Background

The environmental impact of CO2 capture plants is an area where the IEAGHG remains committed to facilitating discussion amongst the academic community, technology suppliers and utility companies. Following on from a successful workshop, Environmental Impacts of Amine Emission during Post-Combustion Capture, in 2010, the IEAGHG held the above seminar to discuss the potential for, and control of formation of nitrosamines in the capture plant process. E.ON, Gassnova and GdF Suez co-sponsored the seminar held at the Zeche Zollverein world heritage site near Essen, Germany. Sixty of the world’s leading technical experts from 13 different countries representing academia, technology suppliers and the utility sector were in attendance.
The potential for nitrosamine formation in CO2 capture plant by the side reaction of amines with NO2 is now part of the public debate on CCS. In the public domain, there is significant uncertainty as to the expected levels of nitrosamine formation in capture processes and the potential for emission of these harmful compounds to the environment. Gaining widespread public support for CCS is very important for its successful implementation and this seminar provided a forum for experts to discuss this particular issue and find a way forward in order to address it. Key topics were nitrosamine formation pathways, verified measurement techniques and methods to minimise the formation of nitrosamines in the process. Considering the above mentioned motivation, this workshop was held aiming to answer the following questions:

• What inputs can we expect in terms of NO2 levels and amine quality?

• How to improve the reliability and plausibility of nitrosamine analysis?

• What level of accuracy is possible in nitrosamine detection?

• Which concentration of nitrosamine can be expected until the first reclaimer operation?

• How can nitrosamine levels be minimized?

• How likely is the formation of volatile nitrosamine?

• How can we move forward with providing reliable information to the public?

Conclusions

Hallvard Svendsen concluded the workshop by highlighting some of the key learning points from the seminar:

• If preventative measures are not taken, nitrosamines could be formed in post-combustion capture plant and maybe emitted (albeit in low concentrations approaching current detection limits). The NA formation was detected during operation with MEA exposed to NOx with NDELA as the main component and also during the emissions measurement done by Statoil at Esbjerg.

• Analytical methods for the detection of nitrosamines are available, but recognised standards regarding sampling, preparation and analysis are still required.

• Production rates of NA are related to inlet gas NOx/NO2 content, oxygen plays less important role.

• UV irradiation shows promise as a method to mitigate against possible nitrosamine formation.

Hallvard also highlighted possible actions to prevent the NA formation from being a major problem. Such actions include among other: the reduction of NO2 content entering the absorber, reduce the rate of formation by radical scavenger type additives (e.g. ascorbic acid) and reduce the amount of NA in both the solvent and washing water by UV-decomposition.

The details of a research programme to be undertaken this year to test the efficacy of UV irradiation in limiting nitrosamine concentrations in the laboratory capture pilot plant at NTNU were presented. The outcome of this test campaign will be published in public and expected to include:

• Demonstrate that UV irradiation can be used to control NA level in MEA and DEA containing solvents

• Determine the formation rate of nitrosamines and nitramines

• Optimize the UV radiation for NA decomposition

• Investigate the impact of UV irradiation on the solvent and check the reaction products of UV-decomposition

• Determine the best location of the UV-irradiation

• Estimate time and energy needed for radiation