As the wind blew in December, turbines contributed a record level of energy to the Irish energy grid, with 24% of the Irish energy mix being generated by wind farms.

The sustained wind volumes forced expensive gas powered plants off the system and this provided downward pressure on wholesale prices.

The result of the wind power was a 1% month-on-month fall in the Bord Gáis Energy Index during December.

Gas and Power trader at Bord Gáis Energy John Heffernan said, while the headline figures appeared quite marginal, there was in fact substantial change in the energy markets.

“The topline decrease of 1% in the Index masks some substantial changes during the month — especially in wholesale electricity prices.

“The substantial contribution of wind energy helped reduce the monthly average wholesale electricity price by 5%.

“Brent Crude oil prices remained steady. However, the outlook for 2014 remains uncertain as growing non-OPEC supplies compete with geopolitical uncertainty to be the key price driver,” he said.

While the contribution of wind kept the price of power down, the price of gas was at one of the highest levels ever recorded by the energy index despite there being no issue with supply.

Mr Heffernan warned that if the weather becomes cold, the price of gas could rise.

“The average Day-ahead gas price for December was 69.26p a therm which is high given the relatively normal and stable conditions experienced in the month (there were no significant issues with supply, and temperatures over the entire month of December were not extreme).

“The December 2013 price was the third highest monthly price recorded by the Bord Gáis Energy Index. Looking ahead, weather will be the key determinant for wholesale gas prices over the remaining three months of winter 13/14,” he said.