|The bioreactor process. Click to enlarge.|
GreenShift Corporation, a business development company that is aggressively expanding its portfolio of renewable or sustainable energy companies, has acquired rights to Ohio University’s patented cynaobacteria-based bioreactor process for reducing greenhouse gases emissions from fossil-fueled combustion processes.
In concept, this is very similar to GreenFuel Technologies’ “Emissions-to-Biofuels” reactor; the implementation is, however, quite different.
Using $1 million in U.S. Department of Energy funding, assistance from Keith Cooksey, a microbiologist at Montana State University who had been researching bacteria found in the mineral hot springs of Yellowstone National Park, and a system of parabolic mirrors, fiber optic cables and slabs of acrylic plastic called glow plates developed by scientists at Oak Ridge National Laboratory, Dr. David Bayless at OU designed a bioreactor based on a newly discovered iron-loving cyanobacterium (blue-green algae), tentatively named Chroogloeocystis siderophila, that Cooksey discovered thriving in a hot stream at Yellowstone.
The algae grow in the bioreactor on membranes of woven fibers resembling window screens interspersed between the Oak Ridge glow plates. Capillary action wicks water to the algae, fiber optic cables channel sunlight into the glow plates, and ducts bring in the hot flue gas.
Spreading the cyanobacteria on membranes maximizes surface area for growth, minimizes water and optimizes the use of sunlight.
This enables us to take one square meter of sunlight and spread it out over 10 square meters of growth surface.—Dr. Bayless
The algae use the available carbon dioxide and water to grow new algae, giving off pure oxygen and water vapor in the process. The organisms also absorb nitrogen oxide and sulfur dioxide, which contribute to acid rain.
A prototype is capable of handling 140 cubic meters of flue gas per minute, an amount equal to the exhaust from 50 cars or a 3 megawatt power plant.
Once the algae grow to maturity, they fall to the bottom of the bioreactor and are harvested for other uses—processing into biodiesel, used as feedstock for gasification, or for other purposes such as fertilizer.
GreenFuel, by contrast, uses an implementation of an air-lift reactor (ALR), which is a type of pneumatic contacting device in which fluid circulation takes place in a defined cyclic pattern through channels built specifically for this purpose.
The process, called photomodulation, rotates the algae in and out of the sunlight, rather than bringing the sunlight to the algae, as in the GreenShift-OU system. The GreenShift-OU system, however, should require less of a structural footprint to acquire the needed sunlight.
|The GreenFuel ALR|
The GreenFuel bioreactor consists of a riser tube or channel, a gas separator, and a downcomer tube or channel, applied in a triangular configuration. The difference in the apparent fluid densities between the riser and downcomer provides the driving force for liquid circulation.
GreenFuel inaugurated its first beta test at the 20MW MIT Cogeneration Plant, known as MIT Cogen, on 22 July 2004.
Independent testing documented that the beta system delivered 86% NOx reduction under all conditions, along with 50% CO2 reduction on rainy days, and 82% CO2 reduction on sunny days.