A Porous Liquid and Artificial Trees: Examples of CDC processes (Part 2)

This blog is a continuation of last week’s blog, hence for a greater understanding of CDC, please read Part 1.  

Today, I will refer to two recent CDC processes under research that may be effective and are close to being implemented.  Firstly, the porous liquid is a relatively new type of CDC, which creates many inquiries due to being such a new process.  Secondly, the artificial trees, is a process Lackner has been working on for a very long time, where solid matter is used to absorb CO₂.  Lackner’s proposal may be very close to being implemented in real life. 

The Porous Liquid

The porous liquid was bought to my attention when talking to a colleague (please feel free to visit his blog on extinction of species).  This porous liquid is the first liquid to have ‘holes’.  These ‘holes’ (micropores) are very small, invisible to the naked eye and can be used to capture CO₂ and also methane (another gas increasing global temperatures) (Zhang et al 2015).  Hence, it may be very beneficial, as the capture of CO₂ and methane will reduce global temperatures and decrease global air pollution (Lepisto 2015).  However, when reading through Zhang et al, there is not enough detail concerning how it may be used and to what scale.  A fundamental question that remained unanswered, is what happens once all the pores of the liquid are filled with CO₂.  Additionally, there are no suggestions where this liquid can be placed.  If this liquid is placed on lakes and dams, this questions if oxidation will be able to take place and if it will impact water species due to oxygen deprivation.

Nonetheless, provided that there are no negative environmental impacts and it is a relatively cheap process, this could also be a viable process, reducing climate change impacts and remaining in the desired 2^oC threshold (Luntz 2015).  However, further clarification and research is essential for this process to take place and be effective in the real world.

Artificial Trees

Another feasible process to capture CO₂ is through artificial trees.  These artificial trees are designed by Lackner, and are composed of a resin that binds CO₂ and forms a bicarbonate (Lackner 2009).  This resin is found in a ‘pale beige polypropylene plastic embedded with 25-micrometer particles’ (Figure 1) (Biello 2013).   This process can be used to create artificial trees that will have the ability to absorb more CO₂ than plants.  Hence, this may be an effective process in stabilising CO₂ levels to 400ppm, or it may even gradually reduce CO₂ levels below this threshold  (Biello 2013).  Once the CO₂ is captured in this resin it can be stored by being pumped deep underground or inputted in oil or gas to be re-used.

Figure 1a: Sample of Artificial tree
Source: Schiffman 2013

Figure 1b: Chamber Absorbing Carbon dioxide using Artificial tree sample
Source: Biello 2013

Problems Induced by Artificial Trees

 Although Lackner’s process is relatively cheap, there are three main problems with the artificial trees.  Firstly, this process accounts for 700kg of carbon capture in 24 hours (around 13 people breathing for 24 hours).  Hence, a large amount of these artificial trees will be required to reduce CO₂ emissions, needing large amounts of space and money.  Nonetheless, Lackner et al 2011 proposes a solution, by suggesting highly emitting industries should pay for these artificial trees.  Furthermore, the government needs to determine a viable process of paying for these artificial trees through either implementing a carbon tax or applying a carbon footprint process.

Additionally, it is suggested that high amounts of water are essential for the CO₂ capture to take place (Lackner 2009).  Hence, questioning if these high amounts of water are available.  With increasing population rates, water is essential for agricultural, domestic and sanitary use.  Thus, the artificial trees create an opportunity cost for water, divided between the everyday use of people and artificial trees.  Therefore, water use must be sustainable to ensure water security.  This may be achieved with some difficulty, by increasing technological advancement or recycling water.

Lastly, once the CO₂ is captured, it needs to be disposed of or re-used.  This process can be relatively expensive, hence it may be very difficult to achieve this.  The high economic costs may be significant and need large amounts of energy, which will not reduce CO₂ levels to the aspired amount (Lackner 2009).  Hence, it is questionable to what degree this process will be effective.

Nonetheless, provided that this process becomes cheaper and more energy efficient, it could be a highly successful process to reduce or stabilise CO₂ levels (although this may take a few decades) (Schiffman 2013).  There are minimal or no environmental risks when undertaking this process, suggesting a high level of safety for habitats and avoiding pollution of freshwater ecosystems.

Thoughts:

I believe these processes may be highly effective, provided they work efficiently and have no risks in regards to degrading the environment.  I believe the artificial trees method has a higher potential of being effective compared to the porous liquid.  This belief is determined as the porous liquid has a higher potential of being unsafe towards the environment and more research is essential.  Therefore, the artificial trees may become a new way of decreasing CO₂ levels.  I also think I would be more comfortable using this process compared to SRM processes, as there are less negative impacts.  Nonetheless the problem with artificial trees is the high water requirements, which needs further investigation.  Furthermore this process may be a disincentive for industries and governments to reduce their carbon emissions.  Hence, questioning the ethical and moral issues surrounding this topic.  What do you think? Do you believe CDC is a feasible process?