How possible is economic autarky?

[FaxModem1]

Due to certain decisions made by current American leadership, with trade between nation's facing high tariffs and trade war, let's consider the opposite to globalization. Autarky, the idea of a nation being as self sufficient as possible in it's economic needs.

Could it be done by a modern nation? Could it be done by the US?

What all would be needed for it to be possible? How far would a nation have to go for it to be possible?

If not possible, what happens if a nation attempts it regardless of it being doomed to failure?

Discuss.

[madd0ct0r]

Well, holistically spealing, this entire planet is an autarky. We dont really import/export anything to the wider solar system. If i limited it to just Sealand, even allowing unlimited trade to build it up it doesnt have much in the way of resources. So autarky is possible, but The complexity possible is a function of scale - land and population.

For a specific country i usually pull out the trade atlas to see what they import. Not having native uranium deposits only matters if you use nuclear power, for example.

The next question is for substitution resources how much less effcient they are? We can grow tomatoes in the uk, but it takes a lot more resources then potaoes.

[Nicholas]

Of course it is possible for a modern state to exist without trade. It works better the larger and more self sufficient the state is. So the U.S. the E.U. (assuming that counts as a state for this purpose) or China would find it far easier then Luxembourg or Vatican City. There are two questions here. First, what is the minimum size at which a modern economy can function (Vatican City is certainly too small)? Second, how much efficiency do you lose by doing things yourself that others could do cheaper? I can only take the wildest guesses at answers to these questions but I would expect that Continental scale is probably the smallest a modern economy can operate without either some trade or severe inefficiencies.

There is also the question of transition costs, a move to autarky would require those industries that produce for export to close or retool and those industries that rely on imports to find local sources. That change will be disruptive in the short to medium term but survivable if the country is large enough to maintain a modern economy without trade.

By the way, when you say trade are you including information flow? If so then no autarky is not possible because knowledge is to easy to move for its movement to be stopped by something as inefficient as government.

Nicholas

[Broomstick]

Due to certain decisions made by current American leadership, with trade between nation's facing high tariffs and trade war, let's consider the opposite to globalization. Autarky, the idea of a nation being as self sufficient as possible in it's economic needs.

Could it be done by a modern nation? Could it be done by the US?

What standard of living are you aiming for?

Absolutely there are some modern nations that could do this, but if they did, they'd take a hit in their standard of living and definitely in imported luxuries. And some nations can't do it, because they are too small/too populated, or both.

What all would be needed for it to be possible?

A willingness to sacrifice a great deal to achieve the goal.

How far would a nation have to go for it to be possible?

Depends on what resources the nation has within its borders.

If not possible, what happens if a nation attempts it regardless of it being doomed to failure?

Famine. Also probably political unrest and/or revolution because people do not want off to starve quietly in a corner. They tend to get pissed before they get too weak to cause trouble/violence/revolution.

For example, North Korea has moved, or at least attempted to move, towards autarky. It's not a pure autarky, but close enough for today's world and to use as an example.

When things are going well people there have enough food to survive, adequate clothing, shelter, and some forms of education and entertainment. When things are not going well.... people starve. That, first and foremost, is the worst effect. Shelter, after all, tends to be durable and can endure for some time even with neglect and minimal to no maintenance. It won't be great shelter, but it will be enough to keep you alive. Likewise clothing, and it can be patched/mended/layered if necessary. Energy can be an issue - generating electrical power can be problematic, but provided you don't have so many people they strip the land of trees you could, if you had to, use things like firewood, candles, animal power (if you have sufficient fodder for livestock) and human muscle. Lack of food, though - a bad harvest, a flood, a wildfire, interrupted supply lines between country and city - that kills people. One of the big advantages of modern global trading is that it tends to even out the famine/abundance thing around the world. One disadvantage to the modern world in respect to the viability of autarky is that there are just too damn many people, and they're often highly concentrated. Tokyo can not be an autarky, as an example. Nor could Mexico City, New York, London, etc. They can be part of an autarky, but they'll need a lot of surrounding farmland with a low population density.

