[HN Gopher] Wheat yield potential in controlled-environment vert...
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Wheat yield potential in controlled-environment vertical farms
Author : tosh
Score : 60 points
Date : 2020-08-08 17:27 UTC (5 hours ago)
(HTM) web link (www.pnas.org)
(TXT) w3m dump (www.pnas.org)
| kickout wrote:
| https://thinkingagriculture.io/what-silicon-valley-doesnt-un...
|
| Just say no to vertical farming for row crops. Can't beat the sun
| (and scale)!
| aaron695 wrote:
| Has everyone gone insane?
|
| The only thing worth growing in vertical farms is branded
| "Vertically Farmed" artisanal products for the rich.
|
| Surely you can see wheat is not great for this.
|
| You still then have to put the world's most expensive wheat
| through the artisanal bread making process. How will this be
| profitable?
| tosh wrote:
| naive question: would it help w/ energy costs to have the
| vertical farms under ground and to use mirrors to redirect
| sunlight (I guess it will still not be enough and require
| additional artificial lighting?)
|
| one argument against vertical farming seems to be the high
| occupancy costs in larger cities. Why not build them outside of
| cities and connect them?
|
| https://en.wikipedia.org/wiki/Vertical_farming#Problems
| rtx wrote:
| Because occupancy cost is very low outside the cities.
| AnimalMuppet wrote:
| Either I missed something, or your answer doesn't actually
| address the question.
|
| Could you explain what you mean a bit further?
| rtx wrote:
| It's about why don't they move the vertical farms outside
| the city. Farming on lands outside population center is
| cheaper than on vertical farms at the same locations. This
| is due to low cost of land and benefits of mechanisation.
|
| Right now we have excess food production.
| AnimalMuppet wrote:
| I see your point. But if they get the claimed several
| hundred times the productivity, then they need several
| hundred times less land. That land is still several
| thousand dollars an acre, even out in the sticks. That's
| a _lot_ of money that can be saved on the land.
|
| > Right now we have excess food production.
|
| True. If this vertical approach produces wheat for less
| money, then it will take over. If not, then it won't...
| today. There's this whole climate change thing. People
| suspect that it's going to harm food production. Can we
| control this smaller environment well enough for it to
| still be productive? Better than we can control outdoor
| farms.
| bufferoverflow wrote:
| Your larger cities are already shaded to hell, and the
| skyscrapers are fighting each other for the remaining scraps
| that are left.
|
| Your system of mirrors will occupy the same amount of space (or
| close to) as your farm would need. But it will be expensive to
| build and expensive to maintain and to protect against the
| elements.
| eadan wrote:
| The problem with vertical farming is where does the energy come
| from? An acre of solar panels is not capable of supplying enough
| energy to grow an acre of crops, even with the efficiency gains
| we've had in photovoltaics and lighting with wavelengths tuned to
| crop growth. What's the point in having fields of solar panels
| when we could have smaller greenhouses filled with crops? If only
| nuclear energy was politically viable in the west we could have
| vertical farming and so much more.
| aalleavitch wrote:
| We're closer than you'd think. Chlorophyll is only something
| like 28% efficient at absorbing sunlight, we have experimental
| solar panels pushing 45%. Collecting wavelengths the plants
| don't use and then lighting them only in wavelengths they do
| use has a significant potential for efficiency gains, though
| we're not quite there yet...
| m4rtink wrote:
| Well, can't easily grow crops on untreated desert ground, but
| easy to put solar panels there to power your enclosed vertical
| farm.
| aalleavitch wrote:
| Yes, soil, temperature, and weather control are huge, as is
| the lack of need for pesticides. Hard to over-state how much
| controlled environments can improve yields and crop quality
| and reduce costs of maintenance (in return for large initial
| capital investment).
