Ember can be stored in Crystal Cells according to the Ancient Codex. During testing on Eterna (nightly 15), using an ember emitter connected to a Crystal Cell to provide power to an ember receptor connected to an LV Ember Input Hatch doesn't cause the hatch to receive power.
However, the cell itself loses energy, and the animation for moving ember plays, while the hatch itself stays on 0 Ember
Video here: https://discord.com/channels/738517355537236129/1340557160689696889/1448059856450879500