The current (haha) mechanism for energy usage calculates energy per unit time which means that if you accelerate constructor speed you get an added buff in that the energy costs can be reduced to literally nothing. Making the energy costs recipe based would eliminate the grind of waiting for the constructor without giving a "and as a bonus you don't need to drain your capacitor bank" benefit and would also give more tunability for balancing (ie brewing refined pentaxid should be much more expensive than brewing coffee) sort of thing. (Might also help position for dealing with the stalling timer on the constructor if that's related to code used to deal with an exploit on power/material costs)
I guess this is only an issue that people trying to run a base on solar run into. After I find the first pentaxid deposit energy pretty much becomes a non-issue for me in every play through I have experienced. Fuel needs are present enough to have to swing by an asteroid once in a while, but never to a point I have to think even this remotely about energy consumption.