Green Party MEP Ciaran Cuffe has praised Fine Gael's Maria Walsh for breaking party ranks in a European Parliament vote on energy projects such as the controversial Shannon LNG terminal.
It comes as the liquefied natural gas terminal moved closer to reality after MEPs voted against a motion objecting to it and other priority energy projects.
A US company is planning to build the €500m LNG terminal on the Shannon Estuary in County Kerry.
Critics of the project - including Hollywood actor Mark Ruffalo - have warned it will impact on Ireland's climate aims and could see fracked gas imported from the US.
However, it remains one of around 150 projects - including 32 gas projects - listed as an EU 'project of common interest'.
The designation means that the project would be eligible for EU funding and fast-tracking if the list is ultimately approved by the bloc.
Earlier today, members of the European Parliament voted to reject an objection to the list of projects, calling for the Commission to put forward a new list that "avoids the construction of any new fossil fuel infrastructure with potential lock-in consequences".
The motion, which was put forward by MEPs including Ireland's Mick Wallace and Clare Daly, was defeated - but Maria Walsh broke European People's Party (the EU party Fine Gael is a member of) ranks and voted in favour of the objection.
She was one of only three EPP members to do so.
Ms Walsh told Green News she supported the objection as fracking is “bad for the environment and public health”.
Dublin Green MEP Ciarán Cuffe praised Ms Walsh for her vote.
He said: "I was really pleased to see Maria Walsh from Fine Gael break rank with her party colleagues.
"Maria had fantastic videos saying she wanted to tackle climate change, and if we're to do that we have to vote for clean energy.
"That means [back] some of the projects that are good ones - like the Celtic Interconnector which will allow us to export Irish wind electricity to Europe, and import clean energy from Europe when we need it."
Fine Gael MEP Seán Kelly, meanwhile, voted against the motion today - suggesting Ireland needs security of gas and energy supply.
He argued: "By rejecting one particular project on the basis that it might have fracked gas won't reduce one iota the amount of fracking that will take place in the United States or elsewhere.
"We are now dependent on a third country, the United Kingdom, for our supply - if they change rules, we might find a situation down the line where we'd have no gas to heat our houses, run our industries and power our transport."