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 <WSD>meal</WSD> around a campfire, had to collect wood and then spend time and effort coaxing the heat of friction out from between sticks to kindle a flame. With more settled people, animals were harnessed to capstans or caged in treadmills to turn grist into meal. 
Meaning of the word marked with <WSD> tags:  (food that is prepared and eaten)Food that is prepared and eaten, usually at a specific time, and usually in a comparatively large quantity (as opposed to a snack).