It doesn't need to be more economical than outdoor growing is right now to be viable. We are already using of a large fraction of the arable land that is well

It doesn't need to be more economical than outdoor growing is right now to be viable. We are already using of a large fraction of the arable land that is well suited to outdoor grain cultivation. It isn't clear that yields can be increased enough to feed people as we approach peak Earth population. Indoor growing allows for an extension of agriculture to new land. Efficient Climate control, combined with high efficiency LEDs with optimized output spectra make the concept more viable. It will be more expensive than current outdoor-based agriculture, but we'll be wealthier by the time this is needed.