COMMENT | Realising circular carbon economy via microalgae
The concept of reusing in the circular economy involves prolonging the lifespan of products. But for a circular carbon economy, it is about reusing captured carbon dioxide (CO2) in various applications.
Carbon capture may involve the use of technologies such as...
COMMENT | While the circular economy aims to minimise waste and make the most of resources through reducing, reusing, and recycling, a circular carbon economy leverages these principles but focuses on mitigating carbon emissions.
The concept of reusing in the circular economy involves prolonging the lifespan of products. But for a circular carbon economy, it is about reusing captured carbon dioxide (CO2) in various applications.
Carbon capture may involve the use of technologies such as Carbon Capture, Utilisation, and Storage (CCUS) to reprocess CO2 from the atmosphere or emission sources for beneficial purposes.
Once CO2 is captured, it can be reused as feedstock for various processes in the petrochemical industry, which produce fertiliser, synthetic fuel, polyols, concrete building materials, and many more.
Similarly, recycling in a circular economy extends the life cycle of products, allowing these materials to be repurposed rather than dumping them in landfills as waste.
For the circular carbon economy, this means regenerating natural land systems to remove CO2 from the atmosphere and recycling the carbon efficiently via practices such as soil carbon restoration.
In the pursuit of net zero, technologies like CCUS cannot be the only solution for carbon capture and utilisation. This is especially true when its applications are still at an early stage of commercialisation.
We should explore other options such as biologically mediated carbon capture and utilisation by microalgae. But one may ask, ‘‘is algae better than trees for CO2 absorption?’’
Microalgae in carbon fixation
Photosynthesis in terrestrial plants and trees is an important process for the bio-fixation of CO2, but their efficiency is limited due to slow growth rates and environmental constraints. On the other hand, microorganisms like algae and cyanobacteria can fix CO2 much more rapidly.
It is estimated that algae and cyanobacteria can fix CO2 10 to 50 times faster than terrestrial plants and trees. The ability to fix CO2 at a faster rate highlights their importance in the global carbon cycle and potential applications in carbon capture and bioengineering.
According to a 2023 study entitled “Carbon dioxide utilisation using Chlorella microalgae”, Politaeva, N et al suggested that 100 tonnes of microalgae can fix 183 tonnes of CO2 during the period of maximum growth of biomass when cultivated for eight to 10 days.
This value will vary depending on many factors, ie temperature, cultivator design, CO2 supply method, and type of microalgae.
Microalgae as superfood
Besides carbon fixation, microalgae are rapidly gaining popularity for commercialisation as food and health products like spirulina-infused beverages, microalgae snacks, and many more.
I was particularly interested in a company known as “Atoz Carbon Cycle Platform” of World New Energy Centre Sdn Bhd. What makes this company special is that it offers regenerative agriculture solutions using microalgae!
In addition to the range of microalgae-based products manufactured, ie soy milk, cookies, and animal feed, Atoz is driven by higher purposes than profit when it looks at how microalgae can improve soil fertility via field trials on durian orchards and paddy fields.
In general, farmers tend to over-fertilise their crops to boost productivity, but agrochemicals often fail to improve soil fertility and may lead to runoff in ponds and lakes. Microalgae can replenish soil nutrients and their mobilisation to crops.
Microalgae-based regenerative agriculture also offers a promising approach for cultivating monoculture oil palm in a manner that restores degraded soil and protects biodiversity.
Cleaning wastewater like a pro
As the process of palm oil extraction generates a large amount of wastewater known as palm oil mill effluent (Pome), treating the contaminants in Pome before discharge will be very crucial.
The common Pome treatment methods include anaerobic digestion, feedstock for biodiesel, and composting.
However, treating Pome with microalgae is found to be a better way compared to the above-mentioned conventional methods.
Microalgae can grow in any environment and easily remove pollutants from wastewater. The heavy metals removed are used by microalgae for their growth and development.
As a result, this allows for a reduction in the overall treatment costs and the potential threat the untreated wastewater has on the environment.
With their rapid growth rates, high productivity, and versatility, microalgae are indeed poised to play a significant role in addressing pressing global challenges related to climate change mitigation and environmental sustainability in the future!
CHONG YEN MEE is a climate change analyst by training and enjoys writing doomsday stories that make people act.
The views expressed here are those of the author/contributor and do not necessarily represent the views of Malaysiakini.
