A major environmental initiative has been announced to make Croke Park a carbon-free stadium. The Dublin-based stadium currently emits 4,500 tonnes of CO2 a year The new joint project between the Gaelic Athletics Association (GAA) and the Electricity Supply Board (ESB), entitled Cul Green, aims to dramatically reduce the carbon footprint of Ireland's most popular sporting venue over the next six years. Croke Park has an annual output of 4,500 tonnes of carbon emissions and Cul Green aims to cut this by more than two-thirds.