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July 24th, 2020 at 11:20 pm

This former semiconductor factory is now the worlds largest indoor farm, producing 10k heads of lettuce per day


This indoor Japanese farm uses LED lights and hydroponics to produce lettuce 2.5 times faster, with just 1% of the water, when compared to an outdoor farm.

When we think about factories, and what we decry as “factory farms,” we probably don’t think very highly of them as being a key component in the future of agriculture, but if we can take what factories do best, such as use technology to build efficient production lines, and pair that with what nature does best, which is growing biomass from light and water and minerals, then growing food in plant factories starts to make a lot of sense.

Converting what were formerly industrial buildings into indoor farming operations, especially in urban areas and locations that aren’t conducive to year-round outdoor food production, could be an excellent reuse of existing resources (the buildings themselves, the infrastructure that supports them, and their locations in or near cities) to help build a more sustainable food system. And this sort of operation can be done in a way that’s both highly efficient and productive (PDF), in essence turning our ideas about industrial-scale factory farming on their heads.


In Miyagi Prefecture, in eastern Japan, plant physiologist Shigeharu Shimamura is showing how it can be done inside a former Sony Corporation semiconductor factory, using special LED fixtures and hydroponics to grow massive amounts of food in an incredibly space- and water-efficient manner.

This plant factory is now the world’s largest indoor farm lit by LEDs, and the 25,000 square feet operation is producing 10,000 heads of lettuce per day. Per day. Every day.

That’s a staggering amount of food, considering we’re not talking about an enormous plot of land, and because of the high-tech methods used by this indoor farm, crops can be grown 2 1⁄2 times faster than outdoors, with just 1% of the water, and a loss rate of just 10% of the produce (which can be as much as 30-50% of the plant biomass in conventional operations).

Part of the reason that Mirai, Inc., is seeing such efficient plant growth is due to special LED fixtures developed by GE, which are ‘tuned’ to emit the optimal wavelengths of light for growth. These LED lights were designed to be slim enough that they could fit inside the closely spaced plant racks, while also standing up in the high humidity environment, allowing for uniform lighting to all of the plants. All told, there are 17,500 of these LED lights across 18 plant cultivation racks, which are then stacked up 16 levels high in this indoor farm.

The farm also uses technology to tightly control the humidity, temperature, carbon dioxide levels, and the irrigation in the growing stacks, which is another key to their success in drastically reducing the water required to grow the plants, while also supporting maximum growth rates. When coupled with the advanced LED lighting, the operation can make the most of both day and night cycles, producing the optimal conditions for indoor food production.

“What we need to do is not just setting up more days and nights. We want to achieve the best combination of photosynthesis during the day and breathing at night by controlling the lighting and the environment.” – Shigeharu Shimamura

This plant factory could be a harbinger of a whole wave of new-school industrial agriculture, with the potential to add more food production near to where it will be consumed, and help boost at least one aspect of food systems in an efficient manner. And expansion is in the works, as Mirai and GE are said to be working on building more plant factories in places such as Hong Kong and Russia, about which Shimamura says “Finally, we are about to start the real agricultural industrialization,” which will feed 10 billion people.

On their own, these indoor farms aren’t going to feed everyone, and we’ll continue to need many farmers and quite a bit of farmland in production growing food outdoors with traditional farming, but these types of high-tech plant factories may be a key part of the much bigger puzzle of effectively feeding a growing population with the optimal use of one of our most precious resources, water.




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