Airtricity was paid €32m to run power station for just 50 hours
State energy company Eirgrid paid €139m over the past four years to a power plant that produced energy for just 552 hours.
That is €6m per day, or €252,000 per hour of energy generation.
Figures obtained by the Sunday Independent show the 40-year old power plant earned €32m for its British owner in 2014 alone - even though it only actually ran for less than 50 hours.
The Tarbert oil and gas-powered station in Kerry is one of the oldest of its kind. British energy company SSE acquired it in 2012 when it bought the Irish arm of Spanish utility Endesa for €360m. SSE also owns Airtricity, from which it earned a €70m dividend last year.
The €139m payment to Tarbert was funded by consumers, via charges built into their energy bills.
It was overseen by Eirgrid, which operates the country's electricity network.
Eirgrid said the payments, known as capacity payments, are necessary to keep power plants available in case of emergencies - even if they are never actually run.
"Capacity payments are in place to ensure there is enough electricity generation available to meet an all-island generation security standard," said a spokesperson.
The spokesperson added that the Tarbert power station's principal function is to help maintain security of electricity supply by being available to operate on quick responses to peaks in national energy demand.
However, a source said that because of its age, the Tarbert station takes much longer to power up than newer plants, - one of the reasons why it is so rarely used.
Some €575m was spent on capacity payments to power generators last year.
The payment is the same for all providers, calculated according to the average cost of producing energy - meaning older, less efficient plants push up the price.
Irish consumers pay the fourth-highest energy bills in Europe, according to EU statistics. Little of the large recent falls in wholesale gas and oil prices have been passed on to consumers.
Sunday Indo Business