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.
Coal is extracted from the ground by coal mining, either underground mining or open pit mining (surface mining). Coal is the largest source of fuel for the generation of electricity worldwide, as well as the largest worldwide source of carbon dioxide emissions.