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The Future of Food on Urban Rooftops

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Re: The Future of Food on Urban Rooftops

#21

Post by ChuckMcM »

This makes a tacit assumption about roof loading, which, by default, cannot support the load of an aquaponics installation (the logical choice). The ability to source some greens locally is useful, but as many have pointed out the win comes when you can locally source something like rice or beans. The water requirements for rice make it especially heavy on a per square foot basis. The folks in Watsonville [1] were trying it on flat ground first, it doesn't seem they were successful [2]

[1] http://www.santacruzsentinel.com/general-news/20130810/futur...

[2] http://www.viridisaquaponics.com/

Re: The Future of Food on Urban Rooftops

#22

Post by ilaksh »

thaumasiotes wrote: post #16
ilaksh wrote: post #13

Maybe work on high tech ways to grow high value foods like sweet potatoes, soybeans and wheat indoors. Aeroponics with additional support structures maybe.

Are these techniques likely to be all that different from the techniques used to grow marijuana indoors? I was under the impression that a decent amount of R&D already went toward this.

There is a fair amount of R&D for indoor growing, but not much emphasis on those high-value foods, especially for the most advanced techniques like aeroponics. And marijuana growers don't have the same goals in terms of energy efficiency or cost-effectiveness.

Re: The Future of Food on Urban Rooftops

#23

Post by asciimo »

Aquaponics proponents rarely mention that you have to feed the fish. The fish are essentially filters that reduce other matter (mostly other fish) into nitrates. An efficient system would remove these inefficient filters and add nitrates directly to the soil.

Yes, you can eat the fish. But it takes 240 days to raise (feed) a tilapia to 1 lb of weight. There are cheaper and faster sources of protein. For example, soy beans take 45-100 days and yield .25lb of pods per plant.

Re: The Future of Food on Urban Rooftops

#24

Post by legulere »

beambot wrote: post #2

Conventional wisdom says each person requires ~1 acre (43k sq-ft) to source enough foodstuff for themselves. With two people per 1k sq-ft apartment... you need ~100-fold improvement over the conventional wisdom to get full 100% sustainability. So let's assume you can magically get 10x gains in "land use" efficiency, and that you can stack those units 10 levels high (piping 1/10 of the 1kW/m^2 solar incidence to each…

Not all food is equal. Most of the acre (~4k m²) is needed for high energy crops like wheat or rice. It's pretty efficient to transport those into the cities. They can be stored pretty long and are pretty robust for transport. They're also pretty low price. Vegetables and berries are way more interesting as they're the opposite of all those factors.

Re: The Future of Food on Urban Rooftops

#25

Post by giltleaf »

boxcardavin wrote: post #11

You're losing a lot (if not all) of the efficiencies of growing outside urban centers. The efficient distribution and consumption of irrigation water and fertilizer is more of a cost ($ & CO2) than the final transportation of food to consumers. This is likely feel-good solution that produces great food, but not net savings to consumers or society.

Consumption of irrigated water actually plummets with aquaponics (article cites 90% less water use), and, depending on the system, may not even need any fertilizer at all since the fish manure is circulated. You still have to feed the fish, true, but often that is supplemented with byproducts of the final produce production and is not as environmentally damaging as artificially produced nitrogen fertilizers (agriculture standard) anyways.

So, quite frankly, your statement that the efficient distribution of water is fertilizer is more is just wrong.

I'm not saying the tech is perfect or that it can't improve, but if even a fraction of the research dollars were put into this as is put into traditional/industrial research and development, I think aquaponics (especially when designed vertically) will outpace it easily.

I will note that this isn't true for many staple crops like corn, soy, or wheat. But that's not the point. You would need to compare specialty crop production, not commodity crop production.

Re: The Future of Food on Urban Rooftops

#26

Post by giltleaf »

asciimo wrote: post #23

Aquaponics proponents rarely mention that you have to feed the fish. The fish are essentially filters that reduce other matter (mostly other fish) into nitrates. An efficient system would remove these inefficient filters and add nitrates directly to the soil. Yes, you can eat the fish. But it takes 240 days to raise (feed) a tilapia to 1 lb of weight. There are cheaper and faster sources of protein. For example, soy…

Aquaponics critics rarely mention that you can often close much (though not all) of your production loop by feeding the waste products from the final produce back to the fish. And with tilapia (and to a lesser extent catfish), feed sources are trending in the direction of insect meal, which has a super efficient protein conversion rate.