| afiori wrote:
| My understanding is that this is how the Netherlands became
| one of the biggest food exporters of the EU
| brippalcharrid wrote:
| Ultimately this is about removing the limitations of agriculture
| as it stands (1 acre/acre, 1kw/m2, 330ppm CO2) so that we can
| convert energy and chemicals into food in a scalable, reliable
| and repeatable way. This has obvious medium-term applications
| outside of our atmosphere and gravity well, but if we allow
| energy costs to come down by orders of magnitude by continuing to
| make advances in nuclear energy, it will inevitably lead to a
| system that's preferable in terms of land use, both in terms of
| former agricultural land that can be returned to forests and
| relatively small high-density power plants that will replace
| sprawling renewable infrastructure. I don't understand why people
| keep bringing up the idea of using high-rise buildings in an
| urban/near-urban environment; surely you'd want to do it in
| lights-out factories on the cheapest available land, and if
| energy is cheap enough to make vertical farming profitable,
| shipping costs would be negligible. A single 1km X 1km X 1km
| underground vertical farm could be sufficient to feed millions of
| people while leaving the land above it available for
| forests/grassland/tundra, or provide district heating to a
| sizeable population.
| nradov wrote:
| We have plenty of land for growing crops. Land is not an issue.
| X6S1x6Okd1st wrote:
| We already use half of all habitable land for agriculture.
|
| "The expansion of agriculture has been one of humanity's
| largest impacts on the environment. It has transformed
| habitats and is one of the greatest pressures for
| biodiversity: of the 28,000 species evaluated to be
| threatened with extinction on the IUCN Red List, agriculture
| is listed as a threat for 24,000 of them"
|
| https://ourworldindata.org/land-use
|
| Do we really want to keep eating into what wilderness
| remains?
|
| Just because we "have" it doesn't mean we should convert it.
|
| We already produce enough food to feed the world and likely
| won't have trouble producing enough food to feed the coming
| extra billions, but if we can focus on increasing yeilds and
| moving away from raising animals for consumption we can also
| reduce our footprint on the world.
| kickout wrote:
| Yep. This is the correct answer
| brippalcharrid wrote:
| Crops in fields are subject to pests, infections and
| flooding; look at East Africa, South Asia and China at the
| moment for examples. It's a lot easier to achieve food
| security when your food production is industrialised and
| hermetically sealed in a relatively small area. Not depending
| on precipitation and being sheltered from hail/frost is also
| an advantage once you have sufficiently cheap energy that
| enables desalination on a mass scale. And while it isn't a
| pressing issue at the moment, it would certainly be
| preferable not to have to use half of the world's habitable
| area for agriculture (that tends to be heterogeneous so that
| it can be done efficiently at scale) with millions of acres
| used to grow grain with nitrate fertilisers and pesticides
| and to use it for stuff that's more biodiverse, sustainable
| and aesthetically pleasing instead.
| tomcam wrote:
| > It's a lot easier to achieve food security when your food
| production is industrialised and hermetically sealed in a
| relatively small area.
|
| Citation? Sounds good in theory but many problems could
| arise, such as molds, fungus, or complete wiping out of a
| monoculture from disease.
| brippalcharrid wrote:
| The environments can be compartmentalised and sterilised
| between crops; if it's a sealed environment and the only
| inputs apart from the seeds are sterile (via UV treatment
| of water, for instance), there's far less risk of
| disease, and by carefully controlling the handling of the
| seeds (and ensuring that there's a reasonable degree of
| genetic diversity amongst them) that also reduces the
| risk of widespread crop failures. It's also far easier to
| monitor and continuously test crops in a controlled
| environment like that, and it wouldn't need to be just a
| few massive factories; there could be large number of
| smaller ones that were geographically distributed.
| terramars wrote:
| I like how this whole yield paper and model is based on the
| results of a 3'x3' trial area...
|
| "With artificial lighting increasing the intensity and duration
| of light beyond what can be captured from the sun in a field, the
| short indoor growth cycle produced mean grain yields of 14 +- 0.8
| t/ha per harvest at 11% grain moisture based on a 1-m2 edge-
| protected experimental area"
|
| How tf can you say your yields are going to extrapolate from that
| tiny space to a hectare scale facility? It's ridiculous. We have
| a huge problem achieving lab-theoretical yields on working farms,
| outside of the super optimized and most destructive conventional
| agriculture methods. They didn't even do a full greenhouse trial.
| Come on guys, you can say it's promising but to say you can get
| 1000+t/ha out of a vertical farm because of this is fantasy.
| Havoc wrote:
| At present I think it makes more sense to focus on high value
| crops.
