Humanity has been harvesting energy from the wind for centuries. The practice goes back at least to 8th century Persia where the first known historical records of windmills came, but likely extends even further back than that. Compared to the vast history of using wind energy directly to do things like mill grain, pump water, saw wood, or produce fabrics, the production of electricity is still relatively new. Despite that, there are some intriguing ways of using wind to produce electricity. Due to the unpredictable nature of wind from moment to moment, using it to turn a large grid-tied generator is not as straightforward as it might seem. Let’s take a look at four types of wind turbine configurations and how each deal with sudden changes in wind speeds.
Predicting the Future
First, though, it is important to note that wind patterns on the order of a year or more in any particular area are well-known and used for the design of wind farms. Furthermore, wind speed forecasts on shorter timescales like a day or a week are also accurate enough to get a very close estimate of power production capabilities on those timescales, although there is a large public misconception that wind isn’t a reliable source of electricity because it doesn’t always blow. Quite the contrary; extremely accurate predictions of average wind speeds are available hours and days in advance because of how good weather forecasting has gotten in the last few decades, allowing generators like fossil fuel plants to scale down production as more wind generation becomes available with plenty of warning.
Brake For Emergency
Even though long- and short-term wind forecasting is extremely robust, wind gusts are much harder to deal with and remain a challenge for any wind turbine. While it might be easy to think a turbine will simply apply a mechanical brake to slow the rotation when a gust happens, for large turbines this generally not an economically viable solution. It would mean sending technicians up to replace brake pads constantly, not to mention the mechanical stresses on the turbine the constant braking action would cause. While there are also blade pitch systems, also known as aerodynamic brakes, which can turn the blades (or just the blade tips) into or out of the wind in order to stay as close as possible to the turbine’s ideal design rotational speed, these pitch systems are still too slow for some gusts.
Mechanical brakes are necessary, though. They’re typically only used during an emergency stop when a technician is in physical danger, as a last resort for stopping a major overspeed event if the blade pitch system fails, or for temporarily “parking” the turbine rotor during certain maintenance processes only after the aerodynamic brakes have been applied. Offline turbines, such as those waiting on generator or gearbox replacements, may not use the brake long-term, either, as turbines with blades pitched out of the wind can “pinwheel” for long periods of time even in heavy wind without risk.
Even for maintenance tasks that require stopping the turbine’s rotation completely, they’re typically used only long enough to install a rotor locking mechanism. Instead of using these brakes to control rotational speed during operation, much more clever electrical solutions to the problem of wind gusts have been found that reduce the amount of wasted energy, reduce the amount of maintenance that otherwise would need to be done on the braking systems, and which sometimes can harvest the energy from the gust itself. The first solution is incredibly straightforward.
Type 1 Wind Turbines: Fixed Speed
The type 1 wind turbine, sometimes referred to as a fixed-speed turbine, actually doesn’t concern itself much with dealing with short, transient changes in wind speed. Using the inherent properties of an induction generator solves this problem effortlessly. In this configuration, the output of the generator is connected directly to the grid, and the grid’s inertia keeps it mostly at the correct rotational speed. When a gust arrives, the generator will simply “slip” a little past its synchronous speed, and will then recover back to a normal state after it has absorbed the gust. If the gust is too much, turbines in this category may also employ an electric “brake” which dumps the excess energy into a resistor bank or equivalent device, slowing the turbine slightly.
The benefits of induction machines in this regard are largely simplicity and cost; generally only small (or old) wind turbines use simple induction generators like this now due to their higher electrical losses compared to other generator types. There aren’t just electrical losses to consider, either. The aerodynamic losses of operating at a fixed speed can be significant when a lower or higher rotor speed might otherwise be more efficient. Other noteworthy downsides include the inability to provide reactive power to the grid as well as being extremely sensitive to voltage and frequency variations on the grid, meaning they more easily trip offline for electrical transients.
An example of a Type 1 wind turbine used for bulk energy production was the Zond Z-40, produced in the 1980s. Smaller yet modern turbines for home power production or distributed generation may often fit into this category as well.
Type 2 Wind Turbines: Variable Speed
The type 2 wind turbine, also called a variable-speed turbine, attempts to solve some of these problems. A device called a converter is integrated into the turbine to precisely control the magnetic field within the generator’s rotor. This means that the turbine can change how much slip there is within the generator and, as the name implies, can allow the turbine to operate at a more aerodynamically efficient rotational speed even as average wind speed changes. Not only does this improve the electrical and aerodynamic efficiencies, but by varying the rotor’s magnetic field the turbine can provide or absorb reactive power from the grid.
There are some downsides, though, largely with respect to complexity and cost. To control the magnetic field in the rotor a slip ring is required, which can be a maintenance-intensive piece of equipment compared to the type 1 turbines. The converter itself is also an extra maintenance item, and there are some other additional components that add costs as well such as thyristors which help the generator smoothly connect to the grid. The benefits of having rotor control greatly outweigh the small downsides, though, and the type 2 turbine largely replaced the type 1 turbine for large-scale energy production in new wind farms around the late 90s and early 00s.
Type 4 Turbines: Huge Inverters
In order to save the most interesting for last, let’s skip ahead a bit and discuss the Type 4 turbine layout. Type 4 turbines span a wide array of seemingly unrelated machines, but they all have one thing in common: the electrical output from the generator is “fully inverted” meaning that 100% of the generated energy passes through a power electronics system which converts it to grid voltage and frequency. Any wind gusts that come along that aren’t absorbed by the turbine’s pitch system are simply handled by the power electronics. These converters are similar to the converters used in the type 2 machines except that the power electronics systems must be massive to handle the full rated power of each turbine’s generator.
