Capturing CO2 is crucial to successfully reversing the damage global warming could soon inflict on our climate. However, there is a conflict between what human civilization ideally wants to achieve and the reality on the ground. The Paris Agreement marked a global commitment to keep the increase in global average temperature well below 2°C above pre-industrial levels.
While sincere efforts were required to limit the increase to 1.5 degrees centigrades by moving away from fossil fuels, power plants fuelled by coal and gas continue to dominate the global electricity sector, reports the International Energy Association (IEA).
In fact, despite a global drive to move more vigorously towards renewable energy sources, power generated from fossil fuels has increased by 70% since 2000. Coal remains the largest fuel source for power generation, at 38%, followed by gas at about 20%.
Policies implemented globally are keen to tackle the issue of emissions from existing coal-fired power plants and those being built today. Yet, a reduction or decline in CO2 emissions does not guarantee the absence of heat-trapping carbon. IEA suggests that even after CO2 emissions from the existing coal-fired fleet decline by approximately 40%, annual emissions would still amount to 6 GtCO2 per year in 2040.
In such a scenario, meeting our climate goals would not be possible by reducing emissions only. Alternative solutions would be required to capture carbon so that it could be utilized and stored at scale. But, these solutions would have to be holistically viable, cost-effective, and viable in the long run.
Recently, in a study published on May 1 in the journal ACS Energy Letters, researchers at CU Boulder and collaborators revealed that a popular approach many engineers are exploring to capture carbon would fail.
However, the team of researchers, comprising scientists working at the National Renewable Energy Laboratory in Golden, Colorado, and Delft University of Technology in the Netherlands, did not stop at pointing out the flaw in the existing system but also recommended an alternative and more sustainable solution to not only capture carbon but also convert it to fuel.
In the coming segments, we will look into what the original solution recommended, what its flaws were, and how those flaws could be corrected with an alternative solution!
The Original Solution to Capture Carbon
By original solution, we refer to one of the most widely used direct air capture approaches that involve air contactors, which are huge fans that pull air into a chamber filled with a basic liquid. Since CO2 is acidic in its chemical nature, the basic liquid binds to and reacts with it to form a carbonate or bicarbonate.
With CO2 trapped in the carbonate or bicarbonate, engineers can separate it from the liquid and turn it into products like plastics, carbonated drinks, etc. If these carbonates and bicarbonates go through further processing, they can even act as fuel to power homes and, potentially, airplanes. On the other hand, the basic liquid returns to the chamber to capture more CO2.
While the solution seems to be a perfect arrangement to capture carbon and upcycle it for further use, there exists a problem.
Click here to learn how managing methane might be the key to meet global climate goals.
The Problem with the Original Solution
The problem lies in how the carbonate or bicarbonate is separated from the liquid. Releasing the trapped CO2 requires companies to heat the carbonate and bicarbonate solution to at least 900˚C (1,652° F). This is a temperature that renewable energy sources like solar and wind can not achieve. And therefore, achieving this temperature requires the burning of fossil-based fuels like natural gas or pure methane.
While speaking about this catch hidden in the system, Wilson Smith, a professor in the Department of Chemical and Biological Engineering and a fellow of the Renewable and Sustainable Energy Institute at CU Boulder, had the following to say, which essentially summarizes the problem:
“If we have to release CO2 to capture CO2, it defeats the whole purpose of carbon capture.”
The good thing is that researchers went over and above the task at hand. Apart from pointing out the flaws of the system, they suggested an alternative that could cure the discrepancy.
The Alternative Cure for the Original Solution
The researchers suggested deploying the reactive capture process to fix the issue. However, they recommended tweaking the reactive capture process’s conventional realm.
Reactive capture, in its traditional form, refers to a process where electricity is applied to the carbonate and bicarbonate solutions, zapping the CO2 and basic liquid apart in the chamber. It is also called a closed-loop system that can capture more CO2 in its recycled liquid form.
However, in this case, the researchers noted a drawback. It saw that in an industrial setting, electricity would fall short of regenerating the basic liquid to re-capture more CO2 from the air. It would be such an inefficient process in its original form that after five cycles of carbon capture and regeneration, the basic liquid would hardly be able to pull any CO2 out of the air.
The researchers recommended adding electrodialysis to the process as a solution. This method offers multiple benefits. Primarily, it can operate on renewable electricity. Additionally, it can split more water into acidic and basic ions, sustaining the basic liquid’s ability to absorb more CO2. Wilson Smith termed this team’s achievement as “solving multiple problems with one technology,” and rightly so!
While it is the task of researchers to innovate new solutions and fine-tune the existing ones to increase efficiency, companies and businesses also have a responsibility, and many companies are doing great in fulfilling that responsibility. In the segments below, we will look at a couple of such companies that have come up with innovative, efficient solutions in this field.
Click here to know whether trapping carbon in oceans a viable solution.
#1. Graphyte
Graphyte positions itself as the world’s first and only carbon dioxide removal solution that is durable, affordable, and immediately scalable. In durability, Graphyte claims its solutions to be capable of removing carbon dioxide for more than a thousand years.
