Wouldn’t it be cool if we could capture CO₂ before it is emitted into the atmosphere and then store it somewhere (like underground)? Well, we can! This process is called carbon capture and storage (CCS).
CCS can help remove emissions from wherever CO₂ is released. Whether it’s from burning or chemical reactions, CCS could be used to capture it!
Generating power with CCS tech is particularly exciting as it allows us to burn some fossil fuels for energy, without releasing any CO₂. But how does it work, and is it affordable? Let’s have a look.
There are three ways to capture and store carbon:
Pre-combustion carbon capture (preCCC): Here, carbon (in the form of CO₂) is removed from fossil fuels before they are burnt .
Post-combustion carbon capture (postCCC): Here, carbon (in the form of CO₂) is removed from fossil fuels after they are burnt .
Oxy-fuel combustion: Here, pure oxygen is used to burn the fossil fuels, which makes capturing the CO₂ much easier .
This chapter will focus on the preCCC method while also giving some insights on how we can use this carbon once it’s been captured. For more information on the postCCC and oxy-fuel processes please see our advanced chapters on the industry course. Now, let’s see how preCCC actually works.
How does preCCC work?
Simplified diagram of how preCCC works
Let’s go through this step-by-step!
1. Syngas production
Firstly, we need to break down the fossil fuels into what is called syngas. This is a mixture of mostly carbon monoxide (CO) and hydrogen (H₂) .
Steam reforming natural gas to produce syngas
2. Water-gas shift reaction
The CO in syngas is then converted to CO₂ by reacting it with steam. This creates even more H₂, which can later be used as fuel :
Creating more H₂ (to use as fuel) by reacting the syngas with steam
3. Separation and storage
The CO₂ then needs to be separated from the H₂ . It is then, finally, transported into storage.
We are now left with just H₂!
If we produce water instead of CO₂, then we can use hydrogen as a cleaner energy source than the initial fossil fuel!
How feasible is preCCC?
The increased costs and decreased efficiencies of using preCCC
As we can see, the installment and running of preCCC to a gas power plant increases the cost of the energy output from the plant and decreases the efficiency of the plant because of the added energy required to run the preCCC systems.
At what stage is the technology right now?
There are currently no test plants for preCCC power . There will therefore need to be a lot of research, development and testing if preCCC is to become more common and begin capturing significant amounts of carbon.
What will preCCC be like in the future?
Reducing the energy requirements of preCCC will be necessary if we are to make this technology efficient and cost-effective in the future.
Despite these limitations, preCCC is still possible. So what can we do with all of this captured CO₂?
Storing carbon
Most of the CO₂ that we capture will be stored away underground. But what if we could use it to make something else ?
How can we make use of captured CO₂?
Just like metal, minerals, and timber, CO₂ can be used as an industrial resource! . Making use of CO₂ captured from carbon capture technologies could make these technologies more profitable, increasing their likelihood of being used widely in the industrial sector . The market for the utilization of captured CO₂ has the potential to be worth billions of dollars .
Fancy Earthly selling CO₂
Where can we use captured CO₂?
Since the beginning of the 20th century, we have used CO₂ in various industrial applications :
Preserved food: Solid CO₂ (dry ice) is used in the refrigeration and frozen storage of foods, like ice cream and meat .
Fertilizer production: CO₂ can be used to manufacture minerals and fertilizer, such as urea, to provide plants with the nitrogen they need to grow .
Where CO₂ can be used
Enhanced oil recovery (EOR): Although controversial, CO₂ can be used in the extraction of crude oil from an oil deposit that could not otherwise be extracted (due to it being very hard to reach) as a way of maximizing the oil reserves that can be recovered . The process works by injecting CO₂ into depleted oil reservoirs.
Using CO₂ for more efficient oil extraction
How can we chemically convert CO₂ into more useful products?
Those are some of the ways in which we can use CO₂ directly in it’s captured state. However, chemical conversions of CO₂ can produce fuels, chemicals, plastics and other useful commodities too .
Why can’t we just use all the CO₂ we capture?
The scale of CO₂ utilization as an industrial resource is very small compared to the amount of CO₂ produced by the industrial sector as a whole . Hence, the global demand for chemicals and materials that use CO₂ cannot meet the amount of CO₂ that needs to be captured and utilized . This is why most of the CO₂ we capture will be stored away.
Likewise, the research needed for developing pathways for CO₂ utilization is still underway, and most technologies and companies working on novel CO₂ utilization are still at a demonstration-scale. This means that these technologies may not be fully developed on a large enough scale in time to mitigate climate change .
CO₂ in the ground is safe for a long time
Lastly, we need to make sure that the carbon utilization process is at least net carbon neutral, if not carbon negative. However, as we urgently try to decarbonise our energy sources, capturing the carbon at the source and removing it from the atmosphere provides a stopgap mechanism, buying time while the development of low-carbon, energy-efficient, and renewable energy technologies continues .
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