With an ever-increasing focus on environmental issues, Southern Company employees have developed a number of patented and patent-pending innovations to address the capture and storage of carbon dioxide and carbon ash. The patent-pending innovation for Deep Well Carbon Dioxide Sequestration, and the patented Systems and Methods for Particulate Filtration, were both developed by company employees solving a business need.
Dan Patel, a Principal Engineer for Southern Company, discovered a way to stabilize carbon dioxide using water, allowing for its safe long-term storage deep underground. Traditional carbon capture and storage involves separating and capturing carbon dioxide – a byproduct of the coal-burning process – and transporting the material underground or to a nearby industrial facility. What Patel discovered was a way to stabilize the stored carbon dioxide, which allows for safe long-term storage deep underground. The innovation avoids use of pipelines for long distance transport of carbon dioxide, an important need for power plants as they are pressed to control costs. Another important aspect is that the innovation beneficially uses plant waters, helping to control the cost of water treatment to meet the Environmental Protection Agency’s (EPA) proposed surface water effluent limits.
“Once the carbon dioxide is captured, it is transported to underground geological formations for storage, eventually in minerals” explained Patel. “In the past, the process of storing pure carbon dioxide deep underground posed a risk in that carbon dioxide had the potential to move from one area into other surrounding geological formations underground.” Deep saline formations are also much more widespread with respect to power plant locations, than are geologic formations suitable for long term storage of pure carbon dioxide.
Current carbon dioxide sequestration processes pose possible migration risk into surrounding geologic formations or aquifers and nearby layers of permeable rock, sand or gravel through which groundwater flows. Numerous studies have been conducted on injection of carbon dioxide deep underground, but the process that Patel developed prevents any potential migration of the gas once it has been stored underwater in deep saline geologic formations.
Patel’s innovation has been successfully tested at an independent test laboratory facility with positive results.
Another innovation helping capture carbon was developed by Gerry Klemm, a principal engineer for Southern Company; a low-cost option for removing powdered activated carbon, or (PAC) with electrostatic precipitators, or (ESPs). ESP’s are not designed to remove such particulate in the same way as other control devices. Therefore, a solution needed to be found to enable ESP’s to not only remove PAC from the gas stream, but also to retain it. . Fortunately, Klemm had previously performed extensive studies on loss-on-ignition (LOI) particulate behavior in conjunction with other clean air initiatives. LOI and PAC share similar properties as both are very high in electrical conductivity, which can cause short circuits on the porcelain insulators. They are also very light in weight and tend to float right through the ESP after it has done its job in mercury removal without being captured.
PAC is a highly adsorptive material that is injected into the gas stream where it is exposed to the oxidized mercury in the flue gas. After being exposed for a minimum length of time, the PAC must then be removed from the gas path. This is generally done by scrubbers or baghouses. In some cases it must be done with ESPs, but depending on their size, this may be a challenge. Oxidized mercury exists in exceeding minute concentrations so the PAC particle size must be very small. This adds to the difficulty in collecting the particulate.
Patented baffling designs were developed by using laboratory physical and computerized modeling as well. The baffles were installed in the dust hoppers where they produce the benefit of retaining the PAC after it has been collected.
The above innovations have been, and are currently being installed in various Southern Company units. Field testing has confirmed the successful increased removal of carbonaceous material and, as such, these designs have been included in the Mercury and Air Toxics Strategy (MATS) compliance plans.
Based on the results, Klemm developed the Systems and Methods for Particulate Filtration, which has been patented by the United States Patent and Trademark Office. “This innovation is cost-effective and is easily retrofitted into existing units capturing fly ash particles before they enter into the final flue gas stream. This patented innovation is now operational at several plants in our system,” says Klemm.
“By looking at things in a different way, they both were able to come up with a great solution. It’s one of those things that we could have just kept doing the same way and nobody would have thought much about it. But they understood that we could create a much more efficient and cost-effective process to help address some of the environmental concerns affecting our company and because of innovative thinkers like them, our company continues to be a leader in the electric utility industry.” said Christopher Savage, Intellectual Property manager for Georgia Power.
Southern Company has been granted a patent for Klemm’s Systems and Methods for Particulate Filtration, and has filed a patent for Dan Patel’s Deep Well Carbon Dioxide Sequestration. If you are interested in either of these innovations, please contact Christopher Savage at CHSAVAGE@Southernco.com or 404-506-7396