Soy is probably more efficient, but soy is not fish and soy does not promote the healthy growth of other specialty crops like lettuce etc.

But, if you have a study that talks about the efficiency of nitrogen added directly versus the nitrogen that comes from the fish, or how it differs, I would be super curious to read it.

Re: The Future of Food on Urban Rooftops

#27

Post by thecolorblue »

mkent wrote: post #4

On the opposite end of success we have a rooftop greenhouse in Vancouver being sold on craigslist: http://www.cbc.ca/news/canada/british-columbia/craigslist-va... ( http://vancouver.craigslist.ca/van/bfs/5133023654.html ).

Is this related to verticrop on kickstarter: https://www.kickstarter.com/projects/verticrop/verticroptm-t...

Re: The Future of Food on Urban Rooftops

#28

Post by logfromblammo »

beambot wrote: post #2

Conventional wisdom says each person requires ~1 acre (43k sq-ft) to source enough foodstuff for themselves. With two people per 1k sq-ft apartment... you need ~100-fold improvement over the conventional wisdom to get full 100% sustainability. So let's assume you can magically get 10x gains in "land use" efficiency, and that you can stack those units 10 levels high (piping 1/10 of the 1kW/m^2 solar incidence to each…

For caloric sufficiency, you're probably growing sweet potato or potato, at 70 Mcal/ha-day and 54 Mcal/ha-day, respectively. For a 2 Mcal/person-day diet, that's a minimum of 0.03 ha/person, or about 0.07 acre/person eating sweet potato. For potato, 0.04 ha/person, or 0.09 acre/person.

(http://www.fao.org/docrep/t0207e/T0207E04.htm)

Assuming at minimum that hydroponics provides 2.5x normal yield, and aeroponics 3.5x normal yield, one person eating exclusively aeroponically grown sweet potato would need 880 sq.ft. dedicated grow area, or 1.75x the example's (500/person) apartment floor area. If you can stack 4 levels of plants on one floor, that's still 1/3 of all building volume that would have to be occupied by growing plants.

Bear in mind that 2 Mcal/person-day is only enough to sustain children and little old ladies.

So ultralocal farming is probably not going to meet 100% of the needs of a building's residents without some extreme change in the way we design residential buildings. What you really want to grow on your roof is flavorful, nutrient-dense foods that are not quite durable enough for long-distance shipping. Then you ship the durable, bruise-resistant commodity staples from actual farms.

You eat your potatoes shipped in from the farm garnished with fresh green onion from your rooftop. You get your durum noodles from elsewhere, and eat it with sauce made from your rooftop tomatoes and herbs. Truck in the dry solid foods from far away, and grow the wet squishy foods as close as you can to your plate.

Re: The Future of Food on Urban Rooftops

#29

Post by soylentcola »

This article is about much larger scale stuff but it's interesting timing since we're about to put a roof deck on our townhouse (flat roof) and I've been researching some of the various "DIY EarthBox" plans out there.

My goal isn't so much to become self-sustaining by starting a rooftop farm but we'll have this big, flat, sunny area and I'm thinking if I put these or some other type of quality container garden around the perimeter, I can have a bunch of fresh vegetables during a good portion of the year and also make it feel a little more like a garden than just a hot, sunny, wooden platform in the middle of a city.

Any suggestions or experiences with this stuff? I've done smaller bucket type container plants on the patio but I'm interested in this for aesthetics, food production, and just for the learning experience.

Re: The Future of Food on Urban Rooftops

#30

Post by fweespeech »

slapshot wrote: post #20
dicroce wrote: post #19

Earlier quoted context omitted.

Also roofed in gardens don't need pesticides...

You have clearly never dealt with a spider mite invasion. They. Are. Everywhere. They routine infest indoor houseplants, even in places you wouldn't expect. They'd find their way into a roof garden. And because most predators require a wider range than most prey, there may not be as many natural predators available. Commercial greenhouse growers definitely try to isolate their plants from invasion, but still rely on…

http://www.amazon.com/000-Live-Adult-Predatory-Mites/dp/B00I...

Predatory mites work fine if other mites are the only problem. They aren't particularly expensive either.

But yes, you can't use natural predators. You basically need to introduce them, let them do their jobs, and then most of the predators will die once the problem is controlled for.

But give its a $50 problem, its not a very expensive problem and on par with pesticide costs.

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