The Americian company and its biotech subsidiary have developed a proprietary patented algae photobioreactor technology that they claim accelerates growth and boosts yield efficiency. The closed system monitors and manipulates a wide range of cultivation parameters, and then replicates those conditions at commercial volume.

The initial studies about microalgae cultivation took place in the 40’s, where microalgae was investigated for its potential as a source of food. Researches Sydney et al (2019) suggested that the interest in the use of microalgae in wastewater treatment grew with the increase of awareness on climate change in the 60s and eventually moved its focus to renewable fuel production in the 70s. 

The popularity of microalgal biofuel grew with the increasing price of oils in the 00’s, attracting the attention of the industrial sector and its investors (Sydney et al, 2019). 3.1 Microalgae as a tool for carbon sequestration Microalgae is a group that covers both prokaryotes and eukaryotes. 

While a cyanobacteria (blue-green algae) facilitates the process of photosynthesis through the photosynthetic membranes in its internal organization, the eukaryotic autotrophic microorganism rely on their light-harvesting photosynthetic pigments to generate energy for its growth (Sydney et al, 2019). The photosynthetic microorganisms convert carbon dioxide into organic compounds and release molecular oxygen with the help of solar energy. 

(1) The reaction shown above describes the photosynthesis process of microalgae: algae transform light, carbon dioxide and water into biomass and oxygen through the catabolic process and the storage of energy in organic form (Eloka-Eboka and Lnambao, 2017). In other words, the cultivation of microalgae achieves the decarbonisation of CO! in air and the production of energy feedstock at the same time. 

The carbon fixation ability of micro algae is another attractive topic in the field of biotechnology. The research done bym Yahya et al (2020) is an example: the research looks into the use of native algal species for carbon fixation at coal-fired power plants. Eduardo et al (2019) also wrote a chapter in the literature “Biofuels from Algae”, dedicated to the use of micro-algae as both energy feedstock and biological carbon capture solution.

1.3 Microalgae research at Cementa Öland

In Öland Cementa, researchers Olofsson et al (2015) looked into the transformation of cement flue gas into valuable biomass in the cement factory, where industrial flue gas was used as CO! sources for micro algal cultivation. Olofsson et al (2015) examined the impact of cement flue gas toxicity on algal biomass production, the compositions such as lipids, proteins, and carbohydrates are examined to assess the feasibility of using cement flue gas in algal biomass production. The algae cultivated with cement flue gas was compared to the natural micro algal community and the results show that high quality and high production of micro algal biomass can be achieved with the integration of industrial flue gas. The research results concluded that micro algae cultivation is a feasible biological solution to convert industrial waste into renewable energy sources (Olofsson et al, 2015). The research is particularly referential for other Cementa power plants that hope to explore more alternatives in their sustainable development program.

(2) 10 Researcher Li et al (2013) in the literature of Bioresource Technology indicated the carbon content of microalgae is approximately 50 percent. This means that roughly 1.83 ton of CO! is needed to produce 1 ton of microalgae. The research result from Li et al (2013) is endorsed by Yahya et al (2020): as seen in equation 2, the balanced photosynthesis formula on the ratio between carbon dioxide moles and molecular formula of biomass indicates that approximately 1.8 gram of CO! can be fixed by every gram of microalgae produced. 

While microalgae has been successfully used for fixation of atmospheric CO!, it is important to consider the difference of CO! concentration between atmospheric air (0.038 percent) and industrial flue gas (4-14 percent). The endurance of flue gas components varied between different microalgae species, therefore it should be considered while implementing a microalgal biofuel project.

As seen in table 1, the species Chlorella sp shows that the CO! fixation performance and biomass productivity change with the temperature CO! concentration of NOx/SOx concentration (Zhang, 2015). The CO! fixation rate can be stabilized at 50 percent while the nutrient, temperature, light and CO! concentration are controlled in a reasonable manner. Thus, the average proportion of carbohydrates in microalgal biomass can be estimated as 55.5 percent as suggested by Yahya et al (2020) and Li et al (2013).