Carbon dioxide (CO2) is an important and most commonly produced greenhouse gas that helps trap heat in our atmosphere. This heat-trapping gas results from both human and natural activities.
Natural sources include processes like volcanic eruptions and animals exhaling carbon dioxide as a waste product. Meanwhile, human activities leading to CO2 emissions include wildfires and energy production that involves the extraction and burning of fossil fuels such as natural gas, oil, and coal. About 45% of CO2 emitted by humans actually remains in the atmosphere, substantially contributing to global warming.
Without carbon dioxide, the planet Earth would be extremely cold, making it uninhabitable. Having said that, the increased concentration of this gas in our atmosphere is now raising average global temperatures.
In 2019, the US alone emitted 5,130 million metric tons of energy-related CO2 while the global emissions have been 33,621.5 million metric tons, as per the US Energy Information Administration estimates.
Consequently, there is growing interest in carbon sequestration, a process that captures and stores atmospheric carbon dioxide. This approach aims to decrease atmospheric CO2 levels and mitigate global climate change.
Efforts to support this goal include transitioning to clean energy systems and decarbonizing high-emission sectors such as transportation and construction. Among these initiatives, carbon sequestration, in particular, stands out as a collaborative method with the natural environment to address climate change.
Carbon sequestration is a key method for removing carbon from the Earth’s atmosphere, primarily focusing on the permanent storage of CO2. This process can occur in two ways: biologically and geologically.
Geological carbon sequestration involves storing CO2 in underground formations. According to the United States Geological Survey (USGS)’s 2013 nation-wide assessment of geologic carbon sequestration, there’s an estimated mean storage potential of 3,000 metric gigatons of carbon dioxide. As per the organization’s assessment, the Coastal Plains region including coastal basins from Texas to Georgia has the most storage potential for CO2.
One of the ways it’s being done is via graphene production, which requires CO2 as a raw material. Graphene is a light, flexible material with a very high resistance, which makes it beneficial in the construction, energy, electronics, and health sectors.
Then, there are engineering molecules, the shape of which is changed to form new compounds by capturing CO2 from the air. Carbon Capture and Storage (CCS) meanwhile involves capturing CO2 produced by industrial activity, compressing and transporting it to deep underground facilities, and finally injecting it into rock formations for permanent storage.
Injecting carbon dioxide into underground reservoirs offers the benefit of enhancing oil production. However, this method is not without its drawbacks. Issues such as carbon dioxide migration and leakage, groundwater contamination, and seismic risks associated with injection can arise. Additionally, many parts of the world lack suitable geological features for reservoir injection.
Biological carbon sequestration is called an ‘indirect’ or passive form of sequestration. In this method, CO2 is stored in the natural environment in what is called ‘carbon sinks,’ such as soil, forests, grasslands, oceans, and other bodies of water.
Forests are actually considered one of the best forms of natural carbon sequestration. After all, forests store twice as much carbon on average as they emit. During photosynthesis, CO2 binds to plants and exchanges it for oxygen. An estimated one-fourth of global CO2 emissions are sequestered alongside forests in other vegetative forms, such as grasslands, fields, prairies etc.
Now, regarding soil: CO2 is captured and stored as carbonates, which accumulate over thousands of years as they combine with elements like calcium. Although CO2 is eventually released from the Earth, this process takes thousands of years.
In aquatic environments, including large bodies of water, these account for one-fourth of the CO2 removed from the Earth’s atmosphere. It is primarily the upper layers of oceans that store carbon, but excessive amounts can lead to water acidification and adversely affect biodiversity.
A growing focus now has been on developing technology that can allow carbon sequestration to happen on a massive scale.
Click here for a list of top biotech companies working on finding a solution to the menace of global warming.
Ultrafast Way of Carbon Sequestration
Researchers from the University of Texas at Austin have found a new and extremely fast way of storing the carbon captured from the atmosphere. Not only is it faster than conventional methods but also does it without requiring the harmful chemical accelerants used in conventional methods or mechanical agitation.
Published in ACS Sustainable Chemistry & Engineering, the new research has developed a technique for ultrafast formation of carbon dioxide hydrates. These materials are unique and ice-like that can bury CO2 in the ocean and prevent their release into the atmosphere.
“We’re staring at a huge challenge — finding a way to safely remove gigatons of carbon from our atmosphere — and hydrates offer a universal solution for carbon storage. For them to be a major piece of the carbon storage pie, we need the technology to grow them rapidly and at scale.”
