Ключевые слова: background, black, black background, black gold, board, bucket, carbon, carbon dioxide, chp, coal, coal pile, coal structure, combustible, dark, deposits, energy, energy source, energy storage, exploitation, extraction, fossil, fossil fuel, fuel, hammer, hand tool, hard, industrial, industry, lump, metal bucket, metal clamp, mine, mineral, mining, night, pick, pollution, potential, production, raw material, rock, shale, solid fuel, stone, to be burned, tool, unclean, underground, wealth, wooden box,