Continent-spanning nations could potentially be autarkies - the US, Australia, Russia, Canada.... but population density is a critical factor. Not just what the current density is, but what the geography can support. China has the same arable land area as the US (roughly) but can't be an autarky because there are just too damn many people. Not sure about Russia. The US might be able to do it. Canada could - they have a relatively low population for land area, abundant energy resources, and significant viable farmland as well as access to ocean resources. Getting tropical foodstuffs like citrus would be a problem, but while orange and lemons are nice they aren't essential.

Let's say the US tried to be an autarky. Food and energy resources are adequate, although we might have to go to more coal and more nuclear, and it might not be able to find enough petroleum within its territory to maintain current levels of gasoline and other petrochemical consumption. There are work-arounds, but they're more expensive. Transportation is going to be a lot more expensive for anything or anyone. In theory there should be enough land area, but much of the low-population-density territory is not considered desirable for habitation. I think the US could achieve autkary in food, but it would lose certain tropical items, all imported luxuries, and would probably have to shift some of the corn production to other foodstuffs. No sugar from sugar cane, but beet sugar is already a large industry, as an example. The biggest problem is that so much manufacturing has moved out the country... but given a bit of time that can be remedied. The biggest problem will be resistance from the population that is suddenly cut off from foreign goodies while other stuff is going up in price.

Basically, a nation that is a net exporter of essential items like food and energy is a potential autarky... but that doesn't mean folks living in such a place are going to have a lifestyle more fancy than, say, the Amish.

The UK could NOT be an autarky - too damn many people for the amount of available farmland. This stared them in the face during WWII, hence all the rationing and that was with stuff still coming in from outside. Any other nation with more population than their farmland could support (Japan, SIngapore, etc.) can not be a viable autarky.

[Zaune]

The UK could NOT be an autarky - too damn many people for the amount of available farmland. This stared them in the face during WWII, hence all the rationing and that was with stuff still coming in from outside.

Maybe if we stuck all the management consultants, advertising executives, telephone sanitisers etc. in a huge ark and sent them off to colonise somewhere else?

In all seriousness however, the percentage of our population we would need to... downsize by... to be fully self-sufficient in basic foodstuffs is not huge, if you define "self-sufficient" as "everyone achieves the minimum daily caloric intake to be healthy". This is vaguely reassuring when you look at our long-term demographic trends, but very much the opposite when you look at the company some of our politicians have been keeping lately.

[Jub]

@Broomstick: With regards to population and arable land, couldn't a nation hellbent on autarky crash build massive vertical farms during the transition period? Yes, this would be very expensive and probably use a lot of power to keep things properly lit and heated year round but it should be possible.

[madd0ct0r]

@Broomstick: With regards to population and arable land, couldn't a nation hellbent on autarky crash build massive vertical farms during the transition period? Yes, this would be very expensive and probably use a lot of power to keep things properly lit and heated year round but it should be possible.

You could do a conservation of energy check.
To produce 3000kcal is how many joules. Multiply by population. Double it to account for cooking storage and digestive inefficiency. Multiply by 25 to match the 4% efficiency of photosynthesis. Increase again for inefficiency of growlamps. That gets you the amount your grid needs to supply.
Triple that for high efficiency coal power. Triple again (location depending) for solar. Check against known insolation energy. Is it possible?

[Jub]

@Broomstick: With regards to population and arable land, couldn't a nation hellbent on autarky crash build massive vertical farms during the transition period? Yes, this would be very expensive and probably use a lot of power to keep things properly lit and heated year round but it should be possible.

You could do a conservation of energy check.
To produce 3000kcal is how many joules. Multiply by population. Double it to account for cooking storage and digestive inefficiency. Multiply by 25 to match the 4% efficiency of photosynthesis. Increase again for inefficiency of growlamps. That gets you the amount your grid needs to supply.
Triple that for high efficiency coal power. Triple again (location depending) for solar. Check against known insolation energy. Is it possible?

You're missing a lot of discounts in this assumption chiefly natural lighting and heating, passive water and nutrient recycling, using crop waste for fuel, and I'm sure there are others I'm missing. These vertical farms are going to have to be built to squeeze out every little efficiency if they're going to have a chance.

