By P Gosselin
When green energy ideology clashes with the laws of Engineering and physics…
Manfred Haferburg, power plant engineer, explains the problems of the German power grid in connection with the green energy transition at online site Achgut. The result is a very informative article. It is not primarily about blackouts due to a lack of power.
The author begins by explaining three important terms: The n-1 criterion, reactive power and instantaneous reserve.
“Let’s translate all the technical gobbledygook. The experts at the power transmission grid operators have been ‘preoccupied”‘ with the topic for a long time, but politicians have not understood it because ‘it is a very complex issue’. And then comes the kicker: the German transmission grid can no longer cope with the ‘n-1 error’ in every case. This means that if, in a tense situation, one of the large transmission lines suddenly fails due to a lightning strike, long-wave conductor vibrations in high winds and snow, sabotage or a transformer/high-voltage switch fault, ‘the electricity grid could become unbalanced’ – in other words, it could collapse in a domino effect. This could result in a partial grid failure or, in the worst case, a blackout. This time it’s not me saying this, but the team leader for system behavior in the strategic grid planning department at TransnetBW. I wrote this on this site years ago and was berated for it.”
“Here, too, an attempt at layman’s language: the large rotating generators of the power plants are ‘grid-forming’ machines; due to their large mass, they keep the frequency of 50 Hz constant in the range of seconds. For our colleagues at the Feferal Ministry of Economics and Federal Grid Agency, inertia is a physical property that ensures that power fluctuations are cushioned in a range in which the time for human intervention is too short. Wind turbines have only small masses and solar panels have no rotating parts at all, they are ‘grid-following’ with their inverters; this means that they are connected to the grid of the ‘grid-forming machines’ and do not have a stabilizing effect. Incidentally, gas-fired power plants tend to be ‘grid-following machines’. The large power plant generators have also been responsible for maintaining the voltage in the grid through reactive power control.”
At the end of the article, Haferburg comes to the conclusion that we will continue to see coal-fired power plants in operation for a very long time.
Read the full article on Achgut.
(Note: Today’s modern translation tools do a pretty good job at translating the text into English)
Question from ignorance:
Don’t gas-fired plants also have large rotating generators? Why are they not also ‘grid-forming’ machines? The only explanation I can think of (IANAPPE!) is that coal-fired plants generate steam which spins heavier turbines than gas-fired plants which skip the steam stage, but to illustrate my ignorance, I don’t even know if that’s the case.
That was also my thought. A CCGT (combined cycle gas turbine) uses the kinetic energy of the hot exhaust gas to drive a turbine, and the heat of the exhaust gas to generate steam to drive a second turbine. In both cases, together with the generator, there is a large rotating mass. Well that is my uderstanding.
A CCGT has two generator elements that each have inertia. The gas turbine is the first one. If you consider that the turbine is produced from designs aligned with the development of an aircraft turbine, using similar light weight materials, you’ll rapidly grasp the concept that the turbine does not have a high mass shaft, nor high mass blades. Without significant mass, the GT just can’ provide much rotational inertia to the grid frequency.
The down stream, steam turbine, which is powered by the waste heat of the GT is secondary to the main plant and is sized to suit. Since the fuel load is already half consumed in the GT, the steam turbine is often much smaller and lacks the same heavy build and mass of a coal fired unit.
So, when comparing two equal capacity electrical generators, CCGT and coal fired, the coal fired unit will have much higher, (single machine), capability to provide inertia. The CCGT machine has two turbines, both lighter and on independent shafts, hence not as capable and not capable of working as a single spinning mass.
Hope that helps.
Excellent explanation. Succinct and clear.
Does that apply to nuclear plants as well? ie, nuclear also has large rotating masses, right? So for “grid-forming” power your choices are coal or nuclear. Maybe hydro as well?
You are correct, nuclear and hydro turbines are very large and heavy, as well.
