A. Banboukian, D. Kamath, S. Nimbalkar
Oak Ridge National Laboratory,
United States
Keywords: integrated pulp biorefinery, LCA, carbon fiber, fertilizers, bioplastics, industrial symbiosis
Summary:
Fertilizers, carbon fiber and plastics are three distinct products that are projected to have significant market growth and demand in the coming years. These are also three products that are highly energy and emission intensive. Similarly, the pulp and paper industry (PPI), while integral to the manufacturing industry in the United States, remains an energy- and emission-intensive industry, accounting for 11% and 7% of the manufacturing sector’s energy consumption and energy-related carbon emissions, respectively. One of the novel approaches to decarbonizing this industry is through converting existing pulp and paper mills into integrated biorefineries to boost biomass resource utilization efficiencies and minimize potential greenhouse gas (GHG) emissions. Studies have shown that fertilizers, carbon fiber, and plastics can be produced as part of integrated pulp biorefineries, thereby increasing the value of those mills, and leading to better economics and a zero-waste scenario. PPI-based biorefineries are industrial symbiosis systems that share materials and energy between the production processes of pulp and value-added products. This results in reduced usage of virgin materials, energy use, emissions, and waste generation. Therefore, targeting specific product markets could lead to net improvements in the total environmental impacts of the system. However, these integrated biorefineries consist of different changes and processes, highlighting the need for a more comprehensive understanding of their feasibility and comparativeness in terms of costs, environmental impacts, and energy use. In this study, we use life cycle assessment (LCA) and techno economic analysis (TEA) to investigate and compare the costs, carbon, and energy impacts of three different biorefinery approaches. The objectives of this study are to evaluate the embodied energy, carbon footprint and production costs for the different integrated pulp biorefineries and to identify the flows of carbon that need to be addressed to make them net zero or net negative. We evaluate different integrated biorefinery concepts that produce (a) carbon fiber, (b) fertilizers, or (c) bioplastics in addition to pulp. Evaluating the alternative ways to produce these value-added products that can help maximize emissions reductions is fundamental to understanding which scenario would maximize economic profitability, minimize environmental impacts, and lead to a potential net zero biorefinery. For each of these three products, different biorefinery concepts are analyzed to highlight whether the products are produced from waste sludge, lime mud, or lignin from the Kraft pulp mill and how the concepts compare to each other. Since there are multiple products with multiple functions in the considered system, one metric ton of pulp was chosen as the functional unit. Additionally, the system expansion methodology with substitution was used to account for the avoidance of conventionally produced products. Our expected LCA and TEA results will identify the most cost-effective biorefinery concept(s), determine the technologically superior performer, assess their different environmental impacts, evaluate market viability, and identify their comparative ranking. Furthermore, the results will also highlight the flows of carbon and hotspots needed to be addressed to make these biorefineries net zero.