|Concept of the Hydrogen Harvester. Click to enlarge.|
In what recently-appointed Chief Technology Officer Dr. Brian Goodall calls “a landmark discovery”, OriginOil, Inc., a developer of technologies for algae cultivation and extraction (earlier post), says it is developing a new technology to harvest hydrogen from living photosynthetic algae, providing an additional energy source from bioreactors. (Previously, Goodall served as Vice President of Downstream Technology at Sapphire Energy, Inc., where he worked with Continental Airlines in helping to achieve the first US commercial demo flight using an algae-oil blend.)
OriginOil says that its new Hydrogen Harvester—which is currently at bench scale—uses little or no external energy inputs, requires no sulfur deprivation or other stressing of the algae, and no genetic modification of the organisms. The process employs viable, high growth rate, high oil content algae strains.
The co-generation of hydrogen at the algae production site is a critical development for the realization of a completely integrated algal biorefinery. All routes from algae to ‘drop-in’ fuels such as renewable diesel and jet fuel require hydrogen and hydrotreating. The Hydrogen Harvester technology would eliminate the need for hydrogen pipelines and dependence on existing refineries which are typically far removed from ideal sites for algae growth.
—Dr. Brian Goodall
|Direct water-splitting technologies—using photoelectrochemical devices or photosynthetic microorganisms—are the “Holy Grail” of the hydrogen economy... They are the ultimate clean and sustainable hydrogen production methods. Although not ready for prime time, photoelectrochemical and photobiological technologies show great promise for the future and are the focus of long-term R&D efforts at NREL.|
|—NREL Research Review 2003|
Certain green alga such as Chlamydomonas reinhardtii use sunlight to produce hydrogen directly from water. The alga also produce oxygen—which inhibits the function of algal hydrogenase, the enzyme that catalyzes the release of hydrogen gas. Under normal conditions the alga cannot sustain hydrogen production for more than a few minutes.
In a publication in its 2003 Research Review, the US National Renewable Energy Laboratory noted that researchers were attempting to make such photobiological hydrogen production viable at commercial scale via two primary approaches:
By using advanced molecular engineering to design hydrogenase enzymes that are more resistant to oxygen inactivation.
By identifying and characterizing the process conditions that allow the algae to produce either oxygen or hydrogen, but not both simultaneously. A metabolic switch enabled the cycling of algal cells between a photosynthetic growth phase, which produces oxygen, and a hydrogen production phase.
The switch is based on withholding sulfur, essential for maintaining normal photosynthesis; without it, the algae decrease their photosynthetic activities to low levels (such that any oxygen evolved is immediately consumed by the respiratory activity of the culture) and become anaerobic in the light.
(In 2009, an international team of scientists from the UK, Germany and France discovered how oxygen stops photosynthetic organisms such as green algae from producing hydrogen. They reported their results—which are helping to advance development of the microbial production of hydrogen from sunlight and water—in two papers, one in the Journal of the American Chemical Society and one in the Proceedings of the National Academy of Sciences. Earlier post.)
The Hydrogen Harvester technology, which could bolt on to OriginOil or other bioreactors, enables the algae to pump out both hydrogen and oxygen, Goodall said. The company is now working to optimize the technology, and quantify parameters such as yield and rate.
In 12 months time we will have done all the work we need to do to calibrate, to be able to have projections, about how big a Hydrogen Harvester would have to be to supply all the hydrogen for hydrotreating.
—Dr. Brian Goodall
The company recently filed for patent protection of the new hydrogen harvesting technology—its tenth patent application, entitled “Bio Energy Reactor”. While the invention is applicable to any photosynthetic organism, algae is thought to be most productive.
The Hydrogen Harvester will be integrated into OriginOil’s existing portfolio of algae growth technologies, including the recently announced MultiReactor. (Earlier post.)
“New Horizons for Hydrogen”, NREL 2003 Research Review