Carbon capture technology still faces a number of issues that must be addressed before it can become a viable way of ensuring global temperatures do not rise above 2°C in line with the Paris Climate Accord, the latest research from IdTechEx suggests.
Carbon capture technology may be essential in the global green future.
Deployment of such technologies has ramped up in recent years, with global CO2 capture capacity surpassing 40 million tonnes in 2020, although significant scale-up is required before it can reach the levels for meaningful environmental impact.
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The report analyses and lays out methods for boosting the effectiveness of capture technology and facilitating scale-up and implementation of what the report describes as a "vital technology" in the fight against climate change.
Current methods for sequestering carbon in the atmosphere primarily involve the "solvent method" where the CO2 is exposed to a liquid medium that absorbs the CO2 by either a physical or chemical mechanism.
It is then regenerated using high temperatures, which creates a pure stream of carbon dioxide.
The report hints all current methods for extrapolation are highly energy-intensive, which may result in a lot of energy waste in the process.
Further enhancements will need to be made to boost sustainability and economic viability, it adds.
With many nations having set themselves ambitious climate goals for the mid-century in line with the Paris Accord, scaled-up adoption and significant advances in carbon capture technology may be necessary.
Chemical absorption solvents are the most mature method of capturing CO2, with most carbon capture facilities currently relying on them.
The process is based on a chemical reaction between the CO2 and the solvent. However, this can form weak bonds and chemical absorbent solvents are generally more selective than forms of physical absorption, which means it should be viable even in instances of low pressure, increasing overall yield.
Most chemical absorption solvents are based on amines, with amines having been used for CO2 removal in gas treatment industrially since the 1950s.
Moreover, despite high chemical reactivity and stability, this form of carbon capture still sees high consumption levels with much of the R&D in this field looking to reduce this.
A diagram displaying how the solvent method works. Credit: IdTechEx
"Options include sterically-hindered amines that form weaker bonds with CO2 during the reaction, facilitating solvent regeneration, non-amine solvents that can offer novel chemical trapping mechanisms, and blends of amines and/or non-amines that can optimize CO2 capture for a given situation," Dr Michael Dent, the report's author, states.
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Another form of capture technology is known as "physical absorption," which involves solvent selectively capturing CO2 when in contact with a gas stream without a chemical reaction occurring.
Regeneration with this form is relatively easy as carbon capture can be facilitated with relatively low temperatures, although solvents are often less selective which means it may be less effective at lower pressures.
Physical absorption solvents - such as Rectisol - utilise a range of different compounds, with each solvent being suited to a specific use case.
Research in this field is now focusing on developing physical solvents with high thermal stability, improved selectivity, low vapour pressures, and low flammability and toxicity.
Promising avenues include fluorinated solvents and ionic liquids, however, both face challenges with high viscosities and production costs.
The report hints that amine scrubbing will likely dominate the CC market for the next few years, there is currently a burgeoning market for alternative capture methods.
However, the current alternatives, such as solid sorbent-based CO2 capture and membrane-based CO2 separation often incur high manufacturing costs.
Coal carbon capture technology
Carbon capture technology.
There are a number of storage methods - cryogenic freezing, biochemical membranes and 3D printing habitats - which aid commonplace acceptance of these methods, the report hints.
Beyond solvents, solid sorbents, and passive membranes, companies and researchers around the world are working to develop novel methods of capturing CO2 that can overcome the limitations of the more established technologies.
Dr Dent mentions "Cryogenic Carbon Capture," where gas streams are cooled to temperatures below -140°C, causing the CO2 to desublimate, forming a solid, which is then separated, gasified, and pressurized for utilization or storage.
The report claims this method can achieve up to 99% CO2 capture at a much lower cost than the conventional method.
Other methods include developing fuel cell technology specifically for carbon capture, using electrochemical membranes to separate CO2 from industrial waste gas streams or a method developed by a team at Oak Ridge National Laboratory which suggests the use of additive manufacturing in carbon capture, developing creative heat exchangers and mass-exchanging contractors for efficient carbon capture.
Although amine-based solvent capture methods are likely to remain the dominant choice over the next few years, a growing number of companies is innovating in the space of capture technology, developing a range of creative solutions for tackling the issue of CO2 emissions.
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It is likely that carbon capture technology will be essential in the global energy transition, with companies and nations alike setting extra goals past their mid-century climate goals of actively removing excess carbon from the atmosphere.
However, many of the concepts mentioned in the report are still on the drawing board, so economic viability in the current climate cannot be truly assessed.
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