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How much water does a habitat need to have on hand?

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Tue, 2012-07-24 16:33
#1
Trekkin Trekkin's picture
How much water does a habitat need to have on hand?
Aside from the obvious short answer that it depends on the hab, neither I nor any of my group can figure out how much water, say, an O'Neill cylinder has in it when its running, let alone any kind of cluster hab. On the one hand water is incredibly valuable in space, but on the other it's needed in very large quantities to support the tens of thousands of inhabitants listed as normal for larger habitats. Then, too, there's the question of the relative efficiency of the various hab types with regard to water usage. I ask primarily because one of the players in my game posited an O'Neill cylinder or Bernal sphere with water covering its window regions as a way to economize on mass, and it occurred to me that they may well need to have enough water to have a fairly deep ocean covering them, but I've no idea where to begin with the math on it; any type of plausible ballpark estimate would be sorely appreciated.
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Tue, 2012-07-24 17:25
Pyrite Pyrite's picture
The thing to remember is that
The thing to remember is that an O'Neil cylinder is 1/3 park land, and so the amount of water needed is an ecological consideration more than simply an architectural one. I didn't find any quick answers for 'how much water does a mile of parkland need' when I searched, but that's the kind of scale you're looking at. Still, it feels like large, open pools as your friend proposes might be an element of a particularly ecological or decadent habitat.
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Tue, 2012-07-24 19:00
TadanoriOyama TadanoriOyama's picture
Well according to the MAYO
Well according to the MAYO Clinic an average person needs between 2 and 3 liters a day in our time. I assume that transhumans can make due with slightly less so we'll call it 2 liters per biological transhuman. So, let's assume we have a fairly big habitat, a half million transhumans. 10% might be synthmorphs and another 10% infomorphs (indentures, infolifes, etc.) so 800 kiloliters of water that needs to be circulated daily for the purpose of drinking. [url=http://www.extension.org/pages/14080/corn-water-requirements]Some quick research[/url] leads me to calculate 2240 kiloliters of water is required per acre of high-yield corn per year. If a cylinder is 2k across then 2[i]pi[/i]r / 6 sections would be ~1 kilometer across for each section. 1 square kilometer is ~240 acres. 2240 kiloliters of water per acre for 240 acres is ~534 megaliters of water required for a year of crop growth. [url=http://www.agronext.iastate.edu/corn/production/management/harvest/produ... we assume exceptional return per acre[/url], which seems reasonable for transhumans, then that's 2.1 megaliters of corn (72,000 bushels). I have no idea if that's enough corn, too much corn, or not enough corn but I will tell you one thing: that's alot of water. I think I've circled back on my point here somewhere so I'll swing back to another point I want to make: Standing water can be good for holding heat and assisting in the creation of a smaller temperature range, something a habitiat probably wants.
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Tue, 2012-07-24 19:44
Trekkin Trekkin's picture
Numbers!
Rough math indicates that would be enough corn for a population of 7348 normal humans for a year, assuming they ate nothing but 2000 kcal of corn each day. Put another way, that's 5,378,971,038 kcal of corn. If those numbers are for soil farming, though, hydro- and aeroponics can reduce the water use by one or two orders of magnitude, respectively, although the numbers I'm finding seem too pat to be based on data. If we assume transhuman agriculture functions at those efficiencies, 5 megaliters of water annually seems fairly sensible. I guess the thing I'm missing, then, is time lag. Does the system hold a day's water consumption? A week's? What kind of reserves would be considered an acceptable margin of safety for a given point in the universe?
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Tue, 2012-07-24 19:57
TadanoriOyama TadanoriOyama's picture
It's difficult to say. With
It's difficult to say. With nanofabrication all you really need are the materials to make the water but it's not a perfect system; new materials do need to enter the cycle every so often. Waste, for example, is filtered directly into disassemblers and recreated into new materials but there is some lose in the chain. It would make sense to have a reserve of some kind, as an emergancy, if you lost fabrication capable for some amount of time but most of the books state that equipment failures are extremely uncommon and most individuals don't expect to have to deal with them (Gatecrashers does anyway so that might have been focused more on stuff brought along when crashing). In an O'Neill it probably functions more like a city: central waste management with filtration. On smaller stations things are likely localized, each "room" having it's own small maker and break down system.
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Tue, 2012-07-24 20:25
nick012000 nick012000's picture
I'll point out that it's
I'll point out that it's entirely possible for a transhuman habitat to recycle all of its biological waste into feedstock for makers to make more food out of much more cheaply than actually grown it. Food made from plants that have actually been grown is likely to be an expensive luxury on most habitats.
