Some Influences of Underground Coal Gasification on the Environment

Increasing energy costs and energy demand have renewed global interest in clean coal technologies. Underground Coal Gasification (UCG) is an industrial process that converts coal into product gas. UCG is a promising technology with a lot of health, safety and environmental advantages over conventional mining techniques. UCG carries risks to human health, agriculture and the environment. This article briefly analyzes the advantages and negative environmental impacts of UCG. It describes experimental objects, mathematical models as tools for simulation cases and it used coal from UCG experiments in Cigel, Barbara and Wieczorek mines to analyze the environmental impacts of UCG. The gasification converts the carbon in the coal to syngas and heat. We carried out a numerical simulation of the two-dimensional unstable heat conduction in the coal and overburden, with the aim of judging the influence of this heat source on the surroundings, including the surface. The results show that the temperature in the surrounding rock first increases and then decreases with time, the peak of the temperature curve decreases gradually, and its position moves inside the surrounding rock from the ignition point. A small amount of potentially dangerous syngas leaks from the UCG cavity and channels into vulnerable areas depending on working pressures. The danger of explosion and poisoning in vulnerable zones was evaluated by the simulation model. The results show that the danger is real but by monitoring and controlling the air in the vulnerable area it is possible to reduce this risk.