I think I prefer lowercase. It becomes "Earth-bin" rather than "Earth Bin".
🌎 bin, or Earth-bin, sounds to be like a universal take on the kbin/mbin network. In the end they're both *bins; Replacing the * with 🌎 makes this website 🌎bin.
🌎 Bin, or Earth Bin, sounds to me like a garbage can for the earth.
The difference is obviously not that huge, but that's my intuition at least. :)