This category examines how energy is produced, stored, moved, and used in the real world, and how those systems are changing under technical, economic, and political pressures. Coverage at Interesting Engineering spans conventional power generation, renewables, nuclear, grids, storage, and emerging energy technologies. Energy systems are defined by constraints. Reliability is as central as sustainability, especially as energy systems become more complex and more interconnected. Energy also examines who builds these systems, who pays for them, and what determines whether new energy projects survive beyond early pilots.