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For Climeworks, CFD simulation with CADFEM supports the journey towards larger-scale CO2 removal

Climeworks’ journey of scaling up direct air capture to mitigate climate change

Climeworks is not only a technical adventure to tackle climate change, but also a human adventure that Nathalie Casas, Head of Technology at Climeworks, shared with cofounders Christoph Gebald and Jan Wurzbacher, and Markus Dutly, CEO of CADFEM (Suisse) AG. Climeworks has had a special relationship with CADFEM since its creation.

Climeworks’ mission of empowering humanity to permanently remove CO2 from the air

When it comes to mitigating climate change, we all now understand that different solutions are needed to tackle this challenge. 

First, we need to reduce carbon dioxide emissions from fossil energy that fuels transportation, heating, electricity production, and more. We urgently need to invest in renewables, switch to electric vehicles, and increase heating efficiency. However, in order to keep 1.5 degrees within reach, drastically reducing emissions alone will not be sufficient in reversing climate change. The latest IPCC report, released on April 4, 2022, has reconfirmed that we need to actively remove billions of tons of CO2 directly from the atmosphere. One way to achieve this is by planting trees and stopping deforestation. However, it takes time for trees to grow, and forests can be destroyed by wildfires, as we often see in Australia or in the Amazon, which releases the absorbed CO2

Since its founding in 2009, Climeworks has developed its direct air capture (DAC) technology to remove CO2 directly from ambient air. What makes DAC a unique approach is that it is one of the most effective carbon removal approaches because it:

  1. Offers permanent removal when combined with geological storage,
  2. Is fully measurable and thus transparent, and
  3. Is one of the most scalable carbon removal solutions: Deployment is modular and flexible, requiring relatively little land and therefore does not compete with food and water security.

In the past years, the efficiency of Climeworks’ DAC technology has been increased by highly skilled engineers, such as Nathalie Casas (Head of Technology). She takes advantage of simulation tools and CADFEM (Suisse) AG supports to reduce time to market.

About Climeworks

Climeworks was founded by Christoph Gebald and Jan Wurzbacher in 2009. Based in Oerlikon, in the City of Zurich, Climeworks is the first company that has combined DAC with the underground mineralization of CO2 for permanent and safe carbon dioxide removal. The company runs the largest number of direct air capture facilities in operation across Europe, proving that its technology is efficient in diverse climatic conditions, collecting several tens of thousands of operational hours. It is now operating the world’s largest direct air capture and storage (DAC+S) plant “Orca” in Iceland. It also offers the highest-quality carbon dioxide removal currently available on the market (it is the only company with a 5-star rating in CarbonPlan’s database).

Climeworks’ mission is to empower humanity to remove carbon dioxide from the air. My mission is to make this technology available and efficient.

Nathalie Casas, Head of Technology

How does Climeworks’ DAC technology work and how does it remove CO2 from the air?

Carbon dioxide is the greenhouse gas that has contributed the most to climate change as it remains in the atmosphere for thousands of years. Using direct air capture technology, Climeworks removes historic and unavoidable CO₂ emissions from the air, which can then be safely and permanently stored underground. With this method, the removed CO2 will no longer contribute to global warming.

DAC is one of the best ways to remove excess amounts of CO₂ from the Earth’s atmosphere. Climeworks’ CO₂ collectors capture carbon dioxide in a two-step process:

  1. Air is drawn into the collector with a fan. Carbon dioxide is captured on the surface of a highly selective filter material that sits inside the collectors (“adsorption”).
  2. After the filter material is full with carbon dioxide, the collector is closed. The filter material is then heated to approximately 100 °C – this releases the carbon dioxide (“desorption”), which can be collected in high purity and high concentration form.

What makes Climeworks unique compared to other DAC companies? They exclusively use renewable energy or energy-from-waste to power their plants and their air-captured CO2 will never be used to extract fossil fuels. They also strictly sell the net carbon removal of their plants, meaning that they compensate for the (very low) grey emissions of 10% that are caused by their plants.

Multiple Life Cycle Analyses (LCAs) have been performed on their technology with independent partners (e.g. this study by the university RWTH Aachen), which confirm that over its entire lifecycle (including construction, operations and recycling), a typical Climeworks plant re-emits less than 10% of the carbon dioxide it captures with the use of low-carbon electricity. This means that out of 100 tons of CO2 captured, only 10 tons are re-emitted. 

Orca is Climeworks’ latest plant and the world’s first large-scale DAC+S plant in commercial operations. Orca takes carbon dioxide removal to the next level by combining Climeworks’ direct air capture technology with the underground storage of carbon dioxide, which is carried out by the Icelandic company Carbfix. With a nominal capture capacity of 4’000 tons of carbon dioxide per year, it is Climeworks’ largest facility to date. Orca is located near the Hellisheiði geothermal power plant in Iceland, which provides Orca and the Carbfix CO2 injection sites with renewable energy to run the DAC+S process. Through natural mineralization, the carbon dioxide reacts with the basalt rock and turns into stone within a few years and is thus permanently removed from the atmosphere for thousands of years. 

