A lot of us ag guys congregated in one particular dorm back in the Dark Ages, which made it very likely that you could join into a lively discussion about the future of the art and science of agriculture any evening in a commons area.
Some of us believed we would be doing a lot of farming indoors by now. I was open to the idea myself, because I was a cornucopian at that time, in terms of believing that technology would continue to provide us with cheaper glass, steel and aluminum, plus more efficient construction techniques as well.
But we weren’t engineers, and we didn’t really understand the problems involved in scaling up greenhouses to the sizes needed to run the necessary machinery indoors. We just assumed the engineers would make it possible to build such gigantic greenhouses.
Half a century later, it’s still impossible to produce any staple food in a greenhouse in competition with ordinary growers working outside. ( Staples almost by definition can be easily stored and shipped. Consider bananas, which can’t be stored , but they do last long enough to be shipped to market easily. Bananas are a true staple food only in the areas where they are produced. )
But it’s possible that a greenhouse revolution will come to pass, because with ever more people, and ever less good land and ever less reliable weather, the cost of growing staple foods conventionally may rise to the point that inside production is a viable option in some places, maybe a LOT of places.
Steel, aluminum, and glass are still expensive, and will be ever more expensive from here on out, considering the depletion of ores and fossil fuels and so forth, but on the other hand, we now have an incredible array of awesome new and at least potentially affordable technology available to RUN greenhouses, such as cheap electronic controls and automated or robotic equipment capable of doing almost all the work.
Depending on the “make an ass out of u and me” assumptions you start with, indoor production of some staple foods might happen in some places.
It works already for non staple tomatoes ( and a few other non staple crops) because the high cost of green house production is sufficiently offset by the cost of shipping and storing the crop, and because of seasonal shortages that result in high prices during the off season.
Let’s say you live in a rich country such as the UK, which is short of agricultural land, and you’re collectively worried about the costs and risks associated with importing a large portion of your food from now until ………..
If you were to go at it on the grand scale, it’s possible that producing some staple foods indoors will turn out to be a viable option. A military establishment large enough to guarantee access to imported food ain’t exactly cheap. Exporting enough stuff to pay for imported food may turn out to be a real problem in a world short of food but well supplied with cheap labor to make the junk that fills up stores and driveways these days.
I can visualize the UK having some super sized greenhouse operations up and running within the next few decades and producing SOME staple foods in them. It won’t work on the nickel and dime scale though, any more than renewable energy will save us using it on the nickel and dime scale. Lowering the cost of doing it will depend more on scaling up than any other factor.
It won’t just be greenhouse farmers that want robots and automated machinery, everybody will be wanting these tools, and I assume robots will be cheaper every year . Robots and or automation are cheap already, compared to human labor, in countless applications.
A hell of a lot of the expense associated with going indoors can at least potentially be offset by the simply ENORMOUS savings that are possible by way of using less water, less fertilizer, fewer or even no pesticides, avoiding lost production due to bad weather, and losses associated with shipping, storage, and marketing over long distances.
Just going indoors is enough to break the life cycle of most and potentially all of the major insect pests. If a given insect CAN reproduce in a greenhouse environment, once you have wiped it out once, you can usually KEEP it out, indefinitely, if you are a good enough manager with well constructed and well maintained greenhouse.
Various blights and rots will be problems, but these are problems that are manageable, and potentially more easily and more cheaply controlled in a greenhouse than outdoors.
Waste heat is available in staggering amounts, if we organize things so that super sized greenhouses can be located close to heavy industries. Sewage can potentially be treated in large part right INSIDE greenhouses, enabling us to recover most of the vast quantities of NPK ( the big three) and trace elements that currently wind up as water pollutants.
The cost of producing nitrogen is always going to be determined by the cost of energy more than by any other factor, and as energy gets to be more expensive………..
There AREN’T any substitutes for P and K, and there never will be, period.
Depletion is a hell of a problem that eventually must be dealt with, because the cost of producing these two will obviously go up as these resources deplete, as is the case with steel, coal, aluminum, etc. Recycling will be more and more attractive as time passes. It’s not the total quantity in the world, there’s a million times more iron and aluminum than we will ever use, ditto P and K. It’s the quantity that is easily accessible and affordable that counts.
