There are quite a few very simple, highly efficient methods to store renewable energy. For example, see "gravity battery" or "thermal battery". If these seem

There are quite a few very simple, highly efficient methods to store renewable energy. For example, see "gravity battery" or "thermal battery". If these seem "creative", it is only because there was never a need for them before. The ultimate "creative" realization is the fact that the earth is one giant "thermal battery" that stores energy from the sun. All the renewable power civilization needs is stored beneath your feet. We just need to find efficient ways of extracting it.