– Vaibhav Bahadur, a professor in the Walker Department of Mechanical Engineering
The research shows that hydrates can be grown quickly that too without using any chemicals that neutralize the environmental benefits of carbon capture. Moreover, the team sees it as a highly effective way for gigascale carbon storage. And if some kinks and issues can be overcome, hydrates can become a preferred way to capture and store carbon.
The team noted that creating these hydrates to capture carbon has not only been a slow process but also energy-intensive, which has been keeping this from becoming the popular way of carbon storage at large scale, until now.
In the new study, the researchers were able to accomplish as much as a six time increase in the hydrate formation rate in comparison to previous ways. The fast speed of the process along with being free of chemicals make hydrates suitable for the large scale storage of carbon.
But what actually eliminates the need for chemicals, which allows for enhanced absorption, energy-efficiency, and cost-effectiveness, is magnesium, which was the ‘secret sauce’ of the research.
Magnesium (Mg), a shiny gray metal with low density, low melting point, and high chemical reactivity, occurs naturally in combination with other elements. The metal here serves as a trigger that removes the requirement for chemical agents. The addition of magnesium is supported by the bubbling of carbon dioxide at a high flow rate in a particular reactor configuration. The reactor pressure here is the primary factor of the sequestration rate.
So, the enhancement in the CO2 sequestration rate, which is based on net gas consumption, results from the high flow rate of constant gas inflow and outflow in the presence of magnesium. This method increases the growth rate by continuously renewing the gas–water–hydrate interface.
What makes the technology easier to implement is that it works pretty well with seawater, which means it doesn’t need complex desalination processes in order to create fresh water. The swift formation of foam with saltwater will significantly boost the economic performance of the technology, as per the team. According to Bahadur, who led the research:
“Hydrates are attractive carbon storage options since the seabed offers stable thermodynamic conditions, which protects them from decomposing.”
In this way, the carbon storage is essentially ready for use for every nation on the planet with a coastline. Hence, making this method of storing carbon “more accessible and feasible on a global scale and brings us closer to achieving a sustainable future,” he added.
According to the researchers, the foams will enable new approaches to transport and sequester CO2. But the implications of this advancement go beyond just carbon sequestration. The ultrafast formation of hydrates can even find its applications in gas separation and storage and desalination.
This way, the new technology offers a versatile solution for various industries. Hence, the researchers have filed for a pair of patents related to the tech, and are even considering a startup to commercialize it.
Not All Initiatives are Successful
Given the importance of decarbonizing the environment, scientists and world leaders are all exploring different ways and new technologies to meet climate goals.
Last year, scientists discovered a microbe off the coast of a volcanic island near Sicily that eats CO2 “astonishingly quickly.” The microbes, originally found in September 2022, are “hyper-efficient at consuming CO2 through photosynthesis”, faster than other known cyanobacteria. Scientists stated that microbial processes are far more capital-efficient than technological interventions and are also “inherently scalable” as they “can be deployed in diverse environments, from open ponds to bioreactors.”
A few months ago, the National Institute of Standards and Technology (NIST) scientists reported developing testing equipment with high accuracy for measuring the performance of materials (sorbents) used to trap and remove carbon from the air. The apparatus enables NIST to create research-grade test material (RGTM) sorbents for the direct air capture (DAC) industry. It allows companies to test their sorbents and verify their effectiveness before scaling up.
Just this month, Australian researchers proposed using solar power to capture and store carbon in mining waste. They are currently doing the first assessment and analysis of using concentrated solar heat for serpentine activation to produce activated feedstock materials for carbon capture and storage processes via mineral carbonation.
Scientists are even discovering ways to convert greenhouse gases directly into solid fuels that can be used to heat homes or power industries. For example, researchers at MIT and Harvard University developed and demonstrated the process of capturing and electrochemical conversion of the gas into powder. The solid formate is then used in a laboratory to produce electricity via a fuel cell.
So, there has clearly been a greater focus on capturing and storing carbon, with a lot of research and funding being invested in such efforts. However, not all initiatives have been successful. A prominent example of this has been the US-based climate start-up Running Tide.
Under Running Tide’s carbon removal process, a network of floating wooden buoys develop “microforests” of seaweed to “gobble up carbon from the air and water” and limestone to “serve as an antacid for the surface layer of the sea.” The seaweed is subsequently cut to sink into the ocean, where it absorbs CO2 and stays buried deep for thousands of years.