Absolutely and gas still has spinning mass,. There may be less of it but its still coupled at some level to a generator, and it’s the generator that has the mass more than the turbine. Gas and steam turbines turbines are (stainless steel?) blades with lots of space in between.
Likewise in the UK the black start (no grid at all startup) is supposed to be performed by Dinorwig pumped Hydro plant, amongst others. Although the latest plans involve using batteries to jump start an all ‘renewable’ grid
I suspect our German friend is simply speaking of the way the German grid is operated not universal limitations
The part providing the inertia is the rotor inside the stator. In many generators the rotor can weigh 800 tons or more and this spinning at 3000 r.p.m. in many countries ( 50 hz) or 3600 r.p.m (60 hz) keeps the frequency up and hence the voltage. With an increasing load which tends to drop the frequency and voltage that huge mass keeps it maintained until the governors sense the need for more fuel and increase power.
Pembroke ‘B’ 2200 MW CCGT power station has five Alsthom (now GE) units, each on a single shaft. Gas Turbine – Generator – Steam Turbine.
(Most impressive; I had a guided tour a couple of weeks ago.)
To improve grid stability they are now installing a Synchrous Condenser to provide extra inertia because of nearby onshore and future offshore wind turbines.
As one of the most efficient power stations in NW Europe, it’s frustrating that they are not allowed operate at maximum capacity all the time.
Ed D
Typo: should be ‘Synchronous Condenser’
I think that a synchronous condenser is a DC motor that is powered by DC electricity from wind or solar, connected to an AC generator that outputs AC electricity to the grid. The set includes what is technically known as a big ass flywheel to provide inertia.
Please correct me if I am wrong.
No it’s simply a large AC synchronous motor connected to the grid with no load attached to the shaft.
siemens is supplying 3 x 200mva units to Lithuania to provide grid inertia once they disconnect from the Russian grid.
if you attached a dummy rotating load to the shaft you’d have more inertia but that means more complexity, more draw to spin up to speed, more points of fail.
I would suggest a second “inertia” factor, namely, adding coal to a coal furnace does not have the almost instantaneous effect of increased energy that you get from “punching the throttle” of a gas or diesel engine. Therefore, coal systems must be maintained at high heat (load generating) levels versus GT systems that are designed to respond to demand, just not fast enough to maintain a stable grid.
In reality there is a considerable amount of high pressure steam that can be tapped for ‘instantaneous ‘ response from a coal plant that is running at less than full power.
Likewise hydro is more or less instantaneous.
No plant can come up from cold instantly, not even diesel. Hydro is the fastest, then diesel, then open cycle gas and right at the bottom coal and nuclear which take more like days to settle down
According to this series of four articles modern Advanced Ultra Super Critical and Steam H coal plants are able to start from cold in less than 30 minutes. Still not instant but pretty quick.
https://papundits.wordpress.com/2021/05/29/coal-fired-power-dying-not-so-fast-part-one-introduction/
Links to the other parts in the above
Great answer, yes, but that brings up a second question: why aren’t steam turbines as light as gas turbines?
Mostly because gas turbines are adapted aircraft jet engines and are built light . But the generators all weigh the same anyway.
And they are the heavier components
Thanks. It’s amazing how much knowledge the world has, and somehow I just don’t know enough, no matter how smart my brain thinks it is.
I strongly agree with your observation. Sometimes I think to myself” that was a close one” when I almost took away a wrong conclusion on something I thought I was being so smart and inquisitive about.
Whatever the turbine is, the rotor of the generator is still a large spinning mass, that is where the inertia lies. It’s the same wk2.
“Don’t gas-fired plants also have large rotating generators?”
Generally just tiddlers compared to the turning mass of a big coal fired power station.
No, you are right. Gas plant is often kept as ‘spinning reserve’ in the UK, but it costs more than coal does in that guise.
Best of all would be nuclear, if Germany had any left…
Rotational inertia is actually such an issue that there is a company that makes Cruise ship engines, that has significantly shifted over into providing rotational services to the Texas grid. I can’t remember the name but I heard about it in one of the Gulf Coast Power Association events.
