The Matrix

The body generates 100 watts a day, which is like a light bulb. Getting all of that electricity out would require giant banks of batteries being crawled by electrical spiders. A similar design was proposed in the 1960s because we hadn't invented the lithium ion battery yet. There are many ways to extract electrical energy from the body that don't require raising us in a simulation and draining our life forms. They might not be as visually impressive but they're very evocative.