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Tue, 2012-07-24 20:36
TadanoriOyama TadanoriOyama's picture
Nanofabbing isn't a 100%
Nanofabbing isn't a 100% recycling solution. Waste doesn't contain all of the materials that it's original form did. New materials have to enter the system at some point. So large scale farming might not be needed but the process itself can be helpful to sustaining a large habitat as part of the synthetic-biosphere.
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Tue, 2012-07-24 21:06
Trekkin Trekkin's picture
Ah, good point. I guess the
Ah, good point. I guess the crops thing is still useful as a metabolic benchmark; if we assume that respiration of plants has a reasonably small lag time and/or is genetically controlled, there's still a lot of water consumed to provide hydrogen for the light reactions of photosynthesis that's effectively caught up in the green spaces. And I was under the impression that water was a base material for EP industry?
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Tue, 2012-07-24 21:42
nezumi.hebereke nezumi.hebereke's picture
The numbers for corn are
The numbers for corn are going to be very high, since corn is such a water-inefficient crop. Something like hydroponics will be MUCH more efficient.
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Tue, 2012-07-24 22:23
Trekkin Trekkin's picture
nezumi.hebereke wrote:The
nezumi.hebereke wrote:
The numbers for corn are going to be very high, since corn is such a water-inefficient crop. Something like hydroponics will be MUCH more efficient.
Ah, C3/C4 respirators...the numbers could probably all be adjusted downwards by a lot, although the difference in respiration rate per unit biomass between plants is probably not as great as the massive savings in water caused by hydroponically growing them -- even corn. Incidentally, why is it hydroponics that's held up as the standard methology for greenspaces and not aeroponics?
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Tue, 2012-07-24 22:29
The Enemy The Enemy's picture
I think something that
I think something that everyone is forgetting, is that most of the water lost by a plant, is lost due to evaporation. A habitat, by it's very nature, is a closed system. So, that water isn't lost, it shows up as humidity, and eventually, condensation. Or what have you. It isn't really lost in any sense of the word, it just changes places in the habitat, where it can be captured anew.
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Tue, 2012-07-24 22:40
Trekkin Trekkin's picture
The Enemy wrote:It isn't
The Enemy wrote:
It isn't really lost in any sense of the word, it just changes places in the habitat, where it can be captured anew.
That was what I meant by lag. The water in the plants today is going to be in the air tomorrow, but between their respiring it and the filtration systems collecting and reclaiming it, it's not actually available to the inhabitants, but there's always water on tap in the ideal habitat model (or, as I perhaps confusingly put it, "on hand"), so there's got to be a quantity of water in the reclamation systems itself. Similarly, since the respiration rate and demand cycles and so forth aren't going to be perfectly synched, one would logically expect a reservoir to be in place to cover the shortfall; something as simple as a habwide day-night cycle adds a significant variance in demand, no? I guess I should have phrased my question as "if I wrung an O'Neill cylinder dry, how much water would I get, and where would it have been before I did that?"
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Tue, 2012-07-24 23:57
The Green Slime The Green Slime's picture
Trekkin wrote:
Trekkin wrote:
Incidentally, why is it hydroponics that's held up as the standard methology for greenspaces and not aeroponics?
Hydro is by far the older, more established and at present sounder technology; aero still has a lot to prove before it is to be considered viable, and principally entails many more points of failure, greater upkeep and lower error tolerance (the energy demands are high, the foggers need to be kept constantly operational, and plants will very rapidly perish in event of a shutdown). Even with practically flawless nanotech cleaning systems, it may not be worth the extra stress to keep everything running smoothly. The more closed-loop solution would likely be some kind of aquaponics setup (with hydro backup to preserve plant health should the fish ever fall ill), possibly with all kinds of creative permaculture plug-ins: algal & cyanobacterial farms, vermiculture, insects, fowl, rodents, integrated with natural predators for population balance, etc. The larger and more diverse the system, the more stable and productive. It's become fairly apparent that our traditional model of preserving monocultures and limiting biodiversity, i.e. industrial agriculture, is simply too stupid a concept for even the Earth to support, much less the confined economies of space habs. Modeling Earth's nature as a whole, and taking it with us, will be our best bet. Selecting the parts of it we like and engineering ways to keep them in some kind of impossible stasis (hydro & aero both belong to this ethos) would very much be at odds with the networked transhuman way of doing things.
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Wed, 2012-07-25 00:02
The Enemy The Enemy's picture
Ah. My bad. Shouldve read the
Ah. My bad. Shouldve read the first post more carefully.
