• Transactions of the Korean hydrogen and new energy society
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• v.19 no.4
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• pp.322-330
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• 2008

This paper deals with an economic evaluation of domestic photobiological hydrogen production. We evaluate the economic feasibility of domestic photobiological hydrogen production utilizing green algae and cyanobacteria. In addition, we make some sensitivity analysis of hydrogen production prices by changing the values of input factors such as the price of a photo-bioreactor and the value of solar to hydrogen efficiency. The estimated hydrogen production price of the two-step indirect biophotolysis was 12,099won/kg$H_2$. It is expected that the hydrogen production price by the two-step indirect biophotolysis can be reduced to 2,143won/kg$H_2$ if the solar to hydrogen efficiency is increased to 10% and the price of a photo-bioreactor is decreased to $25/$m^2$. The two-step indirect biophotolysis is evaluated as uneconomical at this time, and we need to enhance the solar to hydrogen efficiency and to reduce the prices of the photo-bioreactor and system facilities.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.2
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• pp.104-110
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• 2010

Photobiological hydrogen production by nitrogen-fixing unicellular cyanobacteria has long been considered to be an environmentally sound and very promising method for the future supply of renewable clean energy. We tried to find out the optimum cell concentration for $H_2$ production in each of the two new Korean nitrogen-fixing unicellular cyanobacterial strains to compare with Synechococcus sp. strain Miami BG043511. The two Korean strains, Cyanothece sp. KNU CB MAL-031 and KNU CB MAL-058, were isolated from Korean west coasts. Cell concentrations up to 17 billion cells $ml^{-1}$ were applied to the tests. High cell concentration over 15 billion cells $ml^{-1}$ resulted in drastically reduced $H_2$ production in all the three strains. The two domestic strains, however, produced 2-3 time more hydrogen than Synechococcus sp. Miami BG043511 at cell concentrations of 5-10 billion cells $ml^{-1}$. At lower cell concentrations than 2 billion cells $ml^{-1}$, MAL-031 exhibited highest $H_2$ production followed by Miami BG043511, with far less production in MAL-058. Present result suggests that Cyanothece sp. MAL-CB031 might be one of the ideal nitrogen-fixing unicellular cyanobacterial strains for the photobiological hydrogen production.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.1
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• pp.20-28
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• 2013

Photobiological hydrogen production by nitrogen-fixing unicellular cyanobacteria has long been considered to be an environmentally sound and very promising method for the future supply of renewable clean energy. Using six Korean nitrogen-fixing unicellular cyanobacterial strains and the Synechococcus sp. strain Miami BG043511 we performed cultivation experiments to find out the strain-specific optimal temperature for population growth and $H_2$ production. Under $20^{\circ}C$ the population growth of all the tested strains was significantly retarded in contrasts to the faster and higher growth under 25, 30 or $35^{\circ}C$. The highest growth rates in all the 7 strains were measured under $30^{\circ}C$ while the maximal biomass yields were under $30^{\circ}C$ (strains CB-MAL 026, 054, and 055) or $35^{\circ}C$ (strains 002, 031, 058, and Miami BG043511). The difference between the maximal biomass yields at $30^{\circ}C$ and $35^{\circ}C$ was not greater than 10%. The quantity of photobiologically produced $H_2$ was only slight larger under $35^{\circ}C$ than that under $20^{\circ}C$. Our result may suggest a two-step process of $H_2$ production which includes rapid and sizable production of biomass at $30^{\circ}C$ and the following high $H_2$ production at $20^{\circ}C$ by the test strains of marine nitrogen-fixing unicellular cyanobacteria.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.5
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• pp.663-670
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• 2011

Under a daily photoperiod of 14h light and 10h dark synchronization of cell cycle in Korean Cyanothece spp. strains and $Synechococcus$ sp. strain Miami BG043511 was analyzed as to be applicable to enhanced hydrogen production. For all strains peaks of double cell were observed during the light period of a daily cycle. Peaks of maximal cell size measured by a coulter counter appeared at the peak of double cells observed under light microscope reconfirming the synchronization of daily cell cycle. The cell cycle synchronization became weakened within two days when treated with continuous illumination. Rapid detection of the peak time of double cell percentage by coulter counters may contribute to quasi-realtime feedback control for efficient production of photobiological hydrogen by unicellular cyanobacterial strains.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.1
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• pp.12-18
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• 2010

Photobiological hydrogen production using Rhodobacter sphaeroides KD131 was studied on the effect of light intensities and nitrogen sources. Media containing malate and glutamate were shown higher hydrogen production rate than that containing succinate and $(NH_4)_2SO_4$ at the $110\;W/m^2$ illumination by halogen lamp at $30^{\circ}C$. Media lacking glutamate as the nitrogen source exhibited higher hydrogen production than that containing glutamate. Initial cell concentration was optimized to 1.0 at the absorbance of 660 nm. Hydrogen production was increased by increasing the light intensity from 0 to $216\;W/m^2$ but the increasing rate declined over $108\;W/m^2$.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.2
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• pp.136-142
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• 2010

