ABSTRACT
Fossil fuel combustion leads to increase in atmospheric CO2 thatposes great risk to worldwide sustainability. With the advent of the industrial revolution and increasing economic growth, the trend is going to increase (IPCC 2007). Available technologies for CO2 removal or absorption rely heavily on chemical and physicochemical methods and
CONTENTS
6.1 Introduction ........................................................................................................................ 111 6.2 Marine Bioenergy .............................................................................................................. 112 6.3 Marine Feedstocks ............................................................................................................. 113
6.3.1 Microalgae............................................................................................................... 114 6.3.2 Macroalgae .............................................................................................................. 114
6.4 Biomass Cultivation and Harvesting .............................................................................. 115 6.5 Pretreatment ....................................................................................................................... 115
6.5.1 Pretreatment of Algal Biomass for Utilization of Carbohydrates ................... 115 6.5.1.1 Enzymatic Hydrolysis of Carbohydrates ............................................. 116
6.5.2 Pretreatment of Algal Biomass for Lipid Extraction ......................................... 117 6.6 Fermentation ....................................................................................................................... 117 6.7 Classication of Fermentation Process ........................................................................... 119 6.8 Types of Fermentation ....................................................................................................... 119
6.8.1 Aerobic Fermentation ............................................................................................ 119 6.8.2 Anaerobic Fermentation ....................................................................................... 120
6.8.2.1 Biomethane or Biogas ............................................................................. 120 6.8.2.2 Dark Fermentation for Biohydrogen Production ............................... 122 6.8.2.3 Bioethanol Production from Algae ....................................................... 125 6.8.2.4 Biodiesel Production ............................................................................... 126
6.9 Different Operating Fermentation Systems ................................................................... 126 6.9.1 Batch System ........................................................................................................... 126 6.9.2 Continuous System ................................................................................................ 128 6.9.3 Fed-Batch (Semicontinuous) System ................................................................... 128
6.10 Marine Microbes ................................................................................................................ 130 6.11 Summary ............................................................................................................................. 130 References ..................................................................................................................................... 131
geochemical storage into deep vents that always have a risk of leakage into the surroundings. Bioenergy is the energy from biomass or organic matter. It has the potential to greatly reduce our greenhouse gas emissions by using carbon dioxide from the atmosphere for its growth. The process is called photosynthesis. Biomass generates an equal amount of carbon dioxide as fossil fuels, but it utilizes CO2 for its growth. Therefore, the net emission of carbon dioxide will be zero. Bioenergy can include energy from biomass in the form of biofuels, biopower, or other bioproducts. Biofuels are basically transportation fuels like bioethanol, biodiesel, biohydrogen, and biomethane. Biopower consists of direct biomass burning or converting it into gaseous fuel or oil to generate electricity. Among various biomass feedstocks, both micro-and macroalgae present a sustainable alternative (Singh and Sai 2010).