Despite the huge cost and complexity of large power electronics systems, this opens up a huge number of other design options. For example, essentially any generator can be used and operated at any speed. For AC generators this means that the turbine no longer needs control of the rotor’s magnetic field like a type 2 turbine would; even permanent magnet generators can be used in these setups. AC generators can often require two stages of converters though, one to turn the generated AC to DC and another to take the DC and convert it to grid voltage and frequency. However, it’s also possible to skip the first conversion step by using DC generators directly, much like the unique Clipper Liberty turbines did with their four-generator system.
And, speaking of Clipper, a type 4 machine can also allow the gearbox to be eliminated from the design. Some of the largest wind turbines in the world like the Siemens Gamesa direct-drive turbines are examples of turbines with no gearboxes, which are generally (but not always) found in type 4, fully-inverted configurations.
With type 4 turbines, since the energy all passes through an inverter it makes essentially no difference how much or what kind of electrical energy is produced. Essentially the only downside of the type 4 machine is the huge cost of the power electronics, which brings us to perhaps the most elegant solution to this problem.
Type 3: Doubly-Fed Induction Generators
Combining all of the perks of the type 2 machine with some of the perks from a type 4, we come at last to the doubly-fed induction generator, also known as a DFIG (pronounced “dee-fig”). It gets this name because, unlike the type 2, both the stator and rotor are capable of sending energy to the grid. During startup or during periods of low wind speed, called “sub-synchronous speed”, the rotor converter draws power from the grid to drive the magnetic field on the rotor. However, above the generator’s natural synchronous speed, called “super-synchronous speed”, the process reverses and the rotor is able to generate energy instead, sending it back through the converter to the grid. At all points in the turbine’s operation, though, the magnetic field of the rotor is meticulously controlled to keep the generator at the ideal rotational speed.
Not only does this allow for control over the generator’s power factor (meaning that DFIG turbines can provide or consume reactive power and support the grid like a type 2 turbine) and allows for much more robust ride-through of low voltage events on the grid, this also means that a much smaller converter is needed since only the rotor’s power has to be sent through the power electronics. Unlike a type 4 machine where 100% of the power goes through a massive inverter, a DFIG’s stator is connected directly to the grid, and only the rotor uses a converter, meaning that around two thirds of the turbine’s energy passes directly to the grid. The cost savings are significant and the only major downsides are slightly increased complexity in the control systems and the maintenance associated with a slip ring.
The DFIG offers an elegant solution to many problems with wind turbine design, although like other types of turbines handling wind gusts is only part of the story for why a particular configuration might be used. It’s not a technology seen often outside of the wind industry, either, since precise control over a generator is generally not needed when the input speeds are more constant than wind allows. But DFIGs do see some use in pumped storage facilities where the flow through the hydroelectric generators isn’t constant, and they can also be used like a synchronous condenser to provide voltage and frequency support to local or isolated power grids.
The ability to predict wind generation capacity doesn’t make wind energy reliable. At best, it makes it predictable, so that loads can be curtailed and/or dispatchable generation like coal, gas, and to some extent nuclear, can have advanced warning of the impending shortage.
True, but I can’t help but wonder if you’re arguing that the prediction is more around validation of the quantity of wind that can be relied upon, or suggesting that the wind could all of a sudden turn itself off/have sudden, long-term changes in quantity.
I believe he is referring to this part:
“…misconception that wind isn’t a reliable source of electricity because it doesn’t always blow. Quite the contrary; extremely accurate predictions of average wind speeds are available…”
[Chris] is (I assume) talking about the discontinuity between those two sentences. The fact that we *know* when it is or is not going to blow does not negate the fact that there is not always wind blowing.
Wind is almost always going, if you go up high enough. We live our lives 10 feet off the ground with lots of obstacles, trees etc that give a perception of no wind. But up a few hundred feet and it’s always moving just a bit more or less.
Build nuclear or die. It is this simple.
Exactly. You have to boil water to make electricity, its that simple
Technically, that is not true. There are various methods to produce power that do not require boiling water. including gas turbines, solar cells, wind turbines, etc. Dump the imaginary climate emergency and concentrate on reasonably clean, reliable, and reasonably affordable energy. The mix of resources depends on location.
Even gas turbines involve boiling water nowadays. The exhaust gas feeds a wasted heat recovery boiler. The generated steam feeds a steam turbine. This increases the efficiency from 34-42% to about 64%
How about try to make demand shape itself to supply? A very large percentage of the load is HVAC, which pairs great with thermal storage.
Ground fluid heat exchange tubing feeding a car radiator & fan in-house. NO pricey, power-hungry heat pump NEEDed! Also run fluid grid underneath solar panels to get them more efficient & circulate the heated fluid into your hwhtr htr’s heat exchanger coil. U gotta use wind AND solar..with good flexible LiIPo battery bank. Try a wind- funneling propeller air scoop/shroud ahead of blades with good tail in back for better blade pwr.//Steve.
> there is a large public misconception that wind isn’t a reliable source of electricity because it doesn’t always blow. Quite the contrary; extremely accurate predictions of average wind speeds are available hours and days in advance
That’s not even answering the same argument. Being able to predict when wind isn’t going to blow doesn’t make it a reliable source of energy – it still isn’t going to blow when you need it, so you can’t rely on it.
“it still isn’t going to blow when you need it”
What exactly is base load then? How does the wind know when we don’t need power?
“Baseload” is provided by larger units which operate cheaply and efficiently at or near full output because of economies of scale, and/or because of cost structure like with nuclear power. These units do not ramp up and down quickly and don’t respond well to wind power. See the other comment below.
> How does the wind know when we don’t need power?
It doesn’t need to “know” – sometimes it fits the power demand curve, other times not. Wind power has the property of being “spiky”, because the output is proportional to the third power of wind speed, while the probability of such high wind speeds is low – meaning that it comes and goes in big surges which correspond to at least half the energy it generates. Dealing with these surges is the difficult part even if you can predict them, because you can’t choose when you’ll have them.