From my very basic understanding of all these issues, I see that:
1. There needs to be a stable base load provider, be it 100% or not is disputable.
2. All renewable energy is there to provide peek demands.
Base load comes from coal, natural gas or nuclear. Take your pick but India and China seem to be picking winners vs the West.
Renewables tend to derive from unicorn frats and pixy dust, and as reliable as such.
The West is trying its hardest to kill itself economically as well as agriculturally. That covers Europe, UK, USA and Australia.
I have at best only seen computer models that we are doomed.
From my experience with computer models in mine ventilation all I can say is they tend to be crap as they deal with variable as static values.
I have gone through the code of these ventilation simulations and found so many abridged assumptions it’s unreal.
My suspicion is climate modelling is ramped with such assumptions to make them unrealistic.
I am old and all I am doing is reinforcing my home to be “Climate Change idiot” proof.
These sheeple will kill society faster than a world war.
Here endith the rant
Computer models can work quite well if what is being modeled is well understood AND all of the factors affecting them are predictable AND one doesn’t try to stretch them too far into the future. Examples: Gravity is quite well behaved therefore we can predict the future position of satellites with considerable accuracy. Exception: Satellites in very low orbits are much more subject to drag (which is not very predictable) than those in higher orbits. That’s why we can predict within a few days or maybe hours when a dying satellite will finally burn up in the atmosphere. But we often can’t predict all that well the exact time or location.
Likewise, modern weather models can most often predict next week’s weather with considerable accuracy. (A remarkable accomplishment BTW). And they aren’t all that bad on the week after. But errors accumulate and get larger the further one goes. Seasonal forecasts are still pretty much WAGS. And they are likely to stay that way for a long time.
Climate models? Two many poorly understood variables. And far too long a time span. I wouldn’t expect them to work. And so far, to the extent they are testable, they seem to live up to my expectations. A gypsy fortune teller with a deck of tarot cards would be far cheaper and likely at least as accurate.
The very long time: 5-6 years.
A political cycle? Interesting.
Maybe shorter.
Its a report of the views of some seriously qualified people. All of the climate activists who pronounce on this topic are invariably complete amateurs whose idea of network planning is at the level of literary criticism.
The people quoted make two points. One is that instability is entering the net with the increase in renewable penetration. They mean by this that a fault, perhaps triggered by a lightning strike, can lead to cascading faults and a very large scale blackout. The second is that once its gone down, there is no ‘black start’ capability in wind and solar generators.
The attempt to get to net zero in electricity generation, while at the same time doubling demand by moving to EVs and heat pumps, is bound to fail. There are three reasons.
One is intermittency. You just cannot supply reliable consistent power using wind and solar. In the UK as an example, given the UK and North Sea weather, you would need somewhere between 500GW and 1,000GW of wind to supply the 100GW+ demand that the move would produce. It cannot be done, certainly not by 2030 as the UK Labour Party is promising. And even then you would need a huge amount of storage.
Read the Royal Society report. They were among the first to look at weather patterns over previous decades and take the implications into account. Tells you a lot that everyone had been enthusiastically pushing for net zero using wind and solar, without ever bothering to look back at a few decades of the weather that this would make the country dependent on.
The second is synchronicity Mirjam König is quoted as saying:
„Im Austausch mit einem erfahrenen Kollegen haben wir kürzlich festgestellt: Wir befinden uns in der zweiten Stufe der Energiewende. Wir sind mittendrin in einem Wandel von einem Synchronmaschinen-basierten hin zu einem Umrichterbasierten System. Synchrongeneratoren befinden sich in den bisherigen konventionellen Kraftwerken – Umrichter befinden sich in den ErneuerbareEnergien- und STATCOM-Anlagen bei Elektrolyseuren und Batteriespeichern.
