Only forty years ago, the number of mobile-phone users in the world was tiny. Consider the 1980s. Mobile phones were not yet part of people’s everyday lives; in fact, they were hardly within reach of ordinary people at all. At that time, total global electricity consumption was about 7,300 terawatt-hours (TWh) per year. [1 terawatt = 1 million megawatts = 1 trillion watts.] By 2024, following the rise of thousands of electricity-dependent technologies—including