|
| Eg I'll pay a premium for pesticide free, fresh salad from a
| Urban vertical farm. Wheat less so
| ssorallen wrote:
| High value and highly perishable. Wheat can be stored for
| years, but the shelf life of your kale/arugula/romaine salad is
| a matter of days.
| jsilence wrote:
| Sorry, but growing grains in vertical farms absolutely does not
| make sense. unless you'd have a very very cheap zero emission
| energy source. which would have a plethora of other sensible
| applications.
|
| The single most sane way to change agriculture for the better is
| to eat much less beef. hands down. simple as that.
| fsflover wrote:
| > unless you'd have a very very cheap zero emission energy
| source
|
| Like nuclear?
| ThomPete wrote:
| I think history have shown us that if you want people to change
| their behavior you have to come up with something better not
| just something that you or I or someone else think is easier or
| more rational. The world doesn't work like that.
| Melting_Harps wrote:
| > The single most sane way to change agriculture for the better
| is to eat much less beef. hands down. simple as that.
|
| I think addressing the issue of not having to succumb to the
| model that ensures 1/3 of all food produced is lost would do
| FAR more than that, recapturing the losses and creating
| alternative processes to create more efficient supply chains
| would ensure we could curtail so many more problems.
|
| I say this as a person who has actually farmed, worked
| professionally in culinary (including vegetarian and vegan
| cuisine) and has a background in Logistics/Supply Chain for
| Auto-Multinational Corps.
|
| So, if you think Conventional (chemical) Ag Grain/Vegetable
| monocrops (which is what most people eat) are really that much
| better for the Environment/Humans than a sustainable (ideally
| Biodynamic) Livestock raising model is better, you really have
| no idea what you're talking about--I've worked on both, too.
| Although I agree the US' consumes way too much meat in general,
| but there are much bigger problems to solve and changing a
| culture's palette is typically generational barring a massive
| catastrophe (think: War). I think many Millennial and Gen Z
| diets are moving toward plant-based more than their Boomer
| counter-parts, which I have some reservations about: the image
| of a 'vegan' toddler at the Farmer's Market I worked at during
| my apprenticeship comes to mind and I thought he was undergoing
| chemo-therapy he looked so unhealthy.
|
| Also, I like the fact that these things are being explored,
| obviously for terrestrial applications the use-cases are
| limited, but experimentation for long-term Mars colonization
| will require in-situ crop cultivation if it is to be
| sustainable, and what applies to Vertical farming could help
| design the new container garden model. Vertical farms are
| essentially playthings for hobbyists on Earth, even a Community
| garden with a moderate size greenhouse for off-season grows
| will yield (in every sense of the word) way more per/sqft with
| the exception of perhaps the now defunct business models:
| selling micro-greens to fine-dining restaurants in a post COVID
| World.
|
| Detroit showed how the solution to Food deserts isn't Container
| Gardens/Vertical farming, though its not entirely against it
| either, but its a reversion to Agrarian practices which include
| re-purposing large plots of land to Urban Farming, which
| created a Renaissance of sorts in the last decade. I guerilla
| gardened as an activist before farming, and while vertical
| farming should be encouraged; if nothing else as a form of
| Community building and as small step in CO2 sequestration as
| well as an improvement aesthetically speaking.
|
| Personally speaking: As a person who grew up in CA the Valley
| has to be the ugliest part of CA to me because of how modular
| and cookie-cutter everything looks, it looks like an
| 'Industrial Model' to Civilization.
|
| A few creeping grape/pea vines and spontaneous gardens won't
| solve the massive Homeless issue that ones associates with the
| vista of the Valley but it could really help improve the
| overall feeling of the place: I seriously had to flee to Sonoma
| every chance I got to keep from going crazy when I was there as
| it looked and felt so alien to me.
| javert wrote:
| That doesn't make agriculture better. It just makes food worse.
| [deleted]
| seiferteric wrote:
| Something I have been thinking about for a few years... How far
| away are we from being able to grow seeds on a substrate directly
| and skip growing the plant at all? What I envision is a substrate
| that is able to provide the nutrients needed for embryo growth,
| maybe with micro channels or pores. You could "seed" the
| substrate with embryonic plant cells, then when they are done,
| you just scrape them off. Is that totally crazy?