Rough summary: they have only just realized that as well as changing fuels they are also moving from synchronous to inverter based generation, and the implications of that.
They only just realized! Who had they been talking to? Not, one gathers, an erfahrenen Kollegen, an experienced colleague. A typical example of armchair planning that characterizes almost all political establishment approaches to energy nowadays.
Its the move to inverter based that increases instability and leads to the risk of cascading system failures.
And then you have the lack of any ‘black start’ capability.
This is not going to work. The only question is how its going to fail. It could fail because governments persist to the point of grid collapse. It could fail because they blink and keep coal and gas going. Or it could fail with the worst of all possible situations, a bit of both. Probably most likely.
But fail it will.
“ 5-6 years.”
Before German industry collapses completely !
If Nut Zero was really about CO2 emissions and global warming, rather than political power and control, a nation would build more nuclear power plants to replace aging coal power plants.
And the few nations claiming they are targeting Nut Zero by 2050, with just over 1 billion population, would spend every week trying to convince all the other nations, with almost 7 billion population, to join them. That does not happen. There are obviously more smart nations than dumb nations.
Consider Germany
More nuclear power plants being built for Nut Zero?
No
All the existing nuclear plants were closed almost a year ago?
The Grohnde, Gundremmingen C and Brokdorf nuclear power plants were shut down on 31 December 2021. The last three nuclear power plants in Germany were shut down on 15 April 2023: Isar 2, Emsland and Neckarwestheim 2. Their shutdown had been planned for 31 December 2022.
Germany had 38 coal power plants as of July 2023, the seventh largest number for any nation. China, #1, had 1,142 coal power plants. The US, #3, had 210 as of mid-2023
Some of the German plants burn lignite. Burning lignite generates more CO2 emissions than hard coal, and between three and seven times more than gas. Lignite coal, aka brown coal, is the lowest grade coal with the least concentration of carbon. Lignite has a low heating value and a high moisture content and is mainly used in electricity generation.
Number of coal power plants by country 2023 | Statista
USA & China Electricity Generation TWh & CO2e Trajectories Since 2000 Are Startling
https://cleantechnica.com/2024/03/01/usa-china-electricity-generation-twh-co2e-trajectories-since-2000-are-startling/
USA lowered its emissions by changing from coal to GAS.
Don’t let the facts get in the way of your non-argument.
China’s energy consumption…
And China’s electricity production.
The increase in coal since 2015 is greater than the current total of wind and solar.
Story Tip..
Britain’s e-bus ticking timebomb: How nearly TWO THOUSAND electric buses worth £800m face urgent recall over fears they could see burst into flames | NOT A LOT OF PEOPLE KNOW THAT (wordpress.com)
£800m?
Pocket change.
“”Coal Plants Will Be Needed “For A Very Long Time””
ie Für immer….
And that is a long time.
Never underestimate the power of religious zeal. I get the feeling there’s a bunch of true believers out there that would happily condemn us all to go back to living in the Dark Ages.
And certainly, many who are so dumb or ignorant that they can’t see where this Net-Zero nonsense is heading…
One of the aspects about all of these wind turbines and solar panels that I try to point out (in overly simplified terms) for people (most of the people I worked with were not engineers) is that this sort of power needs to be “cleaned” in order to be added to the network. (Cleaning is a simplistic term used to get past the complexities of ensuring that the power in the grid is maintained 60 cycle.) Power from a solar panel is simply “dirty energy” (direct current and not generated at 60 Hz), and must be “cleaned” so that the square wave (power from a DC source) can be made sinusoidal, or power from a wind turbine must be “cleaned” so that its odd harmonic sine wave from the facility can be made harmonic (i.e. 60 Hz).
The vast majority of people I met thought all you had to do was set up a solar panel or rotating machine and you had power to use (and the plate information told you how much). They did not understand that in order to maintain a safe system, power had the be meticulously maintained at 60 cycles (they might see 60 Hz on an electrical device, but not understand its meaning), and this took intervention by the central utility through the use converters (and other tools) to ensure harmonics.
