Microalgae Biomass as an Alternative Substrate in Biogas Production

Abstract

The running down of fossil energy sources makes the production of bioenergy an expected need worldwide. Therefore, energy crops have gained increasing attention in recent years as a source for the production of bioenergy because they do not compete with food crops. Microalgae have numerous advantages such as fast growth rates and not competing with food production. Because of the fast growth, many high valuable products are generated, e.g. food, biofuel, etc. Due to the energy crisis, renewable energy becomes a popular issue in this world today and there are several alternatives such as bioenergy, solar, wind, tide, geothermal, etc. For bioenergy, algae are the third generation biofuel crop. There is an increased demand for biogas in the society and one way to meet this is to use cultivated microalgae as fermentation substrate. In the present study, we maintained algae growth process and biomass production in autotrophic condition continuously for over 2 month’s period. Growth system (photobioreactor) was setup under room temperature and continuous illumination light through fluorescent lamps; light intensity was average as 48.31 [µmol-1m-2 per µA]. In reactor, dominant microalgae species were including Anabaena sp., Chlorella sp., Oscillatoria sp., Oedogonium sp. and Scenedesmus sp. The content of total solids (TS) and volatile solids (VS) in the algae biomass was measured; the results were average as 12500 g/m3 and 6320 g/m3, respectively. Furthermore, microalgal biomass is a potentially valuable fermentation substrate, and produce over 60% of methane gas.