The challenges of developing effective DAC plants

One challenge for every DAC technology is the large volume of air that needs to flow through the DAC collectors. The pressure drop of the filter structure is thus a key factor for an efficient system.

Another challenge every DAC technology faces is that the feed stream is ambient air, whose temperature and humidity varies a lot around the globe. Therefore, it is necessary to verify that the technology suits the local conditions. 

On its scale-up journey, one big challenge Climeworks faces is the creation of the logistics and supply chain required to build a plant like Orca. The DAC industry is in a similar situation as wind power was some twenty years ago. In Iceland, for example, Climeworks built three kilometers of pipeline for the CO2, which they own and operate.

Another example is their plant control system, which is partly based on standardized components, but also has some specialized parts that are not yet available as standard components. To implement larger plants, DAC players like Climeworks need to build a corresponding supplier industry. Another Orca-specific challenge was the industrial design of the plant. Due to its location in Iceland, Climeworks had to make sure it can be smoothly integrated into the beautiful Icelandic landscape, including space optimization.

CFD and structure simulations support Climeworks in achieving its vision

Climeworks is continually optimizing its technology to make the capture process more efficient. In the case of CO2 adsorption, a few percent can be a lot. Climeworks is working to optimize pressure drop, increase the throughput speed and lifecycle of DAC facilities, and reduce the weight of their collectors in order to provide robust technology to effectively remove CO2 from any location around the globe.

Computational Fluidic Dynamics (CFD) played a major role during the development and optimization of DAC. Ansys CFX/Fluent for air flow simulation allowed Climeworks to optimize pressure drop and manage heat transfer applications in the DAC system. Climeworks engineers could analyze and improve the pressure drop, to secure the efficiency of the filtration.

The full-scale plant, including its environment and external buildings, was modeled with the most recent CFD methods. A multiphase model approach considering the difference in CO2 concentration of the filtered air and the approaching ambient air was implemented. In addition, simplified models including the fan flow characteristic coupled with a “momentum source loss model” reproducing the pressure losses within the filters have been applied. This comprehensive type of modeling enables a better large-scale understanding of the overall flow behavior and the local loss behavior around the plant, which are both crucial for performance predictions and operation characteristics. Performance-driven optimization can be done to avoid air recirculation of already filtered air within the facility or reduced volumetric flowrate at the fans caused by wind effects or the plant layout.

Climeworks chose Ansys Workbench Mechanical for structural analysis to assess the mechanical stability of the plant in the actual environment (fatigue, wind) and reduce the quantity of material and space needed for the entire plant. Additional analyses were conducted such as buckling and FKM verification with CADFEM’s specific tools inside Ansys. Eventually, the entire plant could be tested in its environment with Ansys to improve the life cycle of the plant.

Nathalie Casas (Head of Technology at Climeworks) confirms that simulations within product development enable a quick evaluation of concepts and therefore accelerate and support the entire concept phase. Simulation also allows insights into details that are very difficult to obtain using other methods. Design optimization can be much more extensive and detailed if the experimental activities are extended by simulation. This increases the chances of further optimizing the technologies and processes. For example, the filter design could be optimized aerodynamically to increase the energy efficiency of the application. Simulation allowed analyses which would otherwise be difficult or impossible to carry out. This information is very useful as part of the scaling process of such plants. 

Finally, Orca’s adsorption process, heat distribution and the mechanical strength of the structure have been improved compared to Climeworks’ first generation DAC technology. Additionally, today’s flow distribution is being further improved based on real data collected in order to validate and improve the old model. Thanks to simulation, plants are now designed for modular and rapid scale-up, which strengthens Climeworks’ leadership with every new plant they build.

Despite a high professional environment, we have a friendly relationship with CADFEM’s team. CADFEM helped us to develop a better product using the best and most affordable solutions. With CADFEM we find all the services we need such as trainings, consulting, IT, software adaptation to our needs, advanced support and best practices on software usage.

Nathalie Casas, Head of Technology

The winning combination of simulation and human skills

At CADFEM, we know that simulation is more than software. Therefore, the biggest challenge is always the user behind the software: success depends mainly on the user, their skills and their training. CADFEM always helps companies raise the level of their users to the level required to use simulation tools efficiently. Markus Dutly (CEO of CADFEM (Suisse) AG) contends, “it’s a big mistake to think that software features will solve your problem. Simulation has its risks, but if the user has the right skills, or is willing to learn them, the benefits of it can be the difference between average and excellence”.

