Discussion > A question of PR
David Porter, wrong. If it is nameplate capacity, how did Germany manage to get 22.68 GW at one point last week (in April mind you, not summer)?
BitBucket
BB
Look again at the graph you referenced and you will note that it relates to the peak output at 12.45pm. Before and after is significantly less and you might also notice that there was nothing produced overnight. Take my word for it, BB, solar panels have an efficiency of at best 10%. So you can get a high spike of power when the sun is at its maximum but averaged over the year it will not exceed 10% of its name plate capacity.
David Porter
Mike Jackson,(6.36PM)
Yes, you have that right Mike. I am not answering on behalf of Nial, by the way. Just the logic of your argument.
David Porter
David Porter, I see what you mean. On that 24 hours overall efficiency was about 20-25% (don't know exactly how much solar there is). On long, sunny, summer days it will be significantly higher; one dark short winter days it will approach zero. Whether that averages to 10% I don't know.
On Mike Jackson's "it costs pretty much the same to keep that generating equipment ticking over (inefficiently) whether it is producing electricity or not, that sounds like a sceptic myth to me. Does a gas turbine really need the same fuel supply independent of load? If you load a turbine does it not turn more slowly? On a bright sunny day, do you really keep all of your gas turbines spinning as reserve? Sure, you need some reserve in case a nuclear or coal station trips out, but the sun, the wind and the clouds are predictable and change relatively slowly (over whole-country areas).
BitBucket
Nial,
Mackay talks about pumped storage in "Sustainable Energy — without the hot air"
http://www.inference.phy.cam.ac.uk/sustainable/book/tex/sewtha.pdf
Starts at page 190 (pdf page 203)
There are currently four pumped storage facilities with about 30GWH capacity.
There's potential for a few more in Snowdonia and 13 more potential sites in the North of Scotland, which brings up the total to 400GWH at a stretch. This is far short of the 1200GWH he reckons is needed for dealing with short term lulls from an all renewable grid.
The costs would be astronomical and the political and eco-political problems enormous.
Long term lulls, such as from having a significantly solar powered grid producing essentially nothing for six months of the year, would require an order of magnitude more pumped storage.
The 400GWH is with Mother Nature having done the civil engineering heavy lifting and conveniently provided two lakes in close proximity and one hundreds of metres above the other.
cosmic
BB,
"Does a gas turbine really need the same fuel supply independent of load?"
==================
Of course not, but to have it spinning and synched to the grid and ready to go immediately takes fuel and has it running inefficiently.
Or as something of an analogy, if you have a small petrol generator running and producing 240V, if you have a 2KW electric fire connected, it will may get through a tank of fuel in a couple of hours; with no load, so just losses from friction and in the engine being imperfect, it will still get through a tank of fuel in seven or eight hours. So if you want the convenience of having it there, ready to supply on demand, it's expensive.
cosmic
Cosmic, yes clearly it takes some fuel to keep a turbine in reserve, but that is not what Mike Jackson likes to say. He prefers to claim that renewables save no CO₂ because the gas turbines have to be kept running in reserve - or to quote from him above "it costs pretty much the same to keep that generating equipment ticking over (inefficiently) whether it is producing electricity or not". I've never seen anyone other than me dispute his claims before, so it is good to get that from you.
BitBucket
BB,
I'm agreeing with Mike Jackson, not with you. You are clutching at straws.
You haven't looked into these things enough.
cosmic
Cosmic. now you are contradicting yourself...
BitBucket
but ... the wind [is] predictable ...Move your foot out of the way before you pull the trigger next time, BB.
As for the rest, why not try reading what I actually wrote. I know it's a novel idea as far as you're concerned but it doesn't hurt. Honest.
Mike Jackson
BB,
You're desperate to advance arguments about things of which you know nothing, as has been shown numerous times on this thread.
Go and read David Mackay's book for a start. I gave the link above.
cosmic
Cosmic, first you agree that a gas turbine's fuel demand is not independent of load (ie. it takes more fuel when generating than when 'ticking over') and then you say you agree with Mike Jackson that it costs the same to keep the turbine ticking over whether or not it is generating electricity. Which is it?
Sure, spinning reserve is inefficient, but such reserve is needed whatever source of power you use. Renewable output may vary greatly over a day but when it covers a large geographical area it varies slowly; in contrast, demand can vary very rapidly and fossil stations can trip, denying the grid of several hundred MW in a few seconds.
BitBucket
If the reserve is needed whatever the source of power then why not just use the reserve rather than the unreliable power sources?
Demand can and indeed does vary widely and power station managers and grid operators have over the last 100 years become extremely experienced and very good at gauging the variations in demand and their timings as well as the level of back-up required to handle potential station failures with the result that I cannot remember the last time I suffered a power outage of any sort, let alone one due to a power station tripping.
Can you?
On the other hand the idea that renewable — which means wind, BB, since the level of solar in the UK is and always will be so negligible as to pointless — varies slowly is so ludicrous as to be barely worth even debating.The wind can vary between too strong and too weak within a matter of minutes and the proliferation of turbines and access points to the grid will only make the situation worse as the system tries to cope with sudden variations of supply from hundreds of separate points on the network.
Yes, the overall input may be fairly steady over a 12-hour period (doubtful if it will be for more than that) but that input is coming from a number of different sources any one of which can, and probably will, cut in and out in a manner which cannot be predicted.
You really do not know what you are talking about.
