PAPERmaking! Vol11 Nr2 2025

R Buitrago-Tello et al.

Original Article: Linerboard production and decarbonization

high operating cost for the mill given the large area required in the membranes. The area required to treat the volume of black liquor was substantial –176 400 m 2 for the four- membrane system and 240 580 m 2 for the five-membrane system – with a membrane cost of $200/m 2 . This recurring expense impacted the economic viability of this technology. The high-efficiency recovery boiler represented a significant capital investment ($256 million), which was partially offset by natural gas savings and revenue from surplus electricity sold to the grid. Despite these operational benefits, the initial investment magnitude posed a significant barrier to implementation. Electric boilers, despite requiring moderate capital investment ($18.55 million), increased operating costs substantially due to the high electricity demand, making them economically challenging under current grid conditions. When examining the relationship between costs and environmental performance, the overall energy efficiency of the linerboard mill varied significantly across the evaluated technologies, ranging from 52.0% for the base case to 59.5% for the membrane system with four membranes (Supporting Information, Table S15). This variation in energy efficiency correlated with GHG emissions reductions, as the most energy-efficient technologies generally achieved the greatest carbon reductions. For instance, the membrane systems and condebelt technology, which improved overall energy efficiency by 7.5 and 1.6 percentage points respectively, also delivered the highest GHG emissions reductions of approximately 15%. However, energy efficiency improvements do not always translate to economic benefits. Technologies implemented in the paper machine (shoe press, nylon felt) and the MVR system offered moderate efficiency improvements (2.5–3.7 percentage points) with favorable economics (negative costs of avoided carbon ranging from −$67 to −$19 per metric tonne CO2-eq) but the membrane systems and high-efficiency recovery boiler required substantial capital investments despite their superior energy performance. This demonstrates the importance of considering both environmental and economic metrics when evaluating decarbonization pathways for the linerboard industry. Marginal abatement cost curve –missions Scope 1 and 2 emissions Figure 5(a) presents the MACC considering emissions from Scope 1 and 2. The nylon felt, shoe press, and MVR technologies each exhibited a negative CAC, indicating that implementing these technologies generated income for the mill. These alternatives provided operating cost savings that

offset the capital investment, resulting in a positive NPV over a 10 year period. They also required the lowest capital investment, with operating cost savings ranging between $4 to $7 million. The condebelt technology, while offering higher operational cost savings and greater carbon reductions than the shoe press and nylon felt, had a higher CAC of $45 per metric tonne of CO 2 -eq. avoided due to its significant capital investment, making it less cost effective. The four-membrane system achieved the highest carbon reduction, as illustrated by the bar width in Fig. 5(a), but with high operating costs resulting from the annual replacement of the membranes. This, along with the capital investment, implied a CAC of $300/metric tonne of CO 2 -eq. avoided. The implementation of an additional membrane increased the indirect emissions (Scope 2), and the operating cost (additional area), increasing the CAC to $487/ton of CO 2 - eq. avoided. Finally, the high-efficiency recovery boiler made the system self-sufficient in terms of electricity and offered a profit from the surplus electricity but required a high capital investment, resulting in a CAC of $487/ton of CO 2 - eq. avoided. The CAC was also determined assuming revenue from avoided CO 2 -eq. emissions, considering only Scope 1 and 2 emissions. Two prices were considered for the avoided emissions: $11 per tonne of CO 2 -eq. avoided, expected by 2030 for technologies that prevent CO 2 emissions, and $47 per tonne of CO 2 -eq. avoided, the projected value by 2050. 32 The NPV and the CAC for each offset price are shown in Table 3. The CAC improved by assuming a profit from avoided carbon emissions. For instance, in the nylon felt scenario, the CAC changed from a saving of −$80 to −$108/ton CO 2 - eq, assuming a price of $47/ton CO 2 -eq. avoided. However, for the condebelt, the membrane system, and the high-efficiency recovery boiler, the revenue from the carbon avoided was not enough to counter the changes in the operating cost and the capital investment, resulting in a positive CAC, even for an offset price of $47/ton CO 2 -eq. avoided. For these alternatives, the minimum carbon price to prevent a cost for the mill, which means an NPV equal to zero, ranged from $75/ton CO 2 -eq. avoided for the condebelt technology to a maximum of 809/ton CO 2 -eq. avoided for the five-membrane system (last column in Table 3). Marginal abatement cost curve considering emissions from Scopes 1, 2, and 3 Regarding the MACC considering emissions from Scope 1, 2, and 3 (Fig. 5(b)), the CAC was reduced for all the alternatives.

Made with FlippingBook. PDF to flipbook with ease