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Wed, 2012-07-25 00:41
NewtonPulsifer NewtonPulsifer's picture
You don't need agriculture -
You don't need agriculture - the nano-fabbers are all you need. It simply becomes a matter of having enough energy to input in the fabbers to cover inefficiencies, and then how well you can radiate the waste heat so you don't cook yourself. Diamonds or unidirectional carbon nanotubes are awesome heat conductors so I don't think radiating the waste heat away would be an issue at all.
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Wed, 2012-07-25 01:17
The Green Slime The Green Slime's picture
But a plant will pretty much
But a plant will pretty much grow itself, with far less resource requirements, and with positive feedback to the rest of the habitat's biological systems. Why not let nature take its course and free up that energy for other uses? It strikes me as a handwave too far when nanofabbing is portrayed as more efficient and practical than simple biology. It's apt to become the sci-fi equivalent of magic, a boring quick-fix for any and all holes in the setting.
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Wed, 2012-07-25 02:28
Trekkin Trekkin's picture
The Green Slime wrote
The Green Slime wrote:
Selecting the parts of it we like and engineering ways to keep them in some kind of impossible stasis (hydro & aero both belong to this ethos) would very much be at odds with the networked transhuman way of doing things.
I could certainly see more environmentally concerned Reclaimers taking this viewpoint and running with it. It does make me wonder, though, if some enterprising, inventive scum genehacker might come to the same conclusion and attempt to engineer a completely biological hab, or at least a totally biological life support system, designed to get at least a basic carbon, nitrogen, oxygen, and water cycle going in a tin can, then adapt, maintain and repair that system in the face of external stresses and expansion of the habitat. Sort of like the inverse of some elements of the back-to-nature movement, or perhaps an unusual type of terraforming. Or, taken to an extreme, the Edenist habitats from Night's Dawn. I can't see them being nearly as efficient as nanotech, but there is a certain attractive elegance to the idea of creating a biosphere that could naturally support flats. I may have to look into how successfully aquaponics could be implemented in space, and how many functions it could feasibly take on without becoming overburdened--it may end up being a lower bound on my original attempts at water budgeting.
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Wed, 2012-07-25 05:17
Arenamontanus Arenamontanus's picture
Water is extremely useful in
Water is extremely useful in a habitat, you will want to have as much as possible. This is because it also makes a good radiation shield (put tanks under the ground or even surround the whole habitat with it), it can be pumped around to change the mass distribution of the habitat (important for controlling precession and direction), it can be used as a thermal sink (either just by being heated by the habitat or by spending it through evaporation into space), and of course you will use it in the life support system. Biosphere 2 had a total footprint of the airtight area of 12,700 m^2 with a combined volume of 200,000 m^3 with a total water capacity of some 6 x 10^6 liters of water. So that gives us two possible estimates, 472 liters/m^2 or 30 liters/m^3. Taking O'Neill's Island Three, 8 km diameter and 32 km long we get a surface area of 4*10^8 m^2 (I halved it for the windows)and a volume of 1.6*10^12 m^3. So the water requirements would be somewhere between 1.88*10^11 and 4.8*10^13 litres. That is pretty big: a cube of water with a side between 500 m and 3 km! Still tiny compared to the total habitat, but habitat building obviously requires lots of ice.
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Wed, 2012-07-25 11:59
NewtonPulsifer NewtonPulsifer's picture
The Green Slime wrote:But a
The Green Slime wrote:
But a plant will pretty much grow itself, with far less resource requirements, and with positive feedback to the rest of the habitat's biological systems. Why not let nature take its course and free up that energy for other uses? It strikes me as a handwave too far when nanofabbing is portrayed as more efficient and practical than simple biology. It's apt to become the sci-fi equivalent of magic, a boring quick-fix for any and all holes in the setting.
I agree the high efficiency of nanites in EP don't make much sense when analyzed. Photosynthesis isn't that efficient. It is at *best* 8-9% efficient. Usually alot less than that ( [url=http://onlinelibrary.wiley.com/doi/10.1111/j.1751-1097.1991.tb03668.x/ab... ) So if in my EP universe photosynthesis is more efficient than nano-fabrication (let's say I pick it that nano-fabrication is only 3% efficient)...then there's alot of implications that would reduce the capabilities of nanites in my universe by quite a bit if I want to remain self-consistent, too. Most nanites could not run without large amounts of energy input and waste heat generated. You'd need to be constantly hosing them down with beams of microwaves or something. Which is actually how they probably [i]would[/i] be in reality, honestly. I think your instincts on this subject are quite sound....but the capabilites of the nanites in EP imply that they're empirically *better* than biological life. Maybe a subject for another thread, unless the OP doesn't mind a thread-jack into a thermodynamic analysis of nanites.
