A carbon storage research project involving Southern Company has hit a significant milestone with the beginning of carbon dioxide injection into a coalbed methane well near Tuscaloosa, Ala.

Injection, storage and monitoring got under way in June at the Black Warrior Basin site and will continue for 45 to 60 days. The test is designed to evaluate the feasibility of combining carbon storage in coal seams with enhanced recovery of coalbed methane, which is a primary component of natural gas.

“We are involved in several research projects looking at various scenarios for storing CO2, and coal seams have potential as a geological ‘sink.’ Our view is to explore all worthwhile options that might help us reduce greenhouse gas emissions from coal-based power generation,” said Richard Esposito, Southern Company principal research geologist.

The Black Warrior Basin Coal Seam Project is being conducted by the U.S. Department of Energy’s Southeast Regional Carbon Sequestration Partnership (SECARB), of which Southern Company is a member. Southern Company is providing funding and technical consulting and performing the field soil and groundwater monitoring.

According to the DOE, the northern Alabama site was chosen because it is representative of the Black Warrior Basin, an area of about 23,000 square miles that contains enough coal to potentially sequester, or store, 1.1 gigatons to 2.3 gigatons of CO2.

In addition, enhanced coalbed methane recovery combined with CO2 storage could squeeze another 1.5 trillion cubic feet of natural gas from the coal seams, according to the DOE.

 
CO2 tanker at the Black Warrior carbon storage site.

Esposito said researchers will be watching how the coal reacts as it absorbs the CO2 to determine its suitability for permanent storage.

The process itself is similar to that of the recently completed pilot injection of CO2 at Mississippi Power’s Plant Daniel and is utilizing some of the same type of equipment and procedures.

However, there are significant differences. At Plant Daniel, the CO2 was injected into a deep saline rock formation, 8,500 feet below ground. In the Black Warrior test, carbon dioxide is being injected into coal seams at much shallower depths, ranging from 940 feet to 1,800 feet.

Also, the amount of CO2 is smaller in the Alabama project – 240 tons, compared with 3,000 tons at Plant Daniel. And the methane recovery element applies only to the coalbed tests.

“These projects along with our other carbon storage tests are rapidly advancing what we know about a technology that is a key part of our commitment to cleaner energy,” Esposito said.

Other partners in the Black Warrior project include the Southern States Energy Board, Geological Survey of Alabama (local manager of the project), El Paso Exploration and Production, the University of Alabama and the Virginia Center for Coal and Energy Research at Virginia Tech.