Japanese plant experts produce 10k lettuce heads a day in LED-lit indoor farm
independent.co.uk
independent.co.uk
Unfortunately, growing lettuce isn't going to keep any people alive if drought, crop failures or natural disasters occur, since lettuce is mostly water by weight and has low amounts of macronutrients (2.23g carbs and 1.35g protein per 100g lettuce).[1] I wonder how much harder it would be to produce crops like rice or beans indoors?
[1] https://en.wikipedia.org/wiki/Lettuce#Nutritional_content
But land is, particularly arable land, and particularly in a country like Japan. You can see for yourself in the picture that they have ~15 tiers of gardens, compared to a maximum of two or three when using sunlight. And sure, you could probably devise some method of piping and reflecting sunlight through to the lower tiers just to avoid consuming electricity, but then it wouldn't work at night, wouldn't work as well in winter, and so on.
Water is though, especially water that is fit for food production. This process (and others like it) makes a huge improvement on the amount of water required in comparison to traditional outdoor farming.
>The lights give them the ability to control temperature, humidity and irrigation, allowing it to cut its water usage to 1 per cent of that needed by outdoor fields, while also growing lettuces two-and-a-half times faster, the experts claim.
If you could capture all the energy from the sun with a solar panel from the future, then it could power many more lettuces if you transformed all that energy into the important wavelengths rather than waste it in heating the floor and making leaves look green and pretty to the human eye.