Cradle-to-Grave LCA and Cost Assessment of Next-Generation Low-Temperature District Heating Networks

This study presents a cradle-to-grave Life Cycle Assessment (LCA) and cost analysis of next-generation low-temperature district heating networks based on water-condensed electric booster heat pumps. The research, conducted within the ENEA Portici Research Center framework, evaluates multiple case studies to assess environmental and economic sustainability. The system boundaries include heat generators (geothermal heat pump, solar thermal, and photovoltaic-thermal hybrid), network configurations (tree vs. ring), supply temperatures (25 degrees C vs. 45 degrees C), and renewable electricity shares (0-100%). Environmental impacts were quantified using the Environmental Footprint 3.1 method, focusing on key indicators such as climate change, resource use, and human toxicity. The results show that supply temperature is a critical factor: 45 degrees C scenarios lead to notably higher impacts, while network configuration has only marginal effects. Among generation technologies, the photovoltaic-thermal system proved the most sustainable, despite higher investment costs, whereas the solar thermal system displayed the largest environmental burden but lower costs. Geothermal systems showed intermediate performance, with notable impacts from mineral resource use. Renewable electricity integration consistently improved environmental outcomes, reducing climate change impacts by up to 10%. Storage system comparison revealed lithium iron phosphate (LFP) batteries as the most advantageous solution for electrical storage, and phase-change materials (PCM), particularly Rubitherm15, as the most environmentally favorable option for thermal storage, although traditional water tanks remain more cost-effective. Overall, the study highlights the crucial role of renewable integration and temperature optimization in enhancing the eco-efficiency of low-temperature district heating networks, providing guidelines for future sustainable design and deployment.