In terms of probability, wind power is most likely not producing power when you need it.
https://www.researchgate.net/figure/Wind-speed-distribution-and-power-curve-of-a-23MW-wind-turbine_fig2_270586944
A typical turbine only starts to produce power at around 6 m/s wind speeds, while the most likely wind speed you’ll have is somewhere between 2-5 m/s.
You’re funny.
I wish I were.
Both of you are funny.
>allowing generators like fossil fuel plants to scale down production as more wind generation becomes available with plenty of warning.
Same point. Conventional generators have limited ramping rates – the bigger the generator, the slower it ramps. Being able to predict when you’re going to have a glut of wind energy doesn’t help when the generators can’t shut down fast enough.
What happens is, the larger “baseload” units are taken offline well in advance, and they’re substituted with multiple smaller and less efficient units such as big diesel generators and simple once-through gas turbines without combined steam cycles or heat recovery. Hydroelectric power if you have enough. Simply buying power from other countries and neighboring grids is also a popular option. These can be throttled down quickly enough to respond to the surge of wind power, but they are by and large more expensive and more CO2 intensive ways to generate power (except hydro).
As you build more and more wind power and the required ramping gets worse, you simply can’t operate the baseload units any longer. Conventionally this issue has been solved by operating the grid as normal and simply exporting all the wind power to neighboring countries at very low prices (while collecting producer subsidies), but when everyone’s building more and more turbines, this is no longer an option since everyone’s trying to pull the same trick.
Of course, if things get really bad, you can always curtail the wind power itself – but then you have to pay the producers compensation for the amount they weren’t allowed to produce, so you’re paying them to NOT make power.
That is not financially logical. In the grid of yesteryear, if you wanted to dump unneeded power in the grid, you had to pay money. A producer was not entitled to compensation just because your facility existed and you wanted to produce power. That same principal should be applied to green energy free loaders.
Also, the green energy “subsidies” were suppose to be temporary. As with most government “temporary” aid, it becomes never-ending. It is time to cut off all the pigs at the government slop trough.
I would go further and prohibit campaign donations if a firm is receiving on-going subsidies. However, that might not survive a Supreme Court challenge. The root cause of the never-ending subsidies lies with the feckless politicians receiving re-election money from free-loading companies.
If the “dumper” is not entitled to compensation, which sounds reasonable, what about the wounded party who is loosing opportunity to supply that power for compensation?
In a normally operating grid, the power companies would simply not buy the power, but in the real world the politicians have set up laws that demand priority access to the grid. E.g. Germany, StrEG 1991: “The law obliged grid companies to connect all renewable power plants, to grant them priority dispatch, and pay them a guaranteed feed-in tariff over 20 years.”.
With such laws in place, other operators HAVE to buy the wind power. If the other operators can not, then you have to pay compensation for the power not produced.
https://www.nsenergybusiness.com/features/examining-challenges-costs-wind-farm-curtailment-uk-energy-market/
“According to UK Wind Curtailment Monitor data, in 2022 consumers paid £215 million to turn wind farms off (…) costs forecast to reach £2.5 billion a year by the end of this decade.”
@mike – It’s a flawed dynamic, but on the other hand, nonrenewable energy is a much larger example of freeloading. It’s fundamentally based on using up the resources we inherited from the past to make private profit in the present while making the public pay for the mess and consequences in the present and future. Of course it looks more profitable if we only look at present costs and not how much it’d cost to undo everything if that were even possible.
How about pass it on to the customers in the form of “free” power? Water heaters and dedicated freezers are just two examples of things that can be used to sink power in such a way that less will be used later on, without the user being aware of it.
Are we going to be running 250kv lines into peoples houses, because if not you would have to build in massive extra capacity all the way up and down the grid to handle extra supply. You can’t just run an extension cord to a wind farm.
@Annie Mouse You won’t need to upgrade the lines to peoples houses at all – the lines to their house are already capable of probably 3-5 times what every appliance they own can draw anyway (Those with big machine shops/ server stacks etc being odd exceptions that may well have had a 3-phase or extra line put in anyway).
You may however need to upgrade some of the substations and backbone of transmission – or just only send out the ‘free’ power messages on a rota up to the safe sustained load capacity of the infrastructure in the area. Human life leads to peaks and troughs in consumption anyway, so a ‘free power’ alert that activates enough devices to just keep the energy consumption at or around the peak the system is designed to take anyway…
And that is what is happening in Australia. The coal plants are being paid to be all steamed up and ready to go, another subsidy to make electricity more expensive.
So the alternative is what? Let the grid flatline? The problem is the unreliable nature of green energy. If a country embraces using excessive amounts of renewables, then sufficient alternative resources must be ready to to cover the load, otherwise no power. That might be acceptable for a 3rd world country but I doubt that’s what most Australians ar OK with that.
Better approach is run the reliable units base load, with gas turbine/generators and diesel generators on standby because they can quickly power up. Green energy fills in when it can, but gets nothing if not called upon to run. Basically, green energy covers peak loads, if the machines happens to be available.
>As you build more and more wind power and the required ramping gets worse
You’re assuming all the wind generation is experiencing the same conditions, though. The UK and Italy might have interconnected grids for example, but are the conditions going to be the same off the Atlantic coast of England and over the Alps in Milan? There’s something to be said for the averaging effect which geography provides.
> Being able to predict when you’re going to have a glut of wind energy doesn’t help when the generators can’t shut down fast enough.
That’s true for traditional baseload generation like coal, sure. Increasingly though countries are building lots of solar, which is both very predictable and quick to throttle. With a good mix of traditional, solar, and wind, I don’t think this has to be a problem. Solar can form a good chunk of your baseload, and can be turned off where needed.
