Biological hydrogen production (algae)

The biological hydrogen production with algae is a method of photobiological water splitting which is done in a closed photobioreactor based on the production of hydrogen as a solar fuel by algae.[1][2] Algae produce hydrogen under certain conditions. In 2000 it was discovered that if C. reinhardtii algae are deprived of sulfur they will switch from the production of oxygen, as in normal photosynthesis, to the production of hydrogen.[3][4][5]

Photosynthesis

Photosynthesis in cyanobacteria and green algae splits water into hydrogen ions and electrons. The electrons are transported over ferredoxins.[6] Fe-Fe-hydrogenases (enzymes) combine them into hydrogen gas. In Chlamydomonas reinhardtii Photosystem II produces in direct conversion of sunlight 80% of the electrons that end up in the hydrogen gas.[7] Light-harvesting complex photosystem II light-harvesting protein LHCBM9 promotes efficient light energy dissipation.[8] The Fe-Fe-hydrogenases need an anaerobic environment as they are inactivated by oxygen. Fourier transform infrared spectroscopy is used to examine metabolic pathways.[9]

Truncated antenna

The chlorophyll (Chl) antenna size in green algae is minimized, or truncated, to maximize photobiological solar conversion efficiency and H2 production. The truncated Chl antenna size minimizes absorption and wasteful dissipation of sunlight by individual cells, resulting in better light utilization efficiency and greater photosynthetic productivity by the green alga mass culture.[10]

History

In 1939 Hans Gaffron 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.[11] He never discovered the cause of this change and for many years other scientists failed in their attempts to discover it. In the late 1990s, Anastasios Melis 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.[12] Chlamydomonas moewusii is also a good strain for the production of hydrogen.[13]

Economics

It would take about 25,000 square kilometre algal farming to produce biohydrogen equivalent to the energy provided by gasoline in the US alone. This area represents approximately 10% of the area devoted to growing soya in the US.[14]

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 competitive price to other sources of energy and the economics are dependent on several parameters.
  • A major technical obstacle is the efficiency in converting solar energy into chemical energy stored in molecular hydrogen.

Attempts are in progress to solve these problems via bioengineering.

See also

References

  1. ↑ 2013 - Gimpel JA, et al Advances in microalgae engineering and synthetic biology applications for biofuel production
  2. ↑ Hemschemeier, Anja; Melis, Anastasios; Happe, Thomas (2009). "Analytical approaches to photobiological hydrogen production in unicellular green algae". Photosynthesis Research. 102 (2–3): 523–540. doi:10.1007/s11120-009-9415-5. ISSN 0166-8595. PMC 2777220. PMID 19291418.
  3. ↑ Wired-Mutant Algae Is Hydrogen Factory Archived August 27, 2006, at the Wayback Machine.
  4. ↑ "Archived copy". Archived from the original on 2008-10-31. Retrieved 2009-03-11.
  5. ↑ Melis, Anastasios; Zhang, Liping; Forestier, Marc; Ghirardi, Maria L.; Seibert, Michael (2000-01-01). "Sustained Photobiological Hydrogen Gas Production upon Reversible Inactivation of Oxygen Evolution in the Green AlgaChlamydomonas reinhardtii". Plant Physiology. 122 (1): 127–136. doi:10.1104/pp.122.1.127. ISSN 1532-2548. PMC 58851. PMID 10631256.
  6. ↑ Peden, E. A.; Boehm, M.; Mulder, D. W.; Davis, R.; Old, W. M.; King, P. W.; Ghirardi, M. L.; Dubini, A. (2013). "Identification of Global Ferredoxin Interaction Networks in Chlamydomonas reinhardtii". Journal of Biological Chemistry. 288 (49): 35192–35209. doi:10.1074/jbc.M113.483727. ISSN 0021-9258. PMC 3853270. PMID 24100040.
  7. ↑ Volgusheva, A.; Styring, S.; Mamedov, F. (2013). "Increased photosystem II stability promotes H2 production in sulfur-deprived Chlamydomonas reinhardtii". Proceedings of the National Academy of Sciences. 110 (18): 7223–7228. doi:10.1073/pnas.1220645110. ISSN 0027-8424. PMC 3645517. PMID 23589846.
  8. ↑ Grewe, S.; Ballottari, M.; Alcocer, M.; D'Andrea, C.; Blifernez-Klassen, O.; Hankamer, B.; Mussgnug, J. H.; Bassi, R.; Kruse, O. (2014). "Light-Harvesting Complex Protein LHCBM9 Is Critical for Photosystem II Activity and Hydrogen Production in Chlamydomonas reinhardtii". The Plant Cell. 26 (4): 1598–1611. doi:10.1105/tpc.114.124198. ISSN 1040-4651. PMC 4036574. PMID 24706511.
  9. ↑ Langner, U; Jakob, T; Stehfest, K; Wilhelm, C (2009). "An energy balance from absorbed photons to new biomass for Chlamydomonas reinhardtii and Chlamydomonas acidophila under neutral and extremely acidic growth conditions". Plant Cell Environ. 32 (3): 250–8. doi:10.1111/j.1365-3040.2008.01917.x. PMID 19054351.
  10. ↑ Kirst, H.; Garcia-Cerdan, J. G.; Zurbriggen, A.; Ruehle, T.; Melis, A. (2012). "Truncated Photosystem Chlorophyll Antenna Size in the Green Microalga Chlamydomonas reinhardtii upon Deletion of the TLA3-CpSRP43 Gene". Plant Physiology. 160 (4): 2251–2260. doi:10.1104/pp.112.206672. ISSN 0032-0889. PMC 3510145. PMID 23043081.
  11. ↑ Algae: Power Plant of the Future?
  12. ↑ Reengineering Algae To Fuel The Hydrogen Economy
  13. ↑ Yang, Shihui; Guarnieri, Michael T; Smolinski, Sharon; Ghirardi, Maria; Pienkos, Philip T (2013). "De novo transcriptomic analysis of hydrogen production in the green alga Chlamydomonas moewusii through RNA-Seq". Biotechnology for Biofuels. 6 (1): 118. doi:10.1186/1754-6834-6-118. ISSN 1754-6834. PMC 3846465. PMID 23971877.
  14. ↑ Growing hydrogen for the cars of tomorrow
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