| NortySpock wrote:
| I wonder if growing yeast, algae, or the CO2+H2 eating microbes
| that Solar Foods is working on will be cheaper to use either as
| an engineered food product or as feedstock for animals.
| seiferteric wrote:
| It's possible for animals, but for people then you have to
| eat "engineered food product" instead of wheat bread. So I
| think people will not like that. At that point we are
| essentially at soylent green. But I like the idea for animal
| food for sure.
| shalmanese wrote:
| The engineered food products were Soylent Red and Soylent
| Yellow. Soylent Green, as we all know, is made of people.
| est31 wrote:
| Isn't bread an engineered food product?
| dredmorbius wrote:
| Wheat, grown in dirt fields under sunlight with water, is
| not.
| aidenn0 wrote:
| Wheat has been undergoing genetic engineering for 10000
| years.
| dredmorbius wrote:
| Is there no conceivably way in which you might see such
| selection over centuries differing in any regard from
| lab-grown, factory-synthesized products?
| coding123 wrote:
| Don't feed the trolls. They understand the difference
| between baked bread and CRISPR editing. They're just
| making political statements.
| drran wrote:
| 1) It may take years, because surface area of seed is so small.
|
| 2) Seed will be contaminated. It will taste as leaf or straw.
| seiferteric wrote:
| I am sorry, I don't understand this comment, can you explain?
| My idea is to replace the host plant with an artificial
| medium that will serve the same purpose. As far as
| development time, should it not be that same as the real
| thing? Or perhaps faster since you can ensure optimal
| delivery of nutrients?
| drran wrote:
| If you already have nutrients, then just consume them. :-/
| seiferteric wrote:
| Mmmm, nutrients. Makes my mouth water.
| TheAdamAndChe wrote:
| That could be either algae or genetically modified yeast.
| h2odragon wrote:
| https://en.wikipedia.org/wiki/Micropropagation
|
| like that?
| jdc wrote:
| With some more lab automation and approachable exposition
| we'll be all set.
| seiferteric wrote:
| Not exactly, that's more about propagation of plants, after-
| which it grows into a normal plant. I am thinking that we
| could only grow the desirable part of the plant, like the
| seeds in the case of corn or wheat.
| khawkins wrote:
| A picture of these vertical farms would have gone a long way
| towards helping me understand what all would be required to
| deploy these things. Yet they decide to use white-space to tell
| me what the population of the world is and estimates of it in the
| future and why farming is important.
| nanomonkey wrote:
| I'm curious if this would be a good use of land in places like
| the Saharan desert, semi vertical greenhouses would optimize for
| water loss and light usage, and there is plenty of sand for
| production of the glass walls and growing medium.
| arminiusreturns wrote:
| I think this sort of work is important because it gives us data
| to focus on improving. Like solar power efficiencies, I think
| there is lots of room to improve on vertical farming output which
| will be vital for a few reasons.
|
| Reason one, is that I think one lesson we've learned and are
| still learning is that the original model of the internet that
| senses damage and routes around it is still a strong model, and I
| think the same applies to food. To reduce the impact of food
| shortages, we need to get more people farming again essentially,
| and a small vertical farm can be had for those people regardless
| of if they have land or suitable land for traditional growing,
| and the cost are likely to be similar to solar panels and be one
| that is subsidized at first or at least given tax breaks.
|
| Reason two is that I think the same work will be of vital
| importance for future space faring missions. If we can get closed
| loop ecosystem sustainability heavily improved we might be ready
| for something like a real Mars trip/settlement etc. Personally I
| advocate for adding other systems to the closed loop to feed off
| each other, aka auqoponics, etc to add a meat source (fish) into
| the loop etc.
|
| So we have a decent study on wheat. Now lets get the yield
| potentials for everything else under the sun so we can start
| optimizing better. Probably end up with focus on whatever has the
| highest calorie output to price to produce ratio.
| yourapostasy wrote:
| > ...the original model of the internet that senses damage and
| routes around it is still a strong model...
