Can I use green hard drives in a JBOD configuration on a server without any sort of RAID? I heard black drives are used for raiding, but what about no RAID or RAID 0
Yes you can but jbod may or may not be recoverable should a single drive fail depending on the controller used. IE - you might loose all data across all drives if just 1 drives fail. research recovering from a drive failure for the controller you will be using.