Tallest wooden wind turbine starts turning | Hacker News Reader

Tallest wooden wind turbine starts turning

bbc.com

79 pointsandsoitis70 comments

The Spruce Goose flies again; in a new form (:

Laminated wood is a pretty cool building material. There's typically a lot of epoxy/resin/glue involved though — it's not "just" wood.

Paging Low-Tech Magazine! I wonder how they feel about these partly wooden turbines:

https://solar.lowtechmagazine.com/2019/06/reinventing-the-sm...

https://solar.lowtechmagazine.com/2019/06/how-to-make-wind-p...

I expect they would be disappointed that it's not all wood, and also skeptical of these being mass-produced with engineered wood rather than made by local artisans out of regular wood. Can the wood parts be recycled or composted? What happens at the end of life?

To quote Low-Tech Mag on composite blades, "The environmental damage of the carbon-epoxy spars can be viewed as acceptable, if compared to the larger damage done by conventional wind turbine blades. However, the waste problem would not be solved, and further growth in wind power would still result in ever larger waste streams."

> If wind would supply a more desirable 40% of (current) power demand, there would be three to four million tonnes of waste per year.

For comparison, New York City produces 14 million tons of waste per year. Doesn't seem as dramatic when put in context.

It’s like that scare mongering about wind turbines killing hundreds of thousands of birds per year. It’s laughable when compared with billions of birds that _cats_ kill.

Any discussion of this topic is ripe with emotionally charged misstatements, I’m careful about taking anything at face value anymore.

Cats kill between 1.3 and 4.0 billion birds a year: https://dariuszzdziebk.wpenginepowered.com/wp-content/upload...

— Smithsonian Conservation Biology Institute & U.S. Fish and Wildlife Service

From https://climate.mit.edu/ask-mit/do-wind-turbines-kill-birds

- Wind turbines kill something around a million birds every year

- Power lines kill something around 25 times that

- And "A 2012 study found that wind projects kill 0.269 birds per gigawatt-hour of electricity produced, compared to 5.18 birds killed per gigawatt-hour of electricity from fossil fuel projects"

Well one thing that occurred to me is this argument could hold water if the wind turbines somehow drastically differ in the kinds of birds they kill. E.g. if they kill a million of some rare species that’s not killed by anything else that could be different. But I haven’t seen any data on that.

I think it's talked about fairly often. Wind turbines kill many more raptors (eagles and hawks) than cats do. Here's some data: https://cowboystatedaily.com/2023/02/19/number-of-eagles-kil...

Possibly a dumb question, but what if this gets struck by lightning?

Not a dumb question, I’m assuming it’s been treated with flame-retardant chemicals, but I’m surprised that it’s fireproof-ness wasn’t addressed in the article.

Since they are the tallest thing around, wind turbine blades get struck by lightning regularly. Fiberglas is an insulator. Aluminum is a good conductor. But carbon fiber is a resistor. Carbon fiber blades have to have embedded conductors to prevent from being blown up by lightning strikes. So there's a layer of aluminum foil or similar to provide a low-resistance discharge path.

Same problem as carbon-fiber aircraft, with similar solutions.

I’m sure they’re still electrically grounded. I’d be shocked if they didn’t have lightning rods, not to mention all of the metallic innards like ladders and wiring that would have much lower resistance than the wood itself.

That's not a dumb question at all. Lightning protection is a different story than when the tower itself conducts. The nacelle (the part that houses the generator) is grounded and so are the blades (they have an integral conducting mesh). All of this is conducted all the way to ground level by conductors much the same as what you'd see on a wooden house with lightning protection. I'm not sure what they've done on the outside of the structure, but I suspect that the chances of the nacelle or the blades being hit are far higher than the chances of the tower itself being hit directly. If it does get hit it might ignite so there is still some part that more detail would help on, I can't see anything special in the photographs accompanying the article.

In my ignorance I assumed the blades would be wooden since that has a lifespan and needs to be replaced.

