Decarbonization of construction supply chains - Achieving net-zero carbon emissions in the supply chains linked to the construction of buildings and transport infrastructure

Sammanfattning: Sweden has committed to reducing greenhouse gas (GHG) emissions to a net-zero level by Year 2045. In Sweden, about 20% of its annual CO2 emissions are from the manufacture, transport and processing of materials for both the construction and refurbishment of buildings and transport infrastructure. Cement and steel, together with diesel use in construction processes and material transport account for the majority of the CO2 emissions associated with building and infrastructure construction. This thesis assesses the challenges associated with reducing CO2 emissions from the supply chains for buildings and transport infrastructure construction. The main aim is to determine the extent to which abatement technologies across the supply chain can reduce the GHG emissions associated with construction if combined to exploit their full potential, while identifying key barriers towards their implementation. The work takes its starting point from material, energy and emissions flow analyses conducted across the construction supply chain, followed by the development of stylized models, which are subsequently used for scenario analysis. This quantitative analysis work is integrated with a participatory process that involves relevant stakeholders in the assessment process. The participatory process serves to identify the main abatement options, as well as to adjust decisions and assumptions regarding abatement portfolios and timelines, so as to make these as realistic and feasible as possible. Supported by a comprehensive literature review, a detailed inventory of abatement options in the supply chain of building and transport infrastructure construction is developed. This includes technologies and practices that are currently available and that are deemed available on a timescale up to Year 2045. The results show that on a national level, it is possible to reduce GHG emissions associated with the construction of buildings and transport infrastructure by 50% up to Year 2030, through applying already available measures. Moreover, it will be feasible to reach close-to-zero emissions by Year 2045, with this requiring comprehensive measures across-the-board, including breakthrough technologies for heavy vehicles, cement and steel production. Attaining the full abatement potential of measures that are already available would rely on sufficient availability of sustainably produced second-generation biofuels, requiring accelerated implementation of alternative abatement measures, involving optimization of material use, mass handling and transport systems, as well as the use of alternative materials and designs, with focus on circularity and material efficiency measures. To realize the potential linked to applying measures across the supply chain, there is a need for extensive collaboration along the whole value chain. Policy measures and procurement strategies should be aligned to support these measures with a clear supply chain focus, so as to enable balanced risk sharing and the involvement of contractors early in the planning and design process. The results also illustrate the importance of intensifying efforts to identify and manage both soft and hard barriers to implementation and the importance of acting promptly to implement available measures (e.g., material efficiency, recycling and material/fuel substitution measures) while actively planning for long-term measures (electrification of heavy vehicles and low-CO2 steel or cement). There are immediate and clear needs to prepare for deeper abatement and associated transformative shifts and to consider carefully the pathway towards these goals while avoiding pitfalls along the way, such as an over-reliance on biofuels or cost optimizations that cannot be scaled up to the levels required to reach deep emissions reductions. Therefore, strategic planning must be initiated as early as possible, as lead times related to planning, securing permits and construction of the support infrastructure (renewable electricity supply, electricity grid expansion, hydrogen storage, CCS infrastructure) and piloting and upscaling to commercial scale of the actual production units will all influence the speed of change.