As its name suggests, coal gasification converts coal into a gas form similar to natural gas. Gasification may occur in a separate processing facility or a coal mine. The gases can be stored or burned for the production of electricity, fuel or chemicals. Gasification usually involves the use of oxygen and steam. This process offers several advantages and disadvantages with regard to efficiency, cost, the environment and other factors.
Major advantages of gasification include its abilities to produce different forms of energy and create useful byproducts. People can use the energy immediately in the form of electricity or store it as a fuel for future and portable consumption. The U.S. Department of Energy indicates that byproducts of gasification include sulfur and ammonia, both of which have important industrial applications. This improves the supply of such commodities and helps make gasification more economical for its operators.
Gasification generates electricity more efficiently than simply burning coal, which reduces the amount of coal mining necessary to generate the same amount of power or fuel. Power plants that burn coal-derived gases also use their exhaust and heat to produce steam, according to the Department of Energy. This steam turns a turbine to generate additional electricity, yielding efficiency rates at least 17 percent greater than those of conventional coal-fired plants.
One of the major disadvantages of coal gasification is the cost to set up and maintain the necessary facilities. The Pacific Northwest National Laboratory indicates that gasifier refractories typically last about one year to 450 days at most, costing roughly one million dollars to replace. They also take approximately 21 to 42 days to install, during which the gasification facility cannot operate. This raises the cost of energy and chemicals produced by such plants, making it more difficult for them to compete with equivalent products generated using conventional methods.
Despite certain environmental advantages, coal gasification still produces more pollution than many energy sources and cannot eliminate the environmental harm of coal mining. The Climate Institute warns that gasification creates significantly more greenhouse gas emissions than petroleum, unless power plants sequester its carbon output. This means that the plant would have to pump the pollution deep underground rather than releasing it into the air. However, carbon sequestration remains impossible in some regions like northern Minnesota, due to safety concerns.