Coal's Future - Hydrogen Storage? 

I came across THIS ARTICLE and found it interesting for a couple of reasons. 

Recent research shows that coal can store gases and the amount absorbed increases with pressure - 600kg per ton of fractured coal. The suggestion is that old coal mines could act as batteries storing hydrogen produced from sources such as wind power. 

I suspect the engineering required for this to happen is some distance in the future, but it is a nice thought.

The other reason this article was of interest was the graph showing the historical contribution of various energy sources. The implications for the future are rather frightening.

Growth in energy supply from different sources since 1800 CE (Credit: ourworldindata.org)