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Wed, 2012-07-25 14:28
Arenamontanus Arenamontanus's picture
NewtonPulsifer wrote:The
NewtonPulsifer wrote:
The Green Slime wrote:
But a plant will pretty much grow itself, with far less resource requirements, and with positive feedback to the rest of the habitat's biological systems. Why not let nature take its course and free up that energy for other uses? It strikes me as a handwave too far when nanofabbing is portrayed as more efficient and practical than simple biology. It's apt to become the sci-fi equivalent of magic, a boring quick-fix for any and all holes in the setting.
I agree the high efficiency of nanites in EP don't make much sense when analyzed.
How do you analyse it? High efficiency actually makes a lot of sense, since nanosystems can be designed for productivity in well-controlled environments rather than self-replication in a messy environment. A cell needs to acquire resources for self-replication and maintenance, which limits how much output of useful stuff it can do. Mechanics-like systems do not spend much or any effort on maintenance or being able to do nearly anything, instead specialising and foregoing self-repair in favour of being replaced with spares. Overall, EP seems to assume efficiencies that are within one or two orders of magnitude of Eric Drexlers calculations in Nanosystems (and some of Robert Freitas' work in Nanomedicine). This is decently mature nanotechnology, and no doubt earlier systems were less effective. The real issue to consider is whether a particular industrial or agricultural process is best done using nanotechnology or something else. Growing food is likely easier in terms of maintenance and industrial control than to manufacture it, since the manufacturing has to occur in a very messy liquid medium involving soft matter. Just like non-replicating hierarchical fabber systems are far more useful for manufacturing than swarms, I suppose aeroponics of bioengineered high yield plants is more useful.
Quote:
Photosynthesis isn't that efficient. It is at *best* 8-9% efficient. Usually alot less than that ( [url=http://onlinelibrary.wiley.com/doi/10.1111/j.1751-1097.1991.tb03668.x/ab... ) So if in my EP universe photosynthesis is more efficient than nano-fabrication (let's say I pick it that nano-fabrication is only 3% efficient)...then there's alot of implications that would reduce the capabilities of nanites in my universe by quite a bit if I want to remain self-consistent, too.
But we already have photovoltaics *far* more efficient than photosynthesis! So what about "plants" that used them to make food? In addition, if it was all about power conversion efficiency, then you should think of fusion instead.
Quote:
Maybe a subject for another thread, unless the OP doesn't mind a thread-jack into a thermodynamic analysis of nanites.
That would make a good thread. I have made various posts in the archives where I have done some calculations on the limitations of nanotech.
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Wed, 2012-07-25 14:30
Trekkin Trekkin's picture
NewtonPulsifer wrote:
NewtonPulsifer wrote:
Maybe a subject for another thread, unless the OP doesn't mind a thread-jack into a thermodynamic analysis of nanites.
Mind? I'd welcome it; it's exactly the sort of thing I need to ponder to GM this well with my party of engineers of various stripes. It'd probably be more helpful for people searching the forums if it was its own thread, though. Besides, given how water's noted as being used as a thermal dump, it would seem to add another reason to have lots of water.
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Wed, 2012-07-25 15:51
NewtonPulsifer NewtonPulsifer's picture
Corn vs. Healing Vat Kobe Beef Analysis
Arenamontanus wrote:
How do you analyse it?
Easier said than done, of course :)
Arenamontanus wrote:
High efficiency actually makes a lot of sense, since nanosystems can be designed for productivity in well-controlled environments rather than self-replication in a messy environment. A cell needs to acquire resources for self-replication and maintenance, which limits how much output of useful stuff it can do. Mechanics-like systems do not spend much or any effort on maintenance or being able to do nearly anything, instead specialising and foregoing self-repair in favour of being replaced with spares. Overall, EP seems to assume efficiencies that are within one or two orders of magnitude of Eric Drexlers calculations in Nanosystems (and some of Robert Freitas' work in Nanomedicine). This is decently mature nanotechnology, and no doubt earlier systems were less effective.
I haven't read them; I'll have to take a look before I can respond.
Arenamontanus wrote:
The real issue to consider is whether a particular industrial or agricultural process is best done using nanotechnology or something else. Growing food is likely easier in terms of maintenance and industrial control than to manufacture it, since the manufacturing has to occur in a very messy liquid medium involving soft matter. Just like non-replicating hierarchical fabber systems are far more useful for manufacturing than swarms, I suppose aeroponics of bioengineered high yield plants is more useful.
