Hacker News Reader

Comment by g42gregory | Hacker News Reader

If windfarms reduce overall wind speed around them and if there are enough of them built, wouldn't this measurably reduce the wind speed in the environment?

And if the wind speed of the environment is measurably reduced, wouldn't this affect the environment itself?

What are the negative effects of this on birds, climate, insect population, etc...? Do positive effects significantly outweigh negatives?

View on HN

The amount we can extract is tiny compared to the volume of energy put into the air every day by the sun. At a certain scale it could definitely become an issue and change the local environment and reduce wind speeds, we have seen that with some of the biggest solar farms where the air temperature is changed and the shade increases vegetation and wildlife so presumably wind speed reductions will have some effect. But compared to the CO2e it saves from being emitted its absolutely worth it currently.

> The amount we can extract is tiny compared to the volume of energy put into the air every day by the sun.

Here's a study in how much wind power you can extract before adding more wind turbines doesn't produce more power overall.

At the 100m mark (as opposed to the whole atmosphere up to the jet streams), they calculate 250TW.

Total human electricity generation is well under 5TW (30PWh/yr, out of around 180PWh/yr of total energy), so we could supply all electricity from wind and still leave 98% of the "extractable" global wind potential in the air, which is itself less than all wind energy because of the Betz limit.

https://www.pnas.org/doi/10.1073/pnas.1208993109

> But compared to the CO2e it saves from being emitted its absolutely worth it currently.

Funny. That’s a huge part of the argument made to justify that burning fossil fuels is OK. The problem with letting small problems linger while you scale is that suddenly you have a huge problem you can’t do anything meaningfully about because suddenly it’s a critical part of your economy.

"It reduces CO2 emissions" is being used to justify burning fossil fuels? And is "a huge part" of the argument? I think you explained yourself wrong.

No, it’s being used to say that ignoring the problems with Wind farms scaling to a huge scale (and fossil fuels is massive and wind has made less than a noticeable dent) means that you’ve solved one set of problems for another and hopes the second set isn’t as bad. I didn’t say the only alternative is to go back to fossil fuels. I personally think that nuclear has much better and cleaner scaling properties with fewer issues than wind and solar (for example it still remains generally true that the only countries that have meaningfully reduced CO2 emissions are those that have offset it using nuclear while solar and wind have a very poor record) .

Please look at a chart of per-MWhr generation costs. Wind and solar are a fraction of the cost of nuclear (with solar plunging by the day, almost) and nuclear is only getting more expensive as time goes on despite being a decade or two away from being a 100 year old technology.

In the US nuclear plants are being phased out and wind/solar projects are replacing them at a ratio of roughly 6:1...with huge savings for grid operators and customers. It's so cheap, even with storage system costs it's still cheaper.

That's where utilities are focused: expanding energy storage and better transmission grid infrastructure. Those, and renewable energy, increase grid reliability.

Of course it does depend on how you measure cost.

If you just measure generation costs then you are missing the other key element of a nation grid - it always working - and that characteristic costs as well, not just the electrons provided.

So those improved transmission and storage investments need to be put on the renewables total costs.

Nuclear also has significant decommissioning costs.

However the biggest cost here is probably that required to adapt to the effects of climate change if we don't take steps.

As pointed out, the cost is only a fraction if you ignore the lack of batteries. Solar & Wind today can only be used economically for peak load. Baseload requires batteries and nuclear & fossil fuels remain more economical.

> wind has made less than a noticeable dent

https://www.nationalgrid.com/stories/energy-explained/how-mu...

Almost 30% is not nothing.

And it's important to understand a lot of solar doesn't show up on the figures as it reduces demand, rather than showing up in supply.

( ie if you have panels on your roof you typically use it first before sending any excess to grid ) so the effect is largely reduced demand not measured increased production.

If the only similarity is ignoring some problem somewhere then those two are massively different and it's not "funny" in the way you're implying.

Yes kinda, although even very large wind farms are small compared to:

1) the total height of the atmosphere and

2) other natural obstructions like cliffs and hills

What happens in surface level winds (which is where windmills operate) are actually controlled by the upper level winds. Obstructing surface level winds has local effects (these are also called "terrain effects" since this is usually caused by geography).

Theoretically, if you were to cover the earth in windmills, this would have a serious effect on surface level winds, where they would generally be blocked by a nearby windmill. This would be especially noticeable at sea where you otherwise don't get terrain effects. The vast majority of the atmosphere (everything above a few hundred feet) would continue to be unaffected, though, and would continue to be driven by ground and sea surface temperatures and the Coriolis effect, mostly.

In terms of negative effects of wind farms on birds... reduced wind speed is truly the least of their concerns.

Wind farms do have meteorological impacts (e.g. onshore ones slightly dry the soil behind them). It is measurable but insignificant.

Then again, in terms of direct threats to birds, ignoring climate change, things like powerlines (25 million birds a year in the US), and more significantly air pollution (200-2000 million), windows (2000 million) and cats (1000-4000 million) even very high estimates of 2 million a year including things like habitat destruction and extra powerlines (more direct estimates from collisions are around the 500k mark) from wind turbines make them in turn seem like the lesser of the problems.

Which is not to say it's not an important factor, especially as they affect very specific kind of birds disproportionately, but it's not like wind turbines are primarily bird-killing devices, and it's even possible they may be net benefits to birdkind by, say, reducing air pollution.

There was a study a few years back that saw radical reduction in bird strikes simply by painting a single blade a contrasting color.

I believe bird strikes went down when they made the windmills much bigger, and the angular velocity of the blades much lower. Not building them on open truss towers encouraging birds building nests under them also helped.

If you’re interested, here is some info about the study I mentioned:

https://group.vattenfall.com/press-and-media/newsroom/2022/b...

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

That's what I was wondering -- couldn't this have some long-term effects on the climate of the area? In its current form, there is probably very little impact. But I imagine as wind farms become more common and dot the country-side... what does this do?

Reply on news.ycombinator.com