Everything can burn. Therefore I wonder if we really are using our coal energy storage to its fullest potential.
The idea is to transform coal using excess energy from solar or other sources. As the diamond is a form of coal there are other allotropes. So what I wonder is if there exists an allotrope of coal we can use as a better battery storage. As an example. The diamond can under high pressure withstand temperature around 3000 C. With high temperature you get higher efficiency.