Black liquor (BL), a by-product of the chemical pulping process, is an important liquid fuel in the pulp and paper industry. It contains almost all of the inorganic cooking chemicals along with the lignin and other organic matter separated from the wood during pulping in the digester. (LULEÅ UNIVERSITETSBIBLIOTEK )

Sometimes, people just need to make the best with what they have got to work with. This is what paper mills are trying to do by burning the "black liquor" waste which is a leftover remnant of chemicals and the lignin. As part of the Kraft process, the leftovers are burned to create steam which turns large generators, which in turn provide electricity for the plant. (AutoblogGreen)

The black liquor waste stream is converted from the paper pulping process into synthesis gas. The synthesis gas can then be processed into a variety of fuels—likely dimethyl ether (DME) and methanol (MeOH), although fuels such as Fischer-Tropsch diesel (FTD), Synthetic Natural Gas (SNG), or hydrogen are also possible. (Conventus Communication AB)