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

Here is Why You Need An Adapter

The outlet and plug type used in Ireland (Eire) is G and in Greenland are C, E, F and K. This is how they look like.

Greenland

In Greenland, outlets of type C, E, F and K are in use.

Type C

Type E

Type F

Type K

Ireland (Eire)

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

Type G