Coal bed pretreatment for enhanced carbon dioxide sequestration

Abstract

A method is claimed for enabling storage of greater volumes of carbon dioxide for sequestration while simultaneously enhancing methane recovery from the coal bed. The process is implemented by injecting hydrogen into a coal bed, such as a depleted underground coal deposit, at a temperature below about 800 degrees Centigrade ( 10 ); extracting the hydrogen together with methane from the deposit ( 20 ); separating the hydrogen from the methane ( 30 ); delivering the methane as a product of the process ( 40 ); reinjecting the separated hydrogen into the deposit to continue the process until sequestration of carbon dioxide is desired ( 50 ); optionally producing hydrogen from methane ( 60 ) and optionally injecting carbon dioxide for sequestration ( 70 ).

1 . A process for pretreating an underground coal bed to enhance the potential for carbon dioxide sequestration and to enhance methane production comprising the steps of, 
 injecting hydrogen into an underground coal bed, wherein the hydrogen is at a temperature below about 800 degrees Centigrade;    extracting hydrogen and methane from the coal bed;    separating the hydrogen from the methane;    delivering the methane as a product of the process; and    reinjecting the separated hydrogen into the deposit to continue the process until the deposit is no longer productive or until sequestration of carbon dioxide is desired.    
   
   
       2 . The process of  claim 1  further comprising the step of cleaning the extracted methane and hydrogen to remove contaminants.  
   
   
       3 . The process of  claim 1  further comprising the step of injecting carbon dioxide for sequestration after the last step.  
   
   
       4 . The process of  claim 1  further comprising the step of producing hydrogen from a portion of the methane to replenish lost hydrogen in the process.  
   
   
       5 . The process of  claim 1  further comprising the step of collecting the separated hydrogen for resale or reuse after the last step.  
   
   
       6 . The process of  claim 1  wherein both the step of injecting and the step of extracting are performed using at least one borehole into the deposit.  
   
   
       7 . The process of  claim 1  wherein the step of injecting is performed using at least one borehole into the deposit and the step of extracting is performed using at least one borehole different than any borehole used for injecting the hydrogen.