It seems like you’re presenting wind power as an ill-conceived technology which only works with the right environment of government subsidy and artificial conditions. That’s simply not true, as evidenced by the decades-long history of the sector across changing conditions.
Well, I can’t immediately find the paper I read years back, but wind power has a self-correlation up to about 1,000 km. That’s about the size of a weather front. That doesn’t mean you can’t have the same weather in both locations – just that it’s random rather than by the same cause.
>That’s true for traditional baseload generation like coal
It’s also true for more modern baseload generation like CCGT and power plants which operate as district heating plants, where the heat output is tied to the electricity output so you can’t arbitrarily shut it down.
Wind power pushes baseload off the grid, either by making it impossible or uneconomical to operate. When you add enough wind power, all the rest of your generators have to be load following or peaking generators, and that’s more expensive.
Good! I’m tired of having a local coal plant when we have plenty of natural gas available. Even if they have to give the combined cycle part of an hour to ramp and curtail the wind early, or they run the open cycle peakers for a short while sometimes, natural gas is cleaner anyway.
I’ve not yet heard of anyone building a “hybrid” CCGT plant where the primary turbines are operated for load following. Reason being that the peaker/follower turbines have to be smaller to respond quickly, and the CCGT plants are built big to make up for the greater cost to build one through economies of scale. Conflicting demands.
There’s now a good market for 50 MW scale diesel engines, originally built for ocean going ships, converted to run on natural gas with fuel oil injected for ignition.
>as evidenced by the decades-long history of the sector across changing conditions.
It’s a history of neglecting the problems because they weren’t a problem at a small scale. There’s nothing wrong with the technology though – wind power is relatively cheap to produce and it works – it just isn’t scalable to the degree that the politicians were promising.
Sticking them offshore, plus less NIMBY.
Offshore would be good. Much better coefficient of production – means greater reliability. Unfortunately, the cost doubles.
There’s nothing cheap about windmills, cost to produce, life expectancy, disposability vs what is produced over that time period.
A small nucellar power station (truck size ) located in and around population areas is the answer—–If you can sell it.
A moderate amount of wind power can e.g. complement a country’s hydroelectric power reserves and improve grid stability and responsiveness – but adding more will increase cost and reduce reliability because the other generators have to dance around the variability of wind power.
The trouble is that this limit is somewhere in the single percentage points – it isn’t really making a difference in terms of overhauling the energy system away from fossil fuels. How could it when the application of wind power implies the use of gas turbines etc. for the bulk of the energy demand just to make the system work?
> There’s something to be said for the averaging effect which geography provides.
There’s one thing to consider. You lose between 1-4% in efficiency for every 100 miles over the conventional AC transmission grid. Getting power from a 1000 km away means losses up to 25%. It’s much much worse if there isn’t a direct high voltage power line between the two points, because each transformer or converter adds more losses. Getting wind power from Italy to UK and back doesn’t really work in the real world – some does get through, but much is lost along the way.
However if you have enough wind that it is so problematic to your baseload generators that they are turned off practically always but you now need to trade renewable over distance more often it doesn’t actually matter if you lose 50% in the transfer.
As long as across the wide span of interconnected nations and the mass of renewables there is enough weather and power making it to all the loads – its effectively free energy as the maintenance cost of a spinning usefully turbine vs one free wheeling/braked is basically identical and the cost of the turbine was already paid. So the losses really don’t matter much, if you can reduce that loss it is great as it means you have way more energy to go around and power can get cheaper still, but throwing away only 30,40 heck even 90% and not 100% of this already paid for ‘free’ energy excess generated in one place so the folks in another have enough is still a win. If I have 20 just under half sheets of Ply left over and you need Ply that size or smaller everyone wins if you buy them off me cheap, you get the material you need without having to buy the full sheet at a lower price, I don’t have to figure out how to dispose of the material that is waste to me!
> that they are turned off practically always
Doesn’t need to be always. That would imply the operating costs are zero. If you cut them down 20% of the time, that can easily be the difference between turning a profit or loss.
> it doesn’t actually matter if you lose 50% in the transfer.
Of course it does. It implies doubling the cost of the power. Do you want to pay 20 or 40 cents a kWh?
>its effectively free energy as the maintenance cost of a spinning usefully turbine vs one free wheeling/braked is basically identical and the cost of the turbine was already paid
There’s always other means to use the money than waste it on transmission loss or curtailment, such as by not building the turbine in the first place. It’s never “free energy”.
>> it doesn’t actually matter if you lose 50% in the transfer.
>Of course it does. It implies doubling the cost of the power. Do you want to pay 20 or 40 cents a kWh?
Except it really doesn’t imply that at all – the cost for that power despite the transmission loss is lower for all involved as you taking from the market of excess cheap power and sending the starved market. Supply and demand the grid with more than it needs is getting something for waste, which helps make that company more profit (or if they have strong ethics makes the energy cheaper to their customers) and the one that lacked doesn’t have to deal with extra maintenance and fuel costs on the backup fossil fuel plants and no longer has a supply so insuffient to the demand that the energy is expensive.
> such as by not building the turbine in the first place. It’s never “free energy”.
Ah but it is ‘free’, you were building them anyway – as to meet even the most modest carbon targets global governments have set themselves there are basically no sane choices for most but wind, solar etc, so you had to build them anyway and then to use them practically you need to be at peak able to oversupply your demand by a fair bit. Which as you can’t control the current performance entirely freely or store near infinite power locally by its very nature means somewhere nearish there will be a place with way way way too much and a place that rather wished the weather was being kinder to them right now…
Nuclear tech is great and all, but some nations are going to find it very hard to actually have nuclear power programs for political and/or geographic reasons..
