Can Poland turn coal into a green energy source ?

The UN's chief climate negotiator, Christiana Figueres, has called on countries to stop burning coal because of the scale of damage to the environment.

She was speaking at a climate change summit in Warsaw, but her Polish hosts are still heavily dependent on coal and they believe they have developed new technology that makes coal much cleaner.

Matt McGrath reports on Poland's controversial efforts to show coal has a greener future.