Advanced nuclear technologies offer large-scale, low-carbon and highly reliable electricity, and heat suited to megacities where demand is dense, continuous and rapidly increasing. Next-generation nuclear designs deliver compact and high-output power plants that can be sited close to urban load centres. 

The World Bank projects that by 2050 more than two-thirds of the global population will live in cities, with most growth concentrated in Sub-Saharan Africa and South Asia. Urban populations in these regions are expected to double within the next two decades, putting significant pressure on infrastructure, energy security and essential services.[1] Megacities – typically defined as an urban area with more than 10 million inhabitants – require sources that can deliver high volumes of clean, reliable energy within limited land areas and close to demand centres. 

Nuclear generation provides firm, low-carbon baseload power where demand is concentrated, reducing dependence on long-distance transmission that can lead to, on average, 5-8% losses and increased exposure to grid disruptions.[2,3] Modern reactors also support multiple urban-service needs. They can co-produce district heat, high-temperature heat for industrial applications, and the production of synthetic fuels such as hydrogen. In water-stressed regions, nuclear-powered desalination can convert seawater or brackish water into potable water at scale, supporting resilient urban water systems. When paired with thermal storage or distributed resources, nuclear energy can provide flexible support to balance renewable variability without the land and material requirements associated with large battery installations. 

Emerging deployment models – including Small Modular Reactors (SMRs) integrated with distributed energy systems – demonstrate how nuclear can complement storage, distributed generation and demand-side flexibility to support resilient and adaptive urban power systems. Together, these capabilities position nuclear as a key enabler of sustainable growth, system resilience and long-term reliability in megacities. 

Main outcomes of the solution 

• Sustainability: Delivers high volumes of low-carbon baseload power on a small land footprint, enabling co-production of hydrogen, desalinated water and district heat, while reducing fossil fuel use across multiple urban sectors. 
• Reliability & Flexibility: Delivers reliable, high-capacity output near major demand centers and provides flexible operation when paired with thermal storage or hybrid nuclear–renewable systems. This combination supports peak demand and smooth integration of variable renewables. 
• System Resilience: Strengthens energy security for megacities by maintaining continuous supply during peak demand, climate-related disturbances or variable resources’ shortfalls; reduces vulnerability to long-distance transmission and reduces cascading grid failures. 

Key deployment and scaling factors 

1. Assess urban load growth and density to determine demand for close-to-load, low-carbon, and high-reliability generation. 
2. Deploy advanced nuclear systems capable of supplying electricity, heat, desalinated water or hydrogen, improving the efficiency of urban infrastructure. 
3. Pair reactors with thermal storage or hybrid nuclear–renewable systems to manage variable renewable output and provide peak support. 
4. Locate firm generation near metropolitan areas to limit ecological impact, reduce transmission losses and improve system stability. 
5. Expand modular and advanced reactor options that allow incremental capacity additions aligned with long-term urban development. Standardized, modular builds can shorten schedules, reduce risk, and align closely with staged infrastructure expansion. 

Case study 

TerraPower (2023), United States 

TerraPower is developing the Natrium advanced reactor complex in Wyoming, which integrates a 345 MWe sodium-cooled fast reactor with a molten-salt thermal storage system designed to increase output to 500 MWe for more than five hours. This hybrid configuration provides reliable baseload power together with flexible, dispatchable capacity – a combination well-suited to the needs of large metropolitan grids that must address peak demand and variable renewable generation. 

Construction of the site began in 2024. Nuclear-island construction is expected to start in 2026, with commercial operation targeted for 2030. The project demonstrates how advanced nuclear designs can deliver high energy density, long-duration flexibility and stable low-carbon power to support growing urban loads. By storing thermal energy and dispatching it on demand, Natrium illustrates a model of nuclear-enabled flexibility that can reduce reliance on fossil peaking resources and enhance system resilience.[4,5] 

Solution and insights developed with contributions from the World Nuclear Association and Foster and Partners.

References:

1. Urban Development I World Bank Group 
2. What Is the Typical Percentage of Energy Loss during Electricity Transmission and Distribution in a Major Grid? I Sustainability Directory (November 2025) 
3. Electric power transmission and distribution losses (% of output) I World Bank Group 
4. Terra Power Company Website 
5. Information provided to the World Economic Forum I World Nuclear Association (November 2025)