Fossil fuel use The energy problem

The ASA-ASTM system established four classes or ranks of coal anthracite, bituminous, sub-bituminous, and lignite, based on fixed-carbon content and heating value measured in British thermal units per pound (BTU lb ). Anthracite, a hard black coal that burns with little flame and smoke, has the highest fixed-carbon content, 86-98% and a heating value of (9.2-10.7) 10 J kg (Speight 2006, see Tables 2.51 and 2.55). This classification was already used 100 years ago (Robertson 1919) and Seyler (1900) used the C/H ratio for the coal classification, from lignite ( 10) to anthracite ( 26). Based on raw coal, the chemical composition varies widely (in %)  

ASTM International (ASTM), originally known as the American Society for Testing and Materials, is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services. The American Supply Association (ASA) is the US national organization serving wholesale-distributors and manufacturers. 

Based on our own studies in different German power plants fired with Australian hard coal. 

The reserve-to-production (R/P) ratio denotes a number of years of continued use of fossil fuels when the reserves remaining at the end of any year are divided by the production in that year. From the year 2008 the world R/P amounts to 122 for eoal, 60 for gas and 42 for oil (BP 2009). Therefore, the limit of fossil fuels to serve energy carriers is one side in approaching the transfer from the fossil fuel era 

The calorific value or heat of combustion or heating value of a sample of fuel is defined as the amount of heat evolved when a unit weight (or volume in the case of a sample of gaseous fuels) of the fuel is completely burnt and the products of combustion cooled to a standard temperature of 298 °K. Net calorific value assumes the water leaves with the combustion products without fully being condensed. Fuels should be compared based on the net calorific value (Table 2.55). The calorific value of coal varies considerably depending on the ash, moisture content and the type of coal, while calorific values of fuel oils are much more consistent. Table 2.55 shows that oil and gas have about 30% less specific CO2 emission than coal, based either on carbon content or energy output the only reason for this difference is the water content of the fuel and the energy loss due to water evaporation. Water condensation and heat recovery seems a way to increase the net efficiency and hence reduce emissions. 

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