CO2-enhanced Methane Recovery Research Articles

A Review on CO2 Capture Technologies with Focus on CO2-Enhanced Methane Recovery from Hydrates

Natural gas is considered a helpful transition fuel in order to reduce the greenhouse gas emissions of other conventional power plants burning coal or liquid fossil fuels. Natural Gas Hydrates (NGHs) constitute the largest reservoir of natural gas in the world. Methane contained within the crystalline structure can be replaced by carbon dioxide to enhance gas recovery from hydrates. This technical review presents a techno-economic analysis of the full pathway, which begins with the capture of CO2 from power and process industries and ends with its transportation to a geological sequestration site consisting of clathrate hydrates. Since extracted methane is still rich in CO2, on-site separation is required. Focus is thus placed on membrane-based gas separation technologies widely used for gas purification and CO2 removal from raw natural gas and exhaust gas. Nevertheless, the other carbon capture processes (i.e., oxy-fuel combustion, pre-combustion and post-combustion) are briefly discussed and their carbon capture costs are compared with membrane separation technology. Since a large-scale Carbon Capture and Storage (CCS) facility requires CO2 transportation and storage infrastructure, a technical, cost and safety assessment of CO2 transportation over long distances is carried out. Finally, this paper provides an overview of the storage solutions developed around the world, principally studying the geological NGH formation for CO2 sinks.

Super-critical CO2 saturation-induced mechanical property alterations in low rank coal: An experimental study

The adsorption of carbon dioxide (CO2) into the coal matrix during CO2-enhanced methane recovery causes significant alterations to the coal mass chemical and physical structures, causing modifications to coal's mechanical properties. Hence, the main objective of this study is to investigate the effects of sequestrated CO2 phase condition on coal strength. A series of unconfined compressive strength tests was conducted on Australian brown coal samples, saturated under various CO2 pressures (2–10MPa) at 35°C using an advanced acoustic emission (AE) system and optical 3D deformation analysis. According to the results, super-critical CO2 has the ability to cause a greater reduction of strength (by 46%) and enhancement of elasticity properties (by 20%) in brown coal compared to sub-critical CO2, because super-critical CO2 has greater adsorptive potential, which eventually creates greater coal matrix swelling. According to the AE and deformation analysis, the coal mass natural cleat system contributes significantly to the observed CO2 adsorption-induced changes in mechanical properties.