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The Mining Town Where People Live Under the Earth (cnet.com)
Claire Reilly, writing for CNET: After spending a night in an underground rock cave in the middle of the Australian desert, I learned three things: The silence is deafening. Your eyes never adjust to the darkness. And if nobody brushes the ceiling before you arrive, that clump of dirt is going to scare the living hell out of you when it drops on your face at 2 a.m. I've flown 1,200 miles for the privilege of sleeping in a hole in Coober Pedy. There's no Wi-Fi down here. The glare of my MacBook feels obnoxious in the subterranean stillness. The TV plays ads for a "local" cleaning service from the next town over, but that just happens to be 400 miles away. Australia is a country defined by "the tyranny of distance," but traveling to the underground opal mining town of Coober Pedy feels like taking a holiday on Mars.
In the middle of the South Australian desert and an eight hour drive in either direction from the nearest capital city (Adelaide to the south or Alice Springs to the north), Coober Pedy is off the grid and mostly hidden underground. More than half the residents live buried in the bedrock in cavelike homes called "dugouts" in order to escape freezing winters, scorching summers and the occasional cyclone. Often, the only sign you're walking on someone's roof is the air vent that's sprouted up next to your boots. While first nation peoples have lived in the central Australian desert for thousands of years, the Coober Pedy we know today wouldn't exist without opals. Miners rushed here in the 1920s, enduring extreme conditions to hunt for the multicolored gems, digging, bulldozing and eventually blasting out earth in a bid to find the elusive seam that would make them rich. Living in Coober Pedy is not just about surviving. It's about carving out a way of life in one of the harshest environments on the planet.
[...] "It's not like we're living thousands of kilometers under the ground," he tells me. "It's pretty similar to living in a normal house." Sam's family, who live in a dugout close to Crocodile Harry's, have solar panels for power -- but those generate only enough electricity for a few hours a day. Diesel handles the rest, he says. "We have to rely on tourists to pay for our fuel," he says. "Gasoline is valuable out here. Fuel is really expensive." That means no fridge running all day and night -- they keep nonperishable food and get the rest from town every day. Otherwise, life is pretty similar to what other 18-year-olds in the city experience. Sam says he can still charge his phone and use the TV "for a bit." "We have internet when the generator's on. Dad's got an Xbox but we don't even try to use the solar for that."
In the middle of the South Australian desert and an eight hour drive in either direction from the nearest capital city (Adelaide to the south or Alice Springs to the north), Coober Pedy is off the grid and mostly hidden underground. More than half the residents live buried in the bedrock in cavelike homes called "dugouts" in order to escape freezing winters, scorching summers and the occasional cyclone. Often, the only sign you're walking on someone's roof is the air vent that's sprouted up next to your boots. While first nation peoples have lived in the central Australian desert for thousands of years, the Coober Pedy we know today wouldn't exist without opals. Miners rushed here in the 1920s, enduring extreme conditions to hunt for the multicolored gems, digging, bulldozing and eventually blasting out earth in a bid to find the elusive seam that would make them rich. Living in Coober Pedy is not just about surviving. It's about carving out a way of life in one of the harshest environments on the planet.
[...] "It's not like we're living thousands of kilometers under the ground," he tells me. "It's pretty similar to living in a normal house." Sam's family, who live in a dugout close to Crocodile Harry's, have solar panels for power -- but those generate only enough electricity for a few hours a day. Diesel handles the rest, he says. "We have to rely on tourists to pay for our fuel," he says. "Gasoline is valuable out here. Fuel is really expensive." That means no fridge running all day and night -- they keep nonperishable food and get the rest from town every day. Otherwise, life is pretty similar to what other 18-year-olds in the city experience. Sam says he can still charge his phone and use the TV "for a bit." "We have internet when the generator's on. Dad's got an Xbox but we don't even try to use the solar for that."
It fits.
That means no fridge running all day and night.
The average energy drain of modern refrigerator is 25-40 watts. Actual power drain while the compressor is running is 100-150 watts. If they have any power at all on a 24 hour basis they should be able to run a refrigerator, though perhaps not open the door for part of the day to keep the compressor from kicking on. Since they do have power part of the day for sure, a 0.5 kWh battery should cover the refrigerator nicely.
