Interestingly, in the three weeks since I posted the parent post, I've been thinking loosely on how I'd like to design #VerticalFarms. And I'm leaning more and more towards #EcosystemInABox more than #IsolatedGrowChamber.
I'm imagining a building designed for passive heating, so it'd be able to maintain a 20°C - 25°C temperature range* with minimal energy input (ideally no energy input towards heating).
The grow environments would have artificial lighting optimised for photosynthesis.
If passive heating and optimised light sources are possible, I'm hoping it would be feasible to have planting area be larger than the dedicated solar cells necessary to run the complex. Lights could maybe be dimmed or off for long periods where plants doesn't need photosynthesis, saving even more energy then.
And if the planting area is stacked on top of itself, the solar cells could be the roof of the complex, and we'd ideally have a food source more efficient than an equal open-air field.
But to be clear, I haven't done any energy calculations or ecosystem studies, so there might be variables I don't know about or some numbers might be off by an order of magnitude, making all of this impossible.
But I dream.
@zatnosk In general, I don't think you can get more light out of sunlight by using solar panels instead of windows, so this sounds difficult to me; definitely good to use roof/wall space for growing, though.
Maybe running supplementary lights would be an application for wind or water electricity generation, though.
@artsyhonker but there's the difference that plants only use some of the light for photosynthesis, so if we capture all the light and emit the energy at the wavelengths the plants are good at absorbing, it could theoretically be possible to let the plant use more of the energy from the sun.
Plus it'd give us control over when the light is given to the plant and how much at a time.
@zatnosk for more information on the actual numbers you might like to look at forums where people discuss growing e.g. tomatoes, marijuana, etc -- there will be people who have tried this. The marijuana folks especially will know about optimum artificial lighting.
Also I think some Dutch farms are basically giant glasshouse robot hydroponics things, that are producing food at a price that's competitively viable on current markets. Economies of scale there!
@zatnosk Meanwhile, a sort of semi-hydroponics often called "self-watering" is gaining popularity. Even IKEA sell kits, with options to enclose them, though those aren't automated. Miracle-Gro sell automated kits, but they still aren't enclosed, and the plant plugs are proprietary and expensive (but totally refillable, I should think).
My questions around that are, again, disease control; and soil micronutrients. We haven't even worked out truly optimum nutrition for humans yet.
Sunbeam City is a solarpunk instance.