So to grow the crops indoors we need to use at least 2.5x as much land.
The sun is not a source of emissions, so why spend time and money replacing it?
I've heard that 1 m^2 of modern solar panels will support >1 m^2 of a low-light crop (like lettuce, unlike grain) under modern LEDs. I haven't done the math myself, and this obviously varies with climate. I think vertical farms (growing entirely by artificial light) are still uneconomic vs. greenhouses almost everywhere, per my other comment here. Supplemental artificial light in a greenhouse is of course highly economic in many climates, and Dutch growers have been using it for decades.
The cost to heat or cool a vertical farm should be lower than for a greenhouse with equivalent growing area, since it's got lower surface-area-to-volume ratio and doesn't need to be transparent. That may be important for stuff like high-end strawberries, where tight control of the day-night temperature swing enables higher sugar content. I again wouldn't expect a useful benefit for grains, though.
On the other hand, wind power would not use up cropland, and the solar panels could be on non-crop land, or water. Stacked grow trays might be more efficient to operate on.
The new Frankenstein rice that does CD4 photosynthesis, and also makes carotenes, seems like a good choice to grow in them. Maybe it can be persuaded to make protein, in the bargain.