Bioenergy polygeneration, carbon capture and storage related to the pulp and paper industry and power plants - Biomass as Energy Source: Resources, Systems and Applications - page 168

Table 10.4. Estimated internal rate of return (IRR) and payback time (Source: Ekbom et al ., 2005).

Methanol DME

Additional investment cost a [million euro] 174 190

Total incremental operation cost [million euro/year] 66.3 66.1

Production capacity b [million m 3 /year] 0.26 0.24

Cost of production c [euro/liter] 0.26 0.27

Selling fuel price [euro/liter] 0.51 0.62

Profit [euro/liter] 0.25 0.35

Profit [million euro/year] 66.5 82.3

Payback [years] 2.6 2.9

Internal rate of return (IRR) [%] 40 45

a The recovery boiler requires total investment

171 million euro
b Production capacity equivalent to gasoline and diesel in m 3
c Annuity factor (%)

=

= 11.1.

Figure 10.6. Estimated internal rate of return (IRR) of different biorefinery configurations (Source:
Consonni et al ., 2009).

kiln for causticization using Chemrec black liquor gasification systems in the black liquor recov-
ery cycle for chemical recovery resulting in extra biomass utilization (Consonni et al ., 2009). In
a conventional recovery system, sulfur is recycled as sodium sulfide whereas a large amount of
sulfur is recycled as hydrogen sulfide in the Chemrec system that results in about 25% increased
causticization load on the lime kiln. The increased biomass usage raises critical issues for future
biomass supply as the limited biomass will result in less availability of biomass to other processes.
The dry black liquor gasification (DBLG) system resolves this issue using direct causticization
within the gasifier eliminating the energy-intensive lime kiln in the recovery cycle.
The electricity deficit is an important system consequence of biofuel polygeneration. The
conventional recovery boiler system has a potential to export electricity after meeting the pulp
mill electricity demand (Table 10.2). However, biofuel polygeneration systems require electricity
to be imported from the grid or generated in biomass-based power plant.
The biofuel polygeneration systems using black liquor gasification indicate economic viability
since the economics of the pulp mill would be less sensitive to pulp prices, due to the diversified
overall economics of co-production of biofuels together with the pulp (Ekbom et al ., 2005). The
internal rate of return (IRR) considering investment and operating cost of black liquor gasification
based methanol and DME production is presented in Table 10.4. Figure 10.6 shows internal
rate of return (IRR) results from another study (Consonni et al ., 2009) estimated for different
biorefinery options e.g. Black liquor gasification combined cycle (BLGCC), dimethyl ether
(DME) production, Fischer-Tropsch (FT) liquid, mixed-alcohols (MA).