Old coal mines can be underground food farms | Hacker News Reader

Old coal mines can be underground food farms

bbc.co.uk

89 pointszeristor78 comments

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.

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.

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.

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.

If startup-ey media is anything to go by, agg-tech has some weird ideas about what the problems are with aggriculture.

The water and land required for vegetables farming isn't a problem. We don't need to move lettuce production into buildings, mines or submarine farms.

Most of the water & land is used for cereal farming.

Whatever you can grow in a mine or a skyscraper can be grown on a "small" farm near a city. Whatever water saving, pesticide minimizing, or other benefits you get have little to do with location.

There are plenty of led/hydroponic farms in normal farming places.

>We don't need to move lettuce production into buildings, mines or submarine farms.

Food crops in general absolutely, some like lettuce could actually benefit from being done indoors though as you could limit exposure to things like E. coli compared to traditionally grown lettuce.

Growing in a largely enclosed system also allows you to prevent runoff, use the least amount of water possible, control all environmental variables etc BUT unless we suddenly develop fusion today and magically start bringing hundreds of fusion plants online a year, using the sun is always going to be more efficient than grow lights.

Economically that’s true, but ignoring capital costs...

LED’s are up to 50% efficient. The best Solar is hitting 44% effecency. So, we can only keep ~22% of the energy from sunlight. However, plants are green because they only absorb a subset of sunlight. So, by designing LED’s that only emit the light best collected by plants you can get fairly close to 1:1 and theoretically you could see a net gain. Thus, 100 years from now things might flip. Further, we can stick solar panels many places we can’t effecently farm.

It’s still going to stay very niche, such as producing ultra high grade produce for high end restaurants.

We could potentially supplement the LEDs with fiber optics that deliver natural sunlight underground.

I think you're exactly right here

in the same vein, vertical farming stuff like this could become appealing if we can design solar panels that function in an opposite (complementary) spectrum vs. plants

The water is forward looking at least given aquifer depletion issues. Land itself is just silly to try to minimize for agriculture however - while you want more yield the strategy is cheap land for farming. Transportation costs (cheap in bulk but still a sizable component given how farmers' markets are cheaper), and freshness premiums might make it viable to centralize agriculture but certainly not land cost.

10% of the entire UK's area available in mines? That seems a tad on the high side at first glance.

No mention of flooding, collapse and the many seams that were well under 6' high. I remember claims that many mines would be inaccessible thanks to flooding and collapse within days of closure during all the mine closures of the 80s. No idea how much of that was hype to try and avoid closures of course.

So what percentage is worth opening up again for possible agriculture? Based on the photo of two chaps using an old shelter the size of a poly tunnel, very very inefficiently, barely any.

Seriously, having seen commercial poly tunnels, I'd expect to have the staging shown but wide enough that a human can only just squeeze down the centre path, and another level, and the entire floor area allocated to growing as well.

I'm gonna need a bit more convincing on this. :)

Here is a link to the UK Coal Authority interactive map:

http://mapapps2.bgs.ac.uk/coalauthority/home.html

There are a lot of old mines in the UK!

[NB I found out about this when researching buying a house outside of Edinburgh - we ended up getting a house near an old limestone mine in Fife although where our house is it's volcanic rock with no mine workings under us].

Edit2: In case anyone is wondering here is a geology map viewer for the UK:

http://mapapps.bgs.ac.uk/geologyofbritain/home.html

Oh yeah, they're everywhere, we've been digging for millennia. Though as anyone who's bought a home around old mining areas knows there's a fair bit of subsidence around old mines and shafts. Leaves me wondering what proportion is feasible without significant effort digging them out, pumping and propping them again?

Then there's the countless seams that were narrow enough to trigger instant claustrophobia. The many crawlable only spaces that don't give space to sit, let alone stand. Plenty of headroom for lettuce, but rather more challenging for harvesting and the associated humans.

