Solid Energy is currently running an essay competition and have sent letters out to schools encouraging students to enter.The essay is to be about 'The role of coal in sustainable energy solutions for New Zealand' see: http://www.coalnz.com/index.cfm/1,282,787,0,html
The competition is only open to students from high schools in regions where there are coal mines (West Coast of South Island, Southland, Canterbury & Waikato) and the prize for is a trip to the World Expo in Shanghai.
The short answer to how coal plays a role in sustainable enrgy solutions is "it doesn't", in fact it is one of the least sustainable energy solutions out there. It's unbelievable that Solid Energy is trying to promote it as a sustainable energy source to high school kids when it so blatantly isn't.
Ironically the lucky winner will be able to experience first hand the chronic pollution caused by China's coal burning power plants. Perhaps they'll change their minds about the miracles of coasl when they get there!