Starships were meant to fly, Hands up and touch the sky - Nicky Minaj
Towards the end, Jedediah the Pilot and his son live in a cave hideout at the end of the railroad line. I believe that was shot in Coober Pedy. listed in the credits.
Take a look at the houses in the story. Nice circular doorways, round rooms. They could use some sprucing up of the paneling and such, but it looks like a Hobbit burrow.
Starships were meant to fly, Hands up and touch the sky - Nicky Minaj
Otherwise, life is pretty similar to what other 18-year-olds in the city experience.
Ummm, no it isn't. It isn't much like life in any city. Not saying it's better or worse but it definitely isn't what I'd call similar. For one thing I'm pretty confident the dating scene isn't exactly a target rich environment. And 24/7 access to electricity and places to go use it is not a trivial difference.
From de article: "have solar panels for power -- but those generate only enough electricity for a few hours a day"
Come on! Solar panels today are cheap enough to supply almost all the power you need. I have just 8 in my house and that's already enough to use power lavishly.
I guess they sort of enjoy to live like that. That's the only possible explanation.
Given that one has to run lights 24 hours a day underground and solar panels are day time only power, isn't it going to take some batteries to supply one's electric needs? I think so. Also, there is the question of wiring lengths. 24V DC needs some pretty large conductors to get very far carrying usable current levels. Not to mention the toxic nature of battery chemistry, marking the need to keep them away from living spaces and providing adequate ventilation. One doesn't need lead acid batteries underground, nor are LiIon options necessarily safe.
Having solar panels while on the grid is one thing, having solar panels as one's sole source of power is quite another, being underground adds additional challanges.
"File to fit, pound to insert, paint to match" - Aircraft Maintenance 101
Remember that bulbs use much less power than they used to. 20W LED uses as much power as a 100W incandescent used to. 12ga cable can carry 20amps or 480W at 24VDC. You can literally run 24 bulbs off of a standard cable on a low-volt system.
The problem is big appliances with motors, not lighting. As far as the batteries, the panels need to be above ground -- you can also stick the batteries in a box aboveground and run cable down to the cave-house.
20W LED uses as much power as a 100W incandescent used to.
Do you want to think about that statement for a second?
systemd is Roko's Basilisk.
Sorry -- I meant PRODUCES as much luminous intensity. Apologizes for typing too fast :D
Even better -- that means the theoretical equivalent of 48 100W equivalent bulbs off one 24V circuit with 12ga wiring. Practically, this number will be lower, but it's still relatively easy to wire for 24v lighting.
So pretty much Mad Max already.
... in the blue sky mine
there'll be food on the table tonight.
12ga cable can carry 20amps or 480W at 24VDC.
Ah, but the ISSUE is voltage drop over the length of the cable. @ 20 amps, 100 ft of 12ga cable is going to drop more than 25% of the voltage, turning that 24 V into about 17. You lose 6.35 V over that 12ga run. The problem with low voltage systems is voltage drop over distances. To keep 100ft of cable to within 10% voltage loss, you are going to spend a pile on wire, running 8ga, which will get you right at 10% loss @ 24 volts in. Most equipment is OK with about 10% of rated input voltage.
So that 480W in will turn into about 380W at the load using 100 ft of 12ga wire (you will lose about 100W) 12 ga may be SAFE at 20A for fire reasons, but it doesn't mean it's usable in a low voltage system.
This is what killed Edison's DC power business and brought Westinghouse's AC power into common use. With AC you can step the voltage up and down at will using transformers, lowering the current for the same power and lose less power/voltage over the smaller cables. BTW, If you go to a 12 V (13.8 actually) system things get even worse for you, with the loss of over half of your input power and half your voltage trying to push 20 Amps over 12Ga.
"File to fit, pound to insert, paint to match" - Aircraft Maintenance 101
Interesting place to visit, but I woyuldn't want to live there. Spent a few days in Coober Pedy during January, 1992 when I was working down south in Woomera. Pretty much a ghost town at that time of year. Crocodile Harry's was a hoot. Took a day trip with a fellow who delivered mail to some of the stations to the east. 300 km on dirt roads for six deliveries.
