[karlkatzke]

In many regions of the world, the only way to grow fresh greens year round (lettuce, spinach, any Brassica oleracea species) is hydroponically. I do happen to like some nice crisp kohlrabi in the summertime, but it even becomes rare in grocery stores at that time of year. If the world climate continues to warm without check, this produce will become even rarer in stores.

The approach done by spacebuckets isn't very efficient. I haven't looked at the site recently and it currently seems to have been hugged to death, but LEDs have a dramatically lower energy consumption compared to individual CFLs, especially if you use one converter and run them all on the same DC circuit.

There are also parts of the world where you could run this concept economically using solar panels to provide greens that are normally impossible to grow out of season without the added cost of transportation. (You would also have to cool the building, of course, but that can also be done in a carbon neutral fashion.)