9. Establishment of Knowledge base for Emission Regulation for the CO₂ Technology Centre Mongstad (2013)

Yolandi Maree^*a, Sissel Nepstad^a, Gelein de Koeijer^b

^aTCM DA, 71 Mongstad, 5954, Norway ^bStatoil ASA, Ark. Ebbellsvei 10, 7005 Trondheim, Norway *Corresponding author

1876-6102 © 2013 The Authors. Published by Elsevier Ltd. Selection and/or peer-review under responsibility of GHGT doi: 10.1016/j.egypro.2013.06.555

Abstract

The CO₂ Technology Centre Mongstad (TCM) is currently regarded as the world’s largest CO₂ capture technology test centre at 100 000 ton/year of CO₂ capture capacity. The main aim of the project was to play an important role in the establishment of proven and cost efficient CCS (CO₂ capture and storage) value chains. At first two technologies are tested, namely and amine plant (designed by Aker Clean Carbon) and a chilled ammonia plant (designed by Alstom) which is fed with two different flue gas sources. The latter will, by normal composition as well as CO₂ recycle design, allow for a large band of CO₂ concentrations available to the various technologies. In principle, the two flue gas sources along with the recycle steam will allow to simulate flue gasses from both gas- as well as coal fired applications.

The work presented here aims to discuss and introduce the interaction between the Norwegian Climate- and Pollution Agency (Klif) and TCM. The importance of these activities are highlighted by the challenges faced to ensure safe emissions levels in order to allocate the emissions and discharge permit and subsequent regulatory measures associated with this permit. Large uncertainties regarding worst case assumptions for emissions from the TCM amine plant had to be addressed in order to deduce safe levels for amine degradation products, like nitrosamine and nitramines. The latter are known carcinogens with variable carcinogenic properties. Thus, a two-folded approach was taken by firstly addressing the knowledge gap towards amine degradation products and their respective impact on health and environment. Secondly, close cooperation with Klif was required to establish relevant regulation for the CO₂ capture facility.

In November 2011, an emission and discharge permit for TCM was approved by Klif. Regulatory levels for amines, ammonia, aldehydes and other flue-gas related species were depicted in the permit, both on immediate concentration levels as well as permitted annual levels and wider environment deposition concentrations. The paper concludes by looking at the first set of measured emissions parameters from the amine plant at TCM and considers the results in relation with the initial risk assessments associated with the permit.

1. Introduction

CO₂ Technology Centre Mongstad (TCM), situated in Norway, currently stands as the largest facility for testing and improving CO₂ capture technologies. TCM aims of playing an important role in establishing proven and cost efficient CCS value chains. Hence, the activities at TCM are focussed on progressing technology development by testing and improving CO₂ capture technologies.

TCM is a company owned by Gassnova (the Norwegian state), Statoil, Norske Shell and Sasol. Initially two technologies will be tested, namely: an amine plant and a chilled ammonia plant. These two technologies will both be tested on two separate flue gas sources. The first source is off-gas from the residue fluid catalytic cracker (RFCC) at the Mongstad Refinery, and the second will be exhaust gas originating from the combined heat and power plant (CHP) at Mongstad. The two plants are designed to jointly capture ca 100 000 tons per year of CO₂. The work presented here aims to introduce and discuss the interaction between the Norwegian Climate- and Pollution Agency (Klif) and TCM in the challenging period when safe emissions levels from TCM were being established and an emissions discharge permit for the TCM facility was thereafter granted by Klif. This paper continues the discussion on emissions raised in an earlier paper on TCM [1].

2. Emissions and discharge permit application

TCM applied for an emissions and discharge permit from Klif in September 2010. At the time of submission of the application, large uncertainties existed for the worst case scenario for emissions from the TCM amine plant. The highest level of uncertainty was related to the possible impacts that amine degradation products, like nitrosamine and nitramines, could have on the public health in close vicinity (<50 km) from the facility.

