Within-Industry Heterogeneity of Emission Productivity and Product Portfolios
Nitschke, J. (2025)
Abstract
This thesis examines how product portfolios shape emission productivity within the manufacturing sector, questioning policy frameworks that aim to achieve decarbonization primarily through efficiency increases. Using firm-level data from the Portuguese manufacturing sector (2004–2021), it explores heterogeneity in emission intensities within narrowly defined industries and assesses the impact of product composition on firm-level emission productivity.
By integrating administrative records on energy consumption, financial data, and product-level sales, the study quantifies the extent to which variations in product portfolios contribute to differences in emission intensity. The findings reveal that firms within the same industry exhibit substantial variation in emission productivity, often exceeding inter-industry differences. Variance decomposition analysis confirms that a significant share of this heterogeneity is explained by firm-level factors rather than sector-wide characteristics.
A classification of products into high- and low-emission categories indicates that firms producing a greater share of low-emission goods tend to have systematically higher emission productivity. Through index decomposition analysis and firm-level panel regressions, the study further examines whether adjustments in product portfolios influence firm-level emission intensities over time. The results suggest that aggregate emission reductions have been largely driven by efficiency gains, yet firms that transition toward lower-emission products show sustained improvements in emission productivity.
These findings contribute to debates on industrial decarbonization by emphasizing the role of product portfolios alongside efficiency improvements. While technological advancements play a key role, the study highlights how decarbonization strategies that focus solely on efficiency gains may overlook the structural impact of production composition. The results also raise policy questions regarding the extent to which regulatory frameworks encourage or constrain shifts toward lower-emission products. By engaging with perspectives from ecological economics and democratic planning, this thesis offers insights into whether market-driven adjustments alone are sufficient or whether additional regulatory measures are needed to facilitate structural changes in industrial production.
Keywords
emission intensity, within-industry heterogeneity, product portfolios, industrial decarbonization, structural change, industrial policy
Citation
Nitschke, J. (2025). Within-Industry Heterogeneity of Emission Productivity and Product Portfolios. PhD thesis, University of Naples “Parthenope” & Université Côte d’Azur.
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Notes
I am grateful to all the people that accompanied me on this journey. Especially to Julian Tiedke without whom I would have never started the final project.