Biological hydrogen production

Biological hydrogen production is done in a bioreactor based on the production of hydrogen by algae. Algae produce hydrogen under certain conditions. In the late 1990s it was discovered that if algaeclarifyme are deprived of sulfur they will switch from the production of oxygen, as in normal photosynthesis, to the production of hydrogen. [ [http://www.wired.com/news/technology/0,70273-0.html Wired-Mutant Algae Is Hydrogen Factory] ]

Bioreactor design issues

* Restriction of photosynthetic hydrogen production by accumulation of a proton gradient.
* Competitive inhibition of photosynthetic hydrogen production by carbon dioxide.
* Requirement for bicarbonate binding at photosystem II (PSII) for efficient photosynthetic activity.
* Competitive drainage of electrons by oxygen in algal hydrogen production.
* Economics must reach competive price to other sources of energy and the economics are dependent on several parameters. A major technical obstical is the efficiency in converting solar energy into chemical energy stored in molecular hydrogen.

Attempts are in progress to solve these problems via bioengineering.

Milestones

1939 German researcher by the name of Hans Gaffron discovered while working at the University of Chicago, that algae can switch between producing oxygen and hydrogen.

1997 Professor Anastasios Melis discovered, after following Hans Gaffron's work, that the deprivation of sulfur will cause the algae to switch from producing oxygen to producing hydrogen. The enzyme, hydrogenase, he found was responsible for the reaction. [ [http://www.ucop.edu/research/publications/pdf/doe2000.pdf Department of Energy report winter 2000] ] [ [http://web.mit.edu/pweigele/www/PBR_background/dissertation_anaerobic_chlamy.pdf 2005-The anaerobic life of the photosynthetic alga] ]

2006 - Researchers from the University of Bielefeld and the University of Queensland have genetically changed the single-cell green alga "Chlamydomonas reinhardtii" in such a way that it produces an especially large amount of hydrogen. [http://www.fuelcellsworks.com/Supppage5197.html] The Stm6 can, in the long run, produce five times the volume made by the wild form of alga and up to 1.6-2.0 percent energy efficiency.

2007 - Anastasios Melis studying solar-to-chemical energy conversion efficiency in "tla1" mutants of "Chlamydomonas reinhardtii", achieved 15 % efficiency, demonstrating that truncated Chl antenna size would minimize wasteful dissipation of sunlight by individual cells [ [http://www.hydrogen.energy.gov/pdfs/progress07/ii_h_3_melis.pdf DOE 2007 Report ] ] . This solar-to-chemical energy conversion process could be coupled to the production of a variety of bio-fuels including hydrogen.

2007 - It was discovered that if copper is added algae will switch from the production of oxygen to hydrogen [ [http://www.physorg.com/news114172068.html Copper] ]

Research

2006 - At the University of Karlsruhe, a prototype of a bio-reactor containing 500-1,000 litres of algae cultures is being developed. The reactor is to be used to prove the economic feasibility of the system in the next five years.

A joint venture between El Paso's Valcent Products and the Canadian Alternative Energy firm, Global Green Solutions has built a $3 Million dollar laboratory to further develop a system that will allow for low cost, mass production of algae in just about any location across the globe. The algae is grown in a "closed loop" and produces more hydrogen than that of naturally occurring algae. While algae grows well in an "open pond", the [http://e85.whipnet.net/alt.fuel/algae.html Vertigro system] uses a greenhouse filled with tall, clear plastic bags, suspended end to end in rows, to breed algae.

Economics

It would take an algae farm the size of the state of Texas to produce enough hydrogen to supply the energy needs of the whole world. It would take about 25,000 square kilometres to be sufficient to displace gasoline use in the US; this is less than a tenth of the area devoted to growing soya in the US but would equal the size of the state of Vermont, or three times the size of the everglades swamp in Florida, all dedicated to raising this form of algae. [http://www.newscientist.com/channel/earth/energy-fuels/mg18925401.600-growing-hydrogen-for-the-cars-of-tomorrow.html] .

The US Department of Energy has targeted a selling price of $2.60 / kg as a goal for making renewable hydrogen economically viable. 1 kg is approximately the energy equivalent to a gallon of gasoline. To achieve this, the efficiency of light-to-hydrogen conversion must reach 10 % while current efficiency is only 1 % and selling price is estimated at $13.53 / kg. [ [http://www.nrel.gov/docs/fy04osti/35593.pdf 2004-Updated Cost Analysis of Photobiological Hydrogen] ]

According to the DOE cost estimate, for a refueling station to supply 100 cars per day, it would need 300 kg. With current technology, a 300 kg per day stand-alone system will require 110,000 m² of pond area, 0.2 g/L cell concentration, a truncated antennae mutant and 10 cm pond depth.

Areas of research to increase efficiency include, engineering mutant algae with truncated antennae, developing oxygen-tolerant hydrogenases and increased hydrogen production rates through improved electron transfer.

History

In 1939 a German researcher named Hans Gaffron, while working at the University of Chicago, observed that the algae he was studying, "Chlamydomonas reinhardtii" (a green-algae), would sometimes switch from the production of oxygen to the production of hydrogen. [http://www.wired.com/news/technology/0,1282,54456,00.html] Gaffron never discovered the cause for this change and for many years other scientists failed in their attempts at its discovery. In the late 1990s professor Anastasios Melis a researcher at the University of California at Berkeley discovered that if the algae culture medium is deprived of sulfur it will switch from the production of oxygen (normal photosynthesis), to the production of hydrogen. He found that the enzyme responsible for this reaction is hydrogenase, but that the hydrogenase lost this function in the presence of oxygen. Melis found that depleting the amount of sulfur available to the algae interrupted its internal oxygen flow, allowing the hydrogenase an environment in which it can react, causing the algae to produce hydrogen. [http://www.wired.com/wired/archive/10.04/mustread.html?pg=5] "Chlamydomonas moewusii" is also a good strain for the production of hydrogen.

ee also

*Algae
*Algaculture
*Biohydrogen
*Hydrogen production
*Photohydrogen
*Timeline of hydrogen technologies

References

External links

* [http://www1.eere.energy.gov/hydrogenandfuelcells/production/pdfs/photobiological.pdf DOE - A Prospectus for Biological Production of Hydrogen]
* [http://www.solarbiofuels.org/biofuels/Templates/biohydrogen.html Solarbiofuels]
* [http://www.fao.org/docrep/w7241e/w7241e0g.htm FAO]
* [http://www.hydrogen.energy.gov/pdfs/review06/pdp_11_melis.pdf Maximizing Light Utilization Efficiency and Hydrogen Production in Microalgal Cultures]
* [http://search.nrel.gov/query.html?col=eren&qc=eren&style=eere&qm=1&si=0&ht=517965421&ct=147558239 NREL reports]
* [http://search.nrel.gov/cs.html?charset=utf-8&url=http%3A//www1.eere.energy.gov/hydrogenandfuelcells/pdfs/30535f.pdf&qt=url%3Awww1.eere.energy.gov/hydrogenandfuelcells/+url%3Awww.eere.energy.gov/hydrogenandfuelcells/+||+algae+farm&col=eren&n=9&la=en EERE-CYCLIC PHOTOBIOLOGICAL ALGAL H2-PRODUCTION]