fu'-el ('okhlah, or ma'akholeth, "food"):
Is mentioned specifically only in the Old Testament, in Isaiah 9:5,19; Ezekiel 15:4,6; 21:32. Its general, literal meaning in these connections is "food for fire," and might include any sort of combustible material. The common forms of fuel were wood of various sorts (even including thorns, Psalms 58:9; 118:12; Ecclesiastes 7:6), and dried stalks of flowers or grass (Matthew 6:30), charred wood as charcoal (Leviticus 16:12; Isaiah 44:19, and frequently), and dried dung (Ezekiel 4:12,15). There is no certain indication that our coal was known to the Hebrews as fuel, and their houses, being without chimneys, were not constructed for the extensive use of fuel for warmth.
Leonard W. Doolan