Ensuring Pipeline Integrity: Real-time Analysis of CO2 Purity for Quality Assurance in Carbon Capture and Storage

insights from industryTrevor TilmannApplications EngineerThermo Fisher Scientific

In this interview, AZoCleantech talks to Trevor Tilmann about carbon capture and storage, analysis of CO₂ purity and more.

Could you start by providing an overview of the current legislative landscape around carbon capture and carbon reduction?

The greenhouse effect is a well-known phenomenon in which the Earth's atmosphere absorbs infrared radiation from the sun. Certain atmospheric compounds, like carbon dioxide and water, absorb heat at the greatest rate. These compounds effectively trap this heat in the lower atmosphere, resulting in the moderate temperatures that we all experience.

Human activity has consistently raised atmospheric carbon dioxide levels year by year since the mid-twentieth century. There is a direct correlation between carbon dioxide levels and the planet's average surface temperature, which has risen over two degrees Fahrenheit since then.

A call to action was issued via the Paris Agreement in 2015 that outlined an approach to the global mitigation of greenhouse gas emissions by 2030, aiming to be net zero by 2050. The overall emission reduction strategy falls to individual countries or regions, and this is often incentivized by government programs such as tax credits.

The European Green Deal requires companies to reduce their greenhouse gas emissions by 55% by 2030 with a goal of being net zero by 2050. In the US, the EPA's greenhouse gas power plant rule requires fossil fuel power plants to reduce greenhouse gas emissions by 90% by 2040.

To achieve these targets, a low-carbon energy source will be required. Hydrogen has been identified as a primary energy carrier that could be used as a direct replacement for fossil fuels to provide clean energy without emissions.

Are there specific methods of hydrogen production currently being investigated?

Hydrogen can be directly integrated into existing power generation processes in place of natural gas, and three different hydrogen production methods are currently being evaluated.

In gray hydrogen production, natural gas is used to generate hydrogen through a process called methane cracking. This offers very little benefit as it still emits CO₂ into the atmosphere.

In blue hydrogen production, an emerging approach, the same process of methane cracking is used to generate hydrogen, but emissions are mitigated by carbon capture, utilization, and storage. The CO₂ emitted by this method is effectively captured, and it can either be used in industry or transported and permanently stored in geological locations.

The ultimate goal is to reach a green hydrogen state globally. Green hydrogen uses green electricity from alternative energy sources such as solar, wind, and tidal sources to produce hydrogen. This electricity is used to split the oxygen-hydrogen bond, which creates a product of pure hydrogen and emits only oxygen into the atmosphere.

However, green hydrogen is currently too cost-prohibitive to be used widely, but this is where the power generation industry will eventually go.

How common is carbon capture in current energy production?

Image credit: Thermo Fisher Scientific 

There are major incentives for companies to offset their greenhouse gas emissions, and while green hydrogen production is out of reach, carbon capture and storage has been identified as an intermediate solution.

Carbon capture can be directly implemented into a plant's existing means of production, and over $6 billion has already been invested globally in carbon capture projects. That investment is expected to grow to close to $175 billion in annual investments by 2035.

The number of operational carbon capture facilities is also expected to grow from approximately 40 currently in operation to over 500 by 2030.

The majority of these carbon capture projects will be in hard-to-abate sectors such as cement, iron and steel production, or power generation. Over the past 15 years, the majority of the industries utilizing carbon capture have been in the natural gas processing and liquefaction sectors.

From 2025 onwards, the range of industries utilizing carbon capture technology and the number of operational carbon capture plants are expected to grow drastically. However, even with this level of investment, carbon capture alone is not enough to meet net-zero targets. We still need to adopt green hydrogen globally to achieve this.

What are the most commonly used methods for capturing carbon dioxide?

The most common approaches to carbon dioxide capture are pre-combustion and post-combustion capture, as well as oxyfuel combustion capture and direct air capture.