Well, a healing vat is able to make a limb in 3 days (let's call that 30kg?). I'm assuming a healing vat is about 2.5 cubic meters and basically full of mostly air plus nanite dust. Now, the word vat does imply it is full of liquid, but that would make the healing vat weight like 2 tonnes+ just from the liquid inside it. If so, certainly gives you different idea of the size and strength of the Dr. Bot from pg. 346. Anyway, if you make space for other things (walkways, workspaces etc) you're probably going to get a multiplier of about 0.3. That is, if you have 75 cubic meters available, you're only going to fit (75x0.3=22.5, 22.5/2.5=9) nine healing vats available. Stick a side of beef in those and you're getting 90kg a day of beef for 75 cubic meters and 9 healing vats. That's about 2kcal a gram for our [url=http://caloriecount.about.com/calories-market-day-filet-mignon-steaks-i8... cuts[/url] and we are generating 180,000 kcal a day here, enough to feed 90 people. Now this is filet mignon - if we went for a fattier cut, we could probably squeeze more calories out of it (kobe beef is more like 2.4 kcal/gram). Anyway, feeding 90 people per 75 cubic meters. Now previous calculations in this thread had 30.61 people fed per acre. It's 4046.86 square meters per acre. If we assume a roof height of 2.5 meters for our meat farm as well as for a grow room for corn, we have 10,117.15 cubic meters. So for 10,117.15 cubic meters of corn grow space, the amount of people you can feed is: [color=#FF0000] 30.61[/color] for Corn [color=#FF0000]12,140.58[/color] for the kobe beef nano-factory Old school methods of making food just can't compete according to what the implied capabilities of nanites are in Eclipse Phase. I don't see any reason why we couldn't stick say a pumpkin in one of the healing vats if you are concerned with diet variety. Now this analysis doesn't answer the question of energy efficiency at all. Let's consider the healing vat built into the Dr. Bot however. It runs off of Dr. Bot's internal energy source. So I'd hazard a guess the energy usage is "not bad". If you have a multi gigawatt fusion or fission plant, you may not care.
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Wed, 2012-07-25 17:46
Trekkin Trekkin's picture
Well, nanites are more
Well, nanites are more efficient than conventional agriculture to be sure, but I wonder if the method by which they're deployed would, in fact, resemble a hydroponic or aeroponic farm for similar applications. To my mind, one of the biggest energy drains for your normal vat-based nanotech assembler is moving the materials and nanites around. To use a modern example, a 3d printer has to go back and forth over the print space at least once per level of the thing to be printed. Nanites presumably don't use print heads, but the mechanics of it are still there; you've got to get a lot of them in and out many, many times. This is compounded when trying to assemble things one atom, rather than one molecule, at a time. As an extreme case, consider the titin in that side of beef; it's got about 35000 amino acids to position precisely, and going down to the atomic level easily bumps the number of elements by an order of magnitude. The energy requirements of this are not ridiculous on the macro scale, but as has been pointed out, shedding waste heat is a bit of an issue when your moving parts have all the thermal inertia of a millionth of a dust speck and have to include molecular dynamics when figuring out their thermal tolerances. Therefore, I could see things like simple biomolecules made using nanites kept as static as possible. Basically, corrugated book lung type arrangements with the raw materials suspended in water on one side, a source of light on the other, and a membrane of nanites acting as enzyme factories in the middle cranking away at, say, nutrient slurry, outputting it on the light-providing side of the membrane so it'd flow along the corrugations and be collected at the end. If you organize those nanites into self-contained little cells with self-regulating repair and replacement mechanisms, you've basically built a nanoscale hydroponics farm. Tiny versions in nanofabbers could do the aforementioned synthesis of molecules and macromolecules; much bigger versions would seem the ideal way to scavenge useable elements out of blackwater after the vapor-compression distillation process described in Panopticon. Basically, while plants are inefficient, it may well be that very plantlike structures are behind a lot of the mechanics of nanofabrication. This would suggest that hydroponically growing plants as support systems for the nanites might explain some of the persistence of hydroponics as an industrial rather than environmental/psychological concern. Although I do wonder why Panopticon mentions growing food with plants, on page 78-79.
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Wed, 2012-07-25 22:06
NewtonPulsifer NewtonPulsifer's picture
Trekkin wrote:
Trekkin wrote:
.......Although I do wonder why Panopticon mentions growing food with plants, on page 78-79.
The writer(s) just didn't do a back of the envelope calculation to see if it made sense :)
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Wed, 2012-07-25 23:19
Thampsan Thampsan's picture
Possibly for smaller
Possibly for smaller communities the sense of novelty from having actual grown, plant food is a selling point? Or perhaps the individuals relying on these methods have yet to do the math on efficiency.
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Wed, 2012-07-25 23:45
Decivre Decivre's picture
Trekkin wrote:Although I do
Trekkin wrote:
Although I do wonder why Panopticon mentions growing food with plants, on page 78-79.
