There's not a way to export badges properly speaking. A badge only gets its metadata stamped into it when a user downloads it or puts into their backpack (if connected.) That's if you want the image file with the data in it.
However, the data is always available in the database, so you can get all the information about an issued badge from there.
Currently, Moodle only supports the Open Badges backpack for direct integation, but in the future it will probably support others. Some people in the corporate world are adding backpack capability to internal systems for collection. You might check out the OB Community site for more info: http://community.openbadges.org/