A steel base would last for all eternity, so what's the point of a wooden base? Wind turbines offset the carbon emissions in the span of a year.

They say it in the article. Its modular and easier to transport so higher towers can be build.

> As long as the wood doesn't end up rotting or being burned, the carbon is not released.

So this is only carbon negative if the trees are net-new and we recycle or sequester the wood at the end of the service life.

I’m skeptical of trees as an effective carbon sink for the purpose of slowing global warming until we have a way to sequester the carbon on geological time scales.

This is a great technology and if wood has a smaller footprint than existing material it is a win. I see how wood could be carbon neutral. I’m less certain about it being net-negative.

If there were no humans to cut forests down, they'd be renewing themselves too. Trees die, fall and rot. Releasing a part of their captured carbon back, and releasing some methane (a worse greenhouse gas than carbon-dioxide).

Now that there are humans to cut them down, it makes no difference in re-release of carbon, as long as we replenish the forests in the same rate as we cut them down. Which we don't, but we could.

Point being, on the grand scale of things, using (not burning) wood is fine as long as it is renewed. Letting it rot or burning it after use, is fine too. It's what the world would do without humans anyway, without that causing a run-off greenhouse effect.

Obviously, processing wood costs energy (footprint), but from what I know when I studied this stuff (early 2000s) steel and concrete are way, way (way!) worse in this, so on that scale too, wood is preferable. It really is magic stuff.

I agree. But you are describing a carbon neutral system. The article claims wooden wind turbines are carbon negative. This is only true on a short time scale. Once all wind turbines are wood and the first generation reaches EOL they become carbon neutral.

Maybe they are "carbon negative" in the same way as many datacenters or international flights are "carbon neutral": by buying it off: e.g. planting more trees than they cut?

But I guess you are right and they're just doing short-term bookkeeping here.

Yeah it's a great technology and we should absolutely pursue it but I think they are overstating the benefits a bit.

They can still be carbon negative if at EOL we don't release the carbon. Turn it into charcoal is an obvious idea, but other options may exist.

The charcoal is only carbon negative if we also bury it. Those “other options” all fall under “sequestration“.

then the wood will compost and turn back into CO2. at least that is how I undersand the process.

Where that CO2 goes matters a lot.

Let's assume that the wind turbine operates and generates power for a few decades, and is them chipped and burned in a biofuel power generation plant - it would be carbon negative.

Where does the exhaust from the biofuel plant go? If it doesn't go into a hole in the ground then the system is neutral, not negative.

Carbon negative means there's less carbon in the atmosphere at the end of the lifecycle. It seems to me that requires long-term sequestration.

How do we burn them? Heat them in a low O2 enhironment would result in enough hydrogen released to renerate power and fuel the reaction while leaving carbon to behind. Not very efficent but it is known to work.

The exhaust goes into the atmosphere. Overall then, assuming low carbon manufacture, the turbine is roughly carbon neutral. But then you factor in the decades of zero carbon operation. Assuming that some small proportion of that capacity is used to power carbon scrubbers/sequestration and you can fairly easily get to carbon negative

How is a positive number minus zero negative? The carbon scrubber itself can be carbon negative if the carbon is sequestered but that’s true even if the power supplied to it emits carbon. The power source doesn’t get to take credit. That only complicates the math and leads to double counting.

I still don’t see how the wind turbine itself is carbon neutral. And even if I did nothing about being made of wood makes a wind turbine more suitable for powering a carbon scrubber.

These terms have meaning and overstating the capability undermines credibility.

Having thought this through again - my argument is rubbish :)

There is no wood wind turbine that large.

The wind turbine has (mostly) fiberglass blades.

The tower supporting the wind turbine is partly made of wood.

Some turbine facts for reference

For a typical onshore wind turbine, the tower can contain approximately 295 tons of steel

The concrete footings are usually 9 feet thick and 60 feet in diameter, requiring about 300 cubic yards of concrete, which is equivalent to 30 to 40 truckloads.

