Within scope of the European Green Deal, it is planned to reduce net (GHGs) greenhouse gas emissions by 55% up to 2030. Eight different principles have been determined in this direction. These can be listed as obtaining the clean water, clean energy, energy efficient building, healthy food, encouraging the public transport, developing the long lasting products and providing the recovery, recycling EoL (end of life) products, ensuring the job creation, increasing the global competitive, respectively. Microalgae biorefinery plants fulfill these purposes, recycling and recovery of the EoL materials, production of the clean water and energy, extraction of the valuable products.

The carotenoids obtain such as β-carotene, lutein, astaxanthin, zeaxanthin, canthaxanthin, fucoxanthin, violaxanthin and lycopene in the biorefinery plant from microalgae. These pigments are used food processing, pharmaceuticals, nutraceuticals, human healthcare, and cosmetics in the areas (Mohan and et. al., 2020). Also, instead of fossil fuels the biofuels are used as a renewable energy for any process within scope of the clean production (Schiano di Visconte and et. al., 2019).

Environmental feasibility of these plants

Water consumption 3.15–3.65 liters is occurred for each liter of the ethanol output in the biofuel production. The use of microalgae in biofuel production reduces CO2 emissions by up to 10% and sulfur dioxide emissions by up to 30%. Eutrophication about 22.8%, photochemical oxidation about 32.9%, acidification about 11.5% in the biogas production (Chia and et. al., 2018). Microalgae based fertilizer was produced in the VegaAlga project, which was carried out in context of the Horizon. In this project, N fertilizers carbon footprint was 9.2 kg CO2/kg N for ammonium nitrate, 11 kg CO2/ kg N for urea, the P fertilizers carbon footprint was 0.56 kg CO2/kg P, the K fertilizers carbon footprint was 0.43 kg CO2/kg K, respectively. A system has been improved that reduces CO2 emissions by 15% by producing 5.8 million L of biodiesel/year from a sugarcane waste source of 10000 ton/d. This system has been developed by producing microalgae with a 4 GW fossil fuel burning power generation facility for high value nutritional supplements of the Seambiotic company (Yadav and Sen, 2018).

Economic feasibility of these plants

One of the biggest obstacle microalgae harvesting method. Harvesting method is important for microalgae cultivation, obtaining biomass, purification and extraction processes, also getting effectively product in a cost reducing manner. The harvesting technologies choice depends upon cell type, density and size. In the secondary dewatering or thickening process to acquire algal cake, energy demand is very high to obtain 15–25% (TSS) total suspended solids in the harvesting method by centrifugation and filtration. In addition, the capital and operating costs too high in the filtration and centrifugation (Gerardo and et. al., 2015). Some extracted pigments have global market value. One of them is astaxanthin. The annual global market value of astaxanthin was estimated to be approximately 240 million US$ in 2010, with synthetic astaxanthan priced at 2000 US$/kg and the natural product from Haematococcus valued at 7000 US$/kg (Hariskos and Posten, 2014). Global market price of the phycobiliproteins in 1997 was approximately US$50 million. The price range per mg was varied between US$3 and US$25 (Yen and et. al., 2013).

What needs to be done for the plant to be economical?

For instance, the drying process cost applied to elevate the microalgae oil content can be reduced or properties of the wet lipid extraction method can be improved (Rizwan and et. al., 2015). The microalgae biomass, extraction pigments, conversion process can be more utilized and less cost by tracking via (Iot) internet of things for biorefinery plants (Wang and et. al., 2021).

Social feasibility of these plants

Owing to the microalgae biorefinery plants ensure to job creation and were manufactured biopharmaceuticals such as diarylheptanoids, contributing to human and environmental health (Budzianowski and Postawa, 2016). However, the employees working in the biorefinery production plants have to use personal protective gear against hazards and risks in the workplace.

Microalgae biorefinery plants in pilot scale

The Nannochloropsis sp. cultivation was brought about for electricity generation at the algaePARC plant in the Netherlands (Pérez-López and et. al., 2017). Algal biomass is produced for flue gas remediation and high value products at Tata Steel and Varicon Aqua Solution, which two different pilot scale microalgae biorefinery plants operate by Swansea University. The microalgae content yield the produced biofuel by using (LED) light emitting diode in reusable tube reactors has been increased in the pilot scale plant operated by InCrops Enterprise Hub.

So what did we understand?

Actually, it is possible to live in a clean, economical and fairly. We must know how to take advantage of the resources in nature, and make their engineering optimizations. We should not be selfish and forget that the world is entrusted not only to us but also to future generations. Although costs are inevitable in the biorefinery plants, it has been concluded that they are environmentally, economically and socially sustainable.

References and Related Links

Mohan, S. V., Hemalatha, M., Chakraborty, D., Chatterjee, S., Ranadheer, P., & Kona, R. (2020). Algal biorefinery models with self-sustainable closed loop approach: Trends and prospective for blue-bioeconomy. Bioresource technology, 295, 122128.

Schiano di Visconte, G., Spicer, A., Chuck, C. J., & Allen, M. J. (2019). The microalgae biorefinery: a perspective on the current status and future opportunities using genetic modification. Applied Sciences, 9(22), 4793.

Chia, S. R., Chew, K. W., Show, P. L., Yap, Y. J., Ong, H. C., Ling, T. C., & Chang, J. S. (2018). Analysis of economic and environmental aspects of microalgae biorefinery for biofuels production: a review. Biotechnology journal, 13(6), 1700618.

Yadav, G., & Sen, R. (2018). Sustainability of microalgal biorefinery: Scope, challenges, and opportunities. In Sustainable Energy Technology and Policies (pp. 335–351). Springer, Singapore.

Gerardo, M. L., Van Den Hende, S., Vervaeren, H., Coward, T., & Skill, S. C. (2015). Harvesting of microalgae within a biorefinery approach: A review of the developments and case studies from pilot-plants. Algal Research, 11, 248–262.

Hariskos, I., & Posten, C. (2014). Biorefinery of microalgae–opportunities and constraints for different production scenarios. Biotechnology Journal, 9(6), 739–752.

Slegers, P. M., Olivieri, G., Breitmayer, E., Sijtsma, L., Eppink, M. H., Wijffels, R. H., & Reith, J. H. (2020). Design of value chains for microalgal biorefinery at industrial scale: process integration and techno-economic analysis. Frontiers in bioengineering and biotechnology, 8, 1048.

Yen, H. W., Hu, I. C., Chen, C. Y., Ho, S. H., Lee, D. J., & Chang, J. S. (2013). Microalgae-based biorefinery–from biofuels to natural products. Bioresource technology, 135, 166–174.

Rizwan, M., Lee, J. H., & Gani, R. (2015). Optimal design of microalgae-based biorefinery: Economics, opportunities and challenges. Applied Energy, 150, 69–79.

Wang, K., Khoo, K. S., Leong, H. Y., Nagarajan, D., Chew, K. W., Ting, H. Y., … & Show, P. L. (2021). How does the Internet of Things (IoT) help in microalgae biorefinery?. Biotechnology advances, 107819.

Budzianowski, W. M., & Postawa, K. (2016). Total chain integration of sustainable biorefinery systems. Applied Energy, 184, 1432–1446.

Pérez-López, P., De Vree, J. H., Feijoo, G., Bosma, R., Barbosa, M. J., Moreira, M. T., … & Kleinegris, D. M. (2017). Comparative life cycle assessment of real pilot reactors for microalgae cultivation in different seasons. Applied energy, 205, 1151–1164.