Wind farms - ugly truths

fclauson

Capt'n Midnight wrote: »

The logic behind Moneypoint is very simple. Coal is cheap and easily dispatchable within the 5 day wind forecast. Moneypoint is also needed for grid stability.

Biomass would be more expensive and IMHO would be better suitable for weaning the peat plants off peat.

BTW This week the Republic got 45.29% of electricity from renewables and 12.43% from coal. Yes it's a warm winter but still...

And today we got 0Mw from wind :rolleyes:

Capt'n Midnight

fclauson wrote: »

And today we got 0Mw from wind :rolleyes:

OMG there'll be a dip in wind generation on Monday afternoon :eek:

Since the latest operation constraints still stipulate that the Primary Operating Reserve has to kick in within 5 seconds there's a tiny chance that maybe there's enough forewarning to handle the dip.




Actually today isn't 0W it's more like 150MW, not a lot but still more than any peat powered station, even one using 1,245,000 tonnes of peat per year.

fclauson

you are missing the point of my original post

no plant can be decommissioned despite however much wind you add to the system

and by the way yesterday (its Thursday we are talking about) wind went to -1Mw (thats -1) in the ROI

So I suppose you could say "wind sucked"

L

fclauson wrote: »

no plant can be decommissioned despite however much wind you add to the system

As a point of information, that's not strictly true.

There's a load of situations where a dispatchable plant is energy limited over a period of time (Hydro, emissions limitations or even pumped/battery storage) so long run energy production from sources like wind do shift what plant you have to keep/build to maintain system security- that's before you get into shifting what kind of generation you need.

The idea that a MW of one dispatchable gen is the same as any other MW of dispatchable gen needs to go away.

djpbarry

fclauson wrote: »

And today we got 0Mw from wind :rolleyes:

Over 1,300 posts in and you still can't get beyond "wind turbines need wind to work".

I despair.

Capt'n Midnight

fclauson wrote: »

you are missing the point of my original post

no plant can be decommissioned despite however much wind you add to the system

And so ?

Some people cycle to work when the weather is good but drive if it's too wet or windy. They save money on petrol and there's less wear and tear on the cars.

ted1

Capt'n Midnight wrote: »

And so ?

Some people cycle to work when the weather is good but drive if it's too wet or windy. They save money on petrol and there's less wear and tear on the cars.

But they still have to pay motor tax and insurance and repayments regardless of how much use the car gets its the same , so the more you cycle the lire expensive it becomes per km.

Capt'n Midnight

ted1 wrote: »

But they still have to pay motor tax and insurance and repayments regardless of how much use the car gets its the same , so the more you cycle the lire expensive it becomes per km.

Yes some of the overheads don't change. But you can get cheaper insurance with lower mileage.

And yes the cost per Km by car goes up. But the total cost of the car is reduced because you are doing fewer Km.

Now here's the thing. Once enough people cycle regularly they might ditch the car and take Taxi's instead. Taxi's cost way more per Km. But again it works out even cheaper because you are doing ever fewer Km.


What this means in a real world context is that always on base load coal stations are being replaced with peaking gas plant. For example here we have very roughly 2GW base load. In the past this would be purely fossil fuel. But now it could be 1GW of high inertial fossil fuel and the other GW could be dispatched from wind / pumped storage / interconnector /gas.


So you still have the same nameplate dispatchable capacity, but you've replaced 1GW of base load "dispatchable" plant that was on 24/7 with plant that's far more dispatchable and spends a lot of it's time idling.

fclauson

djpbarry wrote: »

Over 1,300 posts in and you still can't get beyond "wind turbines need wind to work".

I despair.

So do I - because there are so many tangents in this thread as to be unreasonable

I never disputed you need wind for turbines to work - I was commenting on
a) you can not decommission other plant as you need to cover the zero wind situation
b) 1Mw of wind is not the same as 1Mw of dispatchable plant

ted1 wrote: »

But they still have to pay motor tax and insurance and repayments regardless of how much use the car gets its the same , so the more you cycle the lire expensive it becomes per km.

True - and this is most peoples gripe - why pay twice for one thing

Capt'n Midnight wrote: »

Yes some of the overheads don't change. But you can get cheaper insurance with lower mileage.

And yes the cost per Km by car goes up. But the total cost of the car is reduced because you are doing fewer Km.

