Achieving Carbon Mitigation with Economic Benefits through High-Resolution Analysis of Renewable Resource Integration in Global Coastal Cities.

Coastal regions, home to more than half of the global population and contributing over 50% to the global economy, possess vast renewable resources, such as seawater and solar energy. The effective utilization of these resources, through the seawater-cooled district cooling system (SWDCS), seawater toilet flushing (SWTF), and rooftop solar photovoltaic system (RTPV), has the potential to significantly reduce carbon emissions. However, implementing these technologies in different geographic contexts to achieve the desired carbon and economic outcomes at the city level lacks a clear roadmap. To address this challenge, we comprehensively analyzed 12 coastal megacities worldwide by integrating geospatial building data. Our study evaluated the potential energy savings, carbon mitigation, and levelized carbon abatement costs (LCACs) from a life cycle perspective. The results revealed that using seawater and solar energy within urban boundaries can reduce electricity consumption from 1 to 24% across these cities. The spatial distribution of the LCAC for seawater-based systems exhibited more variation compared to the RTPV. By applying specific LCAC thresholds ranging from 0 to 225 USD/tCOe, all cities could achieve both carbon reductions and economic benefits. These thresholds resulted in up to 80 million tonnes of carbon emission reductions and 5 billion USD of economic benefits, respectively. Our study provides valuable insights into integrating renewable resource systems, enabling coastal cities to achieve carbon and economic advantages at the city scale simultaneously.