You Do Need power plug adapter while traveling from Ireland (Eire) to Libya.

Here is Why You Need An Adapter

The outlet and plug type used in Libya are C and L and in Ireland (Eire) is G. This is how they look like.

Ireland (Eire)

In Ireland (Eire), outlets of type G are in use.

Type G

Libya

In Libya, outlets of type C and L are in use.

Type C

Type L