Photobiological $H_2$ production was compared using purple non-sulfur bacteria Rhodobacter sphaeroides KD131 in the medium containing various organic acids as the carbon source and electron doner under illumination of $110\;W/m^2$ using halogen lamp at $30^{\circ}C$. The organic acids used were 0~120 mM acetate, butyrate, lactate and malate. Initial pH 7.0 and cell concentration 1.0 at 660nm were increased to pH 8 and 4.4~5.1, respectively during 24hrs of photo-fermentation when lactate and malate were used. However, acetate and butyrate increased pH to 9 and cell concentration to 3.2~3.9 of malate at the same experimental conditions. Optimum ranges of organic acids concentration and carbon/nitrogen ratio were 30~60 mM and 10~20, respectively. When malate was used as the substrate, maximum $H_2$ production 1.1 ml $H_2$/ml broth, which is equivalent to 1.97 mol $H_2$/mol malate was observed.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.782-786
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• 2009

Thiocapsa roseopersicina NCIB 8347은 purple sulfur bacteria이며 광합성종속영양 조건에서는 nitrogenase 효소계가 유도되어 질소를 고정하며, 수소를 발생한다. 또한 광합성독립영양 조건에서는 hydrogenase 효소계가 유도되어 3~4개 종류의 특성이 다른 hydrogenase가 membrane에 결합되어 있거나, cytoplasma에 존재하며, 이 중의 일부는 산소농도와 온도의 상승에도 비교적 안정하다. 본 연구에서는 T. roseopersicina NCIB 8347이 광합성종속영양 조건에서 수소를 생산할 수 있는 제반 배양조건을 최적화하고, nitrogenase와 일부 hydrogenase역가를 측정하여 purple non-sulfur bacteria, Rhodobacter sphaeroides KD131의 nitrogenase와 비교하여 수소생산을 최적화하였다. 할로겐램프를 8-9 $Klux/m^2$로 조사할 때와 배양온도 $26{\sim}30^{\circ}C$, 배양시간 72시간에서 균체 성장과 수소생산이 가장 높았다. T. roseopersicina NCIB 8347는 광합성 독립영양, 종속영양 조건에서 모두 성장 할 수 있었다.

• KSBB Journal
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• v.13 no.1
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• pp.101-107
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• 1998

Carbon dioxide is estimated to be responsible for 60% of the global warming effect, and this percentage is tending upward. Studies on removal and fixation of $CO_2$ in the flue gas are recognized as one of the important roles of the future biotechnology. Photobiological systems have considerably higher photosynthetic efficiency than conventional biomass system. The experiment for the photosynthetic fixation of $CO_2$ and the biomass production was performed with various initial cell concentration in a tubular photobioreactor and a bubble column $CO_2$ contactor with a gas sparger of $CO_2$ -enriched air(0.03~20%). Synechocystis PCC 6803 could grow at 10~20% $CO_2$ content under pH control. The highest specific growth rate, 0.0258 $h^{-1}$ , was obtained at 5% $CO_2$-air mixture. The maximum cell production rate, 0.2784 g/L.day, was obtained when the initial cell concentration was 0.45 g/L at 5% $CO_2$ -air mixture. The maximum cell concentration was 2.03 g/L in the tubular photobioreactor when the light intensity was $45.5{\mu}$ $E/m^2$ . s. This system showed 0.482 g $CO_2$ /L . day of the $CO_2$ fixation.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.3
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• pp.131-140
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• 2015

To set up unicellular cyanobacterial strains with photo-biological $H_2$ production potential, live samples were repeatedly collected from 68 stations in the coastal zone of Korea for the four years since 2005. Among 77 cyanobacterial strains established six (KNU strains, CB-MAL002, 026, 031, 054, 055 and 058) were finally chosen as the excellent strains for $H_2$ production with $H_2$ accumulation over 0.15 mL $H_2\;mL^{-1}$ under general basic $H_2$ production conditions as well as positive $H_2$ production for more than 60 hr. To explore optimum procedures for higher $H_2$ production efficiency of the six cyanobacterial strains, the inter-strain differences in the growth rate under the gradients of water temperature and salinity were investigated. The maximum daily growth rates of the six strains ranged from 1.78 to 2.08, and all of them exhibited $N_2-fixation$ ability. Based on the similarity of the 16S rRNA sequences, all the test strains were quite close to Cyanothece sp. ATCC51142 (99%). The six strains, however, were grouped into separate clades from strain ATCC51142 in the molecular phylogeny diagram. Chlorophyll- a content was 3.4~7.8% of the total dried weight, and the phycoerythrin and phycocyanin contents were half of those in the Atlantic strain, Synechococcus sp. Miami BG03511. The growth of the six strains was significantly suppressed at temperatures above the optimal range, $30{\sim}35^{\circ}C$, to be nearly stopped at $40^{\circ}C$. The growth was not inhibited by high salinities of 30 psu salinity in all the strains while strain CB055 maintained its high growth rate at low salinities down to 15 psu. The euryhaline strains like CB055 might support massive biotechnological cultivation systems using natural basal seawater in temperate latitudes. base seawater. The biological and ecophysiological characteristics of the test strains may contribute to designing the optimal procedures for photo-biological $H_2$ production by unicellular cyanobacteria.