If you're this hellbent on going it alone, you might also be among the first adopters of orbital mirrors and/or solar panels to really give yourself a leg up on sustainable renewable energy.

[Steel]

@Broomstick: With regards to population and arable land, couldn't a nation hellbent on autarky crash build massive vertical farms during the transition period? Yes, this would be very expensive and probably use a lot of power to keep things properly lit and heated year round but it should be possible.

You could do a conservation of energy check.
To produce 3000kcal is how many joules. Multiply by population. Double it to account for cooking storage and digestive inefficiency. Multiply by 25 to match the 4% efficiency of photosynthesis. Increase again for inefficiency of growlamps. That gets you the amount your grid needs to supply.
Triple that for high efficiency coal power. Triple again (location depending) for solar. Check against known insolation energy. Is it possible?

To fill in your numbers, using the UK as an example:

3000kcal is ~12MJ (1.2e7 J for a days calories)

Feeding the UKs population of 70 million each day therefore takes 8.4e14 J / day

A crap solar panel at the northern latitudes the UK occupies can produce 0.5 kWh / m^2 per day on average ~ 1.8e6 J / m^2 / day

Total area of the UK is about 250,000 km^2 = 2.5e11 m^2

Total energy influx to the UK that could theoretically be harvested by solar: 4.5e17 J / day

So on pure energy terms, the UK receives about 500 times the energy needed to feed the population.

Throw in your inefficiency factors of 2 (food wastage) * 25 (photosynthesis) * 2 (lamps) and we still have a factor of 5 safety room, so we only need to cover 20% of the UK with solar panels (probably pick the south where there is better power density) to power a vertical farm to feed everyone.

This might be overkill, seeing as current conventional farming techniques are supplying 70%+ of what the UK needs to subsist without outside intervention, and if we convert some land from "nice" food to more calorie dense food then we could probably get by without covering everything with solar panels.

I chose the UK because it is a very densely populated country, and at an unfavourable northern latitude (solar is worse).

[Zaune]

Regarding vertical farms, George Monbiot has a few rather caustic things to say about the idea here: https://www.monbiot.com/2010/08/16/towering-lunacy/

A lot of his criticisms are more about Disckson Despommier airily glossing over the logistical details than the concept itself, but I think his central point is valid. Hydroponics uses a lot of power even if you minimise the use of artificial light sources, requires at least some agrochemicals unless you want to figure out how to apply the same methodology to livestock, and the start-up costs are formidable on a large scale.

[madd0ct0r]

@Broomstick: With regards to population and arable land, couldn't a nation hellbent on autarky crash build massive vertical farms during the transition period? Yes, this would be very expensive and probably use a lot of power to keep things properly lit and heated year round but it should be possible.

You could do a conservation of energy check.
To produce 3000kcal is how many joules. Multiply by population. Double it to account for cooking storage and digestive inefficiency. Multiply by 25 to match the 4% efficiency of photosynthesis. Increase again for inefficiency of growlamps. That gets you the amount your grid needs to supply.
Triple that for high efficiency coal power. Triple again (location depending) for solar. Check against known insolation energy. Is it possible?

To fill in your numbers, using the UK as an example:

3000kcal is ~12MJ (1.2e7 J for a days calories)

Feeding the UKs population of 70 million each day therefore takes 8.4e14 J / day

A crap solar panel at the northern latitudes the UK occupies can produce 0.5 kWh / m^2 per day on average ~ 1.8e6 J / m^2 / day

Total area of the UK is about 250,000 km^2 = 2.5e11 m^2

Total energy influx to the UK that could theoretically be harvested by solar: 4.5e17 J / day

So on pure energy terms, the UK receives about 500 times the energy needed to feed the population.

Throw in your inefficiency factors of 2 (food wastage) * 25 (photosynthesis) * 2 (lamps) and we still have a factor of 5 safety room, so we only need to cover 20% of the UK with solar panels (probably pick the south where there is better power density) to power a vertical farm to feed everyone.

This might be overkill, seeing as current conventional farming techniques are supplying 70%+ of what the UK needs to subsist without outside intervention, and if we convert some land from "nice" food to more calorie dense food then we could probably get by without covering everything with solar panels.