Now here's the thing. Once enough people cycle regularly they might ditch the car and take Taxi's instead. Taxi's cost way more per Km. But again it works out even cheaper because you are doing ever fewer Km.


What this means in a real world context is that always on base load coal stations are being replaced with peaking gas plant. For example here we have very roughly 2GW base load. In the past this would be purely fossil fuel. But now it could be 1GW of high inertial fossil fuel and the other GW could be dispatched from wind / pumped storage / interconnector /gas.


So you still have the same nameplate dispatchable capacity, but you've replaced 1GW of base load "dispatchable" plant that was on 24/7 with plant that's far more dispatchable and spends a lot of it's time idling.

Cap'n - agree with you but it fails to answer one of my other key questions which was does spending all the money we have on wind give us the best ROI and CO2 displacement vs all the other things we could have spent the money on.

If we look at abaitment costs - http://www.seai.ie/Publications/Renewables_Publications_/Low_Carbon_Opportunity_Study/Irelands_Low-Carbon_Opportunity.pdf

it seems that wind has a positive CO2 abatement costs but its not the only play in town

its complex - and I think (disregarding tangents) this thread is a testament to that

Fabo

L wrote: »

As a point of information, that's not strictly true.

There's a load of situations where a dispatchable plant is energy limited over a period of time (Hydro, emissions limitations or even pumped/battery storage) so long run energy production from sources like wind do shift what plant you have to keep/build to maintain system security- that's before you get into shifting what kind of generation you need.

The idea that a MW of one dispatchable gen is the same as any other MW of dispatchable gen needs to go away.

You're wrong - fuel shortage for hydro is the same as fuel shortage for gas plant

Fabo

Capt'n Midnight wrote: »

OMG there'll be a dip in wind generation on Monday afternoon :eek:

Since the latest operation constraints still stipulate that the Primary Operating Reserve has to kick in within 5 seconds there's a tiny chance that maybe there's enough forewarning to handle the dip.

1,245,000 tonnes of peat per year.

yea and the emissions from fast acting plant like ocgt eat into and negate savings from more wind

Fabo

Capt'n Midnight wrote: »

And so ?

Some people cycle to work when the weather is good but drive if it's too wet or windy. They save money on petrol and there's less wear and tear on the cars.

again we are misunderstanding here with flawed analogies.

What happens in reality is you take the bike to work but get your friend to drive the car behind you as back up and for well, voltage control. So the car is run a bit less efficiently behind you than would otherwise be the case. You then use more fuel and emit more emissions than just taking the car in the first place.

Capt'n Midnight

Fabo wrote: »

yea and the emissions from fast acting plant like ocgt eat into and negate savings from more wind

You are going to need to back that up with some figures.

I keep pointing out that wind is predictable days in advance so most of the slack from wind doesn't come from fast acting plant. And besides we are already required to have fast acting plant on standby in case of outages. OCGT here is limited to 2/3rds power for that reason.

We are also required to keep high inertia plant on for regional grid stability, this also provides some spinning reserve.

Capt'n Midnight

Fabo wrote: »

again we are misunderstanding here with flawed analogies.

What happens in reality is you take the bike to work but get your friend to drive the car behind you as back up and for well, voltage control. So the car is run a bit less efficiently behind you than would otherwise be the case. You then use more fuel and emit more emissions than just taking the car in the first place.

Oh dear.

Are you seriously suggesting that for every watt of wind we have to have a watt of fossil fuel generators up and running ??

It's more like being able to hail a Taxi if you feel you can't finish the cycle into work on a day where'd you have taken the car if you knew you wouldn't make it before starting out.

Fabo

fclauson wrote: »

you are missing the point of my original post

no plant can be decommissioned despite however much wind you add to the system

the marginal capacity credit of each new wind farm is too small to justify the env impact

Fabo

Capt'n Midnight wrote: »

You are going to need to back that up with some figures.

I keep pointing out that wind is predictable days in advance so most of the slack from wind doesn't come from fast acting plant. And besides we are already required to have fast acting plant on standby in case of outages. OCGT here is limited to 2/3rds power for that reason.

