TED fellow Viraj Puri talks about his Brooklyn rooftop farming startup. Gotham Greens has ~1500 square meters of hydroponic greenhouses producing herbs and salad greens in a very controlled environment… somewhere between a farm and a manufacturing facility. The system is solar powered, and can operate all year long. They currently produce ~100 tons of food a year, and they believe the business is viable at least in the urban foodie context. I was happy to see Puri readily (repeatedly) admitting (or even pointing out) that the system cannot scale up sufficiently to provide a large proportion of the city’s overall food requirements. This is in stark contrast to the idea of Vertical Farming, which is clearly bunkum — once you’ve covered the roofs with greens, there’s no more farming to be done unless you pipe in light somehow, which is much less efficient than simply farming where the light is naturally.
Just out of curiosity… I wonder how much food could be produced in Brooklyn at full capacity? And roughly how much does the city eat? The land area of the borough is 183 km^2 and it has 2,500,000 residents, or roughly 75 m^2 per person. Their production of 100 tons/1500 m^2 is roughly 66 kg/m^2 per year. So if the entire area of Brooklyn were producing like this greenhouse, you’d get nearly 5000 kg of food per person per year. The average American consumes about 1000 kg of food per year, so if you were able to use 20% of the borough’s area, you’d be close to meeting demand… at least by mass. Gotham’s 59kW solar array probably takes up ~590 m^2 (100 W/m^2 is typical of solar cell power production) and only provides part of the operation’s power. Probably there’s other infrastructure too that’s not actively producing food, so say they’ve got about half their total area dedicated to actual plants… then you’d need to get up to 40% of the land area being utilized to get 1000 kg of greens per resident per year. However, most of the 1000 kg that we actually eat is a lot more energy dense than lettuce. I wonder how many calories per m^2 one can get out of these setups, and what the most productive crops would be? Honestly I’m surprised at how large the potential production is. I wonder what the actually available rooftop area is?
I’m not sure what to make of our willingness to participate in the terraforming of the Earth. To explore it, I’ll consider an alternative history in which Antarctica was marginally habitable, and colonized a million years ago by woolly hominids who developed a Yeti civilization. Our whaling vessels meet up with them in the 1820s, but it’s so cold down there that nobody feels the need to molest them except for few hardy anthropologists, the occasional overzealous missionary expedition, and the usual cohort of scientists who will study the ends of the Earth, no matter how inhospitable. Inevitably, the Yeti spend some late nights with the scientists in their hot tubs watching the aurorae.
They get to talking about the magnetosphere, some atmospheric physics, and the geology of their ice-clad homeland. One day they decide their lives would be better if they could inhabit the entire continent, instead of just clinging to the coastal fringe, and so with the help of some misguided sympathizers, they develop a vast clandestine industrial complex pumping long-lived fluorinated super greenhouse gasses like CF4, C2F6, and SF6 into the atmosphere to warm things up. These compounds are vastly more powerful warming agents than CO2 and methane. They are also long lived atmospheric species, sticking around for up to 50,000 years. If a serious industrial complex were set up to produce and release them en masse, they would close a good chunk of the atmosphere’s thermal infrared window and radically alter the climate for tens of thousands of years. This atmospheric engineering could be done over the course of an election cycle, especially if the Yeti bastards had help from the cold-hearted Canucks and Russkies.
Would the G-20, the OECD or the UN Security Council stand by while a rogue Yeti nation threatened the billions of people who live in coastal cities, or depend on glacial water supplies, all in the name of Manifest Destiny? Of course not. We’d be more likely to bomb their furry white asses back into the Ice Age.
Continue reading The Yeti Homeland Project
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Continue reading Links for the week of June 17th, 2010