Climeworks was founded by Christoph Gebald and Jan Wurzbacher in 2009. Markus Dutly tells us the whole story about Climeworks and CADFEM’s relation. “I met Christoph Gebald several years before he founded Climeworks. He was a high school student. At that time, CADFEM had started a student competition on the Finite Element Method (FEM), and the winner was Christoph Gebald. The prize of € 500 was presented to Christoph at our customer conference in Germany. I had the opportunity to congratulate him. Christoph subsequently decided to study at ETH Zurich, and on the first day of his studies, he met Jan Wurzbacher. Several years later, I heard that they had founded Climeworks, and I invited Christoph to the Swiss Customer Conference. Over lunch, he told me that the lead investor dropped out and I eventually scheduled a meeting with Christoph. That’s where I met Jan for the first time. They explained to me the principle of CO2 adsorption, which they discovered during their master’s thesis. Despite their young age, I was very impressed by the level of their professionalism, and how persuasively they communicated their idea and the bigger picture.”  

Markus Dutly, CEO of CADFEM (Suisse) AG, says : “the founders always make the biggest difference. Smart people with a vision have the ability to unleash great energy and transfer it to others.”

Nathalie Casas is Head of Technology at Climeworks since 2017. She says, “as engineers, we provide the technology to achieve our company’s mission”. In her previous job she used to work on very big projects. Now she works on smaller ones, where she can make more of an impact: “we’re taking small steps in the right direction rather than sitting idly”. Nathalie Casas holds a Master of Chemical and Bio Engineering and a Ph.D. in Mechanical Engineering from ETH Zurich.

More than a software provider to Climeworks: CADFEM and the Ansys startup program

The Ansys Startup Program enables innovative companies to access simulation software for a lower cost. The program is designed for early-stage startups with limited funding and provides full access to simulation software bundles. Nathalie Casas explains how the Ansys Startup Program was beneficial for Climeworks: “the Ansys Startup Program worked very well and was a great benefit for the company, because it allowed the establishment of simulation within the entire engineering and product development process over the last years. This brings major advantages in solving technological challenges to stay competitive. Since you can access a full package, this program gave us the opportunity to have a thorough understanding of the range of Ansys simulation software. And after 2 years we now have a good understanding of what solutions work best for us.”

The Ansys startup program is designed to give young companies the best tools to develop their products with low financial investments. Eligible startups will gain access to Ansys simulation tools that will help build virtual prototypes that will reduce the number of physical prototypes required, which will save time and money.

Markus Dutly (CEO of CADFEM (Suisse) AG) wants to play an active role in the development of new companies, especially those which can have a positive impact on our future. That’s why he says, “we are proud that many startups are among our customers. We support all our customers with full commitment and provide them with our know-how on simulation. We do not make a difference in our services between big companies or a small startups. We have also invested in several startups at an early stage because we believe in their vision. More than software and financial support they also rely on our industry experience and advanced simulation expertise and best practices. We think that makes a big difference. Startups are the future of the country; they offer exciting jobs, future-proof business models and innovative products. With our commitment to startups, we also contribute to strengthening the economy.”

Nathalie Casas (Head of Technology at Climeworks) sees CADFEM as a key partner with high-quality services provided by experts and open-minded individuals. She says, “despite a high professional environment, we have a friendly relationship with CADFEM’s team. CADFEM helped us to develop a better product using the best and most affordable solutions. With CADFEM we find all the services we need such as trainings, consulting, IT, software adaptation to our needs, advanced support and best practices on software usage.”   

What’s next for Climeworks?

Climeworks follows a roadmap to significantly scale up their technology in the coming years. In the time frame from 2022 until 2030, they plan to expand their capacity with a scale-up factor of 5-10x every 2-3 years. After that, they plan for a scale-up factor of 10x every 10 years, which is a rate similar to solar PV, setting the stage to crack 100 megatons by 2040 and gigaton capacity by 2050. Climeworks sees such a strong market demand that the next initial step will be to supply volume to the market with a scale-up factor of around 10x based on a known technology (Orca). They are also already working on the next technology stage that will support an operational global roll-out. The following steps need to incorporate major technological innovations that are already in development.

To achieve their vision of inspiring a billion people to remove carbon dioxide from the air, Climeworks needs to unite a strong network of diverse stakeholders who collectively advance the direct air capture industry, thereby helping to democratize carbon dioxide removal. First, a market demand for carbon dioxide removal must emerge to show that there is a growing interest in these solutions. Pioneering customers, both individuals and organizations, enable this. Second, investor support is crucial to help them scale and pre-finance part of their facilities. Thus, they can continuously increase their capacity and optimize their technology faster. Third, they require a political framework giving security for such investments and reflecting the true costs of CO2 emissions. Fourth, a structured supply chain needs to be developed to ensure they can easily move into mass production.

Within an extensive technology and product development process, simulation-driven engineering can significantly contribute to finding solutions for new challenges. The following video made in 2019, shows the key partnership that already bonds Climeworks and CADFEM and the strategic use of simulation in the R&D process.

03:25 minClimeworks

Climeworks AG

Author: Christophe Ozier-Lafontaine (CADFEM GmbH)
Images: © Climeworks, CADFEM
Published: August, 2022

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