With globalization, populations, and usage of natural resources increasing, climate change has come to a point where now everyone is so pessimistic that we may not be able to reverse its effects. Many fields of scientists have long been trying to find solutions to this devastating problem, however, many of these are more focused on decreasing the greenhouse gas emissions, instead of finding a way to revert the changes. But we have yet been late to see the benefits that what we have the most around can provide to us: algae. Scientists have recently suggested that if large quantities of algae were to be grown, the climate change might go back slightly.
Starting from the Industrial Revolution, fossil fuels have nearly always been the primary source of energy as they are easier and cheaper to obtain and use. However, in every slight usage of fossil fuels, kilograms of toxic gases, what we now call greenhouse gases, are released into the atmosphere and tarnished the natural distribution of those gases. The reason why these gases are considered poisonous is that, as in the working mechanism of a greenhouse, they trap infrared radiation from the sun that would normally leave the Earth’s atmosphere. As the light energy is converted into heat energy, the overall heat trapped in the Earth increases. In long term, this heat trapped increases the average temperature of Earth and leads to the melting of icebergs, rising sea levels, and many other unexpected natural occurrences.
Although greenhouse gases are a few in number, the most commonly emitted and thus, the main triggering factor behind climate change is CO2. Besides decreasing further emissions of CO2, it is more critical to remove what has already been emitted to the atmosphere. Algae play an important role in this aspect. As algae grow and photosynthesize, it absorbs CO2 from the atmosphere and converts it into biomass and oxygen at very fast rates compared to that of a plant’s. According to research, one acre, about 4 thousand m2, of algae is found to consume approximately 2.7 tons of CO2 per day which is about a thousand times larger than the consumption of a forest of the same size. As this data suggests, algae can be a strong agent in our fight against climate change. Recently, some techniques have been proposed on how to cultivate algae in large amounts to create fields of these organisms: open-ocean algal blooms, photobioreactors, and BICCAPS.
Open-ocean algal blooms technique includes the improvement of the living conditions of naturally occurring algae on the ocean surfaces. By providing large quantities of algae with necessary nutrients, scientists plan to increase the growth of algae. One main source that is aimed to be provided is iron (II) sulfate (FeSO4). This compound, by providing iron, increases the growth of algae further than any other nutrient because it is one of the scarcely found minerals in the ocean, but is still needed for growth. Open-ocean algal blooms technique is found to produce the most amount of algae in the least amount of time, and hence, is preferred over the others considering the higher amount of CO2 that is to be absorbed by the higher amount of algae. This technique being cost-efficient and having no limitations of space also makes it a favorable option to utilize. During their lifetime, algae consume tons of CO2, and when they are dead there are two paths in which they can still be useful to the environment: sinking down the ocean or providing biomass. If the scientists do not collect the algae from the surface of the ocean and allow it to sink down the ocean, it will be made sure that the absorbed CO2 is stored safely and is not released into the atmosphere again. As shellfish or other sea organisms will consume the algae, they will convert the algal biomass into calcium carbonate to strengthen their shells. This way, algae will have contributed to the fight against climate change even after they die. Biomass will be discussed later in the article. Besides all these benefits that open-ocean algal blooms can provide, it is important to remember that tons of algae on the surface of an ocean will highly increase the acidity of the ocean, lower its temperature by blocking the light energy from the sun to pass efficiently, and deplete the oxygen levels. Consequently, the marine life in that ocean will severely be harmed.
Photobioreactors are another method that has been proposed to utilize algae to deal with climate change. The main initiator of this method is to overcome the waste production and water contamination that is produced as a result of the open-ocean algal blooms technique. A photobioreactor is an enclosed vessel that uses light to cultivate phototrophic microorganisms such as algae. These vessels can be controlled easily and mainly are designed to provide the temperature, pH, and nutrient levels that can produce the highest amounts of algae. Although the amount of CO2 that can be absorbed in a photobioreactor will definitely be less than that in an open ocean, due to the high concentration of algae in a relatively small space, the rate of absorption is really high. However, this method, as can be guessed, requires high costs to be deposited for the building and maintenance of such vessels, and hence, seems not to be preferred compared to the open-ocean algal blooms technique.
BICCAPS, the bicarbonate-based integrated carbon capture, and algae production system, is a method where the bicarbonate produced when algae absorb CO2 is recycled and used to produce more algae. This way, the waste materials of the initial algae are utilized and more algae are produced over time. The algae that are produced through recycling do not have any difference from the initial algae other than the pH conditions it loves living in being slightly basic. But this aspect of them allows for an easier increase in the efficiency of the system, only by adding sodium to the water. As this method is the most sustainable of all, scientists are now looking for ways to increase the cultivation of algae from this method.
Algae not only help fight climate change by consuming CO2, but also by providing huge amounts of biomass that can be harvested and used as a renewable source of energy: biofuel. Although biofuels are not as energy-efficient as fossil fuels, meaning that they will not produce as much energy as fossil fuels of the same amount, higher production of algal biomass through the cultivation techniques above can allow us to use it to power transportation and subsequently lower our fossil fuel usage. When burnt, algae produces far less CO2 and relatively more O2 compared to fossil fuels. This will eventually increase the ratio of O2 to CO2 and hence, the atmospheric balance can still be hoped to be regained.
One of the most common ways of obtaining algal biomass is through the open-ocean algal blooms method. As there will be tons of algae produced on the surface of the ocean, the biomass left over after they die will be easy to collect and utilize as biofuel. Photobioreactors also provide easy access to algal biomass as there will be an enclosed space with highly abundant algae. So, it is easier to obtain biofuel from the photobioreactors method as well. BICCAPS does not provide as high amounts of biomass as the others.
Overall, algae proved themselves to be strong agents in the fight against climate change. They are highly effective in removing CO2 from the atmosphere, storing it as biomass, and replacing it with oxygen. If the methods discussed above are implemented widely in a way that the drawbacks are considered, there is no doubt that they will be highly efficient to decrease CO2 concentration in the atmosphere. The biomass acquired through the cultivation of algae through these methods can effectively be used as biofuel as they have a high energy value compared to the other sustainable energy systems. However, deeper investigations must be done to use it as effectively as possible. Currently, there is no such technology to produce and utilize enough algae to replace fossil fuels with it. Besides, any attempt to produce mass-scale algae requires a very high cost and it is hard to get funds for a not completely proven approach to energy. Probably, it wouldn’t be enough to cover the energy use of the world, but still, it is worth a try.
Polon, Robert. “Not All Heroes Wear Capes: How Algae Could Help Us Fight Climate Change.” The Aggie Transcript, 10 July 2020, https://aggietranscript.ucdavis.edu/not-all-heroes-wear-capes-how-algae-could-help-us-fight-climate-change/.