Interestingly you can see mining used to stretch under the Firth of Forth between Lothian and Fife. Supposedly, back in the day, the tunnels linked up and you could have walked from Fife to Lothian via the mine workings.

This idea in the article seems like utter nonsense, and the fact that it's in an article on a reputable website doesn't give me any confidence it isn't.

I remember reading about that link - found this article on it:

https://www.theguardian.com/uk-news/scotland-blog/2014/apr/3...

I see it was upstream at Bo'ness where the gap is narrower - I always imagined it being miles and miles, heading from Edinburgh northward. Less amazing, but still pretty cool.

> Firth of Forth between Lothian and Fife

I have no idea what (who? Where?) this is, but now I want to conquer it/ask them out for dinner.

https://en.wikipedia.org/wiki/Firth_of_Forth

It's an area thick with history from before the Romans to more recent times. One example:

https://www.bbc.co.uk/news/uk-scotland-46273928

Is that somehow related to Genesis' Firth of Fifth?

Interesting trade-off - much higher energy costs, but on the other hand, mine shafts are probably largely pest-free. No birds, certainly, and probably a much smaller rate of insect/fungus/mite infection as there's less opportunity for them to be blown in on the wind. The energy costs probably wouldn't be offset by the pest-prevention costs - but it might reduce the damage to the environment, and the increasing fungicide resistance, caused by widespread spraying.

Also you can grow whatever you want whenever season you want. There's no seasonal variability in temperature or hydration - everything's controlled.

Also, presumably, a big space advantage. Using an existing tunnel network should be easier than having to build a giant building or dig out new tunnels.

As opposed to the space advantage of just farming on the surface, and not having to dig tunnels or build greenhouses?

And what do you do in winter? In many mountain areas you can't grow sensitive plants unprotected even in summer...

Generally, you place a thermal "fruit wall" poleward of the plants you wish to protect. In winter, the wall absorbs some sunlight, and reflects some onto the plants, while re-radiating heat. The exact angle is determined by prevailing wind direction. The roots get a thick blanket of mulch.

If you have enough money, you can then stretch a roll of translucent plastic film from the top of the wall and stake it out to form a lean-to. Or, a light frame can eliminate the need for stakes. (If you're really rich, you can put glass panels in the frame.) Throw a straw blanket over the transparent layer at night, and dangit, now you have a greenhouse, which we were trying to avoid doing.

Building an entire field's worth of Chinese-style thermal-wall greenhouses is really cheap, relatively speaking. An unmortared wall made of interlocking compressed-earth blocks will last at least a few years. (Obviously, growing only plants that can survive the local climate without any assistance is cheapest--you just plant the seeds and wait.) Tunneling is a large capital expense. Collapse/subsidence prevention, pumping, and tunnel air management are large ongoing operating expenses. The cost to heat and cool a tunnel, on the other hand, is nearly zero. The greenhouse might need a pile of compost in it to keep it warm enough.

How is this at all better ecologically, considering energy costs? The electrical demands to operate a mine are huge, most of which are used in pumping water out of the mine and air conditioning to make the atmosphere breathable. Air conditioning would arguably go up, since it is possible for plants to suffocate themselves with O2 in an enclosed environment.

To me, this looks like a far worse ecological disaster than conventional farming unless we develop some form of truly free energy like practical fusion power.

Fusion power is not free. The fuel is relatively cheap, but all the high tech needed to keep the plasma burning needs to be maintained and investments for building power plants need to be recovered.

In cold climate it might not be so much more energy because greenhouses need to be heated in winters and it takes a lot of energy too. For instance 2kW heater is not much, compared to a 2kW light fixture which is like 5 strong led consoles that can grow a lot of lettuce (and also provide enough heating at the same time). If you use rotating stands you can optimize it even more. I think much bigger problem will be controlling the humidity and preventing molds from attacking the plants.