Here’s an example:
https://www.researchgate.net/figure/Typical-variation-in-wind-power-generation-on-different-geographical-scales-The-left_fig1_263007788
Germany + Denmark + Sweden + Finland together as a geographical area roughly halve the peak-to-peak variability of wind power compared to Denmark alone. The distance from the north of Finland to the south of Germany is about 2,700 km.
The area you use to average out wind power needs to be quite big to make an impact. That’s why the DESERTEC project proposal needed to wire up the entire Europe and still had to bring in solar power from North Africa and Middle East to get the averages to line up.
> Solar can form a good chunk of your baseload, and can be turned off where needed.
Solar isn’t “baseload” for the same reason why wind power isn’t and it’s actually worse. You don’t have a choice when you have it, it’s only available during a big burst in the middle of the day, and adding more increases the ramping rates required from other generators because it’s all adding to the same peak. A time zone is roughly 1700 km wide, so getting solar power to “average out” over geographical distances requires even longer transmission lines.
And turning off solar – curtailing – means longer payback for investors. If you can’t sell your power, you won’t make ends meet – with the already long payback time of solar power:
https://www.pv-magazine.com/2023/03/31/pv-payback-times-hit-average-of-20-years-in-2022-says-solarpower-europe/
20 years is already at the limit of what the system is expected to last. A single solar panel can technically last much longer, but if you’re counting the average maintenance cost of the whole system at a typical 3% per year, you have to make the money back before 23-24 years or you end up losing money.
That means you’d be better off buying electricity than having solar panels, so the investments would die off – which is why many countries (e.g. Germany) implement right-of-way laws that say the grid operators HAVE to buy all the solar power first, and the governments pay subsidies or mandate net metering to guarantee that the producer gets their payback.
Dude 20 years is in no way the limit of a solar systems lifespan, 20 years is at worst the expected lifespan it is worth keeping them in the prime spots as the new panels get more efficient and the old ones have degraded a bit. So its an economic decision that now this spot will make more money if you replace them! But the actual lifespan should be many decades more than that 20 years. As evidenced by the fact even now stupendously old solar panels made with processes that lead to rather more rapid degradation in peak output still damn work! Reinforced by the fact new panels degrade so slowly it is basically unmeasurable – the dips you will measure in the real world are very very very much more because you haven’t sent the cleaner round than the panel output is really lost.
>Dude 20 years is in no way the limit of a solar systems lifespan
Of course it isn’t, but you still pay money for the maintenance. That means at some point you end up paying as much for the upkeep as you would have buying the thing in the first place.
There’s at least the NREL estimate of around $31 per kW annual maintenance cost for solar PV. Statista claims an average installation cost of $857 per kW for PV systems, which implies 3.6% annual maintenance cost.
That’s 28 years of “economic” lifespan using a linear estimate. Actually, it should be exponential (1.036^x) because the maintenance costs increase as the parts get older (up and beyond the point of replacing everything, since spares always cost more than the original part, especially with parts long out of production), so with that estimate the time to doubling the cost is 19.6 years.
And in the end, so what if you’ve made your money back after 20 odd years? How much did you gain for all that bother? A few hundred dollars? Note that the article compares the difference between using your own solar power vs. grid power.
The main payback for solar PV comes from subsidies, where you’re either paid a guaranteed price in excess and in addition of the market rate, a tax break, an investment payback, or you get to subtract from your electricity bill the amount that you’ve pushed out (net metering). That’s what brings the payback in under 10 years and makes the whole deal interesting. Otherwise you’re better off investing your money in the stock market.
The only reason solar gives a big burst in the middle of the day is that it’s currently the best way to make money with it. If that were no longer the case, people would adapt to capture more morning and evening light rather than keep building new plants facing straight south if it makes the payback period longer. That’s just competition – you never used to expect the same price trying to sell fresh fish on the shore as you could get further inland, but you responded by trying to ship them inland rather than giving up on fishing.
If facing the panels west/east made the payback period twice as long as they are now with the panels facing south, would anyone have any reason to buy them?
>If facing the panels west/east made the payback period twice as long as they are now with the panels facing south, would anyone have any reason to buy them?
Certainly – as facing more east/west can actually make your payback period massively shorter if you are matching best production to consumption for yourself, and even if it didn’t Solar is nearly entirely fit and forget, it will just keep on trucking and pay you back in the end. And if/when the moment to moment cost of electric is reflected better in the price the energy producers get paid by the energy distributors then suddenly the best angle to put your setup is the one that works best for your local area, and the payback time is likely to drop massively as grid exporting is rarely profitable for small scale setups anyway.
>Of course it isn’t, but you still pay money for the maintenance. That means at some point you end up paying as much for the upkeep as you would have buying the thing in the first place.
Even though that is techincally true the cost of a replacement vs a cleaner it is an entirely stupid idea to get new ones. It is one small job that is probably whatever counts for minimum wage around those parts that lets you keep producing nearly eternally for just that low cost a product that is never going out of fashion.
> Actually, it should be exponential (1.036^x) because the maintenance costs increase as the parts get older (up and beyond the point of replacing everything, since spares always cost more than the original part, especially with parts long out of production)
A solar panel has maintenance cost that amount to nothing – it just needs cleaning unless it gets broken at which point you are just replacing as trying to repair a lone panel is technically possible but never worth the effort when they are so cheap to make new ones! Also you don’t need to go looking for a matchin old panel there is no point. The same with the support electronics you don’t need to get the same old out of production ‘expensive’ stuff a brand new replacement is almost certainly just slot in… And all the basic mechanical fittings and fixtures are probably never going out of production – the mechanical ‘standards’ for PV have developed this way because they work really well, so those same standards are likely to endure practically forever. Making new parts there trivial – its like getting a new tyre for your car/bike for 99.9% of vehicles no matter their age its entirely trivial as that part is basically universal with only a few standard options that are always in production.
