The Pulp and Paper Industry
The pulp and paper industry is one of the largest industries in the world. It is also an important source of employment in many countries. A sustainably managed pulp and paper industry can bring several benefits to the local economy and people particularly in rural areas. The industry is dominated by North American, Northern European, and East Asian countries like Japan. Latin America and Australasia also have significant pulp and paper industries. Over the next few years, it is expected that both India and China will become the key in the industry’s growth.
Pulp and paper are primarily made out of wood fibers originating from natural forests or pulpwood plantations. Recycled fiber and other fiber sources such as agricultural residue are also utilized and recycled fiber is becoming more commonly used in pulp and papermaking. There are two significant pulping technologies available that differ greatly in terms of process, i.e. mechanical and chemical pulping. Approximately 30% of the total pulp production in European Union is from mechanical pulping, while the rest is produced by means of chemical pulping (Das 2005; Das and Houtman 2004; Swedish Forest Agency 2008). North America has major pulp and paper industry, about 21% of the total pulp produced is from mechanical pulping and rest is produced chemically.
A pulp mill that produces bleached kraft pulp generates 1.7–1.8 T of black liquor (measured as dry content) per ton of pulp. Black liquor, thus, represents a potential energy source of 250–500 MW/mill. As modern kraft pulp mills have a surplus of energy, they could become key suppliers of renewable fuels in the future energy systems. Today, black liquor is the most important source of energy from biomass. It is, thus, of great interest to convert the primary energy in the black liquor to an energy carrier of high value. Table 9.7 gives the relative annual production of some major fuels (Farmer and Sinquefield 2009). A key advantage of black liquor compared to biofuels and fossil fuels is that it is already at the mill; the handling infrastructure already exists and there are no collection and transport costs.
Table 9.7 Annual production of selected fuels.
Source: From Farmer and Sinquefield (2009).
Production | Million T/Y |
Black liquor solids | 200 |
Paper and board | 180 |
Crude oil | 4000 |
Hard coal | 500 |
Worldwide, the pulp and paper industry currently processes about 170 million T of black liquor (measured as dry solids) per year, with a total energy content of about 2 EJ, making black liquor a very significant biomass source (IEA Bioenergy Report 2009). In comparison with other potential biomass sources for chemical production, black liquor has the great advantage that it is already partially processed and exists in a pumpable, liquid form. Using black liquor as a raw material for liquid or gaseous biofuel production in a biorefinery has many advantages: biomass logistics are extremely simplified as the raw material for fuel production is handled within the boundaries of pulp and paper plant; the process is easily pressurized, which increases fuel production efficiency; due to the processing of wood to pulp, the produced syngas has a low methane content, which optimizes fuel yield; pulp mill economics become less sensitive to pulp prices when diversified with another product; and gasification capital cost is shared between recovery of inorganic chemicals, steam production, and syngas production. Overall, if the global production of black liquor was to be used for transportation biofuel production, then this would correspond to about 48 million T of methanol, compared with current world production from fossil fuels of about 32 million T, a significant impact.
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