NewtonPulsifer wrote:
The writer(s) just didn't do a back of the envelope calculation to see if it made sense :)
There are a few reasons you would want to grow food in the traditional manner, the least of which is cost and resources. Traditional farming requires less machinery, has lower budgetary needs, and doesn't need access to advanced technology to achieve (at least in the inner system). Plus, there is the aesthetic value; many habs likely use agricultural regions to make the habitat more eye-catching. There are benefits to traditional farming, especially when people are looking for things that remind them of Earth.
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Thu, 2012-07-26 00:48
NewtonPulsifer NewtonPulsifer's picture
Decivre wrote:
Decivre wrote:
There are a few reasons you would want to grow food in the traditional manner, the least of which is cost and resources. Traditional farming requires less machinery, has lower budgetary needs, and doesn't need access to advanced technology to achieve (at least in the inner system). Plus, there is the aesthetic value; many habs likely use agricultural regions to make the habitat more eye-catching. There are benefits to traditional farming, especially when people are looking for things that remind them of Earth.
Cost *is* king though. You have indentures without a credit to their account busting their hump for years for a pittance. Industrial agriculture might make sense where there's plenty of acreage for cheap domes (Mars, large moons). Everywhere else (space habs) it is going to be vat grown except for conspicuous consumers or low tech brinkers scraping by. If I was in a hab where they wasted 2/3rds of the space just to grow plants when there's 9 billion infomorphs waiting to be reinstantiated I'd vote to get rid of it. Have some compassion!
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Thu, 2012-07-26 00:58
Decivre Decivre's picture
NewtonPulsifer wrote:Cost *is
NewtonPulsifer wrote:
Cost *is* king though. You have indentures without a credit to their account busting their hump for years for a pittance. Industrial agriculture might make sense where there's plenty of acreage for cheap domes (Mars, large moons). Everywhere else (space habs) it is going to be vat grown except for conspicuous consumers or low tech brinkers scraping by. If I was in a hab where they wasted 2/3rds of the space just to grow plants when there's 9 billion infomorphs waiting to be reinstantiated I'd vote to get rid of it. Have some compassion!
But investment is a key element of economics. Think about it; it takes a significantly smaller resource investment, especially in the capitalistic inner system, to get a traditional farm off of the ground. Some land, access to sunlight, some seeds, some water, and primitive tools are largely all you need to get something going. On the converse, you would need a nanohive, an enclosed aeroponic facility, lighting fixtures, a nutrient shipment, and a multitude of other equipment to do a similar project with more effective processes. The startup costs are the killer here. Even today you see this; despite the advantages of hydroponics, it will cost me a hell of a lot less to get a traditional garden off the ground. The difference is in orders of magnitude: a 4' by 8' garden would cost me nearly $2500 with an efficient hydroponic setup, lighting, and a good tent and ventilation system; whereas I've started similarly-sized traditional gardens on less than a hundred bucks.
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Thu, 2012-07-26 02:21
Trekkin Trekkin's picture
Well, makers are a Low-to
Well, makers are a Low-to-Moderate cost item, so every one purchased is theoretically (part of) another case morph someone doesn't get to have. I don't know the comparable cost for moving large quantities of water around and establishing a proper growth environment, but I suppose a large enough habitat might actually realize a significant benefit in freed up fabber time via greywater hydroponics. Then again, how many people can a maker feed, running as constantly as possible?
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Thu, 2012-07-26 03:01
Decivre Decivre's picture
Trekkin wrote:Well, makers
Trekkin wrote:
Well, makers are a Low-to-Moderate cost item, so every one purchased is theoretically (part of) another case morph someone doesn't get to have. I don't know the comparable cost for moving large quantities of water around and establishing a proper growth environment, but I suppose a large enough habitat might actually realize a significant benefit in freed up fabber time via greywater hydroponics. Then again, how many people can a maker feed, running as constantly as possible?
Makers are a low-cost item, assuming availability and average market scenarios. Many people don't live in places where that might be an option. How does one get a maker on a hab where nanotech is banned? How do you get a maker on a hab where nanotech prices have skyrocketed? There will always be scenarios where nanotech, despite its availability, isn't an option. Just as today, there are plenty of people that don't have computer or internet access today, despite the fact that both have a relatively high level of modern availability.
