Carbon Capture
Elon Musk has offered up $100 million for a viable Carbon Capture technology. So let’s talk about the chemistry of Carbon Capture and how to make you a millionaire.
Carbon Capture and Storage (CCS) is one of the most interesting and relevant topics in the world of chemistry right now. CCS is what the name implies: capturing carbon dioxide (CO₂) from the atmosphere and storing it elsewhere. CO₂ is one of the infamous green house gases that are responsible for global warming. While in the atmosphere, CO₂ traps heat leaving earth and consequently drives global temperatures up. The effect of trapping heat is called the green house gas effect (see below).
Since the industrial revolution (1780-1820), CO₂ levels in the atmosphere have increased by an astonishing 35%. This is a direct result of manufacturing activities and burning fossil fuels to support these practices. The spike in atmospheric CO₂ has caused global temperatures to rise at unprecedented rates, and with the rapid temperature changes comes devastating consequences. Some environmental scientists predict that by the year 2100 entire oceanic and arctic ecosystems could collapse, extreme weather such as floods and hurricanes would become more common and thousands of species of animals would go extinct.
In an effort to combat climate change, policy makers and scientists have put a new emphasis on renewable or “green” energy. In 2019 alone, one fifth of the global power consumption came from renewable energy sources. However, the effort of eliminating fossil fuels is a long-term strategy to combat climate change and requires a concerted shift in industry and infrastructure that will take decades. In the transition period, CCS has emerged as a realistic chemistry for mitigating climate change. The most robust and widely used CCS technology use Metal-Organic Frameworks (MOFs).
Before I dive into the fascinating chemistry of MOFs, I want to quickly write a few words for the climate change nay-sayers. Climate change is not debatable, it is a fact. Instead of linking the thousands of peer-reviewed, proven scientific articles that document climate change beyond any reasonable doubt, I would like to bring your attention to the following graphs:
As you can see, these graphs illustrate the concentrations of carbon dioxide and methane in the atmosphere, both of which are green house gases. The oscillating pattern of atmospheric CO₂ concentrations on the left correlate to periods of global warming and global cooling. As you can see, the rate and magnitude of CO₂ in the atmosphere today is unlike any other period of time over the last 800 000 years. It is the rate of CO₂ entering the atmosphere and consequently the rate of global temperatures rising that is so scary! So let’s stop talking about whether climate change is a real threat and start taking action - like implementing MOFs!
Metal-organic frameworks (MOFs) have become promising candidates for CCS since they are effective at “catching” CO₂. MOFs are porous, crystalline materials containing metal centers or nodes, connected by organic linkers. The self-assembly of these building blocks create a three-dimensional network of channels and pores. MOFs are able to trap CO₂ in their pores at atmospheric pressures.
Once CO₂ diffuses into the framework, it interacts through physisorption or chemisorption processes, which effectively traps CO₂ within the framework. Physisorption refers to intermolecular interactions like hydrogen bonding or Van der Waals forces between CO₂ and the framework, while chemisorption refers to a chemical reaction that takes place between the two species. Once the CO₂ is trapped, the gas can be released from the MOF using low temperatures and sold into laboratory or industrial practices that require CO₂. Another strategy involves burying the saturated MOFs underground for long term storage.
While MOFs have come a long way over the past few years, they are still in their infancy of research; this is where your $100 million idea comes in. MOFs can be further tuned to increase CO₂ uptake, selectivity and capacity. The ability to exchange the metal centers and tune the functionality and length of the linkers make MOFs fascinating to research. Also, there is a need for creative ideas for what to do with captured CO₂ to make MOFs a viable long term solution.
Hopefully this article has informed you about the emerging carbon capture industry. And if you go on to win the $100 million carbon capture prize, all I ask in return is a thank you and/or $1 million.