Underground coal gasification (UCG) and surface coal gasification (SCG) are innovative technologies that enable the extraction of energy from coal resources while minimizing environmental impacts associated with conventional mining. These gasification methods offer potential solutions for accessing stranded coal reserves, reducing surface disturbances, and producing cleaner energy from coal. Continued research and development efforts are focused on optimizing UCG and SCG technologies for broader commercial deployment and integration with sustainable energy systems.

1. CLASSIFCATION OF COAL
GASIFICATION – UCG & SCG
By
Er. T. AYISHA NAZIBA, Dr. D. RAMESH, Dr. S.
PUGALENDHI

2. COAL GASIFICATION
• Coal gasification is a process that converts coal into syngas (synthesis
gas), which is a mixture of hydrogen (H2), carbon monoxide (CO),
methane (CH4), carbon dioxide (CO2), and other gases. Both
underground coal gasification (UCG) and surface coal gasification (SCG)
are innovative techniques used to extract energy from coal reserves
while minimizing environmental impacts

3. UNDERGROUND COAL GASIFICATION
(UCG)
• UCG is a method of converting coal in situ (underground) into syngas
without the need for traditional mining.
• The process involves drilling boreholes into coal seams and injecting a
mixture of oxidants (e.g., air, oxygen, steam) into the coal seam to initiate
gasification.
• Heat from the gasification reactions releases syngas, which is extracted
through production wells and can be used for power generation or other
applications.

5. KEY FEATURES
• In situ Gasification: UCG allows for the conversion of coal reserves
located deep underground without the need for extraction or mining.
• Enhanced Recovery: UCG can access deeper coal seams that are
economically or technically challenging to mine using conventional
methods.
• Reduced Environmental Footprint: UCG has the potential to reduce
environmental impacts associated with conventional mining, such as
surface disturbance and waste disposal.

6. ADVANTAGES
• Efficient utilization of deep coal reserves.
• Reduced surface disturbance and environmental impact.
• Flexibility in accessing stranded or remote coal deposits.
• Potential for carbon capture and storage (CCS) integration.

7. CHALLENGES
• Controlling subsurface gasification processes to prevent ground
subsidence or environmental contamination.
• Managing by-product gases and ensuring effective syngas extraction.
• Addressing potential groundwater impacts and maintaining
environmental safety.

8. SURFACE COAL GASIFICATION (SCG)
• SCG involves gasifying coal at the
surface using gasification reactors or
gasifiers.
• Coal is typically crushed and fed into
a gasifier where it reacts with oxygen,
steam, or a combination of both at
elevated temperatures.
• The gasifier produces syngas, which is
cleaned and conditioned before
being used as a fuel for power
generation, chemical synthesis, or
other industrial processes.

9. KEY FEATURES
• Modular Gasification Units: SCG can utilize modular gasification units
designed for surface deployment and flexibility in feedstock handling.
• Cleaner Syngas Production: SCG processes can incorporate advanced
gas cleaning technologies to minimize emissions and impurities in
syngas.
• Integration with Power Generation: Syngas produced from SCG can be
used in combined cycle power plants (IGCC) for efficient electricity
generation.

10. ADVANTAGES
• Controlled gasification process with enhanced process monitoring and
control.
• Efficient utilization of coal resources with reduced environmental impact.
• Syngas produced can be used for a wide range of applications, including
power generation and chemical production.

11. CHALLENGES
• Managing large-scale gasification facilities and associated infrastructure.
• Ensuring proper handling and disposal of by-products and wastes
generated during gasification.
• Addressing environmental and regulatory requirements related to air
emissions and waste management.

12. THANK YOU