cross-posted from: https://lemmy.world/post/1443397

With office usage hovering near 50 percent of pre-pandemic levels, cities are putting the underutilized space to new use growing food

  • @sauerkraus
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    11 months ago

    Tractors use a lot more energy than LEDs while running. But you can operate LEDs indefinitely. So the source of the energy would be important.

    • @[email protected]
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      11 months ago

      No, it’s not even close. According to that link I posted, growing 1m2 of wheat costs 2,577 kilowatt-hours of electricity. 1 gallon of gasoline has 33.7 kilowatt-hours. That single 1m2 of wheat used the energy equivalent of 76 gallons of gasoline, and that is for a single pound of flour. LEDs are efficient, but vertical farms require extraordinary amounts of them to be on 24/7, whereas a single farm can use one tractor.

      You can just look up how much fuel farms use. The general rule of thumb for cereal crops is 2 gallons per acre per season, and that includes planting, the maintenance, and the harvesting. Multiple that out, and you get that vertical farms use 157,827x more energy. That is 5 orders of magnitude. To put that in perspective, the distance across the US vs the distance to the moon is only two orders magnitude difference.

      edit: In case you don’t believe lowtech magazine, here’s another source. https://ifarm.fi/blog/2020/12/how-much-electricity-does-a-vertical-farm-consume

      It claims that vertical farms use 57.35 kWh per square meter per month for the lowest possible energy consumption crop, lettuce. This is an astounding amount of energy. That is 1.5 gallons of gasoline per month per square meter for lettuce. If you want to grow strawberries, it almost triples. That still comes out to 3-4 orders of magnitude, depending on the crop.