You don't need to apologise but actually the technology with the highest load factor is geothermal, not fossil or nuclear.

Thanks I didn't know that but it doesn't alter the load factor of wind turbine, fossil fuel and nuclear fuel generators.

Macha wrote: »

So you're happy to look at 'new power plants' but want to only look at old wind technology? Apples and oranges to some extent.

No I'm comparing the load factor of new wind turbines and new fossil or nuclear generators.

Macha

Chloe Pink wrote: »

Thanks I didn't know that but it doesn't alter the load factor of wind turbine, fossil fuel and nuclear fuel generators.

No I'm comparing the load factor of new wind turbines and new fossil or nuclear generators.

And I think the figures I've posted above paint an accurate picture.

Chloe Pink

Macha wrote: »

And I think the figures I've posted above paint an accurate picture.

I don't a) because much of the UKs conventional plant is old and b) because those load factors relate to how the plants are being used not to the load factors they are capabe off over a year.
The fact remains that new wind turbines are only capable of yielding a load factor of around 25% over a year whereas a conventional generator is capable of yielding a load factor of around 90% over a year and a geothermal generator is capable of even more apparently.

Macha

Chloe Pink wrote: »

I don't a) because much of the UKs conventional plant is old and b) because those load factors relate to how the plants are being used not to the load factors they are capabe off over a year.

The fact remains that new wind turbines are only capable of yielding a load factor of around 25% over a year whereas a conventional generator is capable of yielding a load factor of around 90% over a year and a geothermal generator is capable of even more apparently.

And?

Chloe Pink

Macha wrote: »

And?

Installing 1000MW of wind generating capacity is only equivalent (in terms of potential annual output) to installing between 250MW and 350MW of conventional capacity - a point the journalist in the OP of this post appeared not to have understood.

Macha

Chloe Pink wrote: »

Installing 1000MW of wind generating capacity is only equivalent (in terms of output) to installing between 250MW and 350MW of conventional capacity.

[mod]Right, you've had your say. Let's try and move this thread onto a debate that hasn't already been beaten to death on this forum.[/mod]

Capt'n Midnight

measured at peak demand wind capacity is actually closer to 40% and the UK has lots of ways of balancing demand too.

UK are ramping up renewables, here's the roadmap.Of interest is the low dropout rate of 7% which shows that wind isn't vapourware and up to 32GW nameplate capacity if it's economic

http://www.decc.gov.uk/assets/decc/11/meeting-energy-demand/renewable-energy/2167-uk-renewable-energy-roadmap.pdf

The Committee on Climate Change recommended in their recent advice that,
unless there is clear evidence of cost reduction, the UK ambition for offshore
wind should be limited to 13 GW by 2020. If industry, with Government support,
can drive down costs, we will be able to go faster and further, ensuring that the
full economic and energy security benefits of our offshore wind resource comes
to the UK rather than our competitors.
...
Establishing a Task Force with industry to set out an action plan for cost
reduction to 2020. The Task Force will drive the work necessary to realise
the vision of reaching £100/MWh for offshore wind, making it cost
competitive with a large proportion of the 30-40 GW of low carbon
generation which will be necessary in the 2020s to deliver the 4th
Carbon Budget.
...
Offshore wind has
historically benefitted from a very low dropout rate with only 7% of projects
being lost from the pipeline

The Crown Estate, which owns most of the
seabed out to the 12 nautical mile territorial
limit, has granted leases to developers in a
series of rounds
Round 1 leases are typically close to shore,
and have been mostly installed already – they
total around 1 GW of capacity. Round 2
identified three strategic areas, totalling
7.2 GW, which are under construction or in
development and will be responsible for the
capacity additions expected over the next 3-4
years.
Round 3 leases offer up to 32 GW of new
generation in 9 zones, which are significantly
larger than the areas identified under Rounds
1 and 2 and likely to use larger turbines. Many
of the Round 3 zones are in deeper water,
further offshore, and are therefore more
technically challenging.

pljudge321

It comes down to the fundamental difference between how synchronous generators and asynchronous generators work.

Imagine the power system to be a long rotating shaft being spun by numerous generators. The synchronous generators are connected to the shaft by the equivalent of bicycle chains so that the speed they rotate is directly related to the rotational speed of the system. Asynchronous generation is connected by the equivalent of a belt, it can add power to the systems buts its rotational speed isn't locked into the speed of the system.

