Carbon dioxide utilization utilizing microalgae offers a potential solution for reducing greenhouse gas emissions. However, challenges such as high production costs, low conversion efficiency, and complex downstream processing must be addressed.
As excessive fossil fuel use by the energy and industrial sector has driven a significant increase in greenhouse gas (GHG) emissions since the 1800s [6], so do multiple carbon abatement strategy has been developed to reduce emissions from both of these sectors. One of which, is Carbon Capture Utilisation and Storage (CCUS), which involves capturing and isolating carbon dioxide from flue gases exerted by the power or industrial sector, to be utilized in an industrial process, or stored in an underground storage facility.
On the other hand, Carbon Capture Utilisation (CCU) does not involve the injection of carbon dioxide into the earth’s subsurface like the CCS, but rather utilizes the captured carbon dioxide as a feedstock to produce value-added products, thereby reducing the carbon footprint of the end products.
In recent years, various methods for utilizing carbon dioxide (CO2) have emerged, ranging from utilizing CO2 in the production of concrete, and the making of synthetic fuels such as methanol, to producing industrial chemicals such as urea and formic acid. However, one application that has been extensively discussed as the low-hanging fruit of combating climate change with the use of carbon utilization is the utilization of CO2 as a feedstock for microalgae cultivation, to produce a wide range of beneficial products.
According to estimates, the worldwide market size for products derived from microalgae-based carbon capture, and utilization (CCU) is expected to reach $320 billion USD by 2030, making it the second largest market potential after CCU applications for concrete production. Compared to other CCU applications such as concrete and direct CO2-based fuel production, microalgae-based CCU offers greater potential for carbon abatement, with an estimated annual abatement potential of 3.2 billion metric tons of CO2 by 2030 [2].
So what makes microalgae special?
What makes this creature special is that it contains chlorophyll, the same substance found in plants that can conduct a photosynthesis process by using sunlight, water, and carbon dioxide, into sugars and oxygen. This means that, the utilization of microalgae as a carbon utiliser can produce biomass while removing carbon dioxide and producing oxygen.
In addition, looking at the cost structure of carbon capturing technology, it can be seen that most of the cost is centered around its capturing costs-which up until now remains one of the main blockers to the massive commercialization of CCS/CCUS technology [4]. The use of microalgae-based carbon dioxide utilization can alleviate this blocker since it does not require a high purity of carbon dioxide, thanks to the growth of algae. This means that flue gas with varying CO2 concentrations can be directly fed to the microalgae, thus reducing or in fact eliminating the need for expensive CO2 capture systems. Additionally, certain combustion waste products such as nitrogen oxides (NOx) or sulfur oxides (SOx) can serve as nutrients for microalgae, further reducing the environmental impact of waste gases [2].
In addition, the uptake of carbon dioxide by algae has the potential to lead to the production of fuels. Various techniques enable the production of fuels from algae, including whole biomass conversion, lipid extraction, and fermentation of carbohydrates.
The Environmental Protection Agency (EPA) demonstrates that algae-based fuel pathways can achieve greenhouse gas emissions reductions ranging from 69% to 85% on a full lifecycle basis, in comparison to petroleum-based alternatives. Furthermore, the EPA has granted approval for algae-based renewable diesel as a qualified advanced biofuel under the RFS, exhibiting more than a 50% reduction in lifecycle greenhouse gas emissions when compared to petroleum-based diesel.
Moreover, specific algae-derived nutraceuticals, such as astaxanthin and beta carotene, have small but established and growing markets, with very high values that can exceed $1 million per ton of product. The sale of these high-value products could offset the capital and operating costs of the operation.
Based on the preceding information, it appears that the use of microalgae for carbon dioxide utilization has the potential to serve as a promising strategy for reducing greenhouse gas emissions. Nonetheless, overcoming several hurdles is necessary to render this approach a viable option on a large scale.
One of the main obstacles is the high cost of microalgae production, which requires substantial resources, such as land, water, and energy. Additionally, microalgae cultivation necessitates careful regulation of environmental factors, including temperature, light, acidity, and nutrients, to optimize growth. These factors can lead to a costly production process, potentially limiting the scalability of this approach [5].
Another challenge is the relatively low efficiency of microalgae in converting carbon dioxide into biomass. While microalgae can convert carbon dioxide into organic matter through photosynthesis, the conversion efficiency is limited, requiring a considerable amount of carbon dioxide to produce a relatively small amount of biomass. This limitation can affect the effectiveness of this approach as a means of carbon dioxide utilization [8].
Furthermore, the use of microalgae necessitates appropriate downstream processing to convert biomass into valuable products. This process can be complex and expensive, necessitating advanced technologies for extraction and purification, which can impede the feasibility of this approach [9].