Nitrosamine and nitramines are partly formed through the degradation of amines within the process itself and partly through the atmospheric reaction involving OH- radicals. Both of these component groups may consist of a wide range of species dependant on the mother amine and the reaction conditions, and some of their resulting nitrosamines and nitramines are known to have carcinogenic effects. For this reason, TCM placed a lot of emphasis on establishing a transparent risk analysis, which includes allowable risk limits relevant to these components. The knowledge base on the toxicology of nitramines is even less than for nitrosamines, but literature and studies to date indicate that nitramines are less carcinogenic than nitrosamines [3].

Focus at TCM during the year following the submission of the permit was on reducing the technical knowledge gap of these degradation components, while the regulating authorities in parallel tasked themselves to establish regulation and limitations levels. The technical knowledge gap was addressed by close interaction with programs like CLIMIT as well as the CCM project, dually by considering and defining the formation of nitrosamine and nitramine species during day and night operation as well as describing the exposure effect of these components to the immediate and wider areas around the TCM facility. The impact and risk of these components were investigated based on both human exposures to air, as well as possible negative effects by potential changes in drinking water quality.

A large number of acknowledged research facilities and institutes were engaged by TCM to address and assess various parts in the amine degradation products knowledge gap. The findings of the various studies have been/will be published by the different institutions as well as by Klif [2]. Therefore this paper will not reiterate these results, but rather describe the events and specific interaction that took place between the regulator (Klif) and TCM following the submission of the emissions and discharge permit application in September 2010. The application, supporting documentation and the resulting permit describe the first risk analysis from amine emissions. De Koeijer et al [11] presents the results on which the health risk analysis was based in greater detail. The main intention is experience transfer to other CO₂-testing and full scale endeavours that in the future are applying for an emission and discharge permit and/or other regulation activities.

2.1 Initial amine degradation product knowledge base

The initial permit application was lodged while acknowledging that a large knowledge gap existed in terms of the impact of amine slip to air and the consequences of this to the direct and indirect environment. The standing knowledge base at that time was the intermediate results from the ADA (atmospheric degradation of amines) research campaign headed by the University of Oslo [4]. The latter was focused at identifying the gas phase photochemical degradation products of amine in the atmosphere, quantifying the products from photo-oxidation of amines, verification and updating of existing atmospheric photo-oxidation schemes as well as assessing aerosol formation during gas phase degradation of amines in air. In parallel to the ADA campaign, preliminary dispersion models developed by NILU indicated that significant levels of amine degradation products may be deposited close within the vicinity of the TCM process boundaries [5].

Subsequently, the knowledge at the time directed towards possible health impacts of amines and their degradation products, but no specified guideline values for nitrosamines and nitramines existed. The Norwegian Institute for Public Health (NIPH) was therefore approached to assess and recommend regulatory values for nitrosamines and nitramines as a first step towards discharge permissions for the TCM facility.

2.2 Studies aimed at closing the knowledge gap

An all encompassing research campaign was launched in order to address the prevailing knowledge gap associated with possible emissions from TCM. Three major areas were targeted: firstly, the atmospheric chemistry and dispersion of amines and their degradation products. Secondly, the fate of nitrosamines in water by means of biodegradation was investigated and the final activity was to establish baseline assessments in air, water and soil. During the selection process emphasis was placed in utilising well established and recognised institutions for these studies.

Main findings from the campaigns indicated that nitrosamine and nitramines are partly formed through the degradation of amines within the process itself and partly through the atmospheric reaction involving OH- radicals [4]. Formation of nitrosamines and nitramine species are highly dependent on the mother amine and reaction conditions. The various nitrosamine and nitramine component groups are known to vary in carcinogenic properties and thus a comprehensive dispersion model was compiled in order to assess the worst case and likely case concentrations for these species in ambient air and deposition in fresh water [11]. Emphases during the studies were placed on reducing the uncertainty while re-assessing assumptions made in the first dispersion modelling work. Furthermore, investigations were also launched into possible emissions levels of nitrosamines and nitramines species from other industrial plants and deducing whether or not these components are being regulated elsewhere [12].

