The former is a broad term and makes sense in biology only in the case of bioenergetics. Ironically the former had more tagged posts (which I retagged to bioenergetics) Though energy is a more popular term, it is too broad and bionergetics is the more appropriate for this site.
Mostly agree; but partly not.
Not agree in part:
Bioenergetics means how the energy is dealt in living systems.
But there could be some other situations where, within biology stack exchange we may have to encounter questions about energy, but not exactly about energy-flow through biological system, but rather about environment, global-warming, etc. to indicate energy flow in the abiotic part of environment.
So, tag bioenergetics could be improper for such situation.
- Agree, (found helpful, but suggesting some-other solution) in the part:
On the other hand, the question points a fact that; in most cases, questions tagged with energy indicates energy-flow through biological system; so in that cases, tag energy is same as [bioenergetics].
More over, there are questions tagged with both energy and bioenergetics at the same time. A simple search in the BioSE (main site) question search box as
[bioenergetics], [energy] displays them. Such as this, this, this and this.
In such cases where we are telling specifically about energy through biological system; we could use only the tag bioenergetics, and in cases where we are talking about energy in abiotic environment; or about something generally applicable for both living and non-living systems; we could suggest more non-specific tag energy