jmgreen

Jason here, CEO at Edenworks.

Roof load is a question we get a lot, and it turns out not to be a dealbreaker if you can distribute weight on the building's columns effectively. Our next greenhouse will be ~ 110 lbs/s.f., which is heavy but nothing a little dunnage can't deal with. On a side note, a research team at Columbia conducted this awesome study showing there's over 5,000 acres of rooftop space feasible for urban farming in NYC (also recommended for any ArcGIS fans): http://urbandesignlab.columbia.edu/files/2015/04/4_urban_agr...

Regarding grains and legumes, you're right and I wouldn't recommend rooftop aquaponics for it - you simply need too much land. I do believe however that urban aquaponics can play a bigger role in supporting a growing, global middle class, which is consuming more vegetables and protein and is especially sensitive to food safety in some regions.

Jason here, CEO at Edenworks.

Sweet potatoes, soybeans, and wheat are very much the purview of traditional big ag. They're highly commoditized, which actually makes them not very valuable. Compare a pound of flour (not even wheat crop itself @ $0.50 retail) to a pound of salad greens ($10-15 retail) or a pound of basil ($15-45). The reason the latter products are so expensive is because they're delicate. They don't travel well, have high shrink rates, and can be premiumized due to freshness. On a unit basis, fresh and highly perishable foods are the high value food. They're also the most nutritious.

I'm Jason Green, CEO at Edenworks. And aquaponics evangelist. Here's why we think aquaponics is the best solution to global protein (and vegetable) production.

Tilapia are protein producing machines. They convert 1.1-1.3 lbs of feed to 1 lbs of protein in 9 months (some factors like temperature, feed rate at different stages of life, and other things affect this ratio). But here's the real kicker--by providing the nitrogen that crops need, the crops can then turn CO2 into into calories via photosynthesis. Super high quality produce becomes the extremely valuable byproduct, effectively, of aquacultured seafood.

From a global net energy perspective, this is huge. Where do you think that nitrate fertilizer for soybeans is coming from? The Haber-Bosch process is crazy energy expensive. Growing soybeans for protein also has huge environmental costs--see deforestation in Brazil for details. 80% of cultivable land on earth is already in use, but food production needs to increase by 70% by 2050. Protein production will need to double due to the rising global middle class. And that middle class wants fish.

On top of all that, there's the fact that people don't want to eat just soybeans for protein. There's now more seafood consumed globally than beef cattle. By 2030, 62% of all seafood will be aquacultured, and there are some suggestions that most of the wild seafood species we know will be either extinct or heavily depleted.