In March 2011 the NIPH published guideline values for nitrosamine and nitramine species by stating that these component groups must not exceed 0.3 ng/m³ for air concentrations and 4 ng/l for fresh water sources or drinking water when considering a 1 in 10^-6 cancer risk for lifetime exposure [2]. Initial “worst case” assumptions for the dispersion model indicated that these guideline values will not be exceeded and thus more emphasis was placed in refining the atmospheric chemistry assumptions while introducing possible environmental degradation of these species through biodegradation studies. The purpose of the “worst case” study was to include worst estimates on the different aspects of formation and transformation, while a more likely parameter update was launched in order to include new findings and thus calculating the most likely impact involving air and water quality. The latter was further referred to as the “likely case”, which in turn resulted in the following main conclusions [6]:

Air concentrations of nitrosamines and nitramines (as a sum) are expected to be lower by a ratio of 3 to 5 when compared to the NIPH guidelines.
Water concentrations of nitrosamine and nitramines (as a sum) are expected to be lower by a ratio of 16 to 22 when compared to the NIPH guidelines.

The likely case dispersion model included findings from other parallel studies by considering the reduction of nitrosamines in water by means of photolysis (3 weeks life-time) and possibly biodegradation (half-life of 40 to 400 days) [7]. Biodegradation reduction of nitramines of 33% over 28 days was also included [8].

Baseline assessments showed detectable amounts of neither nitrosamines nor nitramines [9]. The baseline study paired with the theoretical deposition of nitrosamine and nitramines in air and water therefore strengthened the position that the activities of TCM will not exceed the NIPH guidelines and is thus unlikely to be responsible for any detrimental health or environmental effects.

3. Updated information to Klif and public participation

All updated information was presented to Klif during the first and second quarters of 2011, including the final reports to all of the studies launched since the original emissions and discharge permit submission. During the processing time of the information by Klif, TCM embarked on a community information program in which several meetings were held with various community stakeholders as well inviting any interested parties to the TCM site. It was the first emissions and discharge permit of its kind and therefore public understanding of the risks and implications was deemed crucial if the application was to be successful – not only for the operation at TCM, but it was clear that the way was being paved in which future CCS projects will be governed in Norway and possibly the most of Europe. An open public hearing was also held in the second quarter of 2011 in which both Klif and municipal representatives participated, along with nearly 50 other interested parties. This, along with close communication with the Lindås and Austrheim municipalities, a general understanding towards the risks and acceptance towards the mitigation activities by TCM was received.

4. Final permit approval and conditions

More than a year after the initial application, the final emissions and discharge permit was allocated to TCM in November 2011, with the regulatory levels relevant to air emissions presented in Table 1.

Table 1. Regulatory levels for air emissions according to the TCM emissions and discharge permit [2].

The permission as shown in Table 1 is independent of solvent used. In order to obtain this independence in solvent, the amines were grouped in primary, secondary and tertiary amines based on the risk of each group towards nitrosamines and nitramines formation. The variability of these groups within different solvent compositions will require new evaluations and risk assessments before being introduced to the TCM plant [2].

Further to direct air emissions at source, restrictions are imposed on concentration levels calculated for fresh water and dispersed air for nitrosamines and nitramines. The permit states that emissions from TCM shall not lead to that the calculated concentration of the sum of nitrosamines and nitramines exceed

0.3 ng/m³ for air concentrations and 4 ng/l for fresh water sources or drinking water [2]. These guidelines were derived from direct recommendations as published by the NIPH [3].

Apart from air regulations, the emissions and discharge permit covers all areas of environmental concern. This includes liquid discharges, solid wastes, noise and others. All of the individual regulated areas will not be discussed here as it is regarded as well known areas and have been established by the various governing authorities world-wide.

5. Ongoing and updating studies

In an effort to continuously update the knowledge base at TCM, which in turn will benefit future full scale projects, some study areas have been selected to be updated past the allocation of the permit. The first is an updated dispersion model conducted with IfT (Leibniz Institute for Tropospheric Research) and the other is the biodegradation of nitramines.