The blades have a 20 year lifespan and cannot be recycled, being made from fiberglass reinforced with plastic, also known as glass fiber reinforced polymer (GFRP). With newer ones also incorporating carbon fiber.

All that said, for a turbine to produce enough clean electricity to offset the carbon emissions produced during its manufacturing, installation, and maintenance, is typically around 7 to 8 months.

"....to offset the carbon emissions produced during its manufacturing, installation, and maintenance, is typically around 7 to 8 months." Finally a clear statement. Never found one like that for DAC. Massive steel and concrete buildings and no answer to exactly that question: how long does it take to recover the CO2 footprint of building these structures.

for wind turbines

https://yaleclimateconnections.org/2021/06/whats-the-carbon-...

https://www.siemensgamesa.com/en-int/explore/journal/uniting...

Unfortunely it seems these 'wooden turbines' also use fibreglass blades, which is a shame.

Not all of them.

https://electrek.co/2022/11/16/wind-turbines-made-entirely-o...

Very interesting. On average how long until financial break-even, in terms of total investment vs value of electricity produced/sold?

Depends on the site. In the best sites, something like 3 years. In the worst sites, never. Usually, something like 6-10 years.

Sixty feet in dia. x 9 feet thick is about 950 yards.

They are more cone-shaped than cylindrical.

1. https://www.researchgate.net/figure/Illustration-of-the-rein...

IMHO we should also look at EROI (energy return on investment), which Wikipedia cites [0] to be around ~20, that is a wind turbine will produce 20 times what it cost to make it.

[0]: https://en.wikipedia.org/wiki/Energy_return_on_investment#Wi...

The point here that the wooden wind turbine is carbon negative is also a good one (where-as steel and concrete are a big carbon positive) is also worth tracking.

I do wish I had a little better idea what the costs of wood were. There have to be nutrients and other resources consumed, that wood takes to produce. I'd love to better appreciate the material flow of wood.

Also since it's laminated veneer lumber (LVL) and glued laminated timber (GLT) [1] it's going to have resins/adhesives involved that have an impact as well.

Probably still better than the cement in concrete but I don't have a source for that.

[1] https://www.windpowermonthly.com/article/1660496/windtech-wh...

By weight, much of that wood is actually glue. The structure is wood fiber held together by chemcial glues. It isnt a tree. It isnt a hand-carved covered bridge. It is an engineered structure filled with modern bits and pieces made out of not-wood.

I don't know if your listing these as "fun" facts, or as a means to try to denigrate wind turbines. If it pays for itself in 7-8 months while operating for 20 years that's 3% of its lifespan. That's 232 months of clean energy being generated. That's impressive to me. So I don't know what your intent is here, but I'm on board for all of it as a good thing

That and it's just the lifetime rating for the blades, not the foundation, tower, and hub

I would presume that the tower and its foundations, like a large bridge, are functionally immortal. They sound like they should remain useful for a century or more. In such cases the initial carbon cost of construction shouldn't be much of a factor.

The reinforcement in the footing will eventually corrode and so will the tower (even with the best preventative maintenance). The sea likes to ablate things. But I'm sure the engineers are building extra life into the foundations so they can replace the blades every 20 years, and do the tower every 40 at last a few times.

honestly - I was compiling the facts thinking it was going to be much more time for ROI and was happy to have my assumptions invalidated.

I'm pro-wind turbine though.

I'm puzzled by these comments. It might take well over a decade for a turbine to truly "pay for itself," depending local energy rates and how the project was financed. If you were to put it in the wrong place, there's no guarantee it will ever pay for itself. (not that a wind turbine was ever built for political rather than hard-headed economic reasons - that never happens!)

we're just not stating the assumption that we mean "if placed in wind and connected to customers who will pay".

It's not very interesting to be asked "what if it is built without consideration".

Same goes for any capital expenditure, ROI is zero if it is unwanted

I can unpack this a little. Here's my issue with the way the initial post was stated, and that "7 to 8 months," which I can't even. It's not the pro-wind sentiment that I'm taking issue with!

