Comment by yholio | Hacker News Reader

Comment by yholio | Hacker News Reader

Coal mines are exceptionally dangerous places. They require constant ventilation against methane accumulation and pumping out water that seeps in all the time. The soil is friable and there is a careful trade-off between personel safety and resources invested into consolidation and securing the galleries against collapse.

A mine is not some kind of free underground cave, it's an industrial installation requiring constant engineering. They have 24/7 command centers that monitor and correct safety parameters before anyone is allowed to go in. When mines close, they are flooded, refilled or sealed, to prevent underground explosions and collapse that could kill people above. The closure of mines is itself a dangerous and expensive operation.

Bottom line, if it ain't worth going down there and picking unlimited quantities of coal worth $70/ton, it most certainly isn't worth it to invest and labour for months in a high risk environment, only to get limited quantities of agricultural produce worth $200-$300/ton.

In addition to the dangerous environment, it's also likely to be contaminated with a lot of toxic stuff. In the closed German coal mines the pumps have to run 24/7 to prevent both the rising water from flooding the region* and the flame retardants and other poisons from reaching the surface waters.

* some areas like the city of Essen have dropped by 16m, others up to 40m due to mining. Running the pumps to prevent flooding is considered part of the Ewigkeitskosten (eternal costs, see: https://de.wikipedia.org/wiki/Ewigkeitskosten ).

edit: fixed numbers, added link

> and the flame retardants and other poisons

What did they do with the flame retardants? Spray parts of the mine with them?

A lot of things in a mine is made of wood.

I don't think they are worried about wood. Coal dust

Even worse, a lot of things in a coal mine are made of coal or are covered in coal dust. Flammable powders can be ugly, particularly if they're floating.

Old slate mines, on the other hand, are apparently a great site for underground trampolining - https://www.atlasobscura.com/places/llechwedd-caverns-trampo...

Why on earth would you want to trampoline underground?

Blaenau Ffestiniog

Ahh. It's always raining up top. Makes perfect sense. :)

Never rains in Blaenau!!!

Liquid sunshine butt.

FTA - You're looking at about £30,000 to set up one shaft and the running costs are very low - less than the energy consumed by three houses each year. With natural sunlight, the costs are even less

Looks like they thought this through far more than you give them credit.

How did you reach this conclusion? The schematic in the article only shows equipment needed for growing, and the £30,000 may be referring to just that.

The article makes no mention of the troubles and dangers the original parent suggested.

There are other people, including ex-mine owners also quoted in the article saying they're considering this.

Either everyone in the article, professors, mine owners, etc. are idiots and the grandparent is the one voice of reason in the world, or maybe, just maybe, they've already thought of this.

I was trying to be polite, but the airmchair naysaying on HN is wearing at times.

It definitely can be, but here I think the OP is right.

First, despite all the kickstarters for urban, vertical, undeground or underwater lettuce farms... Lettuce farms are fine where they are. If you want LED grown lettuce, they can grow that there too. Grow outside the city and drive produce to the city in a car. If you want to go green, use an electric car.

There's no need for the farm to be underground... on earth, at this point in time.

This besides the (insightful) about how hard it is to make mines safe to access, barley safe, assuming a very active safety system.

Canadians have been underground farming in mines for nearly two decades now, in order to grow cannabis for the government of all things. Couldn't find any coal mines being used for this, they seem to mostly be copper. - https://webcache.googleusercontent.com/search?q=cache:_ddjRs...

That's funny.

..and ok sure, I concede exceptions. In that case, I think (1) the tradition is of hiding from the law has produced quirky horticultural practices (piping in air and exhaust for plants is normal) (2) they don't really care about unit costs and (3) they're growing a plant that costs $10k per kg! They need security like a jewelry shop.

There's a quote from one professor who's specialty seems to be sustainable energy, not agriculture. The mine owners "considering" this idea is about as non-commital as you can get.

I occasionally feel the same frustration you do with the naysaying here, but I'm even more frustrated by the hand-waving that accompanies some of the innovations presented here. The naysayers were right about Theranos and Juicero, there's a possibility that they could be right about this idea (or on any other topic) as well.

The article mentions only upsides and opportunities. Not a single downside is mentioned, no risks are addressed. Either there are no downsides, or the article is one-sided, in which case we should appreciate the additional context and information provided by the "naysayers" here.

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