Microalgae are photosynthetic organisms that have the unique ability to convert carbon dioxide (CO2) into biomass through the process of photosynthesis. This attribute has made them an attractive option for carbon capture and sequestration (CCS), a method used to reduce greenhouse gas emissions and combat climate change. The basic principle behind CCS is the capture of CO2 from emission sources, such as power plants, and its subsequent storage in a secure manner so that it does not contribute to global warming.
Microalgae strains used in carbon capture include Chlorella, Spirulina, and Dunaliella. These algae types are chosen due to their high growth rates, high CO2 fixation rates, and ability to withstand harsh conditions.
Chlorella is a genus of single-celled green algae that is spherical in shape and about 2 to 10 µm in diameter. It is known for its rapid growth and high protein content. Chlorella has been found to be particularly effective in capturing CO2 when grown in high concentrations.
Spirulina, also known as blue-green algae, is a spiral-shaped microorganism that grows naturally in warm water alkaline lakes. Its high protein content, along with a variety of essential nutrients, makes it a popular choice for dietary supplements. In terms of carbon capture, Spirulina has been found to be highly efficient at photosynthesis, making it an excellent candidate for CO2 sequestration.
Dunaliella is a genus of green algae that thrives in high-salinity environments. It’s known for its high beta-carotene content, which gives it a distinct orange-red color. Dunaliella has been shown to have a high CO2 absorption rate, making it another viable option for carbon capture.
The process of algae carbon capture starts with the cultivation of microalgae in photobioreactors or open pond systems. The microalgae are then exposed to flue gas from power plants or other industrial processes. The CO2 in the flue gas serves as a carbon source for the algae, which they use to grow and reproduce through photosynthesis. This process effectively captures the CO2 and converts it into biomass.
After the growth phase, the algal biomass is harvested and can be processed further for various applications such as biofuel production, animal feed, or even human consumption. Any remaining CO2 can be captured again by the next batch of growing microalgae, creating a closed-loop system that continuously sequesters CO2.
The potential of microalgae for CCS is considerable. However, there are some challenges that need to be addressed before this technology can be implemented on a large scale. These include improving the efficiency of CO2 absorption by microalgae, optimizing growth conditions to increase biomass yield, and developing cost-effective methods for biomass harvesting and processing.
Despite these challenges, research and development efforts are ongoing around the world to harness the power of microalgae for carbon capture. With their unique ability to convert CO2 into valuable products while helping mitigate climate change, microalgae are poised to play a crucial role in our sustainable future.
