How does a large, slowly-spinning turbine materially harm aquatic/bird life after the construction?

(Not OP, and) Not sure about aquatic life, but if those turbines are anything like the ones on land, then the rotors are definitely NOT spinning slowly! And they look even bigger, which would imply a faster speed at the rotor tip for the same rotational velocity.

And as a result there have been issues with them killing lots of birds, esp 1) IIRC large predatory birds which are looking down at the ground for prey and can't change course as easily as a small bird, and 2) being in migration paths. But I think both of those problems are pretty well understood by now and I'm guessing this project takes both into account.

> if those turbines are anything like the ones on land, then the rotors are definitely NOT spinning slowly!

You apparently haven’t seen modern (ie installed in the last 5 years, this stuff moves quickly) wind turbines. They are huge and slow turning, also much quieter than the smaller, shorter, faster spinning ones.

The rotors turn slow in terms of rpm but fast in terms of wingtip speed, due to the very large radius. But many things kill birds, I do not believe that wind turbines could ever make much of a difference.

As an example, the Vestas V164-8MW seems to be one of the largest off-shore wind turbines, and has a rotor diameter of 164m and a rotational speed of between 4.8 and 12.1rpm. [1]

Unless I'm miscalculating, that means that the tip of one of the rotors will travel 515 metres per revolution, which at 4.8-12.1rpm is a tip speed of between 2,472 metres per minute and 6,231 metres per minute.

To put that in more common units, that's between 148km/h and 373km/h.

[1] https://stateofgreen.com/en/profiles/vestas/solutions/v164-8...

Yes all correct. Those top 'tip' speeds where reached with smaller turbines as well. Max tip speed is a design limitation on blades (induced vibrations due to turbulence). What it means is that small turbines had much higher RPM, and the average speed along the blade was much higher in smaller turbines.

Second benefit of larger turbines is much more of the swept area is outside of the normal flight heights of birds. Either too low for migration patterns or too high for most hunting and scooting flight heights (relative to nearest surface).

So one 8MW turbine is likely to kill a lot less than 8 * 1 MW and much, much less than 80 * 100kw, even if it has a much larger swept area.

Now as these are offshore turbines, and Hywind, being for quite deep water. Likely to be far offshore, there are not that many birds around too get hit in the first place.

The nice thing about the slower RPMs compared to smaller tubines (especially pre 2000's) is that slower RPM's make it easier to spot the turbine for birds. High RPM's give optical effects that make it hard to predict where something is going (e.g. wheel looks like rotating backwards etc...) so bigger is easier too avoid for birds.

If wind farms are going to contribute significantly, then there will be a lot of them. In terms of replacing fossil fuels they will likely still be a net benefit, but unless the Audubon Society has been captured by Big Oil etc (which I doubt, but possible) then bird safety still sounds like an open question.

[1] http://www.audubon.org/news/will-wind-turbines-ever-be-safe-...

I would be very happy with all birds being extinct if that is what would take to come up with a solid replacement for fossil fuels. The problem with wind power is it will not replace anything. Wind cannot provide reliable power so it has to be backed by something else that is reliable. Also, wind provides variable power so infrastructure has to be setup such that it can handle such variation.

After accounting for initial setup costs and maintenance of wind turbines (it is worse than Solar in this regard because of the wear and tear in mechanical parts) and power infrastructure (which has to be designed to handle such variation without any impact on consumers), it will take a very long time to break even, if at all. And don't forget that we will still need something reliable like nuclear or fossil fuels to back it up... which we already have enough of to last for thousands of years.

So, basically, all we get with wind is more work for no gain at all (not to mention the unnecessary environmental harm). I am sure Statoil is not ignorant of this. They are just using a small portion of their 100 billion dollar yearly revenue in this to please the eco-terrorists.

Yes they do, because birds are confused by the light signals at night or during foggy days and go towards them. Big glass windows/walls also kill birds. I work in an office with glass curtain walls and a lot of birds end up flying into them. To make matters worse, we also have stray cats around the building, so birds that fall to the ground and are not dead upon hitting the window end up being lunch.

Cats seem to be the main threat to birds.

It also helps if you have a glass wall building or a wind farm around, which means free lunch for all the stray cats.

The ones I'm referring to are in large installations in the last 10 years in the US Midwest. Each rotor blade is transported individually on the back of a flatbed semi-truck.

As pointed out elsewhere in the thread: indeed the RPM can be low, but the rotor tip velocity is high.

Large turbines like the Vestas V164 8.0MW have nominal rotor speeds of ~10RPM. This sounds pretty slow, but with a blade length of 80M, this corresponds to a tip speed of nearly 200mph. Low RPM doesn't mean low tip speeds.

May well have an impact (no pun intended). I think the more relevant question is how that impact compares to other generation schemes, both in the short term (birds flying into large structures) and the long (habitat loss due to climate change).

Some types of turbine require pile driving which makes a lot of underwater noise. This can harm dolphins and porpoises. Floating turbines probably don't have this problem.

The blades go very fast at the outer part of the blade. It will easily kills birds.

It's interesting how HN have quite a bit of right wing extremist comment sprinkle here and there, I always thought it was a rare occurrence.

I also think you simplifying nuclear power. You still need to store the waste and it something quite a few people dislike. And no body is investing in Thorium R&D, at least not in USA.

> aquatic life and birds more

There are several country side plastic patches in the ocean which is cause cause of oil products that cannot biodegrade in a reasonable time.

The global warming cause by oil which in turn cause bleaching, killing aquatic life, causing far more damage than whatever you think wind turbines are causing.

Airplane and free roaming cats kill more birds than wind turbines. I know turbines do kill birds but they can move it away from migration paths.

How plausible is it to put protective nets around wind turbines, and cats? Or requiring reflective streamers attached to turbine blades, and cats?

> right wing extremist

Right wing of where exactly? I am not American but I am assuming you're talking about the US. In that case, you should know that the clean tech industry in the US started and thrived during Bush presidency. The mainstream American right wingers are no less brainwashed than the American left wingers when it comes to renewables and climate change. Climate change deniers are a minority that even Trump disassociates himself from because he knows majority of the right would hate him for it.

>And no body is investing in Thorium R&D, at least not in USA.

People would invest in it if they thought it would work. It's like Solar and Wind, which are complete waste of money, except it is not "renewable" and hence not even cool.

>I know turbines do kill birds but they can move it away from migration paths.

As I already said, I know that it is okay as long as it fits the narrative.