Mike Jackson
Mike, you are trying to push treacle up hill. Bitty has got it into his mind, and god knows how, that there is an argument for windfarms outwith their use to reduce CO2, and that they are a viable source of energy. Of course if there was such an argument they would already be widely deployed by the energy companies because the generation is "free" once the wind mills are up and running. You can talk engineering and finance with him till you're blue in the face, but you won't make contact because he's missing one of the dimensions the rest of us live in, knowledge of engineering. It's not his fault, and he's mostly harmless, but because the dimension is missing he's reduced to reading what you've said and trying to pick holes in it.
geronimo
Mike Jackson, I like that, "If the reserve is needed whatever the source of power then why not just use the reserve rather than the unreliable power sources?" You know, I've got my keys in my pocket and a backup set in the drawer. You've made me realise how silly that is - I could just be using the backup set instead...
Power tripping - yeah it happens every few days here. But I have a UPS so it really doesn't matter.
The wind and sun vary within minutes at any individual site, but not coincidentally at all sites across the country. Yes that means there can be supply variations at many points in the system - but the more of those points there are the more it will average-out and the less of a problem it will present: after all, demand also varies quite suddenly at many more points across the network and the grid handles it - that is what the spinning reserve and the pumped starage are for.
BitBucket
I don't see the relevance.
Now if you'd said that you had a wind-up radio or a hand-cranked television set but that you also had mains electricity as back-up for when your arms got tired then I could understand the analogy.
Nobody with approaching the standard number of brain cells uses the most inefficient form of power as their main source of supply and then uses the most efficient method as a back-up.
Outages every few days? Where the hell do you live? I'm in rural France which is (or used to be) notorious and we've had two in the last three years. Just a few months down the line when a few more efficient power stations have been shut down and a blocking high is covering most of western Europe you might be less complacent.
As for the rest, it's not worthy of comment. It's ignorant piffle — and that's being generous.
Mike Jackson
"You know, I've got my keys in my pocket and a backup set in the drawer. You've made me realise how silly that is - I could just be using the backup set instead... "
If the keys in your pocket disappear now and then only to reappear spontaneously sometime later, whereas the backup keys are always available (irrespective of whether you keep them in the drawer or in your pocket) then using the backup set at all times would indeed make sense.
"Power tripping - yeah it happens every few days here. But I have a UPS so it really doesn't matter."
Good to know that the priorities in the BB household are covered.
social biology
"You know, I've got my keys in my pocket and a backup set in the drawer. You've made me realise how silly that is - I could just be using the backup set instead... "
Inane and daft as ever. It's the cars that you'd back up, you'd keep a Trabant to run round in and a BMW in case your Trabant broke down. Of course you'd also need an AA insurance to get you to the BMW and tow the Trabant to the garage.
geronimo
BB- "Power tripping - yeah it happens every few days here. But I have a UPS so it really doesn't matter."
Wow - your own personal fossil fuel power station tripping in and out whilst the rest of us carry on unaffected! Amazing!
not banned yet
The building has a backup diesel generator so even if I don't notice the UPS tripping when the generator kicks-in, we know for sure we're on backup because we have to close all the windows to keep out the fumes...
BitBucket
... we have to close all the windows to keep out the fumes...Priceless! Shoots himself in the foot again.
Mike Jackson
...we know for sure we're on backup because we have to close all the windows to keep out the fumes...
Haha.
From what he reveals in his comments it is clear that Bitbucket lives somewhere really exotic.
- It's very high though I can't remember the figure he gave.
[Well above the altitude of Colorado Springs (6000ft) , where my ex boss's wife, a keen and fit cyclist with a lightweight racing bike, invited me to come for a bike ride with her, knowing I cycle. I set off behind her on a borrowed heavy mountain bike, trying to keep up. But every time I tried to catch up, my vision went monochrome and I had to ease off. If where BB lives is much higher than that, even climbing the stairs will be a painful effort]
- Petrol is astonishingly cheap there, though BB mentioned he does not drive a car himself. It seemed a bit sad not to be able to take advantage of virtually free petrol after putting up with other privations.
- We now know that the mains electricity has frequent power cuts. Sounds as if even apartment buildings have their own diesel backup generators in BB Land.
There are tables of city and elevation available. Plus tables of the price of gasoline per liter in the different countries of the world.
Add in that the power supply is unreliable and there can't be many places that fit all three parameters. Anyone sufficiently motivated could probably pin down BB's location within minutes.
But take a step back and consider. In view of his having to endure such hardships, it's hardly surprising that the poor chap exhibits, shall we say, "quirks of character". Which of us under such circumstances would not be more than a little bit crabby?
Martin A
"From what he reveals in his comments it is clear that Bitbucket lives somewhere really exotic."
Apr 24, 2013 at 5:01 PM | Martin A
I do wish the (resolved) IP address of a blog commenter (that is available to the site admin at wordpress.com for example) was posted along with the comment. I'm interested in the general location of posters and you could quickly learn to ignore posts from people who only post through proxies.
Rob Burton
BB, how long do you think it takes to start a backup coal fired power station that has been mothballed? And what sort of costs do you think are incurred whether you use the station or not? I ask because you write like you think it would work a bit like a backup diesel generator.
TinyCO2
Nial
You'll know better than me but I reckon that solar power can make a deal of sense where you can guarantee the sun is going to shine (or almost, anyway).
Then there are a lot of things you can do during the day that you don't do after dark. Meanwhile you have hot water that can still be usable for a considerable time after sunset and you use whatever fuel you need to keep services running overnight.
What you don't do, presumably, is use a fuel that may or not be available and is sometimes too much and sometimes too little but you never which from one day to the next or even one hour to the next and expect power generators to keep their equipment on permanent standby to fill the gap when/if it's needed at 10 minutes notice.
Regardless of whether it is theoretically "cheaper" which in practical terms it never can be because it costs pretty much the same to keep that generating equipment ticking over (inefficiently) whether it is producing electricity or not.
Have I got that right?