Fuel Types and Uses Crossword Puzzle

QUESTIONS LIST: fifty: maximum number of years until we run out of oil, tar sands: what crude oil is recovered from (2 words), methane: what natural gas is mostly comprised of, sulfur: smelly nonmetal that releases when petroleum is burned, developing: types of countries that commonly use wood for fuel, anthracite: type of coal also known as "hard coal", phytoplankton: the remains of these form petroleum, charcoal: one of the most common uses for wood in fuel, co generation: term for generating heat and electricity from fossil fuels, refineries: places (plural) that produce fuels from oil sands, lignite: type of coal with the smallest % of carbon, peat: precursor to coal