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Thu, 2012-07-26 06:19
Arenamontanus Arenamontanus's picture
NewtonPulsifer wrote:
NewtonPulsifer wrote:
Well, a healing vat is able to make a limb in 3 days (let's call that 30kg?). I ... Stick a side of beef in those and you're getting 90kg a day of beef for 75 cubic meters and 9 healing vats. ... So for 10,117.15 cubic meters of corn grow space, the amount of people you can feed is: [color=#FF0000] 30.61[/color] for Corn [color=#FF0000]12,140.58[/color] for the kobe beef nano-factory
Very nice BOTE calculation! But what about the price? A healing vat is High = 5000 credits, so plugging it into your calculation the cost of the installation turns out to be ~5000 per person for the beef factory. I don't have any good numbers for a cornfield, but it seems likely that the cost is going to be far below High per person to set it up, even in a space habitat. Especially when you take upkeep into account: the nanovats require specialized feedstocks, maintenance, specialized engineers and so on, while the cornfield does most of the work robustly on its own. I think the key thing is economies of scale. Doubling the size of the cornfield doesn't double the cost (since most of the cost is going to be the farmer salary and harvesting machines) - this is why large-scale farming has come to dominate modern agriculture. Doubling the nanovat might not have the same sublinear scaling: if so, then there is a size beyond which the cornfield wins. So my guess is that food fabbing is most common on smaller habitats and ships, while larger ones have traditional hydroponics and aeroponics, and a few even ultra-traditional agriculture.
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Thu, 2012-07-26 06:25
Anarhista Anarhista's picture
Not to write new thread I'll
Not to write new thread I'll piggyback this one: I wonder what is average population density of habitats? (e.g. O'Neill 12km length, 4 km radius). If it is already mentioned just link/point me where.
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Thu, 2012-07-26 06:47
Lorsa Lorsa's picture
I wish I had time to read
I wish I had time to read through everything but I will answer one tiny question that someone was wondering in the beginning (which probably already have been answered). The best place to store water in a rotating habitat is as close to the central rotating axis as possible so that the centripetal force will pull it out to the user without any pumping being necessary. Then you will have to pump it back from where you collect it but that's what we do today - we store water high so it will naturally fall down to users when needed. So, central tanks it is.
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Thu, 2012-07-26 07:24
Arenamontanus Arenamontanus's picture
Population densities can vary
Population densities can vary quite a lot. When I designed the habitat in http://www.aleph.se/EclipsePhase/My%20invisible%20friend.pdf I used 960 people/km^2 - about the level of Bangladesh or Jersey, a mix of rural and urban environments. A purely urban environment might easily reach 17,929 per km^2 like Monaco, but I suspect most habitats will have a few hundred per km^2.
Lorsa wrote:
The best place to store water in a rotating habitat is as close to the central rotating axis as possible so that the centripetal force will pull it out to the user without any pumping being necessary. Then you will have to pump it back from where you collect it but that's what we do today - we store water high so it will naturally fall down to users when needed. So, central tanks it is.
If you put it at the axis there will not be any force on it at all, it will be weightless. I think you want to put it in a ring a bit out from the axis so that there is at least some acceleration. Note that when you drop the water down there will be a Coriolis force - it is at first not moving much, while the habitat is rotating, so it will seem to bend off in the opposite direction of the rotation. A rain from the axis will spiral outwards. Also, there is angular momentum conservation. If you pump your lake into an axis tank the habitat will speed up its rotation (think figure skater doing pirouette and pulling in her arms), if you pump it out it will slow the rotation. This can be very useful to regulate things.
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Extropian
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Thu, 2012-07-26 12:59
nezumi.hebereke nezumi.hebereke's picture
Also consider that
Also consider that agriculture is not a static science. Agriculture has been increasing productivity yields by double digit percentage points for years. In 2012, agriculture is still the front line for tech like bio-engineering, genetic modification, etc. In a nutshell I'd be amazed if the corn of Eclipse Phase is the same yellow ears on green stalks we're used to now, or if it grows with the same level of (in)efficiency. Instead, I'd take the percentage yield increase per acre for the last ten years or so, average it out, and apply it forward for the next 130 years, to come up with a productivity approximation.
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Thu, 2012-07-26 13:25
Arenamontanus Arenamontanus's picture
Indeed. Just watch this
Indeed. Just watch this productivity curve: http://www.synthesis.cc/Biodesic_US_corn_yield.png
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Thu, 2012-07-26 16:34
Trekkin Trekkin's picture
Arenamontanus wrote:Indeed.