Geology - it's not rocket science; it's rock science
Yep, you're correct about voltage drop in addition to fire safety, though I'd say 10ga would likely be fine at 24 volts and 20 amps. Round-trip resistance is 0.2 ohms per 100 ft, so you'd end up with a 4V drop. Assuming the real voltage of the system is closer to 28V, you'd still be within spec.
12ga is 0.325 ohms per 100 ft. You could keep voltage drop acceptable at 12 amps, which still allows for 25-30 100W-equivalent lamps. Not terrible.
Don't forget that a circuit a round trip... So 100 ft between source and load is 200 ft of wire. 100ft of wire is only 50 ft between source and load.
Low voltage systems (under 48 V) are susceptible to line loss at high current/power levels. It's just a fact of life. And living on solar power is very much a low voltage DC affair without additional equipment. You can do it, my brother did in the jungle with solar panels (and a diesel generator for cloudy and/or high demand days), but he kept the wiring runs short and heavy gauge by building his house stilts with the batteries and generator on the ground. I think his longest run was 15 ft to the solar panels on the roof.
"File to fit, pound to insert, paint to match" - Aircraft Maintenance 101
Firstly Alice Springs isn't a Capital City. Darwin is the Capital of the Northern Territory and it's another 13 hour drive (at 70-80mph) after Alice Springs to get there.
Like all mining towns it's dirty, expensive and doesn't offer much in the way of culture. It exists just because of its location and when the gems are all dug up it will be left as a series of holes in the ground. There are similar places in the US.
Capital of the Northern Territory is Darwin... another ~1500km further North.
Clearly the author of the story possesses neither a map nor any knowledge of Australia. A few corrections to the story: Coober Pedy is not in the "middle of the South Australian desert", it's near the border between two deserts. Failure to understand such things has resulted in others losing their lives due after making poor decisions. Alice Springs is not a capital city, not even close, it's a regional centre. Those "holes in the ground" provide very comfortable living indeed. It seems the author is just another foreign winger that doesn't know shit from desert dirt but want to express ill formed opinions for anyone who is prepared to read them. We have a number of words for people like that and I personally think 'moron' is fitting in this case. By the way fucktard, the light level of the Macbook is actually adjustable, just for such situations.
"The Mole People"
Nope, I used a table of round-trip resistances. Rest of your point stands.
> "It's not like we're living thousands of kilometers under the ground," he tells me.
No, not at all. That would be quite a bit hotter.
From where I stand, they are thousands of kilometers under the ground.
Two options - don't run any low-voltage DC. PV + batteries + inverter to produce 240VAC for everything (plus a backup generator, of course). There are efficiency losses converting PV/battery DC to AC, and losses again when charging batteries, but you don't have to worry about losses in the cable runs. Also, 240VAC cable, lights, and appliances are CHEAP, compared to 24VDC cable, lights and appliances. I should know, I live in a house dual-wired for 24VDC and 240VAC. 24 volt light bulbs either halogen or LED are not cheap, and 24 volt CFLs are non-existent. I've started re-wiring each 24 volt light socket as the 24 volt bulb dies - to take 2 x 12 volt bulbs in serial. 12 volt bulbs are cheap and plentiful.
The other option is to use 240 volt cabling for your DC. Forget the earth wire, and use multiple cable runs. The cost of domestic 240 volt cable is tiny compared to equivalent-rated DC cable. You can afford to put multiple cable runs per room. A 10-amp cable doesn't care whether it carries DC or AC, you just need to make sure the total load doesn't exceed 10 amps. Losses over long runs are still an issue, but that can be calculated in the design, and if your losses are going to be a problem, you can either decide to spend big on heavy-gauge DC cable, or revert to option #1 above.
That's how my place was wired by the original builder. The only heavy-gauge DC cable are the runs from the roof PV to the batteries downstairs. I used to be worried about upgrading light bulbs from 60 or 75 watts to 100 watts, but since drop-in LED Bi-pin bulbs have become available, it's not a concern any more.
