Life cycle assessment of heat provision by parabolic trough-based concentration solar plant

Kurzfassung

Industrial process heat remains one of the most energy-intensive and carbon intensive sectors in Europe, with fossil-fuel-based boilers still dominating heat supply. Concentrated solar thermal technologies offer a promising renewable alternative by directly converting solar radiation into usable thermal energy. This thesis evaluates the environmental performance of a parabolic trough concentrated solar thermal (PT-CST) system for industrial heat production at plant locations in Spain and Germany. The study compares the system with a conventional natural gas boiler, identifies key environmental hotspots, and assesses the influence of thermal energy storage (TES) capacity and other design parameters on environmental performance. A life cycle assessment (LCA) was conducted in accordance with ISO 14040 and ISO 14044 standards using a cradle-to-grave system boundary with recycling potential for selected materials. The life cycle inventory was developed using primary techno economic optimisation data provided by DLR and secondary data from published literature, and Ecoinvent version 3.10. The environmental impacts were assessed using the Environmental Footprint (EF) 3.1 method across 16 midpoint impact categories. The results indicate that the hybrid PT-CST system can significantly lower environmental impacts compared with heat provision based solely on a natural gas boiler, particularly in the categories of climate change, fossil fuel depletion, and photochemical oxidant formation. However, the system does not perform better across all impact categories due to the material intensity of the solar field and the contribution of the auxiliary natural gas boiler required to maintain a continuous heat supply. The solar field and heat transfer fluid (HTF) system were identified as major environmental hotspots due to the high material demand of the steel and glass, and the environmental burden associated with HTF production. Although the HTF is essential for transferring heat throughout the PT-CST system, its production contributes significantly to the overall environmental load. Sensitivity analyses further revealed that environmental performance strongly depends on system configuration, including TES capacity, solar field size, recycled material content, and HTF selection. The findings indicate that technical, economic, and environmental optimisation do not necessarily lead to the same design choice, supporting the need to consider sustainability criteria in PT-CST design.