Climate Scepticism

By Jit

No swings, only whirligigs

Offshore wind harvesters are supposed to be one of the answers to the “climate crisis.” It seems unlikely to me. We know and have discussed one of the major weaknesses of this generation mechanism, its unpredictability. In a rational world, that alone would discount it as the go-to for any modern civilisation. Its characteristics are such that the mugs installing it aren’t the ones making it; nor will they/can they ever be.

If the offshore wind harvesters have anything going for them, it is that they emit (almost) no carbon dioxide in the operational phase.

If anyone can think of another advantage of offshore wind, do enlighten me. (I may have a few to share below.)

To place on the other side of the scale, we have quite a list of potential negative impacts. Not all of these are environmental, and many of them are of minor importance. Nevertheless, I thought it might be worthwhile to sketch out some of the potential impacts of a “typical” North Sea wind harvester deployment. The headings are in part garnered from the environment statement for the Norfolk Boreas wind development. They apply just as well up and down the North Sea, differing only in the specifics.

1. Effects on wave and tidal velocity. The main potential effect is on sediment transport south to north, affecting, ultimately, rates of coastal erosion. In principle, the effect of obstacles in the water column is to slow the passing water, and therefore reduce sediment transport. Probably a minor effect in general, in particular as the turbines are now so large that they are hundreds of metres apart, preventing this effect at one interacting with the same effect at its neighbours.

2. Disturbed sediment in the construction phase, in assembling the uprights or burying the cables.

A. This may include toxins which are re-entrained and could end up anywhere. (E.g., arsenic.) Likely to be a minor issue.

B. The disturbed sediment may have an impact on benthic communities. In soft substrates these will be wormy things (polychaetes, among which the most familiar may be rag- and lug- worms). For Boreas, and other developments, there is the risk of interacting with an “important” worm called Sabellaria spinulosa, which uses sediment grains to produce a tube for shelter (you may be familiar with the calcareous tubes of a similar species, the keelworm, which often decorates washed-up mussel shells, etc.). The point for Sabellaria is that it has no means to move once settled, and is therefore vulnerable to being buried. Another minor issue, especially if care is taken.

3. EMF. Naturally, all the lovely juice has to be squirted ashore, and that means electromagnetic fields. Burying the cables takes care of some of the problem before it starts. For Boreas there will be two HVDC cables 120 m apart, and there will be another two 120 m apart 250 m away for the “sister project” Vanguard. Because EMF falls off with the square of the distance, Boreas is pleased to note that its effect will be highly localised. Of course, it will be highly localised in long parallel lines 120 – 250 m apart. Boreas also says that “no direct evidence of impacts to invertebrates from undersea cable EMFs exists.” This was presumably written before there was such evidence, which there is now, although it is not very well defined. Boreas predicts a negligible impact here – but I’m not so sure. Here’s what Heriot-Watt said four years back:

“Brown crabs can’t resist the electromagnetic pull of underwater power cables and it’s changing their behaviour, marine scientists say.”

We also have the problem of EMF affecting skates and rays, which use magnetic fields to navigate, hunt, detect congeners, etc. There is some evidence of these fish not doing well in proximity to undersea power cables. Could the parallel cables form a barrier to dispersal? Boreas doesn’t think so. Then, they aren’t quite sure what an elasmobranch is. I spotted three different spellings of this in the space of two paragraphs of the ES [392, 393 of Chapter 11 (revised) if you’d like to check.]

4. Getting in the way of fishing. For Boreas, plaice and sole fishers will be excluded from 700-odd square kilometres. They’ll be able to make up the difference outside the exclusion zone. [Plaice was known to be overfished well over a century ago. Is there a hidden silver lining in this cloud?]

5. The effect of piling noise on marine mammals. The risk of permanent auditory injury, or in other words, striking the victim deaf, dumb, and (in effect) blind.

There is “embedded mitigation” against this trouble in Boreas’s case – the choice of installing fewer, but larger, turbines to the same overall capacity. Sure, this means there will be fewer piles driven in. But the cynic in me says this choice had little to do with the banging headaches that our cetacean friends are likely to end up with.

The next “embedded mitigation” is “soft-starts” to the banging, thereby, it is hoped, scaring the harbour porpoises (the most abundant cetacean in the neighbourhood) out of damaging range. See also Mark’s piece on whales, and comments below.

6. Birds.

A. Displacement. Some birds just will not enter the footprint of a wind harvesting facility (e.g., red-throated divers). They are therefore displaced from foraging areas. Other birds go straight through, if they survive the trip. The displacement has an energetic cost, and can cause birds to starve (see also C. below).

B. Collision risk. This is what applies to the less timid birds, for example the little gull that I have a very soft spot for, the kittiwake. Boreas says its “worst case” on kittiwake swats is 200 being downed a year, with confidence limits. I have no faith in such numbers, or of the modelling exercises that produce them.

And it’s not just the regular users of the airspace that are at risk: there are also the birds on migration. Swans, geese, things like that, things that aren’t very manoeuvrable and have the unfortunate idea that it’s good fun to fly at night.

For Boreas, the “embedded mitigation” includes fewer, larger turbines! Why not have one, the size of the moon?

C. Barrier effects. Birds like the red-throated diver now have to make a laborious circuit around an enormous footprint in order to make any progress towards wherever they were trying to get to. There is a large energetic cost to these diversions.

7. Shipping and navigation. The deployment of all this paraphernalia leads to an increased risk of allision, and in order to avoid such, requires a degree of circumnavigation of the hazard.

8. Aviation and radar. The turbines, with a tip that reaches 350 m, are a hazard for all the jellycopters whizzing to and fro, bringing people to the wind-collecting arrays and taking them home again. [Boreas intends to make 2 helicopter transits daily, as well as ship movements.] The whirling blades create radar clutter, which may confuse fliers.

9. Any effect on local climate? I don’t see this mentioned in Boreas’s ES, but we know that extracting energy from the wind partly stills it. On the face of it, this is likely to result in a minor warming effect on the surface of the sea – but who knows? [I haven’t tried to look it up.]

So there we have it – a list of possible drawbacks of installing giant whirly things in the North Sea. Note that this is entirely separate to their usefulness as generators. Nor does it say anything about the cost of such electricity as is delivered. Absent subsidies, it is doubtful whether the likes of Boreas would be viable. In other words, no-one would build such a development and then try to sell electricity into an open market. No mention has been made of the materials required to build these rotating colossi, the concrete in their foundations, etc.

There is also the non-trivial issue of cumulative impacts. Each one of these deployments has an impact on its own; together, all of them have an additive effect. Of course, when it comes to displacement, whether of sensitive birds, or fishing boats, the effect can be more than additive. When it comes to the hearty kittiwake flying through the whizzing blades, maybe it is less than additive: you can only die once.

Here you can find the document library for Boreas’s planning application. There are two thousand documents in all; the document library (pdf) is over a hundred pages long.

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