New Scientist: How much energy does the internet use? It's hard to know where to start. There's the electricity consumed by the world's laptops, desktops and smart phones. Servers, routers and other networking equipment suck up more power. The energy required to manufacture these machines also needs to be included...
Their final answer sounds big. A gigawatt is a billion watts, so running and maintaining the internet is like illuminating several billion 100W bulbs simultaneously. But it's a small number compared with global energy use across all sectors. That figure is 16 terawatts, so the internet is responsible for less than 2 per cent of the energy used by humanity.