There were sharp exchanges between Minister for Transport Martin Cullen and the Green Party's Eamonn Ryan on future energy needs.
Mr Cullen said Ireland, like many other countries, was grappling with the global impact on transport of energy costs and the emissions from the energy sector.
"I presented the solutions to Dublin as in an almost €16 billion investment in public transport, a huge commitment to getting people out of their cars and having a major impact on the environment emissions that come directly from vehicles," he said.
"Clearly, there is an enormous onus on manufacturers, and some of them are beginning to make serious advances in getting turned on to better use of fuel economies in cars, lorries, trucks, buses even." But they were not easy targets, said Mr Cullen, because they were, to a degree, in conflict with demands of a burgeoning, fantastically successful modern economy which Ireland was.
Mr Ryan said his party did not accept that it was a case of a choice between the economy and the environment.
"Minister, without a proper planet, we will not have any economy. The people in this country have the sense to realise that the solutions which deliver that new green future are actually positive for society and the economy. Luas will deliver enterprise. More rail lines will help the country in the future."
Mr Cullen claimed that the Green Party would "crush" the economy if in government with Labour and Fine Gael.
"I do not need any lectures, nor do Fianna Fáil and the PDs in Dublin, from the Green Party about a commitment to the environment."
Earlier, Mr Ryan said oil was getting more expensive and carbon emissions had to be cut down. "Our energy use has increased 150 per cent in the last 15 years, and 8 per cent last year. Road freight has gone through the roof. Not surprisingly, under your management, rail freight has disappeared."
Fine Gael transport spokeswoman Olivia Mitchell said the Minister could show his concern for the environment by stopping the sale by CIÉ of the freight infrastructure and all of the equipment associated with the Guinness contract.
Mr Cullen said he was the first transport Minister in decades to restore the rail network in the State.
