Where's my EFI partition in Disk Utility?

Ubuntu won't use any Apple proprietary file system so you might need a third party driver to access it. I don't remember ubuntu supports HFS+.

 

Open Terminal ( in the Applications=> Utilities folder) then.

Code:

MacUser2525:~$ diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *480.1 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                 Apple_RAID                         30.0 GB    disk0s2
   3:                 Apple_Boot Boot OS X               134.2 MB   disk0s3
   4:                 Apple_RAID                         449.6 GB   disk0s4
   5:                 Apple_Boot Boot OS X               134.2 MB   disk0s5

MacUser2525:~$ diskutil mount /dev/disk0s1
Volume EFI on /dev/disk0s1 mounted

The first command list the disks in the machine there you will see the EFI partition by default Disk Utility hides this information from you. The second mounts the partition so you can use it when done changing the mount to unmount in the command will make it not show up again by unmounting it from the OS/Desktop.