Overview

The hydrogen-to-carbon ratio of carbonaceous feedstocks such as heavy oil, tar sands, oil shale, coal, and biomass to liquid fuels is lower than the hydrogen to carbon ratio of conventional petroleum. In the process, the hydrogen/carbon atomic ratio must be adjusted to that of transportation fuels. One of the methods by which this can be achieved is through the application of the Fischer-Tropsch process to the conversion of synthesis gas to hydrocarbons.

Synthesis gas ( syngas) is the name given to a gas mixture that contains varying amounts of carbon monoxide and hydrogen generated by the gasification of a carbon-containing fuel to a gaseous product with a heating value (Speight, 2007a and references cited therein). Examples include steam reforming of natural gas or liquid hydrocarbons to produce hydrogen, the gasification of coal, and in some types of waste-to-energy gasification facilities. The name comes from their use as intermediates in creating synthetic natural gas (SNG) and for producing ammonia or methanol. Synthesis gas is also used as an intermediate in producing synthetic petroleum for use as a fuel or lubricant via Fischer-Tropsch synthesis (Storch, 1945).

In the context of this book, synthesis gas, which can also be generated from biomass (Chap. 8), is not the same as biogas. Biogas is a clean and renewable form of energy generated from biomass that could very well substitute for conventional sources of energy. The gas is generally composed of methane (55 65 percent), carbon dioxide (35 45 percent), nitrogen (0 3 percent), hydrogen...