Carbon Dioxide Sequestration Potential in Coal Deposits

Abstract

The concept of using gassy unmineable coalbed for carbon dioxide (CO2) storage while concurrently initiating and enhancing coalbed methane production may be a viable near‐term system for industry consideration. Coal is our most abundant and cheapest fossil fuel resource, and it has played a vital role in the stability and growth of the U.S. economy. The energy source is also one of the fuels causing large CO2 emissions with the burning of coal in power plants. In the near future, coal may also have a role in solving environmental greenhouse gas concerns with increasing CO2 emissions throughout the world. Coal resources may be an acceptable “geological sink” for storing CO2 emissions in amenable unmineable coalbeds while significantly increasing the production of natural gas (CH4) from gassy coalbeds. Industry proprietary research has shown that the recovery of coalbed methane can be enhanced by the injection of CO2 over methane which could allow for the potential of targeting unmineable coals near fossil‐fueled power plants to be utilized for storing stack gas CO2. Preliminary technical and economic assessments of this concept appear to merit further research leading to pilot demonstrations in selected regions of the United States. The benefits for considering and using unmineable coalbeds for a system concept of CO2‐CH4 cycle include the following: (1) CO2 is captured from power plant flue gas, pressurized, and transported to injection wells completed in deep unmineable coals; (2) Coals near existing power plants have enormous capacity to store CO2 while enhancing CH4 production; (3) Coal reserves underlie many U.S. power plants with as many as 90% unmineable; and (4) Injection of CO2 into unmineable gassy coals allows for displacement of one molecule of sorbed CH4 while two or more molecules of CO2 are sequestered on the coal surface.

Subtask 7.2 Global Warming and Greehouse Gases

“…The coal bed methane resource is not a small player in the energy field as indicated by the fact that by 1996, production of the total US gas supply had risen to 6%. (20) This resource, much of it untapped and unmineable, is scattered across the inland areas of the US.…”