The water consumption per unit of production in a green house can be and usually is only a very minor fraction of the quantity needed per unit of conventional production, because most of it can be recycled right inside.
I’m currently helping one of my cousins build a small ( about five thousand square feet) but state of the art greenhouse that will incorporate the production of tilapia with the water used for the fish being circulated thru the growth medium so the plants can suck up the nutrients excreted by the fish. There won’t BE any waste water, lol. There won’t be any pollution , and there won’t be any pests to amount to anything, because if he has an infestation, he can wipe it out in such a small space, and by keeping the screens in good order, and the doors SHUT, pests won’t get in very often.
If he gets the prices and production he expects, he will make some money, pretty decent money actually, in terms return on his investment, assuming he pays himself an arbitrary wage of twenty bucks an hour. Twenty bucks is decent money in this area, especially considering he won’t have any expenses he can’t write off, such as commuting to a wage or salary JOB working for the Man, and that he won’t have to kiss any ass excepting those belonging to his customers. If he scales up later, he can probably net a hundred k Yankee with only one or two helpers, assuming he can continue to get today’s prices for fresh organic farm raised fish and herbs.
But he’s not going to be selling potatoes and grain, lol.
Any staple, other than the fish, appears to be economically impossible for now, given today’s market prices, at least in this area.
Consider however that we will likely have perennial grain sooner or later. It will then be possible to run small simple robots on permanent tracks ( simple on tracks will be the cheapest option, probably) to apply fertilizers, plant as necessary, and harvest the crop. Such a farmer would still need a truck, but no tractor or combine. Roof supports can be close together, no need for wide open spaces, cutting the expense of the framing members that hold the roof up by as much as eighty to ninety percent.
Plowing and cultivation can be eliminated almost entirely. Pesticide applications can potentially go to zero, ditto herbicide usage. Most of us farmers tend to think of fungicides as a separate class from pesticides. We would likely still need fungicides and other chemicals to control blights and rots, but maybe not in any greater quantity than we use them already per unit of production.
With integrated management at the city level, sewage could be kept clean enough to use it directly, with very minimal processing, as fertilizer. The biggest problem would be making sure very little, other than number one and number two, go down the drains and into the sewers, because separating contaminants you don’t want in your irrigation slurry is either impossible using current tech, or prohibitively expensive.
Food waste could be kept in a separate garbage stream, and fed to poultry, or fish, with the production of the poultry or fish, (pigs or rabbits anyone ?) integrated with greenhouse management. Chicken litter is one of the very best fertilizers available, WHEN it’s available, lol.
The biggest single problem might turn out to be the need for artificial lighting to support around the clock and around the calendar production, so as to make the best use of the investment.
I can’t see any technical reason why, with some research, that it won’t be possible to use any surplus wind and solar juice to supercharge the lights anytime it’s available, but the lights MUST stay on at least a certain number of hours per day. Maybe one of the schemes to import solar electricity from the Mediterranean area will succeed , or maybe a new generation of nukes that are safer and cheaper will be available.
I forgot to mention all the near free heat that would be available in a city with a subway system if you simply feed the subway exhaust air into the greenhouse complex. It would already be CO2 enriched to some extent, lol.
A greenhouse built to cover the entire roof of a high rise building wouldn’t likely need any heat at all, other than what could be salvaged from the building’s ventilation system, if it were designed with that in mind.
I know of at least a couple of experimental greenhouses that have been built using a lot of duct work buried in the ground right under the greenhouse, with blowers installed for forced circulation. They stay warm enough to work ok even in freezing cold weather without any other source of heat except that from the earth itself, but the excavation and the pipe together cost a hell of a lot.
There’s no need to give up just yet, lol.
I banged this out about as fast as I can type, so some of it may be less than clear. I should have said high rise residential building for instance. Such buildings generally generate excess heat even in fairly cold weather due to the people and appliances and lights and so forth inside them.