Black liquor
In industrial chemistry, black liquor is the by-product from the kraft process when digesting pulpwood into paper pulp removing lignin, hemicelluloses and other extractives from the wood to free the cellulose fibers.
[7] By the 1990s, most kraft mills were consuming nearly all of their black liquor byproduct,[8] and purifying the remainder in biological treatment plants, reducing the environmental effect of the waste waters below the level of scientific significance, except perhaps in very small streams.
[citation needed] Even in the 21st century, some small kraft mills remained (producing at most a few tons of pulp per day) that discharged all black liquor.
[citation needed] In August 2011, a fish and mollusk kill occurred on the Pearl River when a neighboring Louisiana paper mill accidentally discharged black liquor due to a problem in its waste water treatment system.
[8] As a result, the forest products industry has become one of the United States' leading generators of carbon-neutral renewable energy, producing approximately 28.5 terawatt hours of electricity annually.
[citation needed] The syngas can be burnt in a gas turbine combined cycle to produce electricity (usually called BLGCC for Black Liquor Gasification Combined Cycle; similar to IGCC) or converted through catalytic processes into chemicals or fuels such as methanol, dimethyl ether (DME), or F-T diesel (usually called BLGMF for Black Liquor Gasification for Motor Fuels).
The DME synthesis step will be added in 2011[needs update] in the "BioDME" project, supported by the European Commission's Seventh Framework Programme (FP7) and the Swedish Energy Agency.
[14] Used for biofuels production, the black liquor gasification route has been shown to have very high conversion efficiency and greenhouse gas reduction potential.
[15] Hydrothermal liquefaction is suitable for converting black liquor to advanced biofuels due to the process's ability to handle high moisture inputs.
[citation needed] This change meant that, in addition to fish processors, animal renderers and meat packers, kraft pulp producers became eligible for the tax credit as a result of their generation and use of black liquor to make energy.