|
| I wonder if "packetizing" food production in a vertical
| permaculture food forest form factor is feasible? In other
| words, instead of vast monoculture swaths, use interdependent
| crops in interlocking planting patterns, predicated upon the
| assumption that robot-vision-assisted labor is practical.
| cagenut wrote:
| > Now lets get the yield potentials for everything else under
| the sun so we can start optimizing better.
|
| https://www.youtube.com/watch?v=wsaufB5F8dk
|
| That presentation is by one of the same scientists referenced
| in the linked paper, Dr. Bruce Bugbee, the one who grew wheat
| on the ISS.
|
| He has a whole youtube channel that goes into more detail than
| you can imagine:
| https://www.youtube.com/c/Apogeeinstrumentsincorporated/vide...
| nradov wrote:
| Food shortages are caused by natural disasters and political
| problems such as wars, not by lack of places to grow crops. We
| have plenty of farmland and farmers. If your vertical farm is
| caught in the middle of a war or flood then it won't be able to
| operate.
| tosh wrote:
| > yields for wheat grown in indoor vertical farms under optimized
| growing conditions would be several hundred times higher than
| yields in the field due to higher yields, several harvests per
| year, and vertically stacked layers. Wheat grown indoors would
| use less land than field-grown wheat, be independent of climate,
| reuse most water, exclude pests and diseases, and have no
| nutrient losses to the environment. However, given the high
| energy costs for artificial lighting and capital costs, it is
| unlikely to be economically competitive with current market
| prices
| Johnjonjoan wrote:
| If cost is the only issue we should be subsidising it and
| turning farmland into succession forest.
| oillio wrote:
| In addition, it is more dependant on modern supply chains.
| Modern farms are already pretty dependant to get their
| yields. We should think long and hard if we want a long term
| power outage to cause food shortages.
| TheAdamAndChe wrote:
| We could just use solar panels to power the batteries used
| to light our plants!!
|
| Wait...
| yazaddaruvala wrote:
| It's actually more efficient to capture all wave lengths
| of solar store it in a battery and then only produce the
| wavelengths that the plants can absorb.
|
| https://www.scientificamerican.com/article/plants-versus-
| pho...
| schemy wrote:
| In the same way that it's more efficient for me to drink
| high octane fuel rather than eat food.
| yazaddaruvala wrote:
| Probably better to think of it as eating mushrooms rather
| than trying to chew on he bark of a tree.
|
| Chewing on bark will work, if you have enough bark, but
| it's significantly more effective to use a fungus as an
| intermediary.
| the8472 wrote:
| Here "cost" is a euphemism for stupendous amounts of energy.
| Producing it would take up a lot of land in PV panels.
| That'll only give you a little extra forest and entire
| agricultural states covered in PV and vertical farming towers
| instead. I could imagine some rich, arid countries trying
| this but not ones with fertile soil and rain. It's hard to
| compete with the free fusion reactor floating up there.
|
| From the appendix1 (assuming I am reading this right):
| Value of production 405,329$/year Cost of energy
| 15,987,286$/year Area of field for equivalent
| yield 6,333,272m2 Land Area Required for PV Array
| 4,157,293m2
|
| 1 https://www.pnas.org/content/pnas/suppl/2020/07/22/20026551
| 1...
| Johnjonjoan wrote:
| Appreciate this info. Thanks.
| coding123 wrote:
| I don't know who did the analysis on that, but this is easily
| fixed: Solar farming on top of the vertical farming. This pays
| for the electricity needs for the lighting, and any excess
| power pays off the solar panel prices over about 8 years.
| dehrmann wrote:
| Unless you're capturing lots of wavelengths plants can't use
| (definitely green, maybe IR?), why would you add an extra
| loss into the system?
| chipsa wrote:
| What excess power?
| coding123 wrote:
| Actually, you're probably right. However, in many markets
| you actually "make" more money by offsetting the price you
| would pay the utility. In my calculations, you get paid a
| fifth of the excess electricity than just using it (instead
| of paying the utility to use theirs). So when you're a
| heavy user, and you're in great solar area, every panel you
| add actually lowers your cost. So if you want, do a 4 acre
| solar farm for a 1 acre building, and over time this will
| pay for itself.
|
| Of course, this obviously depends on you making money on
| the wheat or other crops.
