Challenges in Developing an Advanced Post-Combustion Capture Technology

During the early 1990's, discussions on the reduction of greenhouse gas emissions, more specifically CO2 came to the forefront with the introduction of the Kyoto protocol. In the following years, the discussions and the resulting decisions and activities on this topic have noticeably increased. Besides increasing current efficiencies and the use of renewable technologies, carbon capture and storage (CCS) presented an alternative to reach defined goals like the 2 degree commitment. For CCS from fossil fired power plants, the following three options are currently discussed:

• Pre-combustion capture
• Oxyfuel technology
• Post-combustion capture (PCC)

Given that PCC is the only option that offers the capability to not only retrofit but also utilize the existing well proven and highly developed technology within fossil fired power plants, BASF in 2006 decided to develop an advanced post combustion capture technology to significantly improve on the current industry standard. One of the crucial factors for a viable PCC technology is a suitable solvent which absorbs CO2 from the flue gas whereby in a second step, the CO2 is further stripped from the solvent and compressed for storage. The solvent moreover has to fulfill various criteria including exhibiting a high capacity for CO2, a high reactivity with CO2, a high stability against oxygen and thermal stress, low volatility, and most importantly a low energy demand for regeneration of the solvent.

The BASF solvent development program was kicked off with a pre-screening of approximately 400 products with comprehensive laboratory testing conducted on nearly 200 compounds. All test results were carefully evaluated using the criteria mentioned above. Since the data gathered was based on results from different equipment under standardized conditions, the most promising solvents were also tested in a so called “mini-plant.” The mini-plant incorporated a fully integrated absorber / stripper configuration including all the necessary measuring devices.

To further validate the above, BASF in 2007 entered into a cooperation with RWE Power (German utility company) and Linde to test the best of the remaining solvent candidates. As part of this cooperation, a new PCC pilot plant was designed, built and commissioned in June 2009 to operate using a slipstream of real flue gas from a lignite fired power plant. The pilot plant was designed to obtain representative results with respect to all process parameters including energy consumption and removal efficiency and will be capable of capturing up to 300 kg/hr of CO2. To provide a benchmark, the plant is currently being operated with Monoethanolamine (MEA) and will eventually be operated with the most promising candidate(s) identified by the solvent development program of BASF.

The development process of the BASF PCC solvent technology including the path forward will be discussed as part of this presentation.