Tuesday, February 01, 2011

Shell sells stake in Cellana to partner

The EnergyCollective reports on Shell selling its stake in Cellana, a company designed to build and operate a demonstration facility to grow and produce oil from algae for biofuel application.


A process for cultivating photosynthetic microbes, comprising:
selecting a species of photosynthetic microbe capable of doubling in biomass in approximately 16 hours or less when supplied with sufficient carbon dioxide in an open system that has a carrying capacity; introducing said species into a closed system; allowing said species to grow in said closed system to a biomass that exceeds 5% of said open system's carrying capacity; inoculating an initial biomass of said species that is no less than 5% of said carrying capacity from said closed system into said open system,- supplying carbon dioxide to said open system continuously, to supply sufficient carbon dioxide to said microbes and to replace carbon dioxide removed by said microbes; and maintaining said species in said open system to double in biomass approximately every 16 hours or less for a period of less than 5 days .

Note separately US 7,770,322 , including the text:

Specifically, this invention relates to a two-stage cultivation process, the "continuous-batch hybrid process," wherein aqueous cultures of photosynthetic microbes (single-cell organisms, including bacteria, cyanobacteria, and algae) are maintained in a state of continuous exponential growth under nutrient-sufficient conditions in a closed photobioreactor, from which a fraction is periodically removed to inoculate a batch culture in an open cultivation system where initial conditions of high light intensity and high nutrient concentrations favor continued exponential growth for a brief period, but wherein nutrients are rapidly exhausted and light becomes the limiting factor due to the proliferation of cells--conditions that favor oil biosynthesis, resulting in higher cellular oil content. "Nutrients," as defined here, are comprised of the so-called "Macronutrients," which are compounds of nitrogen and phosphorus that are generally supplied in large quantities and are the main food for growth, and the "Micronutrients," which include vitamins and compounds containing trace metals like iron or magnesium that are generally supplied in very small quantities. Overall, the continuous-batch hybrid process yields higher oil productivity than can be attained by a single stage process, either continuous or batch. Additionally, the invention provides a methodology for the reliable use of open cultivation systems, which require far less skill and experience to operate than closed systems, but which have proven otherwise unreliable for large-scale cultivation.


As a practical matter, the optimal culture depth for photosynthetic microbes exposed to full sunlight is generally in the range of 10 to 20 centimeters. No advantage can be gained by providing greater depth of the culture, because the concentration of cells per unit Lighted Area will remain the same, and deeper cells will not receive enough light. The optimal depth, then, puts a limit on the normal operating capacity of any culture system, regardless of its Lighted Area. This phenomenon is a critically important feature in the design of cultivation systems. Greater volumes require more materials, at greater cost, but at some point the increase in volume provides no increase in productivity per unit Lighted Area.


Horizontal systems such as flat-plate reactors and horizontal tubes eliminate the need for the structural engineering required of vertical systems. Using the earth's surface for structural support, the potential capacity of such systems might appear limitless. However, the capacity of horizontal systems is generally limited by the requirement for turbulent flow, whether used to maintain adequate mixing or to fill and empty the culture vessel.

Turbulent flow in a pipe or a channel is described by the Reynolds number, defined as the velocity of the fluid multiplied by the "characteristic length" of the pipe or channel, and divided by the viscosity of the fluid. The Reynolds number does not have any units, like inches or pounds, and is therefore "dimensionless," like "one-half" or "two-thirds". The characteristic length of a fluid-filled pipe is its diameter; the characteristic length of a wide channel is its depth.

Biodiesel Magazine reports:

Using naturally-occurring algae strains from the University of Hawaii, HRBP employs a combination of closed-culture photobioreactors with open ponds in a two-stage process. The company claims this hybrid production system is the preferred route for achieving significant breakthroughs in commercialization of algae. HRBP intends to further develop its upstream and downstream algal technology at its Kona demonstration facility with the objective of deploying it at the Ma’alaea site on Maui, Hawaii, Shonsey said.

In passing, note BARD Refines Ambitious Algae Farming Plans


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