Both the U.S. and world economies are linked to an abundant, reliable, and cost-effective supply of electricity. While nuclear, natural gas, and renewable resources will support a large portion of future generation needs, the magnitude of the U.S. demand for low-cost electricity will mandate continued and expanded use of domestic coal-based power generation. Development of viable, cost-effective CO2 capture technologies from coal-based power generation processes is critical for the continued utilization of coal by addressing new legislative policies aimed at reducing CO2 emissions.
Some of the hurdles associated with CO2 capture processes for coal-fired power generation include:
- Lack of commercially available CO2 capture technologies
- High capital and operating costs
- Large footprint required for CO2 capture equipment
- Numerous operational concerns
The NCCC provides the infrastructure and support for technology advancements needed for commercial application of CO2 capture. Technology development at the NCCC focuses on pre-combustion CO2 capture for advanced integrated gasification combined cycle power plants and post-combustion CO2 capture for conventional pulverized coal-fired power plants. Work at the NCCC also aims at lowering costs of IGCC processes to help meet the demand for affordable power generation with reduced CO2 emissions.
The NCCC serves as a neutral, central test facility for third-party developers. The center’s flexibility avoids the need for multiple test sites that each technology developer may have to utilize were the NCCC not available.
Pre-Combustion CO2 Capture
NCCC’s pre-combustion CO2 capture program supports evaluation of solvents, sorbents, catalysts, membranes, and other emerging technologies with coal-derived syngas. The flexibility and size of the NCCC is well suited to test a range of CO2 capture and gas cleanup technologies and accelerate their advancement through the component testing and pilot plant stages of development, rapidly preparing them for demonstration phases.
The infrastructure for pre-combustion CO2 capture testing includes the Syngas Conditioning Unit (SCU), a flexible slipstream facility that can accommodate multiple, small-scale test skids able to be tested simultaneously. The SCU consists of small reactor vessels, arranged to allow operation in series or in parallel, which accommodate a range of syngas flow rates, temperatures, and pressures. The site provides the flexibility to allow technologies to scale-up and supports pilot demonstrations as well.
Post-Combustion CO2 Capture
A major part of the NCCC is the Post-Combustion Carbon Capture Center (PC4), located at the Alabama Power E.C. Gaston plant site. The PC4 utilizes flue gas from Gaston Unit 5, a supercritical pulverized coal unit. The primary purpose of the PC4 is to support development of multiple post-combustion CO2 capture technologies by providing a neutral test site with commercially relevant operating conditions. The site provides a Pilot Solvent Test Unit for developers to test their solvents, as well as several locations for developers to install test skids.
Since construction was completed in 2011, the PC4 has provided test sites for CO2 capture enhancing enzymes, solvents, membranes, and novel processes from several technology developers. In adding the capability to capture carbon dioxide at concentrations typical of natural gas, the PC4 has expanded NCCC value to virtually all of the fossil-fired power generation fleet.
While the previous testing of the NCCC gasification process has led to commercialization of several key processes, important work remains to make Integrated Gasification Combined Cycle (IGCC) units more reliable, efficient, and cost-competitive. In addition to providing syngas for pre-combustion CO2 capture testing, the NCCC gasification process operates to support the development of technologies including automatic gasifier controls, coal feeders, advanced sensors and instrumentation, and high efficiency particulate filtration components. Gasification operation also supports significant related technologies including biomass gasification, warm gas cleanup (such as mercury capture), and fuel cells.
The NCCC gasification process operates with nominally two tons of coal per hour and features many of the key components of a commercial IGCC plant. These include high pressure solids feed systems; a Transport Gasifier; syngas coolers; a hot gas filtration system; continuous ash depressurization systems developed on-site for ash cooling and removal; and a recycle syngas compressor. The process operates with high reliability, allowing consistent, long-term testing of gasification and syngas conditioning technologies.