99% Efficiency in a New Way of Reducing CO2 in Flue Gas, with 30% Cost Reduction

Humanity has always shared some gains (like scientific discoveries), and setbacks (like global warming consequences,) and this trend will endure. Carbon will always be at the centerpiece of the discussion, as all living organisms and many fuels are composed of carbon. At the same time, it’s also one of the primary contributors to global warming.

One huge scientific contribution that Singaporean researchers at NUS have achieved is a new method of reducing CO2 in flue gas, with an impressive efficiency rate of up to 99%. It bypasses the traditional need to purify the CO2 in flue gas through an energy-intensive process, cutting the cost by up to 30%. 

Let’s explore this groundbreaking method and its potential impact on the fight against global warming. Does it have the potential to revolutionize other industries and countries as well?

What’s the Background that Inspired This New Way of Leveraging Flue Gas?

The best way to appreciate a new discovery or pioneering idea is by understanding the current method in place. Inventions and discoveries are meant to improve upon existing processes and systems. Even revolutionary ideas often build upon the work of those before them.

As for this invention, let’s consider the three background problems:

  1. High-purity CO2 is necessary for industrial application.
  2. Intensive energy amounts are needed to purify CO2 as it never exists naturally in its pure state.
  3. It’s untenably expensive to reuse flue gas, which contributes significantly to global warming. 

The Problem with Oxygen Impurities

Flue gas, by nature, has all sorts of byproducts, but the CO2 gas must be free from any other impurities to be usable for the industries like:

  • Ethylene.
  • Ethanol.
  • Plastics. 
  • Polymers.
  • Detergents.

These impurities can cause issues like corrosion, blocked pipes, and more. Moreover, the oxygen impurities in CO2 can react with certain metal catalysts, thus affecting the quality of the final product.

All the undesired side reactions caused by oxygen impurities diminish the energy efficiency necessary for CO2 reduction.

Traditional Ways of Purifying Impure CO2

So, traditionally, industrialists resort to energy-intensive processes to remove these impurities. Some of these prevalent processes include:

According to the leader of the NUS team behind the invention we’re discussing, it costs about $70-100 to purify every ton of CO2 needed for the numerous industrial applications we listed earlier. 

Meet Assistant Professor Lum Yanwei from NUS

Lum Yanwei, a young assistant professor from NUS’s Department of Chemical and Biomolecular Engineering, led his research team to develop a pioneering catalyst technology. But what were they trying to achieve?

This Singaporean team of researchers wondered if bypassing the costly purification processes mentioned above is possible. They wondered if there was a way to reduce the energy demands of CO2 reduction. 

They also wondered if they could find a way to suppress the unwanted side reactions caused by oxygen impurities. After years of researching and experimenting, they finally found the answer in electrocatalysis.


This technique is based on the principles of surface science and materials chemistry. It involves deliberately changing how electrons flow through electrodes to promote specific chemical reactions while suppressing others.

Enabling the direct conversion of CO2 from flue gas to useful carbon-based products allows you to save 30% of the energy consumed for purification. You can manufacture C2 (diatomic carbon) products like ethylene or ethane from treated flue gas as long as you suppress the competing reactions caused by oxygen impurities. 

But How Does This Electrochemical Process Work?

Let’s begin by defining a few terms: 

  • Electrocatalysis is a process where an electron transfer occurs between an electrode and a reactant. 
  • Modulated electrocatalysis involves manipulating the flow of electrons to drive specific reactions.
  • Electrolysers are devices that utilize electricity to break down water into hydrogen and oxygen.
  • Electrolytes conduct electric charges when you dissolve them into water or molten salts 
  • Catalysts speed up specific chemical reactions without getting consumed by the said reactions.

In modulated electrocatalysis, you need to use a specific type of catalyst called an electrocatalyst. Electrocatalysts are designed to control electron flow and promote desired reactions while suppressing competing ones.

These catalysts are typically made of transition metals, such as iron or nickel, and can be tailored to fit specific reactions.

Coupling Catalyst Design with Electrolyte Selection

The innovation behind the NUS research team, headed by Assistant Professor Lum Yanwei, lies in the coupling of catalyst design with electrolyte selection.

According to the assistant professor, the secret lay with:

  1. Using nickel as a catalyst on a copper surface. 
  2. The copper surface was then used as a protective layer to prevent the nickel from reacting with impurities in the electrolyte. 
  3. Acidic electrolytes suppress competing reactions when carbon dioxide is present, allowing for selective carbon dioxide reduction. 

This coupling technique resulted in a more efficient conversion process, eliminating the need for costly purification steps. 

The Environmental Implications of the NUS Discovery

The NUS research team’s discovery holds tremendous potential in addressing the global climate crisis. For starters, industrialists don’t have to spend exorbitant amounts of money on capturing carbon dioxide from the atmosphere.

Moreover, industrialists can avoid up to 30% of the cost of purifying carbon dioxide, as the electrocatalyst helps prevent unwanted byproducts and reactions. That’s a win for people’s pockets and Mother Nature as well.

But the best part is that it enables us to convert harmful flue gas emissions into valuable feedstock. It empowers us to “close the loop” in the carbon cycle, transforming waste into usable and sustainable resources. 

The demand for fossil fuels will decrease if we can use flue gas to produce carbon byproducts like ethylene, ethanol, plastics, and polymers. Consequently, this will reduce carbon emissions, slowing down the rate of climate change. For more context, read this ‘Basic Guide to Air Pollution.’

Huge Potential for Green Energy

The electrochemical designs by the NUS research team and the underlying scientific principles have the potential for far-reaching implications. Like Assistant Professor Lum says, “The research team is getting countless offers from the corporate world to explore the possibilities of this discovery further.”When scaled up, this green energy technology has the potential to revolutionize carbon reduction and energy production. It can serve as a renewable source of energy with minimal negative environmental impact. It may well be one of the best ways to reduce global warming.