As a retiree after over 50 years in the pulp, paper and related industries, I take issue with some of the elements in your "A paler shade of green" (Dec. 10) article and its implied negative connotations.
First, "black liquor" is not used in paper making, it is used in manufacturing wood pulp. While it is common to have both pulp and paper making integrated on a common site as in Luke, standalone pulp mills are also common, producing pulp to sell to paper mills in the worldwide open pulp market. Pulp and paper is a major import commodity for the Port of Baltimore.
Similarly, standalone paper mills are even more common across the world using purchased pulp and substantial volumes of recycled paper as raw materials and no black liquor.
Black liquor is also not a "sludge byproduct” that is "left over from the paper-making process" but an integral part of producing kraft sulfate pulp, a century-old process. If it were not burned, and the residual ash recovered and recycled in a closed loop, pulp producers would have to continuously purchase new chemicals to continue operations with the inherent economical and environmental implications of that choice. The industry term for the unit that burns the black liquor is “Recovery Boiler.” Energy is the byproduct of the recycling process.
In addition, if the black liquor is not burned, it, as the article states, would be replaced by coal, oil or gas with their own carbon implications, plus the carbon dioxide implications of extracting and delivering these energy sources. And what would they do with the black liquor?
Having said all this, I do not agree with or support the windfall benefit to pulp producers, intended or not, for doing nothing more than what they have been doing for over a century and for which they have no alternative.
Joseph Erving, Timonium
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