Energy is the (1) ________ to do work and is required for life processes. An energy (2) ________ is something that can produce (3) _______, power life, move objects, or produce electricity. Matter that stores energy is (4) _______ a fuel. Human energy (5) _______ has grown steadily throughout human history. Early humans had modest energy requirements, mostly food and (6) ______ for fires to cook and keep warm. In today's society, humans consume as (7) ______ as 110 times as much energy per person as early humans. Most of the energy we use today come from (8) ________ fuels. However, they have a disadvantage in that they are (9) _________ on a human time scale, and cause other potentially harmful effects on the environment. In any event, the exploitation of all energy sources, ultimately rely (10) ______ materials on planet Earth