We are also required to keep high inertia plant on for regional grid stability, this also provides some spinning reserve.

why are they building 4 new ocgts ? Over to Eirgrid :

However, the benefits [of wind energy] tends towards saturation as wind penetration levels increase. This is because there is a significant risk of there being very low or very high wind speeds simultaneously across the country. This will result in all wind farms producing practically no output for a number of hours (note that turbines switch off during very high winds for safety reasons). In contrast, the forced outage probabilities for all thermal and hydro units are assumed to be independent of each other. Therefore, the probability of these units failing simultaneously is negligible [Eirgrid 2009].

Fabo

Capt'n Midnight wrote: »

Oh dear.

Are you seriously suggesting that for every watt of wind we have to have a watt of fossil fuel generators up and running ??

It's more like being able to hail a Taxi if you feel you can't finish the cycle into work on a day where'd you have taken the car if you knew you wouldn't make it before starting out.

never said that, you have to constrain off the car when you use the bike, but the car doesnt stay at home, it runs behind you more inefficiently than if you just took the car in the first place.

because capacity credit of the bike is too low.

Markcheese

Fabo wrote:

the marginal capacity credit of each new wind farm is too small to justify the env impact

Whats " marginal capacity credit" ??

fclauson

capacity credit

http://irishenergyblog.blogspot.ie/2015/11/emlagh-wind-farm-capacity-credit-too.html

L

Fabo wrote: »

You're wrong - fuel shortage for hydro is the same as fuel shortage for gas plant

I think you need to rethink your statement.

Hydro is flow rate limited (and non fuel based), gas supply is not meaningfully so (and is fuel based). Additionally hydro units have constraints around how much water they're allowed to hold back, gas units do not have limits on fuel storage (outside investment limits) or long term fuel contracting.

L

Fabo wrote: »

why are they building 4 new ocgts ? Over to Eirgrid :
"However, the benefits [of wind energy] tends towards saturation as wind penetration levels increase. This is because there is a significant risk of there being very low or very high wind speeds simultaneously across the country. This will result in all wind farms producing practically no output for a number of hours (note that turbines switch off during very high winds for safety reasons). In contrast, the forced outage probabilities for all thermal and hydro units are assumed to be independent of each other. Therefore, the probability of these units failing simultaneously is negligible [Eirgrid 2009]. "

Which OCGTs out of interest? I'd guess it's to do with the fair whack of unit retirements that's going on.

I don't think that quote means what you think it means btw. There's a difference between forecast errors (which require quick cover) and highly correlated forecasted drop offs (which are known hours out).

fclauson wrote: »

capacity credit

http://irishenergyblog.blogspot.ie/2015/11/emlagh-wind-farm-capacity-credit-too.html

Quite an old document they're using for that - the modern equivalent would be Generation Capacity Statement 2015-2024 which gives the benefit as roughly two big gas gens worth (it looks like they're assuming in the ballpark of 15% installed capacity).

I'm not a fan of the capacity credit as a metric by itself though - that way lies the UK's capacity auction problem where they got a chunk of inefficient diesel gens sitting in fields. Different aspects need different metrics.

L

These are quite a good pair of articles (solar focused but worth the read):

http://www.vox.com/2016/2/10/10960848/solar-energy-duck-curve

http://www.vox.com/2016/2/12/10970858/flattening-duck-curve-renewable-energy

Fabo

L wrote: »

I think you need to rethink your statement.

Hydro is flow rate limited (and non fuel based), gas supply is not meaningfully so (and is fuel based). Additionally hydro units have constraints around how much water they're allowed to hold back, gas units do not have limits on fuel storage (outside investment limits) or long term fuel contracting.

5 days worth of gas/oil reserves need to be kept at each power station

Fabo

L wrote: »

Which OCGTs out of interest? I'd guess it's to do with the fair whack of unit retirements that's going on.

I don't think that quote means what you think it means btw. There's a difference between forecast errors (which require quick cover) and highly correlated forecasted drop offs (which are known hours out).



Quite an old document they're using for that - the modern equivalent would be Generation Capacity Statement 2015-2024 which gives the benefit as roughly two big gas gens worth (it looks like they're assuming in the ballpark of 15% installed capacity).

I'm not a fan of the capacity credit as a metric by itself though - that way lies the UK's capacity auction problem where they got a chunk of inefficient diesel gens sitting in fields. Different aspects need different metrics.

nah, tarbert was supposed to be retired couple of years ago, now its pushed out till 2025

Fabo

L wrote: »

Which OCGTs out of interest? I'd guess it's to do with the fair whack of unit retirements that's going on.

