America’s tech giants are masters of the digital realm. Yet as they bet stupendous sums on artificial intelligence (ai), their ambitions face constraints in the physical world. Shortages of chips and data-centre equipment such as transformers and switching gear mean soaring prices and lengthy waits. Just as pressing is access to energy as utilities struggle to match the demands of Silicon Valley. On July 24th President Donald Trump published an “ai action plan” which describes stagnating energy capacity as a threat to America’s “ai dominance”. How is big tech coping with a worsening power crunch?