In Ontario, the massive rotating machines used for hydro and nuclear set the base harmonics (but even these require some tuning) and additional power that is to be fed into the grid needs to be cleaned in order to maintain harmonic 60 Hz for that base. This is an on-going job, requiring centralised collection of the power, with on-going maintenance efforts.
Could you give us some idea of the energy lost from the renewables, in the process of their being rendered fit for a grid base harmonic? Just a very rough idea – I imagine the computations are replete with different possibilities.
It isn’t quite like that anymore.
Back in the day power inverters operated at 50Hz (60 in te USA) and used monumentally large lumps of iron and acres of oil filled capacitors to get te square wave approximately sinusoidal.
As a schoolboy I and others visited the very first 160MW DC to AC inverter for French electricity coming ashore in Briain, at Lydd and the hum of all that iron was magical. We at once started singing along with it… ‘sun arise…in the morning”
However I digress. The point being that semiconductor technology at that point wasn’t up to it. The DC was being chopped by mercury arc valves, and no one knew how to do it better than that. In fact although it was expensive, and what came out wasn’t as sinusoidal as was desirable, it was very efficient.
So DC to AC inversion has always been pretty damned good since the 1960s. The variable was (and is) how much you are prepared to spend turning square waves into sine waves.
(We need square waves because when a transistor is off, its not getting hot, because there is no current going through it, and when its hard on, its only getting warm, because there is no voltage across it. The heat happens when its half on. So that faster it can switch, the cooler and more efficiently it runs)
And that is what has happened since then, the advent of high voltage high power switching field effect transistors means we can chop at far higher frequencies than we used to. And the higher the frequency you chop at, the less iron and capacitor you need to smooth the ripple. And that is what is in the tiny USB power supplies and wall arts – very high frequency choppers to make DC from the mains. But it works the other way around as well, and you can use pulse width modulated waveforms to synthesise a lower frequency sine wave. And that’s much easier to turn into a clean sine wave with just a little bit of iron and a lot less capacitor and I would think that that is what renewable generators use.
And that is the problem. The renewable units need to monitor the grid frequency to synchronise their output with it. They are not individually powerful enough to provide a ‘master’ signal so to speak.
This isn’t so much a question of technology, as of sheer power. You need a certain amount of grunt to provide that master across a wide enough area of the grid to be able to bring up other power stations and synchronise with it.
But again I digress. The answer to your question is that these inverters are very efficient. High 90% range, and the harmonic removal is essentially lossless. And quite easy these days
That’s not the part of renewable energy that is pants*…
*UK, slang Rubbish; something worthless.
You’re talking pants!
The film was a load [or pile] of pants..
Thank you. That’s very helpful.
This answer fails to take into consideration gathering and dispatching power from diverse providers.
My understanding from colleagues employed in power generation and dispatch is that, in the process of gathering, wheeling, cleaning and then dispatching power from these disparate sources, the costs can be up to between 20 and 30% of the power generated, depending on whether it is DC (solar) or otherwise, and how far the source is from the central intake to the grid. This is not “free” power as was advertised) and the costs of managing it falls to the central grid operator, which is why Ontario’s current government has made the decision to “subsidise” consumers in the manner it has (in other words, Ontarians were lumbered with these costs by the last government, and the current government now covers those costs).
Well in terms of spinning mass, nuclear power is just as good.
This is all hardly news. It’s common knowledge that batteries are needed on renewable grids to replace spinning mass – never to store sunlight for after dark.
Here is a non-technical question for WUWT readers to ponder. Is it in America’s economic and strategic foreign policy interests to rescue the Europeans from their green energy follies through supplying a good portion of the liquified natural gas needed to fully replace Russian natural gas?
