TRIZ
Brilliant example of Innovation. Moving our energy grids away from fossil fuel comes with many challenges, among them the storage of energy at the yearly/seasonal scale. There are several existing solutions already developed, based on different principles. But pushing these solutions further is raising other, new challenges: using more rare materials creates further environmental damage and generate politico-economic incidents. Some tech may be dangerous at large scale, or too costly, or have a too large footprint.