I chose the UK because it is a very densely populated country, and at an unfavourable northern latitude (solar is worse).

Im on my phone so cant pull up the decc 2050 spreadsheet but i think you're missing an inefficiency factor of nine or so on the solar. Scaling factors account for downtime for maintenance, transmission losses ect.
David McKay's "sustainable energy without the hot air" is a fantastic guide for the uk.

I think you're right on the farm numbers though. Assuming we can keep the fertiliser flowing from another energy source

[Broomstick]

The UK could NOT be an autarky - too damn many people for the amount of available farmland. This stared them in the face during WWII, hence all the rationing and that was with stuff still coming in from outside.

Maybe if we stuck all the management consultants, advertising executives, telephone sanitisers etc. in a huge ark and sent them off to colonise somewhere else?

You might want to keep some telephone sanitizers - they are actually useful for public health. A lot of stuff can get passed on telephones, like the common cold, the flu, strep....

In all seriousness however, the percentage of our population we would need to... downsize by... to be fully self-sufficient in basic foodstuffs is not huge, if you define "self-sufficient" as "everyone achieves the minimum daily caloric intake to be healthy".

Got some numbers on that?

[The Romulan Republic]

Sure its possible, if your system is built to be self-sufficient, and if you have a large population and large, resource-rich territory.

If, however, you are a modern economy that is reliant on many things you do not produce yourself but are accustomed to getting through trade, the process transitioning suddenly to autarky, or even significantly closer to autarky, is going to fuck you up.

Perhaps a better question is why autarky would be desirable. Sure, self-sufficiency can be advantageous, but a country that does not trade is one that is isolated from the world, and that's not really possible. The world will still come to you, sooner or later, in the form of global crises such as climate change, pollution, major wars, and refugees, and all you'll have done is isolate yourself from countries that otherwise might be your allies. Nor is it even possible for a country to achieve that degree of isolation, in my opinion, without being utterly despotic- say, banning all trade with (realistically, all interaction with) foreigners and instituting draconian border controls and punishments (in which case, there will still be a black market).

You're talking about achieving a degree of economic isolation even greater than that of North Korea, and I have a strong suspicion that that's not possible without being even worse than North Korea.

[Eternal_Freedom]

Perhaps complete autarky may not be completely desirable, but I can see some benefits to what I might term "semi-autarkic" - that is, self-sufficient enough to feed and supply your population with a certain minimum lifestyle, while still importing exotic and/or luxury items. If you can manage that then any large-scale crises that significantly disrupts global trade (a major conflict, a significant natural disaster etc) would have a much lower impact on your nation.

As another benefit, being "semi-autarkic" in the manner I describe above would make it a lot easier to protect your country from some sort of global pandemic - if you can feed and sustain a minimum lifestyle then simply closing the borders and enforcing a quarantine would have a much lower impact on your own population.

[The Romulan Republic]

That's reasonable, but any transition towards such a semi-autarky would still have to be gradual and carefully managed, to avoid severe economic disruption to the country in question and its trading partners.

[Zaune]

Got some numbers on that?

Not off the top of my head, other than the fact that roughly 40% of the food we eat is imported. I can't find any specific numbers on what percentage of that is lost to wastage, but it's large enough that a bill got passed making changes to how Use By dates are calculated to try and do something about it not so long ago. And that's before we get into the issues of inequality of distribution, or the amount of agricultural land that isn't in use because it's not commercially competitive.

But please note that I am not in any way suggesting that this is something Britain should attempt to do, because even if we maximised productivity by any means necessary and implemented a system of rationing at least as strict as during the last World War we'd still come up short. Maybe not 40% short, but still a very unhappy number.

And I'm not going to dig up all the figures necessary to calculate the exact number of people who would have to die before Britain could be fully self-sufficient in food, if that's all the same to you: In the present climate I think I'll sleep better at night for not knowing.

[Eternal_Freedom]

That's reasonable, but any transition towards such a semi-autarky would still have to be gradual and carefully managed, to avoid severe economic disruption to the country in question and its trading partners.

That's not in doubt, but I was mainly addressing your point about why autarky might not be desirable. It's obviously not something that can be done overnight, never mind whether it should be done.