The updated dispersion model that is being developed by the team at IfT is aimed at providing the following improvements to the current model:

The model will be based on COSMO-MUSCAT and thus improved meteorology will be used in the base model [10].
The model will include the atmospheric chemistry of amines and thus present the true theoretical yields of amine degradation products to the wider environment.
The model will provide a more detailed tool which will enable the evaluation of other solvents and will not be restricted to MEA (mono-ethanol amine) solvents.

The theoretical yields of nitrosamine and nitramines in the ADA study showed that more nitramines than nitrosamines will possibly be formed [4]. And prior biodegradation studies also indicated that nitramines are more readily biodegradable then their nitrosamine counterparts [8]. These two indications therefore led to the establishment of biodegradation studies with SINTEF on ethanolnitramine (MEA-NO₂), dimethylnitramine (DMNA), N-nitropiperazine (PZ-NO₂), methylnitramine (MNA), 2-methyl-2- (nitroamino)-1-propanol (AMP-NO₂), diethylnitramine (DENA) and methylethylnitramine (MENA). The selection of these components are believed to cover a broad range of future solvents that may be tested at TCM. The results from these studies will in turn also be included in the updated dispersion model developed by IfT.

6. Environmental follow up program, latest results and conclusion

The TCM emissions and discharge permit, as outlined by Klif, entails an extensive environmental follow- up and monitoring plan. Monthly and annual reports have to be compiled in which all discharges and possible environmental impacts are clearly identified and quantified. The main aspects of the ongoing environmental follow-up and monitoring plan are:

Terrestrial and fresh water surveys close to the TCM boundary fence. A background survey was completed by NIVA and bi-annual surveillance will be conducted during operation [13].
Noise modelling and surveillance (these activities are done in conjunction with the refinery at Mongstad).
A comprehensive air monitoring program will be followed in which air quality will be measured with online instruments (FTIR), third party measurements (PTR-TOF-MS with UiO) as well as manual isokinetic sampling conducted in-house (analysed through LC-MS).

During July 2012 the amine plant was started up, which allowed for initial environmental monitoring during August 2012. Considering the fact that this was the first month of operation on MEA solvent, very promising results were gathered with respects to amine emissions. Firstly, very low levels of amines were detected at the bottom of the 101m sample line by the on-line FTIR (less than 1ppm) as well as the PTR-TOF-MS (less than 100 ppb). The FTIR set-up typically allows for accuracy of 1ppm and is thus in line with the much more accurate PTR-TOF-MS which is connected to the same sample line as the FTIR. Secondly, the isokinetic sampling campaigns at the absorber exhaust have shown to exhibit the same low levels of MEA once analysed through LC-MS (less than 0.1ppm). At this early stage the first results serve as a confirmation that the initial risk assessments for TCM DA are realistic and translates that the NIPH levels are not likely to be exceeded for this solvent. It is important to note, however, that these results are not representative enough to be conclusive due to process variation, but it serves as a very promising first indication.

The main ambitions for TCM at conception were to test, verify and demonstrate CO₂ capture technologies while reducing costs, technical, environmental and financial risks. The ground made in terms of establishing the emissions and discharge permit with the Norwegian regulator was the first step in achieving these ambitions in environmental terms. The methodology, interaction and end result gained here will more than likely set the trend for new projects of similar stance throughout Europe and the rest of the world. Other than breaking ground in terms of regulation, the activities resulting from the work presented here also achieved an increase in global understanding in amine chemistry, amine degradation products and their respective environmental impact which is not restricted to CCS based projects alone.

Acknowledgements

This work was funded by the owners of TCM DA (Gassnova, Statoil, Shell and Sasol) in support of their application for an emission and discharge permit for TCM. Aker Clean Carbon is thanked for their contribution to the emission profiles.

References

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9. Establishment of Knowledge base for Emission Regulation for the CO2 Technology Centre Mongstad (2013)