• Prof. Sammy Boussiba, director of The Landau Family Microalgal Biotechnology Laboratory (MBL), has participated in the ‘Biodiesel from Microalgae’ project of the US-NREL and demonstrated feasibility of oil production by outdoors cultivation of microalgae 25 years ago. However, a wide range of problems require intensive research and development efforts for developing large scale production systems. Recently Prof. Boussiba has acted as a consultant for US-NRC. MBL scientists have contributed to outlining the opportunities and shortcomings of various proposed strategies for development of algal biofuels by participating in the FP7 consortium Aquafuels (www.aquafuels.eu).

    MBL has been supported by a development grant from Primafuel, is currently coordinating the FP7 project GIAVAP (www.giavap.eu) for genetic modification of microalgae, and participates in project BIOFAT for demonstration of algal biofuels production at the 10 hectare scale. Led by Prof. Boussiba, Dr.Inna Khozin, Dr. Stefan Leu, Dr. Claude Aflalo and Dr. Aliza Zarka, with over 20 qualified collaborators, MBL has become a hothouse of algal biofuels research developing integrated technologies for economical production of biodiesel from microalgae. Research tasks addressed involve selection and evaluation of improved oil-producing algal strains and their modification by genetic engineering; understanding the ways to manipulate cellular carbon fluxes for modulation of oil production rates; creating drug resistant strains for outdoors cultivation in open raceway ponds; optimized pilot scale cultivation and algal processing technologies; integration of the production process for maximal resource recovery and exploitation; sustainability analysis of different production options and technologies.
  • Theoretical Analysis of Culture Growth in Flat-Plate Bioreactors:
    The Essential Role of Timescales
    Y. Zarmi, G. Bel, and C. Aflalo

    Qualitative characteristics of biomass production in ultrahigh density algal bioreactors with a small optical path (specifically, thin flat-plate reactors) are analyzed and explained in terms of models, which combine the random motion of cells across the optical path with simple models for the photosynthetic process. Characteristics of different models at extreme densities are compared with existing data. An analogy between flashing light illumination and the light regime experienced by the randomly moving cells provides basic insight into the important role of timescales in reactor performance. The emergence of an optimal culture density (OCD), at which the volumetric and areal production rates are maximal, is understood in simple terms. While higher density implies an increase in the number of photosynthesizing cells, it leads to narrowing of the illuminated (photic) zone, hence to a decrease in the time spent by these cells in the photic zone. When the time spent by cells in the photic zone is longer than the time needed to collect the photons required for the photosynthetic process, the addition of cells increases the volumetric production rate. When the time spent by cells in the illuminated zone falls below the time needed for the collection of photons, the volumetric production rate is decreased. The combined effects of changes in density are the cause of the emergence of an OCD. At the OCD, the time spent by cells in the thin illuminated layer of the culture and the time needed for the collection of the photons required for the photosynthetic process coincide.