They sentenced me to twenty years of boredom
Congratulations. History repeats itself.
DC was initially the technology of choice being pushed by the well known Thomas Edison himself. Initially it made inroads in electrification of cities, but the voltage drop problem was real and Westinghouse, armed with Tesla's patents for AC, was the better technology. The only issue AC had was being able to run electric motors, as nobody had figured out how to do this until after Edison already had a foot hold.
My post was an attempt to point out that the proposed DC idea wasn't a good solution and you need more than solar panels to get power around the clock. I didn't propose a solution, but I agree with the one you have proposed. Solar panels are for charging batteries and batteries are for driving the inverter. Personally I'd use the generator as a backup charger too, for cloudy or high demand days.
IF you want to run DC, then by all means, go with 12 V because the available devices designed to use it are cheap. But if you do, keep your power wiring SHORT and watch that voltage drop. Personally, I'd go with an inverter for everything but possibly lighting.
"File to fit, pound to insert, paint to match" - Aircraft Maintenance 101
24V DC needs some pretty large conductors to get very far carrying usable current levels.
I wonder how using rebar would work. Weld on some tabs and tin 'em for corrosion protection, and run at least one conductor through PVC conduit for protection. Is 1/2" rebar fat enough to do any good? It's certainly cheap enough, and bigger than 4/0ga wire...
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
I'll keep the DC lighting circuit (there's a DC refrigerator on its own circuit, too) because I like to have options. My inverter blew a control board once and while it was being repaired I only had the generator for AC - and it's not healthy for electronics to run directly off a generator. I still had lighting and refrigeration running directly off the batteries.
They sentenced me to twenty years of boredom
Which is important there. They also have plenty of mining equipment on hand to dig the holes. They still cost more than an above ground house. But in the heat, you want to be down. Most are dug into the side of a hill.
Cooper Pedy is a wild, unruly place. Lots of people living on the edge trying to strike it rich by finding that one rich seam of opal. Many small mines owner operated. Everybody secretive about what they find. You do not want to be too curious wondering around the mine sites or you might end up joining the many bodies thought to be buried under various shafts.
Worth a visit.
> the government mandates that NBN provides equal internet access to all Australians
It would appear the author somehow slipped into an almost-parallel dimension and has been to the other Australia.
"That means no fridge running all day and night." That's why Uncle Owen told Luke he's shutting down the power for the night. Including the refr. Although Aunt Buru does use an electric food processor.
You mean the one next to Germany?
Given that one has to run lights 24 hours a day underground and solar panels are day time only power, isn't it going to take some batteries to supply one's electric needs?
Umm, yes... This is not a revelation.
Also, there is the question of wiring lengths. 24V DC needs some pretty large conductors to get very far carrying usable current levels.
This is not a serious issue. The issue is digging the hole for the wire, not the gauge of the wire. The cost differential between a big fat wire and a more modest one is extremely modest compared with the cost of solar panels, the battery, and the trenching/digging to get the cables where they are needed.
Not to mention the toxic nature of battery chemistry, marking the need to keep them away from living spaces and providing adequate ventilation.
Just because the people are underground doesn't mean the batteries would need to be. And even if they were that is a well understood problem with well understood solutions. Batteries are used in pretty much every mine on the planet.
One doesn't need lead acid batteries underground, nor are LiIon options necessarily safe.
There are many battery chemistries available and I'm rather confident at least one of them would work just fine.
Elan Musk has already proven that his company can provide solar and battery power to large areas. It would be pocket change for him to toss out a small farm to provide constant residential power to this place. It would also fit is rather eccentric personality to do so. I'm honestly surprised he hasn't done so already to proof of concept his solution to isolated power grids.
the next town over, but that just happens to be 400 miles away
get the [nonperishable food] from town every day
I had to re-read the article at first, thinking it was saying they were 400 miles out of town, and went 400 miles for food every day. And finally realized "Oh, THEIR TOWN is 400 miles away from the next town." Something about this writer's article made me feel like these were just random rovers living in holes I guess. I especially like that the writer complains about his eyes never adjusting to the darkness while at the same time talking about using assumably full brightness on his Macbook.