CCUS in 2021: Top 3 Carbon Capture Technologies

We must reduce our emissions to avoid a temperature increase above 1.5°C. The Intergovernmental Panel on Climate Change (IPCC) assumes some deployment of carbon capture technology will help to ensure this.¹ 

The IPCC is the United Nation’s body on climate change.² It finds that global warming is “likely to reach 1.5°C between 2030 and 2052 if it continues to increase at the current rate”. Worryingly, this will create climate-related risks for natural and human systems, including flooding, drought and extreme temperatures.³ Can carbon capture technology prevent this from happening?

What is carbon capture and storage technology?

Carbon capture and storage (CCS) is a way of reducing our carbon dioxide (CO2) emissions. It involves capturing CO2 produced by power plants or industrial facilities. Then, the captured CO2 is transported and stored underground.⁴ Ultimately, this keeps it from entering the Earth’s atmosphere and contributing to climate change.

CO2 in the atmosphere traps heat and prevents it from escaping into space. As a matter of fact, a small amount is useful as it keeps our planet warm. However, humans have increased the atmospheric concentration of CO2 by 47 per cent since the Industrial Revolution.⁵ We are consequently increasing the planet’s temperature by 0.2°C each decade.⁶ 

Where do carbon dioxide emissions come from?

It is true that carbon capture technology can help us reduce our emissions. But, it is not “essential to beating climate change”, as some argue.⁷ 89 per cent of global CO2 emissions came from fossil fuels and industry in 2018.⁸ In fact, if we stopped producing and consuming so much coal, oil and natural gas in the first place, we could massively reduce our greenhouse gas emissions. As a result, there would be no need to capture CO2 if we were not producing so much of it.

How does carbon capture technology work?

There are three main ways to capture CO2. This includes pre-combustion, post-combustion and oxyfuel combustion. They capture CO2 before, after or during the combustion of a fossil fuel.⁹  

What are the main types of carbon capture and storage technology?

Pre-combustion technology and CO2

Pre-combustion carbon capture is commercially available for industrial facilities.¹⁰ For example, it may be used for natural gas processing.¹¹ However, incorporating this carbon capture technology into power plants requires significant modifications. Therefore, it is more suitable for new plants.¹²

Pre-combustion capture works by oxidising the fuel for combustion into a synthesis gas (or syngas). This is a mixture of CO2, hydrogen, carbon monoxide and other compounds. Then, the synthesis gas undergoes a water-gas shift reaction. It produces hydrogen and CO2-rich gas. After this, CO2 can then be captured in a concentrated stream, ready for transportation. It leaves the hydrogen ready for combustion without releasing any emissions.¹³

Post-combustion technology

Post-combustion carbon capture is the primary method used in existing power plants.¹⁴ It can also be retrofitted to existing power stations.¹⁵ It is relatively easy to modify facilities that were originally built without the technology.¹⁶

This carbon capture technology separates CO2 from the exhaust of a combustion process.¹⁷ When fossil fuels are burned, the exhaust fills with flue gases. These are composed of CO2, water vapour, sulfur dioxides and nitrogen oxides. The flue gas passes through a solvent. It absorbs the CO2. The solvent is then heated to release water vapour and leave behind a concentrated stream of CO2.¹⁸ 

Though post-combustion carbon capture can capture 80 to 90 per cent of carbon emissions, it has a major flaw. It necessitates a large amount of energy to compress the CO2 for transportation.¹⁹ Canadian coal-fired power station Boundary Dam has post-combustion carbon capture technology. However, its CCS facilities use a quarter of the plant’s total power output to operate.²⁰ Therefore, capturing CO2 requires the burning of more coal. This is both inefficient and costly.

Oxyfuel technology

Oxyfuel is the third carbon capture technology in use today. By burning a fossil fuel in oxygen instead of air, combustion occurs at a higher temperature. This improves the efficiency of the reaction.²¹ It also produces a flue gas that is predominantly H2O and CO2.²² This makes it easier to capture, compress and store the stream of CO2.²³

Oxyfuel carbon capture has progressed significantly since 2005.²⁴ The first coal plant with oxyfuel capture facilities, the Callide Oxyfuel Project, opened in 2012. However, operations ceased in March 2015.²⁵

The viability of carbon capture technology to prevent climate change

As a concept, CCS is a useful way to reduce human-caused carbon emissions. It would enable industrial facilities and power plants to continue making products and generating energy without adding CO2 to the atmosphere. 

However, in reality, 80 per cent of carbon captured is used for enhanced oil recovery. This means it is employed to obtain hard-to-reach oil from deep reservoirs.²⁶ Oil is another fossil fuel. Therefore, it releases large quantities of carbon through combustion.

CCS power facilities

Furthermore, there are just 19 large-scale industrial and two large-scale CCS power facilities in operation today. Their CO2 capture capacity is 40 million tonnes per year.²⁷ Meanwhile, however, humans are collectively emitting about 39 billion tonnes of CO2 annually.²⁸ We would need a huge increase in CCS facilities to capture significant quantities of the greenhouse gas.

But, such an increase seems highly unlikely. In fact, there are just 20 additional large-scale CCS projects in development. Moreover, capital projects of this scale require six to ten years from conception to completion.²⁹ To capture enough carbon to prevent climate change, an enormous scale-up of CCS technologies and facilities would be needed by 2030. 

This is simply not going to happen. Therefore, to save our planet, we should stop using fossil fuels entirely and transition to clean renewable energy instead.

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