In terms of affordability, the company makes its solutions available at a levelized production cost of less than US$100/ton and in scalability, the company claims to be able to scale to a level where the removal of billions of tons of carbon is an achievable possibility.
Graphyte’s specific method follows the approach of Carbon Casting, which leverages readily available biomass, such as residues from timber and farming operations. Graphyte dries up and compresses this biomass to turn it into dense carbon blocks. These blocks come with an environmentally safe impermeable barrier that ensures safe storage in state-of-the-art underground sites.
While speaking about Graphyte’s method, Barclay Rogers, the Founder and CEO of the company, had the following to say:
“Carbon casting lets nature efficiently do the work of capturing CO2, then leverages engineering techniques to store it for climate-relevant timescales. It’s a solution that can be done anywhere, that will change the market, and more importantly, that will help save the planet.”
Carbon casting can sustain almost all the carbon captured in the biomass and consumes very little energy. It is a low-cost yet durable process of carbon removal that combines photosynthesis with practical engineering.
Graphyte’s potential has helped it earn the trust and credibility of the investor community. It completed its Series A funding round with a total of US$30 million. The round was jointly led by Prelude Ventures and Carbon Direct Capital and also included contributions from current investors like Breathable Energy Ventures and Overture.
While equity-funded innovative ventures like Graphyte have emerged with their new-age solutions, there are well-established public companies like Linde that have ventured into adsorption-based carbon capture and carbon-di-oxide recovery.
#2. Linde
The HISORP® CC adsorption-based carbon capture solution, the latest addition to Linde’s carbon capture portfolio, complements its tried and tested pressure swing adsorption (PSA) and membrane technologies.
The HISORP CC solution separates CO2 from process gasses over a wide range of CO2 feed concentrations. It leverages multiple Linde technologies, including pressure swing adsorption (PSA), cryogenic separation, and compression, to achieve a capture rate of more than 99%, 99.7% to be precise.
One of the greatest advantages of this solution is that it runs on energy derived from renewable sources. The regeneration process does not require steam, ensuring a minimal carbon footprint.
Moreover, HISORP CC is a low-CAPEX and low-OPEX technology with a minimal specific energy consumption rate and is available at almost no extra cost for solvent management, makeup, and handling.
Linde has ensured that the technology stays widely compatible and inclusive so that it can be combined with the full spectrum of Linde solutions, including steam methane reforming (SMR), auto thermal reforming (ATR), partial oxidation (POX), or gasification. It is conducive to integration in existing and new plants for SMR, POX, and ATR, even with increased hydrogen production.
In 2023, Linde, as a leading global industrial gasses and engineering company, registered sales of US$33 billion.
While companies are committed to their objectives, the learning and exchange between companies and research institutions are mutual. In the concluding segment, we look into technological research in this space that can transform the future of carbon capture by making it more effective and efficient.
The Future of Carbon Capture: A Tool with Transformative Potential
In July 2024, a group of researchers proposed a holistic platform for accelerating sorbent-based carbon capture. They named the platform PrISMa, which stands for Process-Informed Design of tailor-made Sorbent Materials.
The platform attempted to make the large-scale deployment of carbon capture technologies more carbon efficient. It stressed bringing the fragmented components and those who implement them under an umbrella.
While chemists previously focused on materials design and engineers on optimizing processes, the PrISMa platform integrated materials, process design, techno-economics, and life-cycle assessment. It compared more than 60 case studies of capturing CO2 from various sources in 5 global regions using different technologies.
It then simultaneously informed various stakeholders about the cost-effectiveness of technologies, process configurations, and locations. It also revealed the molecular characteristics of top-performing sorbents and offered actionable insights on environmental impacts, co-benefits, and trade-offs. The final output aimed to unite stakeholders at an early research stage, accelerating the development of carbon-capture technology in the race toward a net-zero world.
Scientists responsible for developing PrISMa, Berend Smit at EPFL and Susana Garcia at Heriot-Watt University, are highly optimistic about the method’s real-life usability. According to Professor Berend Smit:
“This innovative approach accelerates the discovery of top-performing materials for carbon capture, surpassing traditional trial-and-error methods.”
PrISMa holds significant potential for the future. By using experimental data and molecular simulations, it can predict the adsorption properties of potential sorbent materials.
It would eventually lead to the developer community becoming capable of making informed choices. PrISMa’s process layer properties make it possible to measure and benchmark the performance of carbon capture solutions by helping scientists compute process performance parameters, such as purity, recovery, and energy requirements.
One crucial parameter that makes or breaks any scientific or technological solution is its economic viability. Prisma can assess the economic and technical viability of a carbon capture plant. Finally, it can evaluate the environmental impacts over the plant’s entire life cycle, ensuring comprehensive sustainability.
Altogether, PrISMa is nothing less than revolutionary or transformative.
We started our discussion with a widely adopted solution that was found to be inadequate and self-defeating. Now, with PrISMa at the scientific community’s disposal, it would be possible to devise solutions that would be environmentally efficient, scalable, and cost-effective from day zero.
Click here for a list of top carbon capture stocks to invest in.