Integrating intermittent renewable-energy supplies into existing electricity grids in a stable way will depend on artificial intelligence. Such a system could process massive volumes of consumption data and adjust power usage almost instantly, giving real-time control over supply and demand. Domestic consumers would be rewarded (with cheaper bills) for shifting their energy demand at short notice when the grid has a power imbalance, as is already the case for large industrial consumers and grid-scale storage systems. Smart meters that collect household consumption data would enable this process. By 2020, the United Kingdom aims to have such meters in 26 million homes and the European Union has a target of 200 million.