This is completely incorrect way to think of it (the comment text below). The maintenance cost doesn’t have to pay off the investment. Those are both costs.
You completely missed the economics which is electricity generated and price received for that electricity. The revenue over the project lifetime has to pay for both the original equipment and the annual costs…
Dude says:
August 30, 2023 at 11:35 am
There’s at least the NREL estimate of around $31 per kW annual maintenance cost for solar PV. Statista claims an average installation cost of $857 per kW for PV systems, which implies 3.6% annual maintenance cost.
That’s 28 years of “economic” lifespan using a linear estimate. Actually, it should be exponential (1.036^x) because the maintenance costs increase as the parts get older (up and beyond the point of replacing everything, since spares always cost more than the original part, especially with parts long out of production), so with that estimate the time to doubling the cost is 19.6 years.
gridwatch.co.uk
Basically for the uk wind and solar suck…. The politicians blew up its coal power stations or converted to gas or wood chip. No replacement or new nuclear. When it’s cold and dark there is no wind or sun so gas is burned.
“”When it’s cold and dark there is no wind or sun so gas is burned.” Yep… Coldest days of the year we had no solar or wind (I work in a utility)….. Would have been a bad few nights if you were relying on that for all your power needs!!! So coal and gas had to ‘cover’ ALL the load. People don’t think about that…..
A hail storm in Nebraska (one of the highest frequency of hail storms in the us) destroyed 14,000 panels. There is presently no economical way to recycle the parts. Life expectancy was 25 years, lasted 4. Somebody has a big bill to pay. It all sounds good on paper but when the rubber meets the road how much are you willing to pay.
Yeah that is a risk and noticable downside. I’ve heard of folks trying an air gap with toughened glass or polycarbonate sheet over a standard solar panel as added protection for those areas prone to such things. IIRC the energy lost to the extra sacrificial cover was noticeable but still down in the 1-4% range.
Then there is the idea of mounting the panel entirely vertically (usually on the walls of buildings) instead – you don’t get the same peak energy year round, but actually get better returns on the shorter winter days. And because the panel is so vertical it is relatively hard for bird dirt, dropped crustaean, hail etc to harm them, and they will never pile up with snow etc.
In that case everything is unreliable. Because if there’s an extended drought then we know later in the year the hydro reservoir will become too low to make power and irrigate crops, or if there’s a hurricane or a heat wave or an ice storm we know that other things will happen.
The point is to schedule things the optimal way, whatever that way actually happens to be. If it’s a bad idea to use the peaker plants, then we know that ahead of time and we won’t do it. If it’s a better idea to ramp up the more efficient combined-cycle gas plants a little early, because we know the wind is going to drop in an hour or whatever, then we can just do that. It’s not like we don’t already do all that anyway, based on predicted demand… which is heavily influenced by the same weather that generates the winds.
>If it’s a better idea to ramp up the more efficient combined-cycle gas plants
Thing is, you won’t have that combined cycle gas plant because the wind power forces its coefficient of production down and the generating costs up by not allowing it to sell as much power. This has already happened in Germany where operators shut down such plants and cancelled plans to make new ones because they wouldn’t get their money back from it.
The more you build wind power (and solar), the fewer hours in a year you have to operate ANY baseload plant, nuclear, CCGT, or otherwise. They just can’t make any money because they aren’t allowed to run.
And as I said, the tragedy is that wind/solar power by themselves never eliminate the need of fossil fuels to act as adjustable buffer – and they actually make it less efficient.
A CCGT plant with heat recovery can be 80-90% efficient. A simple once-through turbine is hardly 30% efficient. You use about three times as much fuel to produce the same energy with a peaker/follower plant. Meanwhile, a system of wind turbines supplying power to some average demand will require about 2/3rds of the energy to come from other sources – which is these less efficient peakers/followers. In the worst case you’re actually using twice the fossil fuels so you could have one third of wind power in the mix.
The best combined-cycle plants are around 55% efficient (lower heating value basis). Simple cycle plants plants are around 40% efficient.
Efficiency is usually applied to how well a machine uses fuel. That is not particularly relevant to green energy. The more important measure is capacity factor. Renewable machines have appallingly low capacity factors while being unreliable. The value of such power is low. In a rational grid, the price paid for such energy is not all that great and good easily be negative.
A bit of a disingenuous of a comparison, but regardless the bit you are missing on what you have said there Dude is rather obvious. If because you have built enough renewable your ‘efficient baseload’ of today are ‘never’ allowed to run it doesn’t matter that the cheaper still burning stuff based backup plants of the future are less efficient – even the over blown ratio you are stating less efficient. You need only say 1kWh and burn 3 units of fuel in the mostly renewable large grid system, vs needing 100000’s of kWh burning 100000’s of units of fuel…
We’re first generation here. I’m aware of a number of major projects where the electricity is converted directly to hydrogen or ammonia (which burns without carbon emissions) and that goes into short term storage to make the power generation not only reliable but constant.
I’m following that as well. It’s interesting, but the efficiencies and costs are still quite terrible.
We’ve spent 20-30 years subsidizing wind power for hundreds of billions or trillions of dollars/euros, to no real practical end, when we should have been subsidizing these technologies to begin with.
Simple as : Energy supply has to equal the demand. That is first concept to understand. They need to balance. When you don’t have enough generation, something has to go. We call this shedding load (turning off service to places until your supply meets demand. When supply is high, some generation needs to be curtailed. Balance is very necessary on the grid. Every time a stove is turned on/off an adjustment in the system needs to be made to supply the need.