If energy costs were to rise, we could reduce the need for heating greenhouses by a lot if we built them a little smarter. For example you can build greenhouses in northern China, where it gets quite cold, that need almost no additional heating:

https://solar.lowtechmagazine.com/2015/12/reinventing-the-gr...

There is a mine ventilation shaft not far from where I live:

https://www.geograph.org.uk/photo/765213

It is very noticeable on cold days that there is a plume of warm moist air coming out of the old workings. Indeed, when I first saw it I thought there must be a fire (although I soon realised what it actually was).

Just about the only ex mines which are useful afterwards are salt mines, some of which are used for climate controlled storage facilities or data centers. Not coal mines.

And the occasional hard rock nickel mine, one of which was repurposed into the Sudbury neutrino observatory.

The town my father in law is from has the Soudan Mine, which is also used for particle research. Kind of a neat tour if you ever get up that way.

https://en.wikipedia.org/wiki/Soudan_Underground_Mine_State_...

The Sanford Underground Research Facility is in the former Homestake gold mine in South Dakota. https://www.sanfordlab.org/

Work recently began to prepare the facility for the massive DUNE neutrino detectors, which will be to neutrino physics what the LHC is for high-energy physics. http://www.dunescience.org/

Dwarf Fortress players have known this for over a decade

Given how badly most of those games end I'm not sure I'd look for designs there.

When I see all these high tech plans to grow food in developed countries, I always wonder how developing countries who sell food to developed countries will get reliable markets.

But then again no one owes poor countries a decent livelihood.

> I always wonder how developing countries who sell food to developed countries will get reliable markets.

They'll stop growing specialty stuff for export and start growing a more diverse range of crops and sell them domestically which will lower food prices and should benefit their economies in the long run.

The US exports 40% of the corn it grows, uses another 20% for ethanol production but we import 40% of our fruits and 20-something percent of our vegetables. We also exports absurd amounts of other grains. If we grew most of our crops for domestic use and stopped importing tropical and out of season fruits and vegetables, we'd have much more sustainable farming practices, less waste, considerably smaller carbon emissions from all the importing and exporting, etc.

Go to your grocery, you'll see mounds and mounds of bizarre looking alien pods which are allegedly fruit and vegetables from far off lands. I can't possibly imagine they sell even 50% of what the stores receive because most people simply have no idea what it is or how to prepare it.

Hell, I have problem finding sweet peppers that are molded and/or aren't wilted leathery looking things when I go to the grocery each week. Week after week, store after store, without fail. That's waste and none of it is grown domestically (mostly Mexico although occasionally the stores near me will have stuff from South America).

*aren't molded

For plants growing in vertical shafts, it seems to me that plants will have to get used to grow somehow horizontally or at an 90 angle (last 2 figures in the article [0]). How would that be possible? I think this may come to a misunderstanding and an oversimplification of this technique and plants would still grow vertically and upwards.

[0] https://ichef.bbci.co.uk/news/624/cpsprodpb/76A1/production/...

Most plants are pretty good at growing towards the light. It's not a suitable way to grow a pine forest, but it should be OK for lettuce.

Great idea! Why would we grow plants where the sunlight is? Illogical! Preposterous! Let’s bury them in caves full of toxins and industrial waste, then grow them using expensive artificial lighting!

One can only eat so much lettuce and herbs though, I believe they’re the most economically viable, but grains, and potatoes not so much.

I'd go for mushrooms and yeast tanks in damp dark places. But you can also eat only so much of them.

Stop eating beef instead of focusing on these BS ideas.

Yeah, i suppose on 2 fronts:

1. Less land needed for actual growth of cattle.

2. Less runoff from cattle.

Pasture raised cattle, and other grazing animals, can actually be very environmentally friendly. Properly managed pasture requires very little to no fertilizer, pesticides, or herbicides and acts as a net carbon sink. It can also have a large amount of biodiversity. The problem right now is feedlot style operations, where corn is grown as a mono-culture in one place and then shipped to a feedlot.

