Done a wee bit more research on this since my last post:
1. There are a few coal mines in Ireland, but a lot farther north of Cork, Counties Monaghan and Tipperary. Most of Ireland's coal for power stations has been imported from Colombia however
2. There is a Coal Quay in Cork City: "the centre of retail in the city", and it is close to the River Lee: still a market now: however the waterway looks somewhat narrow there, so one questions if "The Irish Rover" might have been able to set sail from anywhere so far upriver