Solar requirements for raising plants limits use of solar collectors for other uses in the same space. Energy is lost in conversion; therefore it’s more efficient to use it directly without conversion, and the use of PV collectors and LEDs to grow crops in dark rooms is silly.

Perhaps all this farming could take place on the uppermost floor of buildings, making use of transparent roofing and the heat already generated within the building to increase productivity; also the South sides of such buildings could be made to collect more energy, but only to the extent that they are not shaded by buildings still further south. But urban farming and PV systems are on a collision course.

You can look up the Solar road project in Idaho, a possibility, and wind generators will still allow most of the sunlight to pass through; but solutions will need to be found which consider the entire system before a truly integrated and sustainable urban environment can come to pass.

While urban farming may make a valuable contribution to fulfilling the needs of a city, it seems more likely to me that outlying areas will still supply resources to cities in the future, until cities themselves become more dispersed, perhaps occupying the non-arable areas, in contrast to the current trend of paving over the most productive farmland to create cities. Unless we are willing to use nuclear or some other problematic power sources to supply those LEDs with the energy to grow our food.

There is simply no way to feasibly supply that much energy.

Ask the marijuana factories — their highest cost is electricity for light and heat — and this is their downfall as well, as the drug squad simply taps the electric companies records for excessive users.

This proposal is innumerate – it fails to calculate the actual total energy needs of such a system against costs. May be feasible–if there is ever a population that would actually accept Factory Food–if we had access to free unlimited electricity from cold fusion plants–and about as likely.

These downsides are not drop deads, but strongly suggest that the actual energetics and yields of these systems will be considerably less than what is currently being projected. Pinching and squeezing every bit of useful energy possible from the system may result in apparent high efficiency, but entropy and gravity are merciless task masters.

As for the vision of modular food producing factories being deployed to war and disaster hit regions, this is truly ludicrous. The reason why the local food producing systems in these areas are not functioning is because they’ve been disrupted or there is a lack of security. Those problems won’t disappear just because a shiny food producing widget is parachuted in.

“For every acre of land cultivated in a high-rise urban farm, 10 to 20 acres of current cropland could go wild.”

The best analysis I’ve seen suggests that the opposite may be true. A more likely summary might read,

“…for every acre of land cultivated in a high-rise urban farm, 10 to 20 acres of current wild lands would need to be converted into biofuel crops and wind farms to keep the lights on for the silly thing…”

A good breakdown of the energy requirements for this concept compared to alternatives is posted at the energy farms blog:

http://energyfarms.wordpress.com/2010/12/02/energy-and-vertical-farms/

Well worth a read.

Also worth looking at for more good discussion of the topic:

“Vertical farming: does it really stack up?” (the Economist, Dec 2010)
http://www.economist.com/node/17647627

“Greens living in ivory towers now want to farm them too” (the Guardian, Aug 2010)
http://www.guardian.co.uk/commentisfree/2010/aug/16/green-ivory-towers-farm-skyscrapers

All the energy use you discuss in you first comment is already happening, in food transport, irrigation, and countless other demands of modern agriculture. The point of this system would be to lower OVERALL energy demands, even though growing food would still be energy intensive.

Your alternative, urban farming, does not produce anywhere enough food to support the energy demands of a city. It will never be able to because there is simply not enough space…unless you start stacking farms on top of each other. High rises such as these would be local and they COULD be managed organically.

Ultimately my point is that in a real world you look for real solutions, not ideal solutions. There will always be trade-offs. Agreed problems should be carefully examined before proceeding, but we can’t let fear of change freeze our infrastructure in it’s current state.

[WORDPRESS HASHCASH] The poster sent us ’0 which is not a hashcash value.

“The energy to run all these systems could come from wind, solar, or geothermal sources where feasible. Elsewhere, waste—including the inedible portions of crop plants—could be burned for energy or digested into methane”

This sounds VERY resource intensive to me, and almost assuredly without the benefits of outdoor gardening that can increase (rather than decrease) the nutrition of vegetables.

Also, are wind, solar, or geothermal fields “wild”? Rather than converting swaths of farmland to fields of solar panels or wind farms, why don’t we keep them heading to the right path: of organic produce produced for local markets (there are such things as urban farms) so that our food products can both benefit from the variability of the great outdoors and also benefit the micro-ecosystems that live in them.

Finally, the only good reason I can see for this kind of agrodevelopment is a potential nationwide food shortage. Revolutions in agriculture, such as biointensive, biodynamic, and permaculture techniques, can be applied to systems to revitalize and replenish the degradation of soil and resources, by using a fraction of the input (and a fraction of the START-UP COSTS) that traditional agriculture or a farming building would require.

I think a much more helpful move would be for universities, nonprofits, and the federal system of governments to help fund these local small-scale diverse, organic and very efficient farms than to funnel hundreds of millions of dollars in more skyscrapers.

Some Food for Thought: http://permaculture.org.au/2009/12/11/greening-the-desert-ii-final/

Best wishes for all of us.

This is a very nice idea in concept, but as with any innovation, it is important for developers and designers to consider critical input before making any steps toward this sort of food future. Only 8 paragraphs in, and I have already found two assumptions that sound very tantalizing and are very false. To assume that “there would be no further need to burn fossil fuels” to create skyscraping “vertical farms” or to pump water and nutrients against gravity to a height of 80 floors is preposterous. Cities are a very big user of fossil fuels, and urbanizing our food would not change this. Also, to assume that “indoor” space does not take up “outdoor” space to be made is a fallacy. These are just two very apparent false assumptions outside of the many potential philosophical and ecological problems (such as increasing the separation between humans and outdoors, or presuming that no one lives in rural communities and would not be allowed to) that can arise from this.

On the other hand, the idea has its merits. Proceed with great caution.