Arenamontanus wrote:
Indeed. Just watch this productivity curve: http://www.synthesis.cc/Biodesic_US_corn_yield.png
Extrapolating yield data forward by a century gives me results of between 1.2x and 3x increase in yield, depending on which data set I use, but the r2 values are so low, even when averaged, that I have very little confidence in those numbers. The thing that strikes me as the great unknown here is that all this is based on soil farming. That includes, oddly enough, hydroponic and aeroponic yield increase estimates; they're still based on accomodating a biology that's itself based primarily on soil, except of course for algae tanks. I wonder if part of the vast gulf between the BOTE calculations for nanotech yields and the results for hydroponic yields is at least partially because we're working off the assumption that it's built around corn. Even with modern technology it'd make far more sense to go for something in the Brassica genus, would it not? Given a 2.5 meter ceiling to work with, layering six or seven turnip patches on top of one another would give about two and a half times the caloric yield per acre, just using unmodified Brassica rapa grown in dirt. Presumably by an indenture named Baldrick. I don't really know how to effectively project efficiencies for a hydroponic garden growing plants adapted for hydroponics, though.
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Mon, 2012-07-30 13:07
NewtonPulsifer NewtonPulsifer's picture
Arenamontanus wrote:
Arenamontanus wrote:
Very nice BOTE calculation!
Thanks! And I'd like to express my appreciation for all the great input and participation I see on these forums. It's really been a help for me. Especially your stuff Arenamontanus; very good data. It is actually more like maybe 800 credits per not 5000 (see below), counting just labor and equipment. Rent, taxes, and power bills are unknowns. To share my take on this, I'm using this BOE calculation to boost the price of Healing Vats in my EP universe to 125k (to save "organic" space agriculture in my EP universe). So I agree with the sentiment that space agriculture is cool; it is just the implied economics of it in EP as-is makes it just *so* expensive compared to vat/maker food. This also allows me have the characters to go to seedy underground clinics to get their biomods a la shadowrun or else put up with an official paper trail, as they're unlikely to be able to afford their own healing vat. As an aside, most of my players just don't care about these sorts of obsessive details. However, I'm very particular about my game universes being self-consistent. It may be something the players don't necessarily see, but I feel it is a superior ingredient to the type of final dish I like to make. Cost analysis: Each vat actually fed 10, so it is 500 per, not 5000. Labor - there's a Dr. Bot for "High" cost too. So there's your labor. Let's call it perhaps 8000 (higher end of High) and we're up to 800 credits per. But I chose the healing vat for a reason. To make the comparison that much "worse". Beef costs 6x the cost of grain now, and that's for low end hamburger. If you could really crank out filet, that's pushing 20x the value of grain. I'm sure a maker that just makes sugar, oils, and amino acids is going to be even cheaper, more productive, and more simple (needing less oversight/labor, less "wastage"). So factory made "flour" would be an even more daunting target to match with farming.
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Mon, 2012-07-30 13:52
NewtonPulsifer NewtonPulsifer's picture
Anarhista wrote:Not to write
Anarhista wrote:
Not to write new thread I'll piggyback this one: I wonder what is average population density of habitats? (e.g. O'Neill 12km length, 4 km radius). If it is already mentioned just link/point me where.
I haven't seen it anywhere myself. If you assume 2/3 of the inner surface area is usable for space, you have 8pi*12(times 2/3) sqkm in surface area. Assume the "end caps" are used for other purposes. About 200sqkm. A suburban house plot in the USA is generally around 1/4 acre. Let's allocate 1/2 the usable space to suburbia, the other half to commercial/industrial. I don't think you'd need roads or alleys in a habitat (low gravity, most people who insist of having a vehicle could use a flying one). If everybody lived in a suburban home and wanted to see the "sky", and on average 3 people lived in a house. A 1/4 acre is approximately 1000sq meters, so 1000 homes per square kilometer. That's 3000 people per square kilometer. We're using 100 square kilometers - so 300,000 people. So our Los Angeles sprawl version of our "city" is 300,000 people. Could still be less than that if you want roads, park space, etc. Stack those on top of each other to fill the entire space of 1/2 the cylinder - say put a "roof" over each suburban plot 15 meters high - you can increase this number dramatically. Houses at the "center" would have very little or no spin gravity. This gives 9 meters for 3 "floors" and another double height "floor" for traffic. If you filled up your "house" volume with 3 floors, you'd have 30,000 square feet - a very spacious pad for a family of 3. It becomes a volume calculation instead. 603.43 cubic kilometers (603 billion cubic meters). 15,000 cubic meters per house. That's 120.6 million people. So you get a difference by a factor 400 if you fill the hab's volume completely up. If you went to smaller sized home units (say 120 square meters per family of 3, about 1200 square feet) you could get to 2.5 billion people. Keep in mind though, by doing this you're also increasing the mass of the cylinder by perhaps 100 times (assuming the internal building materials are 1/4 the thickness of the outer cylinder). That's a lot of building material.
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"I fear all we have done is to awaken a sleeping giant and fill him with a terrible resolve."- Isoroku Yamamoto
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