| tlb wrote:
| The amount of energy you get from an acre of solar panels is
| approximately enough to run grow lamps for 1 acre of wheat.
| But not for 10 layers times 1 acre of wheat.
| qppo wrote:
| Is that what it actually comes out to, accounting for the
| efficiency of current panels and what plants actually use
| in photosynthesis?
| unchocked wrote:
| It's not easy at all when you think about the amount of light
| required vs. the surface area available. In fact, it's not
| even thermodynamically possible.
| VMG wrote:
| imagine if we had invested more into nuclear power and 1/10th
| electricity prices
| pfdietz wrote:
| Magically cheaper nuclear powerplants, presumably built by
| the Nuclear Fairy.
|
| The cost of steam turbines and generators alone would prevent
| nuclear plants from producing power at 1/10th the cost of
| current plants. I don't think you're going to find a nuclear
| component of the plant that costs negative dollars.
| yazaddaruvala wrote:
| However, the study doesn't seem to include the costs of
| transportation. I wish they had looked at the wheat supply
| chain holistically rather than only cost per hectare.
|
| Building a close to the city, colocated flour, and/or cereal
| factory under the wheat farm, allowing gravity to help build
| automations would reduce holistic costs. I wonder if that makes
| this farming method profitable?
| ThomPete wrote:
| The cost of transportation is not even worth mentioning as
| long as we don't try to install some super expensive
| electricity grid.
| sacred_numbers wrote:
| Transportation costs are really not that high. Let's say that
| the farm is 2000km away from the city. Average freight cost
| per ton-km via truck is about 12 cents, so an additional
| $240/ton. Via rail it's about 3 cents, so an additional $60
| per ton. CO2 emissions follow a similar ratio, about 97 grams
| per ton-km for trucks and 22 grams for rail, so between 44
| and 194 kg CO2 per ton.
|
| Growing a metric ton of wheat with 100% supplemental light
| requires 150,000-400,000 kwh. That's $3,000 to $8,000 in
| electricity costs at 2 cents per kwh (very cheap) and would
| require electricity to generate about a gram of CO2 per kwh
| at the most to be better in terms of CO2 emissions.
|
| If you have free, non-polluting electricity it would be
| better to use it to synthesize fuel for trucks to carry grain
| from the fields, or to capture CO2 from the air.
| [deleted]
| jimkleiber wrote:
| I wonder how that electricity usage compares to bitcoin
| mining. And by wonder, I really wonder, as I have no idea.
| ssorallen wrote:
| "would be better"
|
| There are other inputs to growing outdoors: fertilizer
| usage, water usage, and insecticide/pesticide usage (likely
| not an exhaustive list). In a controlled environment like
| an indoor farm the use of each of those is dramatically
| less than in traditional farming. It would be worthwhile to
| include all of the inputs of growing food since light and
| transportation are not the full list.
|
| (disclosure: I work for an indoor, vertical farming
| company)
| gus_massa wrote:
| Yes, but does the reduction of the other cost win against
| the increase of cost of illumination? Do you have a table
| with an estimation of the cost in each scenario?
|
| Some back of the envelope calculations: From [1] the cost
| of fertilizer is like $150/acre and from [2] you can get
| about 7 tons/acre, so it's like $40/ton. The numbers
| change a lot from source to source, so let's multiply
| that by 2, and we get $40 of fertilizer per ton.
|
| So in the impossible best scenario where the indoor
| production saves you the 100% of the fertilizer, you save
| $40 per ton of fertilizer that is much less that the
| $3000 per ton of electricity for illumination.
|
| [1] https://farmdocdaily.illinois.edu/2017/07/fertilizer-
| costs-i...
|
| [2] https://www.seedcorn.com/resources/estimating-corn-
| silage-yi...
| qppo wrote:
| I think you should take this idea into 2nd/3rd order effects
| of continuous, controlled food growth that isn't hampered by
| weather or transportation costs.
|
| Immediate second order effect would be the obsolescence of
| grain futures, you don't need to hedge against a bad harvest.
| You probably also wouldn't need to go into debt to buy enough
| seed to plant each season.
