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Comment by Beltiras | Hacker News Reader

Don't bill deep geothermal as any sort of green. There are usually emissions that have health consequences for the population around the power plant. The corrosion of the pipes bringing steam from the drill site to the turbines is massive. Drilling that deep and pumping water into the hole ups the risk of earthquakes.

(source: I live in Reykjavík and have witnessed first-hand the increased stench from the Hellisheiði geothermal plant)

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I don't disagree with you—I've been to an 800 MW geothermal facility in northern California and was taken aback by the giant heaps of sulphur everywhere—but other renewables come with their own downsides.

- contemporary photovoltaic panels require all sorts of strange metals to make, which have environmental impacts via mining. This might change with new materials. Solar also tends to have quite high carbon dioxide impacts due to the manufacturing process. These are obviously way less than gas or coal, but about double compared to other renewables and nuclear.

- hydroelectric is notorious for destroying huge ecosystems stretching far above and far below the dam and its reservoir. Hydro is so bad that California doesn't let large projects count in the Renewable Portfolio Standard.

It's tough; there's no perfect energy source.

...contemporary photovoltaic panels require all sorts of strange metals to make...

This is not quite right. A few kinds of contemporary PV require exotic elements such as indium, gallium, and tellurium. But the market is dominated by crystalline silicon cell technology (about 93% market share in 2015): https://www.ise.fraunhofer.de/content/dam/ise/de/documents/p...

"contemporary photovoltaic panels require all sorts of strange metals to make"

Certain kinds do (e.g. CdTe and CIGS), but not the kind that you'd put on your house. If modern solar panels required significant amounts of rare earths they wouldn't be as cheap as they are.

"Solar also tends to have quite high carbon dioxide impacts due to the manufacturing process."

About 30g/kwh of CO2 vs. coal's ~900g/kwh, and a lot of that is simply because it is usually currently made without green power (i.e. it will go down).

"It's tough; there's no perfect energy source."

There's a lot of half truths told about really good energy sources.

Yeah, coal is obviously WAY worse than solar vis a vis carbon dioxide. I'm not disputing that. But compared to other renewables, it doesn't do as well as you'd expect:

- wind: 11 g / kWh [1]

- nuclear: 12 g / kWh [2]

- solar PV: 45 g / kWh [3]

- gas: 450 g / kWh [4]

Of course, 12 g vs 45 g is NOTHING compared to 45 g vs 450 g (and coal is another 2x atop gas!), so I'm making a bit of a mountain out of a molehill.

[1] http://www.nrel.gov/analysis/sustain_lca_wind.html

[2] http://www.nrel.gov/analysis/sustain_lca_nuclear.html

[3] http://www.nrel.gov/analysis/sustain_lca_pv.html

[4] http://www.nrel.gov/analysis/sustain_lca_ngas.html

Gas actually contributes more to global warming even than coal does because of the methane (~100x as powerful a warming gas as CO2) also released during extraction:

http://inhabitat.com/updated-cornell-study-shows-fracking-ca...

On the other hand, methane breaks down fast. It's only an immediate problem; if we didn't release more CO2 than could be absorbed, then we'd have a fairly decent methane budget as well.

As it stands, of course, it makes everything worse.

> Hydro is so bad that California doesn't let large projects count in the Renewable

10 cubic kilometers of water: It's the worldwide-recognized ratio under which hydro is considered renewable, and above which the ecosystem destruction is too important.

FYI, for deep wells you generally have to switch to supercritical CO2 instead of water, for the corrosion issue.

It is, however, extremely low carbon. Wind turbines kill birds and make noise, solar panels need toxic manufacturing processes. But carbon emissions are the overriding problem.

"Wind turbines kill birds"

15,000x fewer than house cats do though.

Cats kill exactly zero eagles per year.

The bird thing is not as big of a deal as some seem to think. Wind turbines kill a couple hundred thousand birds each year [1]. In contrast, cats kill hundreds of millions of birds each year [2]. People still like cats. I also don't think the noise concern is a reason to discount wind turbines.

Of course, dirty alternatives have their own toll on wildlife.

1. http://www.smithsonianmag.com/smart-news/how-many-birds-do-w... 2. https://www.sciencenews.org/article/cats-kill-more-one-billi...

Also, chickens are birds. Not wild birds, but birds. If the concern for birds is some kind of animal rights perspective, chickens are up into the billions per year. If people want to prevent needless bird deaths, that seems like the place to start.

I think the main issue for most people is biodiversity and ecological impact rather than sentimentality. Very few wild animals pass away quietly in their sleep.

DISCLAIMER: I'm not an expert in this and I can be very off concerning this area.

Having said this, I think the risk of man-made earthquakes is exaggerated. I mean, I think it might be possible to trigger small seismic events, but they should not be the destructive kind. I doubt we can trigger massive destructive eathquakes like this. Also, from what I understand, smaller seismic evnts should lower the energy that the bigger ones have.

Tell that to the people of Selfoss and Hveragerði which have now become accustomed to smaller quakes on a more regular basis than usually in the past.

Is it damaging though? That is the question I want answered. I mean, even in my post, I did not question the presence of more frequent small earthquakes, I questioned if these earthquakes are any sort of real issue that produces damages or simply unfounded panic.

Not being able to trust that the ground you stand on won't shake violently? Are you being serious?

I am being totally serious. Why are earthquakes bad? Because they destroy goods, buildings and kill people. If eathquakes do not destroy goods, buildings and kill people are they that terrible anymore or simply an inconvenience at most?

It might sound alien if you have a certain way of looking at things, but really, is my question not logical?

Spoken from the privileged position of not having to worry about it like it is of little concern to those who do. I'm leaving it as an exvercise for you to think of analogies to other aggrieved groups that would not take kindly to being told their concerns are invalid.

Yeah it would seem like frequent small earthquakes are way better than rare devastating ones, so it would even be better to provoke them rather than wait like in SF and Vancouver... If only, it helps rehearsing the response, convincing taxpayers to purchase tge equipment and finding early which buildings are dangerous.

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