A Cleaner Coal Option - UCG-CCS

The capture and geological storage of carbon dioxide (known as Carbon Capture and Storage, or CCS is a method of abating atmospheric emissions of carbon dioxide (Co2). Also Carbon Capture, Utilisation and Storage (CCUS) where the carbon is used for enhanced Oil recovery.

There are also applications where carbon is used as part of a chemical process.

All of these methods are being researched and deployed all over the world and its success is vital for all in energy.

Close Coupled UCG with Co2 storage

UCG lends itself easily to carbon capture and sequestration. as the  process  produces syngas at temperatures, pressures and CO2 concentrations that enable relatively simple, low-cost carbon removal, prior to use.

 Carbon generated during the UCG production of syngas  provides the opportunity to capture and compress it for underground storage or to transport in a pipeline for enhanced oil recovery (EOR) or enhanced coal bed methane (ECBM)

Co2 Storage in UCG Seams

Research is currently underway in many parts of the world into storing Co2 in and around the coal cavity that has been gasified during the UCG process, or in nearby saline aquifiers - so far the results look promising and will offer increased benefits to UCG Technology, increased yeild, lower costs. see Co2 Sinus website for information

For traditional coal mining, or oil and gas projects the cost of implementing CCS is of concern to many, however, UCG can undertake CCS and still remain price competitive.

Image of CCS configuration

There are three main methods for  CO₂ capture processes .

• post-combustion

• pre-combustion

• oxyfuel

Both Post Combustion and Oxyfuel combustion are suitable for UCG

Post-combustion: involves separating the CO₂ from other exhaust gases after combustion of the fossil fuel. Post-combustion capture systems are similar to those already used to remove pollutants such as particulates, sulphur oxides and nitrogen oxides from many power plants.

Whilst post-combustion CO₂ capture is technically available now for coal-based power plants, it has not yet been used commercially for large-scale CO₂ removal

Oxyfuel combustion (also called oxyfiring) involves the combustion of coal in pure oxygen, rather than air, to fuel a conventional steam generator. By avoiding the introduction of nitrogen into the combustion chamber, the amount of CO₂ in the power station exhaust stream is greatly concentrated, making it easier to capture and compress. Oxyfuel combustion with CO₂ storage is currently at the demonstration phase.

ECBM

Reports suggest that UCG in combination with Co2 injection into adjacent coal seams to enhance coal bed methane (ECBM) is a potentially attractive option, particularly under river estuaries, near-shore and eventually for offshore coal.

Co2 injection into coal seams displaces methane and itself is adsorbed onto the coal in a physical bond as a permanent store. Tests have been made of ECBM in China, Japan, United States and Poland (REPOCOL) with encouraging results.

Recent UCG tests in Australia have shown that considerable quantities of Methane can be extracted using UCG technology and at a lower cost than Coal Bed Methane (CBM)