“Solution” for future heating and cooling towards carbon neutrality

Meeting heating and cooling demands represents one of the most universal forms of energy use, with electrically driven vapor-compression heat pumps and chillers—based on the reverse Carnot cycle—being the most widely recognized technology. Although vapor-compression heat pumps/chillers benefit from grid accessibility and mature technology, reducing high-emission fossil fuel use at the user end, overall decarbonization is achieved only when the electricity is generated by renewable energy sources. Moreover, the widespread use of high-global warming potential (GWP) refrigerants exacerbates environmental impacts. Although renewable energy and waste heat can be efficiently converted into usable thermal energy, traditional thermal networks suffer from high thermal loss and limited working radius, hindering long-distance transportation and utilization of such energy sources. This study proposes a novel urban-scale solution-mediated thermal network, which leverages concentration gradients in hygroscopic solutions to enable high-density, low-loss thermal transport with inherent energy storage capabilities. By utilizing absorption-based cycles, the network supports both heating and cooling at end-user sites, significantly improving annual utilization rates. The thermal network is driven by renewable energy and waste heat, combined with zero-GWP refrigerants, which positions it as a transformative solution for decarbonizing urban heating and cooling. This approach not only addresses the limitations of conventional thermal networks but also aligns with the global transition toward sustainable and resilient energy systems. Despite its immense potential, the large-scale deployment of this concept requires overcoming practical challenges related to urban infrastructure integration, high-vacuum maintenance, working fluid crystallization, and initial material costs.