The power grid is the network that moves electricity from where it is generated to where it is used. It includes generators, transmission lines, substations, transformers, and distribution wires. The grid is often called the largest machine ever built.

It operates in real time. Supply and demand must match instantly. If they drift apart, frequency and voltage falter, and equipment can trip offline. Grid operators balance the system second by second, dispatching plants and calling on reserves. The physics leaves little room for error.

Grids are aging and under strain. Many transmission lines were built decades ago. Renewable energy flows differently than fossil plants, often from remote areas to cities. Extreme weather stresses equipment. Cyberattacks are a growing threat. Modernizing the grid is one of the biggest infrastructure challenges of the century.

Key components

• Generating stations
• High-voltage transmission lines
• Substations and transformers
• Distribution networks
• Control centers