An Environmental Consequence for Dublin Bay of a Shift From Hydro-Carbon to Other Energy Production Methods

The Liffey Estuary and Dublin Bay, Ireland are of a great recreational and conservational value. Until recently, the Electricity Supply Board (ESB) plant at Poolbeg, Dublin, abstracted dilution water from the estuary for cooling purposes and subsequently discharged this water back to the estuary at temperatures that were sometimes 7-9oC above ambient values. Prior to its discharge to the estuary, the ESB cooling water was mixed with the sewage effluent from Ringsend Treatment Works, creating a warmer and less-saline pollutant plume that remained buoyant on the water surface, adversely effecting water quality. The ESB plant has since closed as part of a competitive energy market agreement. This paper examines the impact of this closure on water quality in the Liffey Estuary and Dublin Bay using a three-dimensional hydro-environmental model. Three discharge scenarios corresponding to the periods before and after the cessation of thermal discharges are compared.. The results showed considerably lower E.coli concentrations in the Estuary and inner Bay in comparison to the time when the thermal discharges and extraction of dilution water ceased, although the effect on E.coli concentrations of removing the cooling water was small.