Bioenergy from Microalgae via hyperthermophiles - producing Biogas and Hydrogen

The objective of this proposal is to increase of the energy efficiency of degradation of organic material in a biogas process significantly. This will be done by utilization of microalgae as substrate for the development of a several step process in labo ratory scale involving a pretreatment step with hyperthermophilic microorganisms in a batch process and subsequent degradation of the pre-hydrolyzed algae material in a continuous biogas process. The establishment of this multistep process can be a major step which is likely to reduce CO2 emissions due to the ability of algae to convert CO2 into cell material by photosynthesis. The pretreatment by the hyperthermophiles (HT-process) is a biological hydrolysis step which yields hydrogen as energy rich produ ct and converts a part of the algae biomass into acetate which is the major substrate for methanogens in biogas facilities. Macroalgae were found to be an excellent substrate for hyperthermophiles and the HT process was shown in the Hyperthermics laborato ry to be an efficient pretreatment step increasing the degradation of hardly degradable substrates in a subsequent biogas process. Therefore, the described three step process involving (1) the cultivation of H2-producing algae, which are capturing CO2 and (2) a subsequent hyperthermophilic fermentation making the algae biomass better accessible for mesophilic degradation is likely to increase the energy efficiency of degradation of organic material in (3) a biogas process significantly.