It used to be made by Native Americans, but now "terra preta" [black earth] is going industrial under the name "biochar". With modern technology, a number of research institutions are working on ways to compress organic waste products into a coal-like substance.
Technology Partners: MimirTech
Links:
[1] http://admin.indiaenvironmentportal.org.in/feature-article/coal-makers
[2] http://admin.indiaenvironmentportal.org.in/category/author/martin-bensmann
[3] http://admin.indiaenvironmentportal.org.in/category/journal/new-energy
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/farm-residues
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/coal
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/waste-conversion
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/energy