So wind and solar CANNOT just make more energy on the spot (if maxed out which they usually are). They may be ‘curtailed’ if necessary, but normally they can’t just increase supply ‘immediately’. Predictable somewhat days in advance, but can’t be considered as steady generation that can be adjusted as needed 24×7. That is where coal, gas, nuclear come in which can go up and down on a whim and provide a ‘steady’ base output to meet the demand. Even hydro to a point can be used this way, as Hydro has a ‘pond’ (like a battery) that can only generate so much somewhat depending on the season, but usually is ‘constant’ output 24×7. Here they don’t normally run full out as they have to keep the pond level steady but can ride though small (relatively) upticks (unlike wind/solar) and down ticks of demand usage. Ie. have some ‘reserve’ to handle changes in load.
Of course again if all your base generation is maxed out, and there is still more demand, and system is ‘sagging’… Something has to be load shed to get back to the ‘balanced’ state of affairs. Brown outs and black outs are going to be the result.
Amazing it all works so well as we know it today. But as more ‘renewables’ come on-line the more unstable the system is going to get and more complex to manage. Challenges ahead. Keep a portable gas generator around to help meet your local need :) .
The problem is the three blade wind systems are flawed in that most of the wind blows right through them without producing any energy. Three blade generators only work in small scale, where the blades move at extremely high speed.
We need a scalable design, like the jmcc wing generator.
https://www.youtube.com/watch?v=7ozm1CoXzCg
https://www.jmccanneyscience.com/jmccwinggenfarmranchsubpage
Many problems
1. Theres alot more wind up high than at ground level. This is the reason current turbines are 1-200feet off the ground. The designs you show go all the way to the ground. Inefficient.
2. Size and weight, you are hanging a massive weight on your rotor, making all of your support much larger and making wear on your bearings and seals much higher. Leading to more friction and less efficient.
3. Durability, your blades are fixed, and you block the wind in the whole are of the blades. Meaning when wind is faster than you want it to be, your design can spin itself to death very easily.
4. You stated that the power is generated up in the kV range. That is not a grid compatible voltage and therefore would require conversion and conditioning. Inefficient.
Fix these problems and maybe you got something
There is a 5th type of electrical connection with is a synchronised, synchronous generator. This has the best grid-integration characteristics, not only reactive power but system strength for fault ride-through with 3-10 times rated current in transient events. SInce the generator speed is set by the grid, there needs to be a mechanical variable speed system to allow the wind turbine speed to vary and gearbox torque to be steady. SyncWind’s system (operating reliably in over 100 turbines in New Zealand and Scotland) is called the TLG/LVS system.
Basically a CVT, conceptually, but for a wind turbine? I was going to ask why that isn’t a design option but perhaps you’ve answered it already.
I’ve wondered about applications of Wind Turbines that are at the scale of a home solar system, 5-30kw, exclusively for off-grid use?
Would it be possible to use a 3 phase induction motor, along with starting capacitors and a very large diode pack, to generate DC power much like an alternator? And could this DC source be used to charge batteries via a conventional solar charge controller?
It is possible – however the part that you don’t have in the system is the need to have a way to power the rotor…. in a standard induction machine the rotor is powered by the flow of AC in the stator, so you somehow have to input an AC power into the motor/generator to excite the rotor at a particular frequency which then determines the “Synchronous” speed of the generator and spinning the rotor slower or faster than the particular “Synchronous” speed determine if you have a motor or a generator. From there if you are spinning faster than synchronous speed you can rectify the output to DC with some diodes, inductors, and probably some capacitors for good measure, to then use that power for what ever you need. Again, in an induction machine the AC frequency of the input power partially determines the speed at which the magnetic field rotates in the rotor, hence the influence on determining the “synchronous” speed. This gets back to a “simpler” solution of separately powering the rotor magnetic field and having the doubly-fed induction generator talked about here in this article.
You could always do as Cousineau said: yaw the nacell until its 90 degrees to the wind. Viola it stops.
Hmmm sounds like a fellow Zond fancier.
The Altamont Pass East of San Francisco during the 80’s was a good place to see many variations of the power handling equipment connected to the Tesla substation. We generated at 480 volts, three phase. That was then stepped up to 21,000 volts on our own substations and up to 108,000 volts to the power grid. We used a two speed induction motor/generator, 6 pole 1200 RPM for low speed winds and then switched to the 4 pole 1800 RPM for higher speed winds. Soft start/interconnect via SCR 100 amp control.
Overspeed protection was from synchronous hydraulic loaded tip flaps that would turn from lift to drag on overspeed. When this happened the yaw motor would turn the system 180 degrees where pawls in the gearbox would keep the rotor from turning backwards. The tip flaps then retracted and the machine could work normally again.
Lots more little details but you get the idea that most of these protective systems were quite effective. In retrospect, I suspect the low speed operation wasn’t really that great in producing significant energy in overall power production. Impressive to watch though.
Humans were using wind energy to move boats long before the 8th century.
This type of generator is really one of my favorites as a mechanical engineer, essentially you have the power electronics controlling the speed of the rotating magnetic field regardless of the speed of the mechanical rotation of the rotor. Then varying that speed of the magnetic rotation with respect to synchronous speed as well as the strength of the magnetic field itself to control the flow of both real and imaginary (reactive) power. It is a quite an elegant solution, but complex electronically and has a potential for issues with the longevity of the brush/slip ring system as well as vibration issues.
It amazes me that the precise 60 (or 50)Hz sine wave on the grid is produced so mechanically. Until recently I assumed that power was produced either as DC or AC that changes in frequency with the rate of whatever is turning the shaft and that electronics were used to rectify, invert and synchronize to get the AC we all know and love.
No doubt it’s much more efficient this way. It definitely explains why it is so hard to bring the system back up after a shutdown though!
It’s not very precise. The exact frequency is allowed to vary by quite a lot. Lead or lag in frequency changes the direction of power flow on the AC distribution grid.
