Biomass of Microalgae as a Source of Renewable Energy

Abstract

Climate change, global warming, and rising prices for oil and petroleum products caused by the reduction of energy security are the main reasons why researchers are currently focused on renewable energy from microalgae (Mobin et al., 2014). Microalgae have the potential to be a substitute for traditional crops (rapeseed, corn silage) due to rapid growth and their high photosynthetic efficiency. Algae biomass can be cultivated in a number of different types of photobioreactors, water reservoirs or greenhouses. As examined by Tsai, Chen and Ramaraj (2017), microalgae were universally accepted as the ideal solution for monitoring of the greenhouse gas emissions. The research has shown the perfect uptake of CO 2 (the amount of 159 mgL -1.day -1 with 93% of CO 2 consumption efficiency) (Tsai, Chen and Ramaraj, 2017). Microalgae -production of biomassMicroalgae are the simplest autotrophic organisms (mostly microscopic) with undemanding requirements for growth and increasing growth rates depending on the environmental conditions created in the growth medium. The key factors to control the growth of algae are: water, light, CO 2 , temperature and optimum ratio of N : P : K. During the most important growth phase of algae growth -the exponential phase -there can be observed the doubling of biomass in less than 3.5 hours. The microscopic algae can be used to utilise the waste carbon dioxide (CO 2 ), 1 kg of dry biomass of algae will use approximately 1.83 kg of CO 2 (Brennan and Owende, 2009). Microalgae can be considered as a suitable substrate for anaerobic digestion due to high productivity and reduced need for the use of arable land.One of the most important factors for the overall success of microalgae cultivation is the selection of a suitable genus of algae (Bruton et al., 2009). The selection of optimal and proper types of algae results in a more effective conversion of biomass into methane. When selecting an appropriate genus of microalgae, it should be noticed that one of the most important parameters is the characteristic structure of the cell wall of microalgae, which determines the efficiency of the anaerobic process. Some species lack a cell wall, some microalgae have a wall consisting of a protein without cellulose or hemicellulose, and these parameters are the key ones to easier biodegradability. When selecting microalgae species for anaerobic digestion, it is necessary to take into account other parameters, for instance, productivity and sensitivity to contamination. If the selected species of microalgae have strong cell walls and are resistant to the anaerobic digestion process, algae biomass should be first processed before being used as a raw material in a biogas plant.Due to the high photosynthetic efficiency and intense growth in the context of cultivation of microalgae, there is an ongoing study of green microalgae as a promising feedstock for the production of fuels and chemicals. The cultivation of algae biomass for the production of biofuels is an interesting biomaterial for researchers worldwid...