Britain's coal-fired power generation at five-year low in 2014

* Coal-fired output down 23 pct

* Gas-fired generation up 8 pct

* Overall UK electricity generation down 7.2 pct

LONDON, Feb 26 (Reuters) - Britain's coal-fired power generation last year fell to a five-year low, government data showed on Thursday, meaning it was likely that powerplant emissions of carbon dioxide (CO2) in the EU's second largest carbon polluter also fell.

Coal-fired output fell by 23 percent to 94.9 terawatt-hours (TWh), its lowest level since 2009, provisional from the Department of Energy and Climate Change (DECC) showed.

Gas-fired generation, which emits half the amount of carbon dioxide as coal, rose by 8 percent, to 87.4 TWh.

Utilities are the largest source of demand for carbon permits in the EU's Emissions Trading System (ETS).

The ETS is the Europe's flagship policy for cutting greenhouse gas emissions by charging for the right to emit carbon dioxide, but weak economic growth across Europe has cut industrial production and energy demand, creating a glut of more than 2 billion permits.

Prices for EU allowances (EUAs) have plummeted to less than 7.50 euros ($9) a tonne from almost 30 euros six years ago , leaving the market too weak to spur a switch to low-carbon technology.

Overall, British electricity generation fell 7.2 percent compared with a year earlier to 282.4 TWh

Power generators such as Centrica (LSE: CNA.L - news) have already reported falls in annual profits because of weak demand for gas and electricity after Britain had the warmest year on record in 2014.

The drop in coal-burning came as several power stations such as E.ON UK's Kingsnorth plant have closed over the past two years while Britain's largest coal-fired generator, Drax, is in the process of converting some of its coal-fired units to burning biomass instead.

Meanwhile output from Britain's wind farms rose 11 percent last year, while nuclear-fuelled power generation fell 9.7 percent due to outages at several stations last year. ($1 = 0.8819 euros) (Reporting By Susanna Twidale; Editing by Greg Mahlich)