Carbon Capture, Sequestration and Energy
The impact of green house gases, particularly carbon dioxide on earth does not need an introduction. Today, the two phrases threatening the existence of mankind are global warming and climate change. In fact, they are collectively the premise for renewable energy sources, energy storage technology and carbon capture and sequestration. According to NASA’s climate science department, the current atmospheric concentration of carbon dioxide exceeds 400 ppm. This represents a 47 % increase in the concentration since the beginning of Industrial Age (it was at 280 ppm) and an 11 % increase since 2000 [1]. And hence the need for carbon capture and storage technology which in turn aids in mitigating carbon dioxide emissions.
What is Carbon Capture and Sequestration (CCS)?
Definition: Removal of carbon dioxide from industrial plants and its subsequent storage (in a secure medium/reservoir).
The requirement for this technology stems from the usage of large amounts of low-cost readily available fossil fuels. While there are multiple techniques to minimize carbon dioxide emissions, carbon capture and sequestration falls under the category of carbon-sink based technology. Here, the word “sink” indicates storage. More importantly, it is a low-pollution technology and can capture CO 2 from air.
The process is carried out in two stages, namely, capture and sequestration/storage. Pre-combustion, post-combustion and oxyfuel combustion are the three main techniques to capture CO 2. However, the most popular commercial technique is by using amine solvents that absorb CO 2. Each of the above techniques use absorption, adsorption or a membrane system to separate the gas before capturing it. Finally, the gas is transported to the storage medium by compressing it.
Biofuel: Putting Captured CO2 to Good Use
The biggest application of CSS is invariably in biofuel production. Biofuels use biomass as a source of energy for practical applications. The key advantage is that production of biofuel by using CO 2 as a feedstock is more sustainable than that obtained from the fermentation of crops because the flue gas emissions from the various machinery used in crop production activities will likely result in increased greenhouse gas emissions [2],[3],[4]. Moreover, this prevents biofuels from competing with food production and in turn reduce deforestation [5].
The essential factor in biofuel production is availability of raw materials — carbon dioxide gas and hydrogen gas. And the best part is that we emit CO 2 in abundance from a wide range of sources. For instance, we can chemically recycle CO 2 from natural and industrial sources into biofuel products like methanol and dimethyl ether. Furthermore, this can be integrated into CCS as a part of the reductive hydrogenative conversion process and need not be an additional step. The excess can conveniently be stored away. However, this is not an excuse to continue the nonchalant emissions of greenhouse gases.
Conclusion
While it looks promising, there are a few challenges that hinder its deployment for long-term sustainability like:
- May result in excess usage of land
- Scalability of the CCS technology
- Requirement of expensive catalysts
- Geographic dependence
In other words, governments, researchers,and companies will need to work together to develop comprehensive assessments relevant to the differing conditions of each country.
Despite such issues, CCS has the potential to bring down the concentration level back to pre-industrial era thereby producing carbon-neutral environment. This is why Elon Musk decided to donate $100 million to the best CCS technology!
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