Abstract
Previously it has been shown that green microalga Chlamydomonas reinhardtii is capable of prolonged H2 photoproduction when deprived of sulfur. In addition to sulfur deprivation (-S), sustained H2 photoproduction in C. reinhardtii cultures can be achieved under phosphorus-deprived (-P) conditions. Similar to sulfur deprivation, phosphorus deprivation limits O2 evolving activity in algal cells and causes other metabolic changes that are favorable for H2 photoproduction. Although significant advances in H2 photoproduction have recently been realized in fresh water microalgae, relatively few studies have focused on H2 production in marine green microalgae. In the present study phosphorus deprivation was applied for hydrogen production in marine green microalgae Chlorella sp., where sulfur deprivation is impossible due to a high concentration of sulfates in the sea water. Since resources of fresh water on earth are limited, the possibility of hydrogen production in seawater is more attractive. In order to achieve H2 photoproduction in P-deprived marine green microalgae Chlorella sp., the dilution approach was applied. Cultures diluted to about 0.5–1.8 mg Chl·L−1 in the beginning of P-deprivation were able to establish anaerobiosis, after the initial growth period, where cells utilize intracellular phosphorus, with subsequent transition to H2 photoproduction stage. It appears that marine microalgae during P-deprivation passed the same stages of adaptation as fresh water microalgae. The presence of inorganic carbon was essential for starch accumulation and subsequent hydrogen production by microalgae. The H2 accumulation was up to 40 mL H2 gas per 1iter of the culture, which is comparable to that obtained in P-deprived C. reinhardtii culture.
Highlights
The ability of microalgae to produce hydrogen under the light was discovered more than 70 years ago [1]
We demonstrated that Chlorella sp. can produce H2 gas under phosphorus deprived conditions by using dilution method that was applied before for fresh water microalgae [18]
Having demonstrated that Chlorella sp. cultures are capable for H2 photoproduction under phosphorus-deprived conditions, we addressed the question of improving H2 production yield in the system
Summary
The ability of microalgae to produce hydrogen under the light was discovered more than 70 years ago [1]. If one could implement technically this process with H2 and O2 spatial (or temporal) separation, at low operational cost, in practical scale, and with high rate, the human population could get environmentally friendly and clean energy from a renewable source. Many fundamental and technical problems should be solved before microalgal hydrogen production comes into practical stage. Sulfur deprived cultures of microalgae realize temporal separation of oxygen and hydrogen production. Fundamental mechanisms of this process are under active investigations [2,3,4]. One of the ways to decrease the operational cost is realization of the process in seawater, which is cheaper than fresh water
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