|
| Another would be a more elastic supply chain without the need
| for storage/buffering, which we've seen drastically reduce
| prices and increase production for all sorts of widgets using
| just-in-time manufacturing. If you can scale up/down wheat
| production pretty reliably with only 70-80 days forecasting,
| you can eliminate a lot of the inefficiencies of the food
| supply chain.
|
| Sidenote, a _literal_ vertically integrated bakery would be a
| sight to behold
| memco wrote:
| You'd need to think of them less, but disasters that
| destroy the building or disrupt operations (fires,
| earthquakes, floods, etc.) still happen so there's need to
| be some redundancy and hedging.
| schemy wrote:
| It doesn't.
|
| The sun provides about 300W/m^2 on average at temperate
| climates, that's 7.2kwh per day. Wheat takes about 4 months
| to grow and nuclear power costs 0.77c/kwh.
|
| That's 665.28$/m^2 at wholesale.
|
| [0] https://ag.tennessee.edu/solar/Pages/What%20Is%20Solar%20
| Ene....
|
| [1] https://en.wikipedia.org/wiki/Electricity_pricing#Price_c
| omp...
| wrycoder wrote:
| They mention 70 tons per hectare. That's 1.43 pounds per square
| foot.
|
| To grow 1000 pounds would require an area 26 ft by 26 ft.
|
| For a product worth less than $1000.
|
| Counting space, heat, light, equipment - doesn't sound like a
| paying proposition.
| tonyarkles wrote:
| Less than $1000 _processed_. Around here, a 22lb sack of
| flour costs around $10. Looking at around $500 worth of flour
| there, assuming 100% of the wheat gets turned into flour (I
| think there is some waste during processing)
| rasmusei wrote:
| Some comments have already touched on this, but it is important
| to realize just how much electricity we are talking about. The
| tl;dr is that replacing US wheat production alone would use five
| times the current total US electricity consumption. And that's
| for wheat, occupying about 10% of US cropland.
|
| See p. 12 of the Supporting Information and you'll find the
| following: 2026647 kg wheat grown using 798417 MWh electricity
| means an electricity consumption of 0.4 MWh/kg wheat. In the US,
| the annual wheat harvest is 150-200 kg/capita/yr, which in this
| hypothetical system would use more than 60 MWh
| electricity/capita/yr.
|
| For comparison, the US annually uses around 13 MWh
| electricity/capita.
|
| That is, this hypothetical wheat production in the US would use
| about five times the _total_ present day electricity use.
|
| Soybeans and maize together occupy more than three times the
| wheat area in the US, so that (very roughly speaking) adds
| another annual electricity consumption of ~200 MWh/capita. With
| just these three major crops, the US would have to increase its
| total electricity consumption about 20-fold.
| the8472 wrote:
| So, as usual with all material problems, if we had unlimited
| free energy we could solve them.
|
| https://xkcd.com/1123/
| unchocked wrote:
| These studies are really interesting to think about for space
| settlements.
|
| Terrestrially, you're never going to get more efficient use of an
| acre of sunlight (~4 MW at noon) than you will with photovoltaics
| (~75% loss ~= 1 MW at noon) and conversion to artificial light.
|
| But it could totally work on some future Trantor with flying cars
| and fusion engines.
|
| * edit: another poster has dug into the appendix and concluded
| that you might be able to do about as good w/r/t land use with
| photovoltaics, presumably due to other factors affecting plant
| growth.
| trhway wrote:
| > you're never going to get more efficient use of an acre of
| sunlight (~4 MW at noon) than you will with photovoltaics (~75%
| loss ~= 1 MW at noon)
|
| green plants don't use the middle, thus they are green, of the
| spectrum - i.e. they use only 10-20% of the sunlight. So, very
| efficient photovoltaics (or other type of solar powerplant) ->
| electricity -> only red and violet LEDs may even beat the
| Mother Nature in efficiency a bit. Add to that various
| optimizations - for example with the LEDs you aren't limited by
| the Sun singular position in the sky and can shine light from
| all the needed angles, like no more leaves being in the shadow
| of other leaves, thus increasing the photosynthesis throughput
| of a given plant.
| afiori wrote:
| Some plants (like tomatoes IIRC) even have a better
| photosynthesis efficiency when the light comes from below.
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