That's not the system we have though and going to a grazing based supply for cattle would require drastically cutting back the consumption of beef. Only about 10% [0] of the world's current beef is supplied through grazing pastures and that's already stressing grazing areas in suboptimal climates.

[0] http://www.fao.org/docrep/x5304e/x5304e03.htm

Definitely true, and I didn't mean to imply that. Just think it is important to point out that we do have existing ways to sustainability eat beef, though as you point out it would require cutting back consumption to something more approaching the historical norm. I just think that grazing animals have an important role in our food system going forward as we try to make it more sustainable.

Err, or you could use them as pumped hydro storage and make all that off peak renewable energy useful, like most other countries are doing.

Mines are "perfect" farms? I remember hearing once that in order to grow, plants need this thing called light.

mushrooms don't. Then again, growing mushrooms in the dark isn't much of an innovation, they've been doing it in France since the 17th century.

Mushrooms aren’t plants.

But they are food..

LEDs for fibre options to bounce sun light in.

The tunnels wouldn't get big changes in temperature, would only get the water it needs and you could have light running 24/7.

But you have to pay that power bill for the other 12 hours the sun isn't shining.

Plus, drilling to install fiber-optic cables will be a huge expense. And, in order to collect enough sunlight to light the mine the area above the mine will still need to be blanketed with collectors. After all, you can't collect enough sunlight to feed 1m^2 of plants from a 1cm^2 area at the surface. Efficiency losses will actually require >1m^2 area at the surface to capture adequate light, so why not just avoid all the additional expense and put a greenhouse on the land above the mine?

>so why not just avoid all the additional expense and put a greenhouse on the land above the mine?

If only the article covered the advantages this approach has to offer over surface green houses..... oh, wait!

It's not even that I'm convinced their approach is viable, but how about at least critiquing their answers to your questions?

> But you have to pay that power bill for the other 12 hours the sun isn't shining.

This is really a bizarre objection. What do you think overground farms do at night?

The grandparent specifically said "lights running 24/7"

Try reading the article. For shafts close to the surface they can use fibre optics to bring in sunlight, deeper down they use LED lights.

Sunlight is ~1,000 W/m^2. Even accounting for the efficiency boost of only using photosyntheticaly useful parts of the spectrum, the quoted energy cost feels off by one or two decimal places.

There is also the point that sunlight is free, and greenhouses already solve the same problems. The Netherlands already does this to great effect: https://www.nationalgeographic.com/magazine/2017/09/holland-...

Tunnels have much better and cheaper climate control, easier access to water, cheaper land costs. It's not necessarily a case of one one single variable determining the viability of the whole idea especially when this is, as I said, _covered_ _in_ _the_ _article_.

No idea if this will ever come to fruition, but these people do seem to have done some homework and have prototypes up and running now.

Any ideas what the ratio of drift mines to deep mines is in the UK?

I think most of our disused mines (by area) are deep, and pretty dark places - don't even need to reach pit bottom for total blackness.

Having been down a mine few times not sure I'd want to farm down there!

Surely the real answer is to grow the same foods in commercial greenhouses, heated via geothermal heat pumps and if we're short of land to do this we can always use golf courses for farming!

>if we're short of land to do this we can always use golf courses for farming!

I really would not like to have to test the UK's government on security of food supply vs love of golf courses. I suspect I already know the answer to that one and it comes in a variety of pastel tones.

:-)

Remember reading somewhere that in the UK we use roughly the same amount to land for golf courses as we do for housing.

Of course not all golf courses are suitable for farming but I'm sure there's plenty in Surrey that are!

That's pretty dodgy. It only includes land with actual bricks and mortar on it, not including land with residential use such as drives, paths and patios let alone gardens. Even then the land used by golf courses was probably overestimated by about 2x.

https://www.ft.com/content/79772697-54e4-32c9-96d7-5c1110270...

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