Cost‐Benefit Analysis

A cost‐benefit analysis of BLG‐based bio‐refining in the kraft pulp and paper mill was studied by Larson et al. (2006a) and Consonni et al. (2009). The study assumed that BLG systems are technologically comparable with Tomlinson recovery boilers. Hence, BLGCC or bio‐refinery systems can be integrated within kraft pulp mill replacing the conventional recovery technology.

The reference mill with a base capacity of 2458 T BLS/day was an integrated pulp mill producing uncoated free sheet paper from a 65/35 mix of hardwood and softwood. DME production from LTBLG was compared to HTBLG with identical black liquor input. DME energy flow of 137.4 MW was estimated in the LTBLG integration and 168 MW for the HTBLG case. The power boiler consumed larger fuel (unconverted syngas and wood residues) in the LTBLG case than in the HTBLG case but resulted in 64% more back‐pressure steam turbine electricity production. From the preliminary calculations, it appeared that the LTBLG in DME pulp mill bio‐refinery integration would produce 15–20% less DME than in the HTBLG bio‐refinery, with both configurations requiring electricity import. In addition, the LTBLG case required about double biomass import than the HTBLG, and fuel oil import for the lime kiln was about 25% higher. Table 9.9 compares potential electricity or fuel production from various studies.