wells drilled from the surface. The product gas can be used as a chemical feedstock or as fuel for power generation. The technique can be applied to resources that are otherwise not economical to extract. It also offers an alternative to conventional coal mining methods. Compared to traditional coal mining and gasification, UCG has less environmental and social impact, though environmental concerns exist, including the potential for aquifer contamination. Carbon capture technology Carbon capture, utilization, and sequestration (or storage) is increasingly being utilized in modern coal gasification projects to address the greenhouse gas emissions concern associated with the use of coal and carbonaceous fuels. In this respect, gasification has a significant advantage over conventional combustion of mined coal, in which CO2 resulting from combustion is considerably diluted by nitrogen and residual oxygen in the near-ambient pressure combustion exhaust, making it relatively difficult, energy-intensive, and expensive to capture the CO2 (this is known as “post-combustion” CO2 capture). In gasification, on the other hand, oxygen is normally supplied to the gasifiers and just enough fuel is combusted to provide the heat to gasify the rest; moreover, gasification is often performed at elevated pressure. The resulting syngas is typically at higher pressure and not diluted by nitrogen, allowing for much easier, efficient, and less costly removal of CO2. Gasification and integrated gasification combined cycle's unique ability to easily remove CO2 from the syngas prior to its combustion in a gas turbine (called "pre-combustion" CO2 capture) or its use in fuels or chemicals synthesis is one of its significant advantages over conventional coal utilization systems. CO2 capture technology options All coal gasification-based conversion processes require removal of hydrogen sulfide (H2S; an acid gas) from the syngas as part of the overall plant configuration. Typical acid gas removal (AGR) processes employed for gasification design are either a chemical solvent system (e.g., amine gas treating systems based on MDEA, for example) or a physical solvent system (e.g., Rectisol or Selexol). Process selection is mostly dependent on the syngas cleanup requirement and costs. Conventional chemical/physical AGR processes using MDEA, Rectisol or Selexol are commercially proven technologies and can be designed for selective removal of CO2 in addition to H2S from a syngas stream. For significant capture of CO2 from a gasification plant (e.g. > 80%) the CO in the syngas must first be converted to CO2 and hydrogen (H2) via a water-gas-shift (WGS) step upstream of the