Manual tools like can openers and a simple cutting board and skillet. Manual tools like hammers and saws. Manual tools like pen and paper or a phone. Manual tools like a hug and a smile.
We overlook these simple sources of energy...and resulting benefits.
But human energy comes from intent combined with a goal and some elbow grease...and the results are of a more human scale than when strained through complex certification programs and packaging and airports.
Life has a lot of minutia to it. Breathing. Three meals a day. Sleep. Smiles. And relationships that are often messy. But that's the stuff of life. The energy of life. And yes, human energy is even more precious than petroleum or solar cells or biogas or LEDs.
Human energy makes the adventure of playing with all those other forms of energy into the adventure that passes survival and brings us a life of style!