High School Earth, Space, and Geophysical Curriculum Essentials May 2009 9. Boulder Valley School District High School Earth, Space, and Geophysical. Science Curriculum Essentials Document. Enduring Understandings. are the big ideas central to a content area that have lasting value beyond the classroom and.
See also: Coal gasification and Coal seam gas. Coal gas is a flammable gaseous fuel made from coal and supplied to the user via a piped distribution system. Town gas is a more general term referring to manufactured gaseous fuels produced for sale to consumers and municipalities.
Natural gas is a mixture of flammable gases, mainly the hydrocarbons methane and ethane, that occurs beneath the surface of the Earth. Helium is also found in relatively high concentrations in natural gas. Manufactured gas is derived principally from coal and petroleum.