Life cycle trade-offs of pulp and bioenergy integration in tissue paper mills
Main Presenter: Ricardo Luís Carvalho
Co-Authors: Cristina Nogueira Marques Raquel Alexandra Bértolo Ana Margarida Carta Luís Manuel Machado Ana Cláudia Dias
Session: Virtual Poster Session 2
Globally, the use of tissue products such as toilet paper has been growing. Tissue production is energy intensive usually using energy from the electric grid and fossil fuels for thermal energy. To enhance energy efficiency, the industry seeks to integrate pulp and tissue mills in the same site to maximize slush pulp and bioenergy supply to the tissue mill. Slush pulp production uses less energy than market pulp production because pulp drying is not required. Slush pulp pipeline transfer has also less environmental impacts than market pulp transportation. Bioenergy produced in the pulp mill can substitute electric grid energy and natural gas boilers in tissue mills. No studies were found to evaluate the environmental trade-offs of such integrated systems in relation to existing systems.
This research aims to perform a life-cycle assessment (LCA) of toilet paper produced from kraft pulp to compare impacts of its production via an integrated system (using 100% eucalyptus slush pulp and bioenergy to substitute electric grid energy and natural gas in the tissue mill) in relation to a semi-integrated system (using 87% of eucalyptus slush pulp and 13% of eucalyptus market pulp, as well as electric grid energy and natural gas in the tissue mill).
The LCA was conducted using the software Simapro 9.2 for all life-cycle stages of toilet paper up to distribution. Real data from the production of eucalyptus wood, eucalyptus pulp and tissue paper, as well as from its distribution were used in the life-cycle modelling, complemented with information from the Ecoinvent 3.7 database for the remaining processes. The ReCiPe 2016 method was applied to quantify the various environmental impacts (global warming, eutrophication, fossil resource scarcity, etc.).
For both systems, the energy consumption in tissue paper production is the major source of impacts for all the analyzed categories, except for marine eutrophication (ME) and mineral resource scarcity (MRS), for which the main impacts are related with forest and pulp production, respectively. Except for the ME and MRS, with the integration of processes, the environmental impacts decrease by 6-19%. The benefits achieved with the integration are more associated with the substitution of electric grid energy and natural gas by bioenergy in the tissue mill than with the decrease of impacts related with pulp production and transport. In ME, impacts increase by 7%, mainly due to the increased production of forest biomass for bioenergy. In MRS, no significant differences are observed between scenarios.