The decision by the European Union to approve Britain's €20bn plan to build a new nuclear plant only 150 miles from the Irish coast has sparked controversy.
The EU decision marks a major victory for nuclear energy some three years after the Fukushima disaster in Japan.
The Hinkley Point C power station will be built with French and Chinese help - there are two other power stations at the site in Somerset in southwest England.
Green Party leader Eamon Ryan said the European Commission sign-off allows electricity to be generated at Hinkley at twice the price of alternative renewables.
"The decision supports an uncommon market, which brings us back to a highly-centralised energy model and hinders the development of a cleaner, safer and more efficient energy future for everyone," he said.
"The Irish Government have turned a blind eye to the dawning of this new nuclear age in Britain.
"There is no accounting for the security risks that come with the building of such a plant and no apportioning of the massive clean-up costs that will come when the plant has to be decommissioned."
Mr Ryan called on Environment Minister Alan Kelly to explain what action the Government intends to take over the development of Hinkley.
Meanwhile, Michael Moynihan, Fianna Fail spokesman on natural resources, called on Taoiseach Enda Kenny to say if he made any representations to British prime minister David Cameron on Hinkley.
"Ireland needs to robustly defend its interests here. We cannot stand aside and watch Britain potentially build another harmful nuclear power plant, which could have a devastating environmental impact on the Irish Sea and on the Irish east coast," he said.
Concerns about the project have also been raised by An Taisce.
Hinkley Point is one of the world's most ambitious nuclear deals and is seen as a boost to the industry.
However, critics have complained that there are insufficient plans for the removal of the nuclear waste the plant will produce.
"Energy policy under the Tory government has been at odds with public concerns about the environment and people's health. This is demonstrated by the British government's fervent promotion of fracking," said Sinn Fein energy spokesperson Michael Colreavy.
"There will be obvious concerns from Irish citizens about the construction of a nuclear power plant so close to Irish soil."
The European Commission said Britain had agreed to "modify significantly" the financing for the project, reducing the burden on British taxpayers.
In total, 16 commissioners voted in favour of the project, just one ahead of the 15 votes needed for approval.
Meanwhile, the Austrian government has said it would bring legal action against the commission's decision to the European Court of Justice.
It said the decision is supported by neither economic nor ecological sense.
And other members states are concerned that it flies in the face of the EU's stated aim of promoting renewable energy sources such as wind and solar power.
The older facilities at Hinkley Point produce about 1pc of Britain's electricity. However, this is expected to rise to 7pc when the new facility is complete.
Operations are scheduled to begin in 2023, and the plant will have an operational lifetime of about 60 years.
Hinkley Point C is the first nuclear power station to be built in the UK for 20 years.
The British government has insisted that the plant is an essential part of its strategy to move to a low-carbon economy.
Around 5,600 construction workers will be needed.