Carbon Capture, Utilization, and Storage - A viable answer to Climate Change?

Currently we are emitting about 36 billion tons of CO2 per year globally. According to the IPPC, in order to limit global warming to 1.5 celcius, we will have to get down to 20 billion. Reducing emissions alone might not be enough, we have to find new ways to extract the carbon dioxide back from the atmosphere. Technology and regulation are key and this is where carbon capture comes to the rescue.

Carbon Capture, Utilization, and Storage (CCUS) technology, however, is the target of some controversy because, although some view it as a crucial climate change mitigation strategy, others view it as an expensive fossil fuel subsidy that helps maintain, rather than reduce, our reliance on fossil fuels. I tend to agree with the first position because, if reducing emissions isn’t enough, then this technology must stay on the table. Also, we haven’t seen the full potential of this technology yet, and we will not see it if we do not invest in its further development. 20 years ago having a solar panel on our roofs was unthinkable due to the high prices. This has clearly changed with the cost of solar dropping 80% in the last decade.

How does CCUS work?

As the name indicates, carbon capture, storage, and utilization refers to removing carbon from the atmosphere (this includes biogenic sequestration as well), transporting it in a gaseous or liquid state in pipelines or ships, and either storing it in geological formations or reusing it to promote carbon circularity.

Capture and Storage (CCS)

There are two main tech-based carbon capture methods. One is carbon capture and sequestration (CCS) which involves trapping the CO2 at its emission source (e.g., a smokestack or a natural gas plant). The other method is direct air capture (DAC), which aims to suck carbon dioxide from the air. The latter method is still in its infancy. Most methods to capture CO2 depend on a process called “reversible absorption” where a mixture of gases (air being the prime example) run over a material that selectively absorbs CO2. Then, in a separate process, that material is manipulated to pull the CO2 out of it. The separated CO2 can then be compressed, transported and injected underground.

What happens to the CO2 that is stored?

There are two different ways to store CO2: Geological and Ocean Storage.

Geological storage is the process of storing CO2 in underground geological formations such as oil fields, depleted gas fields, deep coal seams, and saline formations, or in sedimentary basins. The problem with sedimentary basins is that not all of them are suitable for CO2 storage; some are too shallow and others are dominated by rocks with low permeability or poor confining characteristics.

According to the U.S. Department of Energy (DOE), the United States alone has at least 2,400 billion metric tons of possible carbon dioxide (CO2) storage resources in saline formations, oil and gas reservoirs, and unmineable coal seams. However, additional cost reductions, validation, safety testing, and mitigation research are necessary to realize this capacity.

The currently identified world storage capacity ranges from 6,800 Gigatons CO2 to almost 30,000 Gigatons CO2 (GtCO2).

Global geological storage (GtCO2). Sources: Global CCUS Institute : 2019 Report (2019) – IEA (2020)

In ocean storage, CO2 is intentionally injected into the deep ocean and is either allowed to diffuse or be trapped in a specific location, depending on the depth and pressure. According to the International Energy Agency’s Greenhouse Gas R&D Programme, the world’s hydrocarbon reservoirs have a combined storage capacity of roughly 800 gigatons of CO2.

One concern related to CO2 storage is safety. The most significant is probably the potential for triggering earthquakes, nonetheless that probability is too small. Another concern is related to CO2 leakage. To assure public safety, storage sites must be designed and operated to minimize the possibility of leakage. Consequently, potential leakage pathways must be identified and procedures must be established, to set appropriate design and operational standards as well as monitoring, measurement and verification requirements.

The Sleipner project (the world's first offshore CCS plant, operative since September 15, 1996, located some 240 kilometres off the coast of Norway in the North Sea) is storing more than 2,700 tonnes of CO2 per day, injected nearly 800 metres below the seabed. Over the lifetime of the project, it is expected that more than 20 million tonnes of CO2 will be injected into the saline formation. Monitoring surveys of the injected CO2 indicate that over the past 15 years, the gas has spread out over nearly 10 square kilometres underground, without moving upwards or out of the storage reservoir. Long-term simulations also suggest that over hundreds to thousands of years, the CO2 will eventually dissolve in the saline water, becoming heavier and less likely to migrate away from the reservoir.

Future research will continue to fill in gaps about potential environmental concerns as well as resource potential for mineralization.