In pre-combustion capture, fossil fuels are partially burned to form syngas. This syngas is passed through a water-gas shift reaction (WGSR), which creates a product of hydrogen and carbon dioxide. The hydrogen can be used for power generation, and the carbon dioxide is captured and either utilized or stored.

In post-combustion capture, the CO₂ is removed from a fossil fuel emission source, such as a natural gas turbine. The turbine’s exhaust is passed through a solvent-rich bed containing solvents such as amines. Amines have a specific affinity towards carbon dioxide, effectively latching onto the carbon dioxide before being transferred and separated by heating. This carbon dioxide can then be either utilized or stored.

Oxy-fuel combustion capture involves burning fossil fuel in the presence of pure oxygen instead of air, which results in a near-complete combustion reaction. This method is attractive because it eliminates the possibility of creating oxides of nitrogen from the nitrogen present in air. However, it is cost-prohibitive because it requires pure oxygen, which costs money to generate.

Direct air capture captures CO₂ directly from the atmosphere. Direct air capture is very attractive, but if the CO₂ is to be utilized, a very large volume of air will be required in order to achieve the high CO₂ concentration levels required. Direct air capture offers a means for companies to offset their greenhouse gas emissions even if their production is not onsite.

All of these capture techniques can be tied directly into a carbon capture pipeline for storage.

Does captured CO₂ have impurities, and if so, what are these most likely to be comprised of?

Impurities in captured CO₂ will be dependent on both the capture technique and the industrial production method used. For example, CO₂ captured from a combustion source has the potential to include impurities such as oxides of nitrogen and sulfonated species.

In fermentation sources, captured CO₂ could potentially include alcohols, while in ammonia and hydrogen sources, captured CO₂ has the potential to include ammonia or methane from methane cracking. It is important to monitor these impurities, as they can affect the pipeline's overall integrity.

Why is it important to continuously monitor CO₂ streams?

The primary reason to continuously monitor a CO₂ stream is to ensure the safety of both the people around the pipeline and the pipeline itself.

Moisture, sulfonated species, oxides of nitrogen, and carbon dioxide can react to create acidic conditions within the pipeline. This can lead to corrosion because many of the pipelines in use are existing oil and gas pipelines made from carbon steel and, therefore, susceptible to corrosion.

Additionally, monitoring the absolute purity of any permanently sequestered CO₂ is necessary to qualify for tax incentives offered by governments to companies for offsetting their greenhouse gas emissions.

Continuous monitoring is crucial because the process is expected to be highly transient. As more industries adopt carbon capture and storage technologies, the concentration levels of impurities are likely to vary significantly.

Flow dynamics must also be considered. Different impurities will affect the overall behavior of the flow, and continuous monitoring is needed to ensure accurate flow measurements. These measurements are essential for calculating the total mass of CO₂ sequestered.

Moreover, sample characterization is important due to the potential presence of a broad range of different impurities, which could impact both the safety and efficiency of the pipeline and storage processes.

What are some of the different carbon capture points, and why is it important to monitor them?

There are a number of typical carbon capture measurement points to consider. For example, the outlet or emission source should be monitored no matter what capture technique is in use because this has the potential to release greenhouse gases or other byproducts from the capture technique into the atmosphere.

Measurements at the inlet and outlet of a carbon capture facility are important metrics because they provide a value for overall CO₂ capture efficiency and identify any possible impurities.

Measurements taken at periodic points across the pipeline are useful in confirming that no additional reactions are taking place within the pipeline itself.

If liquefied CO₂ is being utilized somewhere in industry, it is necessary to measure the CO₂ in storage facilities to confirm the overall grade of the CO₂.

CO₂ is often transported to permanent locations such as offshore wellheads or even onshore depleted oil beds. Measurements are typically performed before pressurization takes place and the CO₂ is shipped to the final location. It is also important that CO₂ being shipped to new pipelines meets any relevant pipeline specifications—accurate measurements help ensure this.

