Building a close to the city, colocated flour, and/or cereal factory under the wheat farm, allowing gravity to help build automations would reduce holistic costs. I wonder if that makes this farming method profitable?
Growing a metric ton of wheat with 100% supplemental light requires 150,000-400,000 kwh. That's $3,000 to $8,000 in electricity costs at 2 cents per kwh (very cheap) and would require electricity to generate about a gram of CO2 per kwh at the most to be better in terms of CO2 emissions.
If you have free, non-polluting electricity it would be better to use it to synthesize fuel for trucks to carry grain from the fields, or to capture CO2 from the air.
In theory the energy intensity of bitcoin should go down over time because the block reward is shrinking. Of course transaction fees could rise but processing transactions is different to wasting energy to mint a currency out of thin air. Paying transaction fees is like paying your taxi driver. It's expensive but it's absolutely necessary to get a ride.
There are other inputs to growing outdoors: fertilizer usage, water usage, and insecticide/pesticide usage (likely not an exhaustive list). In a controlled environment like an indoor farm the use of each of those is dramatically less than in traditional farming. It would be worthwhile to include all of the inputs of growing food since light and transportation are not the full list.
(disclosure: I work for an indoor, vertical farming company)
Some back of the envelope calculations: From [1] the cost of fertilizer is like $150/acre and from [2] you can get about 7 tons/acre, so it's like $40/ton. The numbers change a lot from source to source, so let's multiply that by 2, and we get $40 of fertilizer per ton.
So in the impossible best scenario where the indoor production saves you the 100% of the fertilizer, you save $40 per ton of fertilizer that is much less that the $3000 per ton of electricity for illumination.
[1] https://farmdocdaily.illinois.edu/2017/07/fertilizer-costs-i...
[2] https://www.seedcorn.com/resources/estimating-corn-silage-yi...
As you said, simply finding ways to reduce the cost (in $ and CO2) of transporting field grown wheat is probably better than co-locating a vertical farm.
[0] https://www.statista.com/statistics/675822/average-prices-us...
The sun provides about 300W/m^2 on average at temperate climates, that's 7.2kwh per day. Wheat takes about 4 months to grow and nuclear power costs 0.77c/kwh.
That's 665.28$/m^2 at wholesale.
[0] https://ag.tennessee.edu/solar/Pages/What%20Is%20Solar%20Ene....
[1] https://en.wikipedia.org/wiki/Electricity_pricing#Price_comp...
But this would probably only halve theoretical costs, and then there are all the losses in the power production chain...
Immediate second order effect would be the obsolescence of grain futures, you don't need to hedge against a bad harvest. You probably also wouldn't need to go into debt to buy enough seed to plant each season.
Another would be a more elastic supply chain without the need for storage/buffering, which we've seen drastically reduce prices and increase production for all sorts of widgets using just-in-time manufacturing. If you can scale up/down wheat production pretty reliably with only 70-80 days forecasting, you can eliminate a lot of the inefficiencies of the food supply chain.
Sidenote, a literal vertically integrated bakery would be a sight to behold