Carbon Capture and Utilization (CCU)

The process of capturing carbon dioxide to be recycled for further usage is known as carbon capture and utilization (CCU). Carbon dioxide is a commodity with some value. It is being used, both directly and as a feedstock by a range of industries for over a century. McKinsey estimates that by 2030, CO2-based products could be worth between $800 billion and $1 trillion.

Among CO2 uses by industry, enhanced oil recovery leads the field. It accounts for around 90 percent of all CO2 usage today (mostly in the United States). The Kearney Energy transition Institute shared in its CCSU factbook a very promising future for the global CO2 utilization industry. From their graphic below, we can see that CO2 is already being used in a couple of industries.

CO2 utilization in different industries (CO2 million tonnes per annum, 2020); source: The Kearney Energy transition Institute

Another exciting use for CO2 is what Covestro is doing. The German producer of polyurethane and polycarbonate based raw materials, has developed an innovative technology that enables carbon capture and utilization by partly substituting oil-based raw materials with CO2.

Covestro - CO2 as an all-round talent

Most potential uses for captured carbon, such as carbon nanotubes and synthetic hydrocarbon fuels, are far from commercialized and require further RD&D in order to bring costs down, but it is definitely a road to explore.

Pros & Cons

Pros

• CCS can reduce emissions at the source. Facilities with CCS can capture almost all of the CO₂ they produce (some currently capture 90 or even 100 percent.

• CCS is used already to prevent almost 40 million tons of carbon dioxide (CO2) per year from escaping into the atmosphere.

• Some industries can directly reuse captured CO2. There are examples in the food industry where CO2 is used to produce beverages or use it as dry ice to transport foods and ingredients that need to stay cold. Such applications do not lead to emission reductions but are ways to utilize the captured CO2.

• There are currently 19 direct air capture (DAC) plants operating worldwide, capturing more than 0.1 Mt CO2/year.

Cons

• Carbon storage technology requires a lot of energy to run, which makes it quite expensive.

• Since CCS deployment is in its early stages, financial returns on a CCS project are riskier than normal operations.

• Calculating the exact capacities of different storage sites is difficult.

• Low public acceptance due to concerns about storage safety and the effects of leaks and contamination.

• For now CCS only captures emissions from industrial and fossil fuel plants, which only account for 25 percent of the total greenhouse gas emissions.

• Sources of captured CO2 are often located far away from where CO2 may be used or stored, creating logistical and cost challenges related to the transport of CO2.

Current and Future Projects

About 70% of operational CCUS facilities are in OECD countries. Although North America owns about 50% of the facilities worldwide, Europe and Asia are planning to accelerate the development of CCUS (about 40 projects). China is now the second country with about 14% of the total facilities. In Europe, projects are mostly being developed in the United Kingdom and in Norway.

Germany’s government is setting up a CCS programme, noting that most studies show the technology to be indispensable for reaching greenhouse gas neutrality by 2050.

According to a 2020 report from the Global CCS Institute, there are now 65 commercial CCS facilities in various stages of development globally.

Several large-scale facilities have been implemented around the world, such as Emirates Steel’s CCS project and the Petra Nova coal power plant near Houston, Texas.

Neste, the largest producer of renewable diesel, is pursuing an alternative where they will be able to make materials from renewable electricity and CO2 emissions.

Northernlights, incorporated in March 2021, is a partnership between the Norwegian government, Equinor, Shell and TotalEnergies. It will be the first ever cross-border, open-source CO2 transport and storage infrastructure network. Phase one of the project will be completed in mid-2024 with a capacity of up to 1.5 million tonnes of CO2 per year.

Run by the Swiss company Climeworks, is the world's largest direct air carbon capture and storage plant, which had started operating in September this year in Iceland. Named Orca, it has the capacity to remove 4,000 tonnes of carbon dioxide from the atmosphere each year.

Final thoughts

I understand the argument “we should not be capturing but stop emitting instead”, although I think it is naive and unrealistic. In our current scenario, we cannot and thus will not stop emitting CO2 tomorrow. From my point of view, we do need both solutions. Disregarding CCUS is simply eliminating part of the solution, with no advantage to doing it.

In order to realize full-scale deployment, additional research and development is required to optimize technology design and integration. Mitigating risk for investors is vital for incentivizing investment and development of CCS.

The public awareness of this technology is extremely low. Educating people on the matter definitely plays a role in order for this technology to thrive. Public support could serve as a stepping stone for governments to invest in this technology.