Company Breakthrough on Microalgae as Novel Way of Carbon Capture and Utilisation
Despite the challenges above, companies remain dedicated to exploring the limits of what is achievable. A noteworthy example of such a company is ALGIECEL, a Danish-based microalgal enterprise that employs novel technological innovation techniques to advance microalgal carbon capture and utilization (CCU). One approach employed by ALGIECEL to address the spatial limitations of microalgal cultivation is the development of container-fitted photobioreactors that facilitate the easy conversion of industrial CO2 emissions into algae-based derivative products.
According to their claims, this single 40-foot container has the capacity to capture 1 ton of carbon dioxide per day. This single 40-foot container is claimed to capture 1 ton of carbon dioxide per day. Furthermore, to increase the capture capacity, the modularity of the container-based photobioreactor design allows straightforward plug-and-play stacking from one unit to another, thereby increasing capture capacity, simplifying installation at the emission source and simultaneously obviating the need for costly extended transportation of carbon dioxide. The output of the bioreactors can produce green products such as bio-omega-3, vitamins, and carotenoids, and can be fractionated into partially defatted biomass and bio-oil [1].
In addition to its technological innovations, ALGIECEL has developed an innovative business model known as “Carbon Capture as A Service.” Under this arrangement, clients are not required to invest in the photobioreactor but instead pay for servicing and maintenance of the system. Additionally, ALGIECEL sells the green products produced by the reactor and shares profits from the sale of these products and sold carbon credits with the clients [1].
Researchers and Academic Breakthrough on Microalgae Carbon Dioxide Utilization
Researchers worldwide have conducted various projects exploring unique microalgae applications alongside companies and institutions. One such example is LIQUID3, an urban photobioreactor that utilizes microalgae to directly capture carbon dioxide from the air. Developed and designed by the University of Belgrade, Serbia, LIQUID3 has the capacity to sequester carbon equivalent to that of one adult tree or 200 sqm of lawn [7].
Another prominent example is the BIQ House, which was introduced by ARUP, a construction company based in Germany, in 2013. The BIQ House is a pioneering residential building located in Hamburg, that incorporates a photobioreactor as a sustainable building component. The photobioreactor comprises 129 vertical glass panels that are filled with a liquid suspension of microalgae. Microalgae convert solar energy and carbon dioxide into harvestable biomass for biofuel and food supplements. The BIQ House photobioreactor captures carbon dioxide and harnesses solar heat for the building’s water tank. The shade provided by the microalgae also contributes to cooling the interior of the building during the summer, making it an energy-efficient, carbon-cap, and sustainable solution for building design [3].
Despite technical challenges in the development of CCU using microalgae, it is noteworthy to observe the concurrent engagement of businesses and academics in tackling these obstacles with the aim of enhancing its capabilities in the forthcoming years. The prospects that accompany these endeavors are promising. In order to fully leverage the advancements made by the aforementioned stakeholders, it is imperative for government to establish regulatory frameworks within the policy-making realm. Designing these frameworks should aim to facilitate the commercialization of products based on microalgae frameworks should be designed to facilitate the commercialization of microalgae-based products.
Source:
Algiecel. 2023. Carbon Capture as A Service. https://www.algiecel.com/carbon-capture-as-a-service/. Accessed on 14 May 2023
C2ES. 2019. Carbon Utilization – A Vital and Effective Pathway for Decarbonization. Summary Report.
Chalcraft. 2013. Arp Unveils World’s First Algae-Powered Building. https://www.dezeen.com/2013/04/15/arup-unveils-worldsfirst-algae-powered-building/#:~:text=News%3A%20the%20world’s%20first%20building,shade%20at%20the%20same%20time. Accessed on 16 May 2023.
Global CCS Institute. 2020. Carbon Capture and Storage: Challenges, Enablers, and Opportunities for Deployment. https://www.globalccsinstitute.com/news-media/insights/carbon-capture-and-storage-challenges-enablers-and-opportunities-for-deployment/. Accessed on 16 May 2023.
Iglina. T. Iglin, P. Pashchenko, D. 2022. Industrial CO2 Capture by Algae: A Review and Recent Advances.
IPCC. 2021. Summary for Policymakers. In V. Masson-Delmotte, P. Zhai, A. Pirani, S. L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M. I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J. B. R. Matthews, T. K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, & B. Zhou (Eds.), Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press.
Liquid3. https://liquid3.rs/ Accessed on 16 May 2023.
Milledge, J. Heaven. S. 2013. A Review of The Harvesting of Micro-Algae for Biofuel Production. Reviews in Environmental Science and Bio/Technology 12(2): 165-178
Miranda, A. Tenorio, F. Ocampo, D. Vargas, J. Saez, A. 2022. Trends on CO2 Capture with Microalgae: A Bibliometric Analysis.
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