https://phys.org/news/2018-06-electrons.html

Electron transfer is among the most fundamental processes for sustaining life and for energy conversion. It occurs when an electron moves from one atom or molecule to another, bringing its electrical energy with it. Photosynthesis, mitochondrial and cellular respiration, and nitrogen fixation are among the many biological processes made possible by the orderly movement of electrons.

Because electron transfer is both ubiquitous and important, scientists have invested enormous efforts into understanding the process, and used what they learned to create solar cells, fuel cells, batteries and many other devices that also depend on efficient electron transfer.