It could be argued that semi-autarky as I mentioned would be the ideal for every nation - it still allows global trade but prevents any one nation from dominating trade in any vital commodity. Of course it isn't possible if we're including things like energy production, petroleum products (not just petrol or diesel fuel, but stuff like plastic and (IIRC) some medicines and pharmaceutical products) under "minimum lifestyle."

[Broomstick]

@Broomstick: With regards to population and arable land, couldn't a nation hellbent on autarky crash build massive vertical farms during the transition period? Yes, this would be very expensive and probably use a lot of power to keep things properly lit and heated year round but it should be possible.

You could do a conservation of energy check.
To produce 3000kcal is how many joules. Multiply by population. Double it to account for cooking storage and digestive inefficiency. Multiply by 25 to match the 4% efficiency of photosynthesis. Increase again for inefficiency of growlamps. That gets you the amount your grid needs to supply.
Triple that for high efficiency coal power. Triple again (location depending) for solar. Check against known insolation energy. Is it possible?

^ This.

Farming requires energy. Vertical farming will require more energy than naturally occurring farm fields. Where does the energy come from?

A nation like the US or Russia could potentially build more nuclear plants as they have the resources needed for that technology, but not everyone could. Does the UK have naturally occurring uranium depsits?

You're missing a lot of discounts in this assumption chiefly natural lighting and heating, passive water and nutrient recycling, using crop waste for fuel, and I'm sure there are others I'm missing. These vertical farms are going to have to be built to squeeze out every little efficiency if they're going to have a chance.

Can I mention that I have actually done hydroponics successfully on a shoe-string budget? I think that's the sort of experience that can give me a teeny bit of insight here.

"Vertical farms", by necessity, are going to require substantial power. You have to light the plants. You have to get water to the plants, which means lifting it against gravity. You'll need to renew/replace whatever growth substrate you use.

You COULD, in theory, use all natural lighting (probably lots of window glass and skylights) and rely on human muscle power to haul water and other supplies to where they're needed... but that's a lot of human effort every single day. The first set up my dad and I did involved lifting a gallon jug of nutrient fluid connected via tube to the growing trays above the trays of plants, letting it drain into the substrate, letting it sit for a bit, then putting the gallon jug on the floor and letting the nutrient fluid drain into the jug. Repeat several times per day.

You could do it. But your people will be spending most of their time and effort at just growing enough food to keep themselves fed.

Theoretically, you could also do it all with nuclear power, too, but there are a lot of obstacles towards achieving success with that.

The problem is that you need energy inputs, and no energy conversion is 100% efficient. In fact, not even close. There's no way to do vertical farming without a LOT of both energy and material inputs. Where do they come from?

[The Romulan Republic]

That's reasonable, but any transition towards such a semi-autarky would still have to be gradual and carefully managed, to avoid severe economic disruption to the country in question and its trading partners.

That's not in doubt, but I was mainly addressing your point about why autarky might not be desirable. It's obviously not something that can be done overnight, never mind whether it should be done.

It could be argued that semi-autarky as I mentioned would be the ideal for every nation - it still allows global trade but prevents any one nation from dominating trade in any vital commodity. Of course it isn't possible if we're including things like energy production, petroleum products (not just petrol or diesel fuel, but stuff like plastic and (IIRC) some medicines and pharmaceutical products) under "minimum lifestyle."

I'd probably mostly agree with that, though I don't think a lot of progress could be made for many, even most countries towards self-sufficiency in terms of energy production.

[Jub]

Can I mention that I have actually done hydroponics successfully on a shoe-string budget? I think that's the sort of experience that can give me a teeny bit of insight here.

That's why I specifically asked for your input in my first post in the thread.

"Vertical farms", by necessity, are going to require substantial power. You have to light the plants. You have to get water to the plants, which means lifting it against gravity. You'll need to renew/replace whatever growth substrate you use.

You COULD, in theory, use all natural lighting (probably lots of window glass and skylights) and rely on human muscle power to haul water and other supplies to where they're needed... but that's a lot of human effort every single day. The first set up my dad and I did involved lifting a gallon jug of nutrient fluid connected via tube to the growing trays above the trays of plants, letting it drain into the substrate, letting it sit for a bit, then putting the gallon jug on the floor and letting the nutrient fluid drain into the jug. Repeat several times per day.