Early in the oil days, they used to flare off natural gas because they didn’t have a way to transport it and it was in the way. Massive amounts was wasted before they ended the practice. We have large quantities of gas but I suspect our price will be higher than Russian gas so what we do will be relatively short term. The other issue is we are making the same mistake. We are shutting down coal plants and our nuclear industry has been stagnate for many years. Both of us need to take a good look at our future needs and stop the insanity.
And Politicians have an ‘event horizon’ that stretches all the way to the next election/reshuffle/opinion poll.
At best.
Good luck with that …
Auto
Dena: “We have large quantities of gas but I suspect our price will be higher than Russian gas so what we do will be relatively short term.”
Do you think Germany will resume buying natural gas from Russia once the Russia-Ukraine war concludes?
Even if this happens in a context in which the Russians eventually come out on top and have managed through sheer force of arms to permanently conquer parts, or even all, of Ukraine?
I thought I answered that but I will expand. Germany still hasn’t returned their reactors to service. They laughed at Trump when he warned them about Russian gas. They spend a lot on off shore equipment to import our gas so if they can find it cheaper elsewhere, the savings will pay off the investment. They have a socialist government that thinks they can talk anybody out of anything. Putin for ex KGB wasn’t such a bad guy when he first took office and maybe the next guy will be better.
You have to remember that most but not all European nations aren’t really fond of the United States. It somewhat has to do with our form of government and the wealth it has created. They don’t like a government that is designed to keep power away from the ruling class. They like our tourist dollars and love it when the tax payer provides them with something big. We end up buying our friends which means when somebody offers a better deal, they will take them up on it.
Germany will go back to dealing with Russia. It might be after Putins death but they will soon forget the hardships they are currently experiencing.
Putin has a tight grip on Russia and its population and could easily live another decade or more. He’s not going away any time soon.
And, as far as I am aware, it is no longer technically possible at this point to return any of Germany’s closed reactors to service.
Not that the current German government would ever give serious thought to returning shuttered reactors to service, even if it were still technically possible.
Not being in the industry, I might not have this exactly right but rotating masses only help with little changes in the grid frequency. Ultimately the grid needs something else to keep it from drifting. That would be a national time standard like WWV which has the atomic clocks that keep our time. While they have a voice announcement, the real standard is the frequency they broadcast on as it’s also driven off the atomic clock. At 5,10 and 15 Mz, this is sufficiently high to keep a 50 or 60 Hz system locked up and accurate. Most of your plug in alarm clocks rely on the power line frequency to stay accurate. The proof of this I saw many years ago when a teacher plunged a 50 Hz clock into 60 Hz. The clock would gain 10 seconds every minute.
Before the days of the massive grid, power line frequency used to drift a few cycles one way or the other. When it was too far out, they would adjust it and allow it drift back to were it should be. In large grids, it just better to avoid the drift as much as possible because of the logistics of applying a correction to hundreds of generators is pretty messy.
I don’t know how many times we have all pointed this out; but very very few of these net zero advocates practice what they preach in any significant way.
I have had the advange of being in some of these alternative energy businesses. I still enjoy fiddling around with it at a small scale entrepreneurial level( wood stoves chimney upgrades etc with a little solar here and there. ) I like it from a survival, off grid , and frugality perspective. BUT, after being involved in this stuff since 1978- I am very very certain that it is a net negative for any sort of modern civilization at scale.
Yet some people just think they can some how find away around laws of physics no matter what engineering calculations you show them. They counter you the exceptions ( the exceptions that prove the rule!) Or articles from click bait news outfits or biased academics. Dillusional
It would be a good idea if some of the brain-washed politicians in most Western countries read such an article. Then maybe they’d realize that their obsession with renewables like wind and solar is not only unrealistic but also irresponsible because it puts businesses, industries and consumers at the mercy of the unreliable. What is particularly irritating is the tendency of these officials to ignore the projections of energy assessments and forecasts which present concrete evidence that fossil fuels will continue to dominate the global energy supply well into the future regardless of what the climate alarmists would have us believe.
Let us hope so,