The Indian Railways spends a huge amount of money on diesel to power its trains each year which, apart from the monetary impact, also takes an environmental toll.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/solar-demu-trains-start-rolling-how-much-indian-railways-will-save
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/indian-express-new-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/solar-energy
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/rail-transport
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/renewable-energy
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/diesel
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/climate-change
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/indian-institute-science-iisc
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/energy