​A biomass plant, Drax, received over £800 million in government subsidies last year at its Selby location, but its method of operation - burning wood and other forms of biomass to generate energy - continues to be a source of controversy.

In fact, new research has revealed that the Selby plant is the third biggest emitter of carbon dioxide across the EU's entire base of power stations if biomass and coal are combined.

The analysis was carried out by Ember, the climate think tank, which revealed its research on an exclusive basis to Sky News.

Ember said that Drax's Selby plant wasn't just one of the largest sources of C02 emissions in Europe but also one of the biggest emitters of PM10, which covers all particulate matter measuring up to 10 micrometres - another measure of pollution.

In fact, the figures showed that Drax was emitting more pollution than some of the dirtiest coal plants in Europe. Yet despite this, its emissions are not calculated as part of Britain's total. This is because biomass is viewed as being carbon-neutral at its point of being burned. The wood absorbs C02 as it grows and then releases it as it is burned.

The UK doesn't include biomass emissions in its overall carbon release figures because, in common with the EU, it views bioenergy as being automatically neutral on the grounds that the carbon released from burning wood will be absorbed by growing trees once again.

However, Ember disputes this assumption, saying that the recent science shows biomass is in fact responsible for a significant degree of emissions.

Drax says that it has cut its emissions by 90%, since it moved away from burning coal and replaced it with sustainable wood.