CO₂ must also be measured at the injection site itself because this is where the total value of the CO₂ sequestered will come from.

What are some of the measurement challenges associated with current carbon capture technologies?

There are a number of measurement challenges to be addressed within the overall CO₂ matrix. The matrix itself is expected to be highly concentrated and have multiple components: more than 95% CO₂ and the potential for high levels of hydrocarbons or other components, depending on the industry.

This is especially the case in oil and gas plants using post-combustion capture, where high levels of hydrocarbons in the matrix can cause cross-sensitivity.

Limits of detection also pose a challenge. For example, all pipeline specifications require impurity measurements to be in the low ppm ranges while simultaneously ensuring over 95% CO₂.

Specifications are ever-changing, and no standardized global specification exists for monitoring impurities in a pipeline. Measurement instruments must have a wide dynamic range to properly account for the various specifications in place.

Many measurement locations will be in remote areas, so an instrument must also offer hands-free operation and be able to operate with minimal downtime.

How can Fourier Transform Infrared Spectroscopy help address these measurement challenges?

Fourier Transform Infrared Spectroscopy (FTIR) is based on the principles of infrared spectroscopy, which is the study of the interaction between infrared light and molecules.

Molecules with polarity vibrate at specific frequencies based on the attractive and repulsive forces between the atoms. When infrared light is introduced to these molecules, and the vibrational frequency matches with the energy of that infrared light, these energies effectively cancel each other out, creating absorbance.

This absorbance is directly proportional to concentration, which allows us to measure both the CO₂ and any impurities simultaneously.

FTIR analysis is extremely fast, allowing real-time monitoring of transient responses in the pipeline. This is important because if there is an issue, the flow of the pipeline can be adjusted in real time to prevent any additional damage downstream.

FTIR also offers a very wide dynamic range, allowing users to measure compounds from the parts per billion level up to 99.99%.

Another key feature of FTIR instruments is the ability to transfer calibrations and instrument methods from instrument to instrument. This is important as more diverse pipelines come online and more impurities are present in the matrix, which means that the instrument does not have to be taken offline to perform calibrations.

Instead, a calibration can be performed at the factory and then uploaded directly onto the instrument to account for additional impurities as they occur.

What features does the MAX-Bev CO₂ Purity Monitoring system offer to users looking to accurately analyze captured carbon?

The Thermo Scientific^TM MAX-Bev^TM CO₂ Purity Monitoring system was originally designed for monitoring impurities in beverage-grade CO₂, but this instrument has since been applied in the carbon capture industry with excellent results. This system leverages the accuracy and precision of FTIR to achieve its results.

The instrument is able to measure the absolute purity of CO₂ up to 100%, plus or minus 0.02 % - meeting measurement standards for governmental incentive programs. Remote measurement and remote data publishing are possible, and this instrument can be tied directly into Modbus to provide a direct feed into whatever data acquisition software the company is using.

We also offer customizable alarming for gas concentrations. Each gas species will have a specification tied to it, and our alarming allows us to alert the end user if concentration results are close to or exceed the limit.

Sampling analysis is fully automated, the MAX-Bev CO₂ system requires very minimal downtime and maintenance, and the instrument is typically online 99.7% of the time.

Our lead time for supplying the instrument is less than 24 weeks, so it can be ready to be installed into a carbon capture network very quickly.

What kinds of studies have been done to verify the performance of the MAX-Bev CO₂ system? Can the instrument accommodate unknown purities?

We recently performed four tests on the MAX-Bev CO₂ system to assess its performance when monitoring impurities to ensure pipeline integrity. Limit of detection, linearity, and accuracy tests were performed to look for acid-causing impurities, including sulfur dioxide, nitric oxide and nitrogen dioxide. We also assessed the absolute purity and stability of the carbon dioxide itself.

For the limit of detection study, we compared the MAX-Bev CO₂ system against a specification provided by Aramis, a CCS project in the Netherlands. Aramis is responsible for designing the transportation network for the Porthos carbon capture cluster.

