The reactors that simulate 'clean coal'

The UN's Chief Climate negotiator Christiana Figueres has called on countries to stop burning coal because it causes so much 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.

Here, Prof Krzysztof Stanczyk from the Central Mining Institute in Katowice shows off the reactors that have been built at the institute to simulate what he says are cleaner ways of burning coal.