To put things roughly, allowing one area of the grid to run slower means it pulls power from adjacent areas that run faster (as one is trying to speed the other one back up to sync), which means the looser the frequency regulation is, the wider the area of the grid that contributes to any local load or power demand. Frequency deviations are necessary to allow power to flow from one area to the next, but it also means you can create weird loops in the grid where the frequencies don’t match and things break down.
Frequency != phase angle.
That. All parts of connected grid must operate at the same frequency. I think what Dude is referring to the nominal frequency of a generator with a real power vs. frequency droop curve. Increasing the nominal (unloaded) frequency of a generator means that for any operating frequency it will take more of the load. Conversely as frequency drops generators that can supply more power will. The frequency (and voltage) at the interconnects have to match or the interconnects will trip. Most grids a designed to ensure load shedding occurs before that point.
How about blades that flex to become less efficient as wind speed exceeds optimum? No complex electronics or mechanics.
The idea that the magnetic field of the rotor can spin at a different rate than the rotor spins takes a bit to understand and absorb. I’d like to learn more about how that works.
To start with, consider that the magnetic field is the result of the sum of the currents flowing in both the rotor and the stator of the generator. The fact that there is a difference in speed between the magnetic field and the parts of the rotor is what causes or induces currents to flow (lenz’s law) and the whole generator to operate.
Ok, let’s start with the stator. It sees a magnetic field rotating inside, which induces the output current. That field may be that of a rotating magnet.
Now we take a look at the rotor. It has to look like a rotating magnet to the stator, so we can put a static magnet and spin it, or we can block it and rotate the magnetic field, like in a synchronous motor (with the rotating part outside).
Next, we combine both options: the rotor moves a little, and the field rotates a little less in respect to the now moving rotor, so the sum of both rotational speeds stays constant. The stator sees the same field as always, but it now consists of two rotational speeds, the mechanical rotation of the windings, and the electrically induced rotation of the field on top of that.
It is like a differential, where the output shaft turns with the sum of the speeds of the input shafts, only that here one of the input shafts is not a shaft, but some wires.
@Dude: thanks for all the comments on this one. I learned a ton. In science and in HaD comments, the most interesting results are the counterintuitive and unexpected ones, and how you describe more wind power means “regular” power plants get used less, thereby actually resulting in less efficient power plants getting used is pretty great (paraphrasing of course).
thx again
It’s a flawed dynamic, but on the other hand, nonrenewable energy is a much larger example of freeloading. It’s fundamentally based on using up the resources we inherited from the past to make private profit in the present while making the public pay for the mess and consequences in the present and future. Of course it looks more profitable if we only look at present costs and not how much it’d cost to undo everything if that were even possible.
Comment glitch!
Are you suggesting not using resources because that means those in the future cannot then use the resource? Unclear who then decides what can and cannot be used. Let the financial markets and innovation drive the process, not unelected government bureaucrats.
Completely ignoring adverse externalities because it is financially sound is no way to run a society. Like it or not, a central authority is the only way to drive progress when the economy is against it.
Demonstrates the wide divide between those advocating freedom and those advocating control by the few.
The idea that the only choices are which kind of dystopia you want is such a problematic view.
Comment glitch again – ^F for 923849028349
“Quite the contrary; extremely accurate predictions of average wind speeds are available hours and days in advance because of how good weather forecasting has gotten in the last few decades, allowing generators like fossil fuel plants to scale down production as more wind generation becomes available with plenty of warning.”
1. ‘Predictable’ doesn’t mean ‘reliable’.
2. ‘Scale down’ only to a point though – you still need significant backup generation capacity and that stuff can’t be switched on and off on an hourly basis.
For example, you have 100% of generation from wind power. Now you predict that tommorrow evening, for 6 hours, you’ll only be able to fulfill 10% of demand from wind power. So you’re still going to need nearly 90% of that capacity available from standby fossil fuel generation with all the concomittant costs (staffing and maintenance) even if 90% of the time it runs at idle just waiting to be called on.
These are not insignificant costs. And if you’re going to say ‘but, yeah, but no, but yeah, but, they’re not burning as many fossil fuels in the standby periods compared to if they were the primary producer’ – then why not nuclear instead?
The reality on the ground that we’re seeing is that wind power doesn’t produce reliably and when it does produce its no where near baseplate capacity.
Now, with that said, its ‘new’ technology and, as the article illustrates, as challenges arise engineers develop solutions – DFIG as an example of one solution to one problem. But right now wind power is hyped up as something its not. Its not ready for widespread rollout because there are tons of engineering problems that are popping up once these installations hit the real world (and this is totally normal – not a hit on windmills here).
In the context I was replying to when the comment glitch happened, I am just saying that while people seem to think it’s unfair that renewable energy is given favorable terms compared to nonrenewable energy, nonrenewable energy has always been given unfairly generous status.
The first being the obvious one – the rate we’re using fossil fuels is so far in excess of the rate they were formed that the supply will run out in human timescales, rather than geological ones or “whenever the sun burns out”. Another being that we accept that people have been and will continue to be harmed in maintaining a high availability of such fuels. That’s something you can say about most activities, including mining for batteries and whatnot. However, as an example, we’ve already seen that we’re getting to the point where we are ramping up the acceptable harm in drilling for oil – issues related to the trend of fracking, for example. Then there’s the unhealthy stuff you breathe, eat, and drink if you’re near a refinery or the exhausts of a million cars or what have you. All that is something we not only accept but don’t bother to calculate the economic costs of. The real cost to do things the conventional way without such issues is huge, and we generally don’t expect it to be paid. And that’s all without ever getting into climate change, which people seem to love denying.
Ugh comment glitch again! 923849028349
Someone said recently We will be mining our dumps in the future.
I may not have read that comment the way you intended it.