You could do it. But your people will be spending most of their time and effort at just growing enough food to keep themselves fed.

Theoretically, you could also do it all with nuclear power, too, but there are a lot of obstacles towards achieving success with that.

The problem is that you need energy inputs, and no energy conversion is 100% efficient. In fact, not even close. There's no way to do vertical farming without a LOT of both energy and material inputs. Where do they come from?

I know that a vertical farm is going to be energy intensive and/or labor intensive but I think that, if push came to shove, we'd squeeze out better efficiency than is being calculated here.

For some level of fluid transfer perhaps you could use the waste heat from onsite refrigeration to convert water to steam and allow it to rise that way. You grow your least water-intensive plants at higher levels and try aeroponics at the very highest levels. You gene-mod the shit out of your plants, possibly even looking at pulling toxins out of cacti to make them edible.

You look at orbital power solutions, maybe just a few mirrors at first to get extra sunlight down to your plants and ground-based solar panels. Then later you go with space-based solar power. I'm not saying that it would be easy, or even desirable but a rich enough nation that wanted it could get it within 50 - 100 years.

[Broomstick]

I know that a vertical farm is going to be energy intensive and/or labor intensive but I think that, if push came to shove, we'd squeeze out better efficiency than is being calculated here.

Eh...

Here's the thing - with traditional agriculture you get the growth substrate for "free" (you may add fertilizers and other soil amendments, but the basic stuff is free, literally just lying out there). You get the water for free in the form of rain. You get the sunlight for free.

With hydroponics of any sort you have to deliver all that yourself.

You have to find a substrate, clean it (because fungal infestations will kill your plants), and load it into some sort of container. You will continually battle against fungus and algae infestations because there is nothing like a natural ecosystem with its check and balances. Everything else wants the free buffet your setting out for your food plants. This crap not only attacks your plants, it can clog up the tubing and pipes that make the rest of the set up work.

With interior plants you have an additional problem - plants have evolved to experience stress. If their stems are not flexed they fail to gain strength. One easy trick is to set up an oscillating fan to imitate wind. A traditional bonsai technique is to manual flex the plants' stems. If you don't do that - and sometimes even if you do - your plants' stems and stalks may not be strong enough to support them or their fruits/vegetables, resulting in breakage and failure to produce a crop. You might need little lattice cages to help the plants support themselves and someone it going to have to build and maintain those, and get the plants situated in them. So... either electric fans, or human labor again.

Then there is the problem of light - the roof/top floor can get adequate natural light, and maybe the sides (if other nearby structures don't shade them) but what about the interior core? You'll need artificial lights. How do you power them?
Where do you get them? Does your hypothetical nation have the means to make them? What sort of power generation do you have?

Hydroponics require more than water - every nutrient your plants require must be delivered by the fluids you use, and that means YOU must figure out what's needed, acquire it, and put it into solution. Well, OK, what the hell, ditch hydroponics - use dirt like in a green house, and engage in composting farm and kitchen waste. You'll still have to move water around, but you won't have the same issues with fungus and algae (although you'll still have to watch out for them), clogged plumbing, and chemistry. You'll still need growlights.

For some level of fluid transfer perhaps you could use the waste heat from onsite refrigeration to convert water to steam and allow it to rise that way.

If you have sufficient power for refrigerator why not just use that power to directly power pumps to move the water around?

You grow your least water-intensive plants at higher levels and try aeroponics at the very highest levels. You gene-mod the shit out of your plants, possibly even looking at pulling toxins out of cacti to make them edible.

Are cacti native to your autarky? (They're native only to the Americas, actually) Does your autarky have sufficient academic resources to develop a technology like gene modding?

Also, there are edible cacti already - the prickly pear has both edible fruit and edible "leaves", the pads. Actually, it's a whole genus of edible cacti that also go by names like sabra and nopales, Dragonfruit is another cactus product. There are others, too, but the Opuntia genus is probably the most cost-efficient.

I'll also point out that the biggest problem with cacti isn't toxins, it's the goddamned hair-fine little microspines an prickers you have to remove prior to eating.