The turbine and generator shaft in a large power plant is a large rotating shaft. The shaft might be in the order of 50 - 100 tonnes rotating at 3000 r.p.m so theres a lot of stored rotational energy in the machine which either needs to be added to or released to change its rotational speed.The rotational speed of this shaft is directly coupled to the frequency on the system.

When a large disturbance happens, such as the loss of a generator or a HVDC link or even a large load tripping out, the balance between generated electricity and demand is affected. The imbalance in instantaneous power goes into either increasing or decreasing the stored rotational energy in the system, most of which is in the generators. Mathematically you can describe like so:

[latex]\displaystyle{P_{mech}-P_{elec}=\omega I_{tg}\frac{d\omega}{dt}}
[/latex]

[latex]{I_{tg}{dt}}[/latex] represents the level of inertia on the system. There's typically around 3 seconds worth of system demand stored. i.e. If system demand is 3 GW there's about 0.0025 Gwh of energy stored in the system.


Re-arrange this for an inbalance in generation and you can get an expression for the initial rate of change of frequency.

[latex]\displaystyle{\frac{d(\Delta\omega)}{dt}=\frac{\Delta P_{mech}}{\omega_{o}I_{tg}}}[/latex]

So the initial rate of decrease or increase in frequency due to a large event is directly related to the amount of inertia on the system. For the system frequency to drop it needs to be able to slow down these large rotating machines. If it drops too far the system will collapse. By having enough inertia on the system it gives enough time for the governors on the generators to kick in and ramp up their power output to address the imbalance and bring the system back to steady state.

Wind turbines are interfaced to the power system either by full converters or doubly fed induction generators. In the full converters where the variable AC from the turbine is rectified to DC and then inverted back to the correct frequency and phase. This de-couples the mechanical dynamics of the turbine from the electrical supply. Doubly fed induction generators are a bit different but the same concept applies. To add a frequency need to do one of the following:

Run at a less than optimal set point so that there's a bit more power to be squeezed out if need be.
Store some energy in a DC capacitor at the DC bus of converter.
Slow down the wind turbine so that some of its stored kinetic energy is released.

None of these options give the same response to a sudden frequency event as a synchronous machine because there is no direct coupling between the stored energy and the system frequency so everything has to been done through controls rather then being a physical property of the system. Mathematically you could say that [latex]\frac{d(\Delta\omega)}{dt}=(\frac{\Delta P_{mech}}{\omega_{o}I_{tg}}[/latex] doesn't hold. Also because the devices are made using power electronics theres a limit on how much power can be pumped through them before they fail. A synchnous machine could pump out three times its rated current output for a few hundred ms and suffer no damage, a power electronic converter would just fry.

You also have the issue that some of these options result in a decrease in output power post frequency event which has to be dealt with.

You can see this effect on the system frequency in Ireland on a windy day compared to a day with little wind. The frequency is far more 'jumpy' on the windy days because the relative amount of inertia on the system is decreased.


Hopefully this explains it.

Capt'n Midnight

pljudge321 wrote: »

It comes down to the fundamental difference between how synchronous generators and asynchronous generators work.

Don't most wind farms use inverters to produce the 50Hz ?
so it's more a problem of control electronics.

same story with the interconnectors

UK is a special case too when the Dinorwig turbine is spinning in air it can ramp up 1,800MW in seconds. Ffestiniog can deliver another 360MW. Together about 3% of UK peak demand.

pljudge321

Capt'n Midnight wrote: »

Don't most wind farms use inverters to produce the 50Hz ?
so it's more a problem of control electronics.

same story with the interconnectors

UK is a special case too when the Dinorwig turbine is spinning in air it can ramp up 1,800MW in seconds. Ffestiniog can deliver another 360MW. Together about 3% of UK peak demand.

Not sure of the exact break down (Ill have a look) but its either full converters (a rectifier and inverter placed back to back) or DFIGS. Both are asynchronous in either case and like the interconnectors suffer from the same problem.

When Dinorwig is spinning in air its acting as a no loaded synchronous motor so its only consuming the energy lost due to friction, it adds all the benefits of a regular generator in this state as well as acting as fast acting reserve. It was originally built because they predicted a surplus of nuclear during the nightly lulls so it made economic sense not to throw that energy away. I don't think that actually happened in the end so it'd be interesting to see an economic analysis of how the plant has performed since it was built. I doubt there's one available though.

Capt'n Midnight

pljudge321 wrote: »

it'd be interesting to see an economic analysis of how the plant has performed since it was built. I doubt there's one available though.