This specification was selected because it had the lowest requirements for the NO, NO₂, and sulfur dioxide readings. The MAX-Bev CO₂ system was confirmed as offering a limit of detection that was orders of magnitude less than the specifications.

The linearity study involved all four components being tested, with each tested at four different concentration levels (including zero) across the analytical range required by the specification. It is important to confirm calibration accuracy across the analytical range, especially if the process will be transient. The results of this study confirmed that the MAX-Bev CO₂ can measure up to the specification without issue.

The accuracy and precision of the measurement was conducted for carbon dioxide, and it was determined that the percent error was 0.8 %, and the precision be 0.3 %. For nitric oxide, the percent error was 1 %, and precision was 5.6 %; for nitrogen dioxide, the percent error was 4 % and precision was 1 %; and for sulfur dioxide, the percent error was 2.4 % and precision was 6.4 %.

Stability and absolute purity were assessed via a 14-day drift assessment performed on CO₂. This was performed with high-quality research-grade CO₂ over a 14-day period without spanning the CO₂ and without taking a new background measurement in between.

It was important to highlight the lack of spanning and background because this capability eliminates the need for the user to adjust the instrument. For example, a background measurement would require the instrument to be taken offline, impacting process efficiency.

The results of this assessment were centered around 100 %, with just a few excursions outside the plus or minus 0.02 % specification.

As more industries adopt carbon capture techniques and as different capture techniques are used, additional impurities are likely to be present in pipelines. Our software can help identify these unknown impurities.

To identify an unknown impurity, users simply highlight a selected region of the infrared spectrum in the software, which generates a pop-up window with a gas and a fit quality indicator.

The gas list pulls directly from our library, with access to over 200 gases, or it can pull directly from the NIST and the EPA library, which has access to over 5,000 gases. If we identify an unknown gas that is not in our quantitative library but in the qualitative NIST and EPA library, we can send a note to our factory to generate a calibration and then upload this to the instrument so it can account for the additional unknown impurity in future measurements.

What sort of applications are currently using - or are anticipated to use - the wider MAX product portfolio?

The Thermo Scientific AutoFlex instrument can be used for flow measurements within a CO₂ pipeline. The AutoFlex can monitor pipeline volume and mass flow during transportation, and the instrument’s outputs can be tied directly into the MAX-Bev software interface to provide one common output.

The MAX product portfolio is already being used to assess CO₂ purity at actual carbon capture plants, particularly carbon destined for utilization. As the MAX-Bev CO₂ system is already able to monitor impurities in beverage-grade CO₂, we envision that these capture plants would be able to verify the overall quality of the CO₂ on site and provide a certificate of analysis to the end customer directly.

We are also exploring the instruments’ use in flue gas measurements, particularly at outlets or emission sources. Users would be able to monitor any greenhouse gases released and any byproducts from the capture technique itself.

Lastly, we are investigating the instruments’ potential for measuring amines as part of process optimization in post-combustion capture applications. By measuring the amines’ carbon dioxide-carrying capacity in real time, the end user can gain valuable insight into when their amines need to be swapped out.

We at Thermo Fisher Scientific are very excited to continue to provide measurement solutions to the clean energy space.

About Trevor Tilmann:

Trevor Tilmann is an Applications Engineer with Thermo Fisher Scientific, Environmental and Process Monitoring. He has a BS in Chemistry from Central Michigan University, with a concentration in Analytical Chemistry. 

He joined Thermo Fisher Scientific in 2023. With a background in source testing, Trevor is an expert in FTIR gas analysis, continuous emissions monitoring, and method development.

This information has been sourced, reviewed and adapted from materials provided by Thermo Fisher Scientific – Environmental and Process Monitoring Instruments.

For more information on this source, please visit Thermo Fisher Scientific – Environmental and Process Monitoring Instruments.