You look at orbital power solutions, maybe just a few mirrors at first to get extra sunlight down to your plants and ground-based solar panels. Then later you go with space-based solar power. I'm not saying that it would be easy, or even desirable but a rich enough nation that wanted it could get it within 50 - 100 years.

There are, at most, 4 nations on the planet that on their own could potentially launch orbital mirrors. That would be the US, India, China, and maybe Russia - while the USSR could to it on its own the successor to the Soviet space program is a joint effort between separate nations now. If your autarky can't run a space program on its own it won't have orbital mirrors beaming power down to the surface.

Again - if most of your people are trying to grow food in those vertical farms who is going to have time to develop these new technologies?

[Steel]

A crap solar panel at the northern latitudes the UK occupies can produce 0.5 kWh / m^2 per day on average ~ 1.8e6 J / m^2 / day

Im on my phone so cant pull up the decc 2050 spreadsheet but i think you're missing an inefficiency factor of nine or so on the solar. Scaling factors account for downtime for maintenance, transmission losses ect.
David McKay's "sustainable energy without the hot air" is a fantastic guide for the uk.

I think you're right on the farm numbers though. Assuming we can keep the fertiliser flowing from another energy source

I believe I am using an all-in actual long term average generation rate for a solar panel in the UK here, so any such factors are already incorporated.

The DECC capacity factor is an average year round generation capacity of 10% of panel peak generation capacity.

This person's recorded data http://www.jaharrison.me.uk/Misc/Solar/index.html indicates he gets about 1MWh per year per kW of panel capacity, which is a capacity factor of 11.5% in southern England, so the DECC figure looks good.

In the UK a 1kW solar installation is 6 m^2, so this looks like a nominal power density of 166 W / m^2, and therefore an effective average power density of 16 W / m^2. This scales up to 1.38e6 J / m^2 / day, so about 20% less than my original figure, however nowhere near a factor of 9.

If we did need an extra factor of 9, then it would be impossible to produce the current 70% of the UK food needs by conventional farming.

[madd0ct0r]

A crap solar panel at the northern latitudes the UK occupies can produce 0.5 kWh / m^2 per day on average ~ 1.8e6 J / m^2 / day

Im on my phone so cant pull up the decc 2050 spreadsheet but i think you're missing an inefficiency factor of nine or so on the solar. Scaling factors account for downtime for maintenance, transmission losses ect.
David McKay's "sustainable energy without the hot air" is a fantastic guide for the uk.

I think you're right on the farm numbers though. Assuming we can keep the fertiliser flowing from another energy source

I believe I am using an all-in actual long term average generation rate for a solar panel in the UK here, so any such factors are already incorporated.

The DECC capacity factor is an average year round generation capacity of 10% of panel peak generation capacity.

This person's recorded data http://www.jaharrison.me.uk/Misc/Solar/index.html indicates he gets about 1MWh per year per kW of panel capacity, which is a capacity factor of 11.5% in southern England, so the DECC figure looks good.

In the UK a 1kW solar installation is 6 m^2, so this looks like a nominal power density of 166 W / m^2, and therefore an effective average power density of 16 W / m^2. This scales up to 1.38e6 J / m^2 / day, so about 20% less than my original figure, however nowhere near a factor of 9.

If we did need an extra factor of 9, then it would be impossible to produce the current 70% of the UK food needs by conventional farming.

um, conventional farms don't have a solar panel in the way of the leaves My farming relatives would pick a fight with me over this approach anyway as it ignores tempreture bands and consquent protein reduction but meh, we chosee 3000kcal for a reason

I think my factor of nine was a misremembered version of the DECC capacity factor of 10%, so yeah, you all ready incorporated it conceeded.

[Feil]

Unless Bugs Bunny is cutting off the rest of the world with a handsaw, you're somehow going to have to stop illicit trade, for which there will be huge incentives and unlimited markets. And then you're going to have to keep yourself from getting Matthew C. Perry'd when your country inevitably falls behind the rest of the world technologically.

[The Romulan Republic]

Yup. As I said: complete economic isolation basically means you become North Korea on steroids.