Since it's already built ya might as well use it.

It's acting as fast reserve / black start so the economics aren't just the operating costs but the cost of providing the additional power stations to fulfill it's roles.

https://en.wikipedia.org/wiki/National_Grid_Reserve_Service - if you dig deeper you will get more numbers, stuff like the charge for capacity is for the peak 3 hours annual usage which sounds odd but it's because that's a charge for the infrastructure needed at peak.

AC has a higher voltage than DC of the same power. So by changing to DC you may be able to send more power over the same cables. For low power use switch mode (rectifier - inverter) have all but replaced large transformers.

If this was to take place on a large scale you'd save a fortune on the copper needed, over time you could change everything to DC and have inverters at local substations providing the 50Hz.

pljudge321

Capt'n Midnight wrote: »

Since it's already built ya might as well use it.

It's acting as fast reserve / black start so the economics aren't just the operating costs but the cost of providing the additional power stations to fulfill it's roles.

https://en.wikipedia.org/wiki/National_Grid_Reserve_Service - if you dig deeper you will get more numbers, stuff like the charge for capacity is for the peak 3 hours annual usage which sounds odd but it's because that's a charge for the infrastructure needed at peak.

AC has a higher voltage than DC of the same power. So by changing to DC you may be able to send more power over the same cables. For low power use switch mode (rectifier - inverter) have all but replaced large transformers.

If this was to take place on a large scale you'd save a fortune on the copper needed, over time you could change everything to DC and have inverters at local substations providing the 50Hz.

I know, it lives of the ancillary services and capacity payments. It'd be interesting to see if the economics would support building it now with the current market and system set up. From an operations point I'd say the guys in the control room love the place.

There's a hell of a lot of challenges that have to be overcome before a DC network is even technically viable before we even consider how much it'd cost. Also the copper savings would be offset by how bloody expensive large converter stations are, the current minimum line length to have HVDC cheaper than AC is about 600 km for an overhead line. You'd also have the problem of local demand growing and exceeding the converters power rating and the fact that HVDC systems have lower reliability and availability than AC.

Capt'n Midnight

pljudge321 wrote: »

I know, it lives of the ancillary services and capacity payments. It'd be interesting to see if the economics would support building it now with the current market and system set up.

I would doubt it.
pumped storage , like waste repositories and decomissioning are part of the huge hidden costs of nuclear power.

Today it's probably cheaper to build interconnectors to Norway

But Hydro stations have very long lives so once built it's a no-brainer to keep the running. It wastes about 1/3rd of the power it generates so totally economic to use as peaking when peak power costs a good bit more than base power.

There's a hell of a lot of challenges that have to be overcome before a DC network is even technically viable

absolutely but the trend is there

from a home perspective how many transformers are used these days ?
most electronic devices use switch mode PSU's
heating doesn't care
devices with universal motors won't care

Devices that require AC are becoming fewer all the time
if you say induction motor , I'll say power factor correction

it would take a long time but AC could be phased out , and the irony is that electronics is ultimately based on the Edison Effect (one of his few actual discoveries)

pljudge321

Capt'n Midnight wrote: »

absolutely but the trend is there

There's been a large resurgence in HVDC research since the mulit-modular converter was invented, particularily focused towards offshore DC grids. My postgrads in the area, there's a massive lack of people though, especially those who know the device level stuff as well as overall power system level stuff. Its this cross over area where the really interesting challenges are in my opinion

Capt'n Midnight wrote: »

from a home perspective how many transformers are used these days ?
most electronic devices use switch mode PSU's
heating doesn't care
devices with universal motors won't care

My tooth brush uses an air core transformer. :pac:

Capt'n Midnight wrote: »

Devices that require AC are becoming fewer all the time
if you say induction motor , I'll say power factor correction

A lot of induction motors are being fed through variable speed drives which eliminates the PF problem as well as a necessity for an AC supply.

Capt'n Midnight wrote: »

it would take a long time but AC could be phased out , and the irony is that electronics is ultimately based on the Edison Effect (one of his few actual discoveries)

Expensive though, we could solve everything if enough money was thrown at the problem. It is funny when you consider how many times some of the power reaching you must have been rectified and inverted. If a tiny bit of wind energy is making its way here from Denmark to power our computers through the interconnectors it might go AC->DC->AC->DC->AC->DC->AC->DC as well as being stepped through several AC voltages.

Tesla FTW.