ATP energy-storing molecule as is no doubt an efficient! as not only it is used as energy storage and provider in all forms of life and has probably been around for billions of years. Even in the time period when the last universal common ancestor of all life roamed the planet. However, can there be something better? as in, can we synthetically create a better molecule? will the cell accept this new molecule? or is ATP the dead-end or the ultimate evolutionary answer to energy provision and storage.