Zero-Point Energy was a limitless power source capable of providing enough power for an entire universe of people, human or otherwise. It was the ultimate power source.
Until the early 21st century, fossil fuels were commonly used. These were replaced by renewable energy and nuclear power. Then, in the late 22nd century, antimatter was used as a power source for the first time. This provided enough power for a long time. However, as humanity became a Type II civilization, even antimatter could not provide enough power. One of the solutions was to try zero-point energy.
Tech Level: 14
Zero-Point Energy was the energy in the vacuum of space. This was the cleanest energy source available for use. The amount of energy was unlimited. With the endless supply of energy particles contained in the gravity fields, zero-point energy was the ultimate power source. It was never replaced with anything else.