Sentence:  Energy has seldom been found where we need it when we want it. Ancient nomads, wishing to ward off the evening chill and enjoy a meal around a campfire, had to collect wood and then spend time and effort coaxing the heat of friction out from between <WSD>sticks</WSD> to kindle a flame. 
Meaning of the word marked with <WSD> tags:  a '''stick''' of woodA small, thin branch from a tree or bush; a twig; a branch.