I don't think that quote means what you think it means btw. There's a difference between forecast errors (which require quick cover) and highly correlated forecasted drop offs (which are known hours out).



Quite an old document they're using for that - the modern equivalent would be Generation Capacity Statement 2015-2024 which gives the benefit as roughly two big gas gens worth (it looks like they're assuming in the ballpark of 15% installed capacity).

I'm not a fan of the capacity credit as a metric by itself though - that way lies the UK's capacity auction problem where they got a chunk of inefficient diesel gens sitting in fields. Different aspects need different metrics.

see page 27 for new ocgts

http://www.eirgridgroup.com/site-files/library/EirGrid/Eirgrid_Generation_Capacity_Statement_2015.-2024.pdf

you wouldnt all this fast acting inefficent plant in a system devoid of high levels of wind energy

Fabo

L wrote: »

Which OCGTs out of interest? I'd guess it's to do with the fair whack of unit retirements that's going on.

I don't think that quote means what you think it means btw. There's a difference between forecast errors (which require quick cover) and highly correlated forecasted drop offs (which are known hours out).



Quite an old document they're using for that - the modern equivalent would be Generation Capacity Statement 2015-2024 which gives the benefit as roughly two big gas gens worth (it looks like they're assuming in the ballpark of 15% installed capacity).

I'm not a fan of the capacity credit as a metric by itself though - that way lies the UK's capacity auction problem where they got a chunk of inefficient diesel gens sitting in fields. Different aspects need different metrics.

the capacity shortage in UK was because of over investment in renewables and economics of conv gen been trashed (along with forced closures by EU regs)

hence, quick fix, start up the diesel gens

L

Fabo wrote: »

5 days worth of gas/oil reserves need to be kept at each power station

Yep, and used when fuel supply is an issue - some of those stockpiles have been sitting there untouched for years. It's a different kettle of fish to be able to have a guaranteed price/quantity gas contract than weather/flooding limited hydro water supplies.

Fabo wrote: »

nah, tarbert was supposed to be retired couple of years ago, now its pushed out till 2025

There's a chunk of other ones - coal units are becoming emission limited, the Ballylumford units are only still around due to the NI capacity margin issue.

Fabo wrote: »

see page 27 for new ocgts

http://www.eirgridgroup.com/site-files/library/EirGrid/Eirgrid_Generation_Capacity_Statement_2015.-2024.pdf

you wouldnt all this fast acting inefficent plant in a system devoid of high levels of wind energy

Well, I'd note that the same page says that, of that table, only the GI CCGT (a high efficiency CCGT replacing 3 oil units) has been realised and the rest are looking like they're not going to arrive.

I'd also point out that the system had much more inefficient plant before wind became a factor - it's usually 70s/80s stock (Tarbert for example or the three old Great Island units). In other words, you would (and did) have them on a non-wind system and arguably in greater number.

Fabo wrote: »

the capacity shortage in UK was because of over investment in renewables and economics of conv gen been trashed (along with forced closures by EU regs)

hence, quick fix, start up the diesel gens

That's not accurate - the diesel gen boom was a consequence of a capacity auction that wasn't properly designed combined with a historic excess of generation making market entry difficult for new generators the last couple of decades. This then hit a crunch when a pile of that old gen declined to upgrade to make it through tightening EU emissions rules and the UK government decided to change horses midstream moving from ROCs to CFDs as their major subsidy measure for clean energy (of all types).

ted1

Fabo wrote: »

5 days worth of gas/oil reserves need to be kept at each power station

I think it's closer to two weeks

Markcheese

Fabo wrote:

nah, tarbert was supposed to be retired couple of years ago, now its pushed out till 2025

Cheap oil price will help tarbert stay in the mix a while longer ... of course that could change if opec and russia come to an arrangement ..

Capt'n Midnight

Markcheese wrote: »

Cheap oil price will help tarbert stay in the mix a while longer ... of course that could change if opec and russia come to an arrangement ..

Perhaps fuel price isn't an issue.
http://www.independent.ie/business/irish/airtricity-was-paid-32m-to-run-power-station-for-just-50-hours-30992601.html

State energy company Eirgrid paid €139m over the past four years to a power plant that produced energy for just 552 hours.

That is €6m per day, or €252,000 per hour of energy generation.

That sort of money would cover a lot of smart meters / smart appliances