There are at least four major variables here, #1 the cost of the turbine and its installation (and maintenance), #2 the cost of financing, #3 the market value of the electricity that's being generated, and #4 the amount of electricity generated as a factor of how much wind the turbine will encounter.

#1 is where we can all be happy - turbines are getting bigger and cheaper. #2, well, you'll have noticed that interest rates can do some wacky things, and so the amount you'll spend financing your turbines might also vary quite a bit. #3 is an interesting one - we'd really like to build more and more clean energy sources, pushing the cost of electricity to the consumer down, but any given turbine is going to take longer to pay for itself if, after its construction, the cost of electricity continues to drop. Conversely it will pay for itself quicker if prices take off for some reason.

Regarding #4 - I guess it hurts people's feelings to think that turbines might be put in a suboptimal place because of politics, but putting that aside, we'd like to eventually put turbines in as many places as practical, and the difference between how productive a turbine on a mountain ridge or on the high plains might possibly be and a turbine in an urban environment might be is really high. I live near a 2.5MW Kenersys turbine that a company put on its urban campus, largely as a publicity stunt. It's glorious, but it's definitely not spinning as often as you'd like, or as much as it would in a better location.

Using some napkin math that doesn't really bear sharing, I believe it will pay for itself (pay for itself in terms of money spent and return on investment via electricity generated - not something hand-wavey and poorly specified involving carbon) well into the second half of its lifetime. That actually seems fine, it beats their getting all that electricity via the local coal plants, but maybe it speaks to the issue with these hand-wavey numbers: it would have paid for itself much, much faster in a better location. That's okay - as long as the turbine pays for itself over its lifetime, it's all good.

What a bizarre take on the entire topic and assumes such bad faith on anyone in the thread. What a absolute load of rubbish to assume being built in a non-windy location as an example for a thought exercise. Such a weasel wannabe politico comment - that never happens!

Take a pill. And then look up what "return on investment" means.

Again with the assumption people don't know what the conversation is about. Like I possibly don't know what ROI means. What a just total waste of comments

I agree that your comments are a waste!

I didn’t read the comment as trying to denigrate wind turbines. It says 20yr operation with 7-8mo payback which sounds excellent.

If anything, I think the understated way the grandparent comment presented the facts added to the impact of the final result.

> and cannot be recycled

This myth just won't disappear.

Fiberglass isn't easy to recycle, but we absolutely can and do:

https://www.energy.gov/eere/wind/articles/carbon-rivers-make...

https://www.siemensgamesa.com/en-int/newsroom/2021/09/launch...

https://www.nationalgrid.com/stories/energy-explained/can-wi...

As is often the case, “nobody will do it at market rates” simply becomes “can’t”

It basically means "shouldn't be recycled"... Unless there is some desperately compelling reason to.

AKA the entire point of the market. Distributed, decentralized decision-making.

A lot of things deemed 'unrecyclable' actually are. It's just that it's usually not worth it.

For planning purposes, "will not be recycled in real life" is indistinguishable from "cannot be recycled".

But who cares? If you grind up and bury fiberglass, you’re sequestering carbon and melted sand. I’m fine with this. People intentionally burying carbon do so to celebration when they’re doing it on purpose and selling carbon credits.

It's interesting how many things over the years get classified as "recyclable" and the secret is simply "we'll put it in cement."

> The blades have a 20 year lifespan

What stops us from making blades with a 60 year lifespan?

it would be interesting if this is a material science issue where UV exposure just breaks things down to the point that after a certain point they are just unsafe from to be spinning at the rates and mass involved. that's a lot of kinetic energy if an unscheduled rapid disassembly were to occur.

Yes, it's a material science issue. With stronger materials they would just make the blades longer because the power produced is proportional to the square of blade length (or cube?). Anyway, the blades will be at the limits of material strength (over a reasonable lifetime).

I think there is another factor limiting blade length which is blade tip speed which needs to be below the speed of sound by a bit.

That just limits rpm

Ablation is one problem, fatigue is another.

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