Large-scale CCS demonstrations and the Kemper Project

Organisation: Mississippi Power

Carbon capture and storage (CCS) technologies have been used for decades in a number of industrial applications and there is over 30 years of cumulative experience in large-scale integrated industrial projects (eg, Sleipner, Snohvit, Weyburn-Midale, In Salah). Commercial-scale power plants with CCS have been slower to develop but a number of projects are advancing and two are expected to come on line in 2014 – SaskPower's Boundary Dam (Saskatchewan, Canada) and Mississippi Power's Kemper IGCC (Mississippi, United States). These projects are critical to demonstrate technology readiness and reduce costs for broader commercial CCS deployment.

The Kemper project will demonstrate TRIG™ (Transport Integrated Gasification), a coal gasification process developed jointly by Southern Company and KBR in partnership with the US Department of Energy (DOE). TRIG™ was a 15 year plus development effort at the Power Systems Development Facility (PSDF) in Alabama (now the National Carbon Capture Center) where the technology operated successfully for over 20,000 hours at pilot scale. The Kemper plant will use two commercial-scale TRIG™ units to gasify lignite (low-rank coal that is mined next to the facility) to produce syngas. After the syngas leaves the gasifiers, it will be cleaned and used as fuel for two combined-cycle power generating units with a net output of 582-megawatts of electricity.

By-products of the gasification process include CO2, ammonia and sulfuric acid, which will all be sold commercially. At least 65 per cent of the CO2 will be captured using the Selexol™ process and compressed to a supercritical liquid (about three Mt per year) rendering the plant's CO2 emissions nominally equivalent to that of a natural gas-fired combined cycle unit. Mississippi Power has built a 60-mile CO2 pipeline from the plant to connect with an existing CO2 pipeline where the CO2 will be transferred to oil field operators (Denbury Onshore LLC and Treetop Midstream Services, LLC) and injected into the subsurface for enhanced oil recovery (EOR). The CO2 from the Kemper plant will displace Denbury's current CO2 source from Jackson Dome, a natural CO2 reservoir.

Gas cleanup portion of the Kemper IGCC plant where carbon capture will occur. (Photo courtsey of Mississippi Power)

Mississippi Power began construction of the Kemper project in December 2010, and start-up is expected in 2014. The initial cost estimate was $2.4 billion (net of incentives) and the Mississippi Public Service Commission approved the plant subject to a cap on total costs of $2.88 billion. The project has experienced cost increases largely due to unknowns associated with a first-of-a-kind plant. Also, the company added and then re-sized the capture unit to capture more CO2 than originally planned. The original front-end engineering and design did not include CO2 removal. As the project advanced, the design team explored three options to optimise CO2 capture (25%, 50% and finally 65% removal), which also led to additional piping, materials and labor costs. While the plant requires sizable capital investment before commercial operation, low-cost lignite ($1.25 - $1.50 per MMBtu) is expected to keep operating costs very competitive over its 40-year life.

The Kemper project is an example of an important public-private partnership. Mississippi Power has been successful in securing several federal grants and incentives including a $270 million grant from the US DOE Clean Coal Power Initiative. Over the life of the project, the company calculates the cost savings associated with the various incentives to be over $1 billion.

In most cases, the first version of any new technology will have higher costs and risks than subsequent plants, which is why government support (eg, grants, tax incentives, loan guarantees, etc.) is so critical in the early stages. As experience is gained and the technology becomes more widely applied (coupled with ongoing research and development), it is expected that the price tag will come down – a pattern of cost reduction called learning-by-doing. Early commercial projects such as Kemper are critical to achieve not only the goal of technology readiness, but also cost reduction for broader-scale commercial CCS deployment. However, technology is just one piece; policy leadership – to address higher capital and operating costs for early projects and help create conditions favorable for investment – is still urgently needed.