1) The energy released during nuclear fission or fusion, especially when used to generate electricity is called nuclear energy.
2) It is not renewable because it is an element that has no way whatsoever to regenerate or replicate itself, nor gets created by any natural terrestrial means, neither makes itself available by arriving from outer space (like sunlight). There is a limited amount of it available on the Earth, and every bit you use is a bit you’ll never have available again (as Uranium atoms get destroyed by the fission process).
The most basic and perhaps powerful example is the fin-tailed fish, whose powerful tail is crucial for mobility, agility, and speed underwater. These adaptations have been underway for millions of years.
