(Couldn't edit anymore, but here what should be added to the post above

In addition: I don't have any of the problems NASA has to fight with. I have gravity, so hot air rises and cooling is much more easy therefor (let alone get rid heat in space at all). I get a parcel of LED for the same money I'd get a CFL delivered for. I don't have that limited space. I could build a 1Ã?1m panel. I bet in the ISS you have to beg for that amount of space big time or pay millions. 20 Luxeon Rebel high-power LEDs (all fitting on the SIM-card of your Mobile) are able to create 3600lm, I have a cool white CFL 4" here, 3350lm. NASA isn't the quickest sometimes, they often just have to depend on tested (aka old) stuff. Changing the lighting system in ISS isn't the same like at home. Again (if possible at all) millions of $ for the sockets alone (you mentioned the freight costs).

So I do see LEDs in (grow-)space very much so