Environmental Engineering Reference
In-Depth Information
Table 10.7. Potential on-site CO
2
offset based on black liquor solids (BLS) availability in 2010 (Source:
Naqvi
et al
., 2010a, 2012a, 2012b, 2012c).
Reference mill
Sweden
Europe
World
BLS availability
a
, Mtonnes/year
b
0.6
14.1
55.2
220
DBLG O
2
(SNG)
Fuel production, Mtonnes/year
0.1
2.4
9.4
37.4
CO
2
on-site savings, Mtonnes/year
0.43
10.1
39.2
156.2
DBLG air (SNG)
Fuel production, Mtonnes/year
0.04
0.96
3.68
14.7
CO
2
on-site savings, Mtonnes/year
0.18
4.3
16.6
66.1
DBLG (H
2
)
Fuel production, Mtonnes/year
0.03
0.71
2.76
11.2
CO
2
on-site savings, Mtonnes/year
0.54
12.7
49.7
198.1
CHG (SNG)
Fuel production, Mtonnes/year
0.15
3.6
13.8
55
CO
2
on-site savings, Mtonnes/year
0.31
7.48
29.1
115.8
a
Based on the Food and Agriculture Organization (FAO) database 2008 (FAO, 2010)
b
Mtonnes/year
10
6
tonnes/year.
=
amount of CO
2
from the synthesis gas concentratedwith hydrogen after thewater-gas shift reaction
(Yan
et al
., (2007). In Sweden, the fossil CO
2
emissions in the pulp and paper industry are not
very large but CO
2
emissions from biomass use are substantial.
By using CO
2
capture technologies integrated with various biofuel production routes, a sub-
stantial amount of CO
2
can be captured. The theoretical annual on-site CO
2
reduction fromvarious
biofuel options using different black liquor gasification technologies based on black liquor avail-
ability in a reference mill case, Sweden, Europe and the world is reported in Table 10.7 (Naqvi
et al
., 2010a, 2012a, 2012b, 2012c). The on-site CO
2
capture potential is important for such
biofuel alternatives where CO
2
separation from the product gas is an integral process of biofuel
production. Note that the scale up is used as a scenario to estimate theoretical CO
2
reductions if
all recovery boilers were to be replaced with black liquor gasification systems and all available
black liquor would be used to produce biofuel. The pulp mills with different energy balances will
result in different on-site CO
2
reductions and CO
2
savings replacing fossil fuels.
10.6 CONCLUSIONS
The use of bioenergy is rapidly increasing to achieve climate change goals as well as to ensure
energy security for sustainable development. The electricity and biofuels can be produced using
black liquor gasification as an additional energy resource replacing a substantial amount of fossil
fuels. The combined cycle of electricity generation using black liquor gasification has the potential
to convert pulp mills from electricity importers to electricity exporters. The potential of biofuel
production in the pulp industry is considerably large, and can replace significant amounts of
motor fuel in the transport sector especially in countries with a large pulp and paper industry. The
biofuel upgrading with pellet production can increase the energy efficiency of the pulp mill with a
possibility of heat recovery from the flue gases from the recovery boiler in the conventional black
liquor recovery cycle. From the economic perspective, bioenergy production such as electricity,
biofuel and pellets in the pulp industry has the potential to diversify the overall economics with
less dependence on pulp prices, integrating co-production of bioenergy products together with
the pulp. The pulp industry is a major consumer of biomass that could potentially contribute to
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