The company, as per its website, is reported to have removed 25,000 tonnes of carbon through two pathways:
- Ocean alkalinity enhancement
- Biomass sinking
Running Tide also sells carbon credits, which represent a tonne of carbon removed from the fast cycle. About a year ago, the start-up delivered the first-ever carbon removal credits from an open ocean project, with the credits pre-sold to e-commerce giant Shopify. Later on, Microsoft also bought carbon credits from the start-up.
In June, the startup announced that it was shutting down. Running Tide founder and CEO Mark Odlin in a LinkedIn post:
“Unfortunately, today we are beginning the process of shutting down Running Tide’s global operations because we are unable to secure the right kind of financing to continue our work with the urgency it requires.”
According to the post, the carbon market is voluntary and there isn’t “the demand needed to support large scale carbon removal” adding, “our integrity will be judged on if we achieve the victory condition and nothing else.”
In the post, he claimed that the startup “executed the largest successful carbon removal project in the open ocean,” that too “at the lowest cost, in the harshest environments, with the highest bar for quality.”
The company is reported to have sunk some 19 thousand tonnes of wood chips into Iceland’s coastal waters. This huge dump has been “completely unsupervised”, stated the Icelandic weekly newspaper, Heimildin, which also pointed out the lack of oversight of the operations, and the lack of verification of the company’s claims that it had sequestered 25,000 tonnes of carbon on the seafloor.
Running Tide’s closure and questions on its operations shows that while all the efforts and research sparks excitement, initiatives don’t always come to fruition and there is a need for more government support and technological breakthroughs to actually bring a change.
Now, let’s look at a couple of companies that can benefit substantially from this research.
#1. ExxonMobil (XOM)
As one of the leading public companies investing heavily in carbon capture and storage (CCS) technologies, with several projects underway to mitigate its carbon footprint, ExxonMobil can benefit significantly from the University of Texas’s research into ocean-based carbon sequestration.
The ocean-based carbon sequestration technology can help ExxonMobil enhance its technological leadership and reduce regulatory costs related to carbon emissions.
Financially, it could save significant sums by lowering potential carbon tax liabilities and creating new revenue streams through the sale of carbon credits. Additionally, these advancements can improve ExxonMobil’s environmental, social, and governance (ESG) ratings, making it more attractive to environmentally conscious investors. It reported a revenue of $413.7 billion in 2023.
#2. Occidental Petroleum (OXY)
Occidental Petroleum is a leader in developing large-scale CCS projects, particularly those that integrate captured carbon into enhanced oil recovery (EOR) processes. By adopting ocean-based carbon sequestration, Occidental can further diversify its CCS initiatives and enhance its sustainability practices.
Financially, this technology provides dual benefits: it aids in reducing carbon tax liabilities and generates additional revenue through carbon credits. Furthermore, leveraging captured carbon in EOR can improve oil recovery rates, thus boosting production efficiency and profitability. The company reported a revenue of $28.92 billion in 2023.
Final Thoughts
Preventing further warming of Earth’s atmosphere and addressing climate change are global priorities. Various measures, including phasing out carbon-emitting fuels and setting legally binding targets for net-zero emissions, have been adopted. Capturing and storing CO2 is yet another important solution to decarbonizing our planet.
This carbon sequestration can be achieved in several ways with ocean depth offering an attractive location to do so. The ocean is a carbon sink, using a biological carbon pump—phytoplankton—to transport surface CO2 to the seabed via the food web, where it is stored long-term. Physical pumps, driven by ocean circulation, also help to sequester dissolved carbon.
Given its vast storage capacity and natural ability to absorb CO2, combined with isolation from the atmosphere, the deep ocean is a popular method for carbon storage. Techniques range from direct CO2 injection into the deep ocean to nutrient addition to stimulate phytoplankton growth and exploiting the high pressure and low temperatures to form solid hydrates.
However, this approach is not without challenges, as illustrated by the Running Tide case, and issues such as acidification, cost, monitoring, verification, and sustainability arise.
It’s only through constant research and development, as done by researchers from the University of Texas that we can find solutions that help store carbon without harming the environment. Overall, ocean depths present a promising but uncertain option for the purpose of carbon sequestration.
Click here for a list of top five carbon capture stocks.