scholarly journals Growth CO2 Consumption, and H2 Production of Anabaena Variabilis ATCC 29413-U Under Different Irradiances and CO2 Concentrations

2006 ◽  
Author(s):  
Halil Berberoglu ◽  
Natasha Barra ◽  
Laurent Pilon ◽  
Jenny Jay
Keyword(s):  
Hydrogen Production ◽  
Gas Phase ◽  
Mole Fraction ◽  
Maximum Growth ◽  
H2 Production ◽  
Anabaena Variabilis ◽  
Operating Conditions ◽  
Half Time ◽  
Consumption Growth ◽  
Co2 Consumption

Hydrogen production by cultivation of cyanobacteria in photobioreactors offers a clean and renewable alternative to thermochemical or electrolytic hydrogen production technologies with the added advantage of CO2 mitigation. The objective of this study is to experimentally investigate the CO2 consumption, growth, and H2 production of the cyanobacteria Anabaena variabilis ATCC 29413-U under atmosphere containing argon and CO2. Parameters investigated are irradiance and initial CO2 mole fraction in the gas phase. The CO2 consumption half-time, defined as the time at which the CO2 concentration in the gas phase decreases to half of its initial value, appears to be an appropriate time scale for modeling cyanobacterial CO2 consumption, growth, and H2 production. The half-time depends on both the initial CO2 mole fraction and the irradiance. Also, two regimes of growth have been identified depending on irradiance. Below 5,000 lux, the irradiance and the initial CO2 mole fraction have a coupled effect on cyanobacterial growth. Above 5,000 lux, growth depends only on the initial CO2 mole fraction. Furthermore, the optimum initial CO2 mole fraction around 0.05 has been identified for maximum growth and CO2 consumption rates. The growth and CO2 consumption were not inhibited by irradiance up to about 16,000 lux. Finally, the proposed empirical models can be used in conjunction with mass transfer and light transfer models to design and optimize the operating conditions of a photobioreactor for maximum hydrogen production and/or CO2 consumption.

scholarly journals Preliminary Equipment Design for On-Board Hydrogen Production by Steam Reforming in Palladium Membrane Reactors

2019 ◽  
Vol 3 (1) ◽  
pp. 6 ◽  
Author(s):  
Marina Holgado ◽  
David Alique
Keyword(s):  
Hydrogen Production ◽  
H2 Production ◽  
Single Step ◽  
Operating Conditions ◽  
Membrane Reactors ◽  
Transport Sector ◽  
Main Role ◽  
Pure Hydrogen ◽  
The European Union ◽  
Membrane Area

Hydrogen, as an energy carrier, can take the main role in the transition to a new energy model based on renewable sources. However, its application in the transport sector is limited by its difficult storage and the lack of infrastructure for its distribution. On-board H2 production is proposed as a possible solution to these problems, especially in the case of considering renewable feedstocks such as bio-ethanol or bio-methane. This work addresses a first approach for analyzing the viability of these alternatives by using Pd-membrane reactors in polymer electrolyte membrane fuel cell (PEM-FC) vehicles. It has been demonstrated that the use of Pd-based membrane reactors enhances hydrogen productivity and provides enough pure hydrogen to feed the PEM-FC requirements in one single step. Both alternatives seem to be feasible, although the methane-based on-board hydrogen production offers some additional advantages. For this case, it is possible to generate 1.82 kmol h−1 of pure H2 to feed the PEM-FC while minimizing the CO2 emissions to 71 g CO2/100 km. This value would be under the future emissions limits proposed by the European Union (EU) for year 2020. In this case, the operating conditions of the on-board reformer are T = 650 °C, Pret = 10 bar and H2O/CH4 = 2.25, requiring 1 kg of catalyst load and a membrane area of 1.76 m2.

Apparent hydrogen consumption in acid reactors: observations and implications

2009 ◽  
Vol 59 (7) ◽  
pp. 1441-1447 ◽  
Author(s):  
C. Dinamarca ◽  
R. Bakke
Keyword(s):  
Hydrogen Production ◽  
Biomass Concentration ◽  
H2 Production ◽  
Dark Fermentation ◽  
Operating Conditions ◽  
Fuel Production ◽  
Hydrogen Consumption ◽  
Operation Conditions ◽  
Green Fuel ◽  
High Biomass Concentration

Investigations of hydrogen production by dark fermentation have received increasing attention as a green fuel production process. Research focus is mainly on yields and rates of hydrogen production under different operation conditions. The importance of hydrogen consumption is addressed here, based on results from lab-scale reactors. Experiments were run using mixed cultures and a variety of operating conditions: HRT 6-40 hours; temperature 25–55°C. Initial hydrogen yields between 0.8–1.5 mol H2/mol glucose and ≈50% H2 in headspace was observed, followed by a decrease in hydrogen production as the culture matures, resulting in hydrogen yields down to 0.02 mol H2/mol glucose. It is concluded that hydrogen or “hydrogen equivalents” consumption is significant, especially in reactors with high biomass concentration and/or high sludge age. Sustainable H2 production by dark fermentation alone is therefore not likely to be developed. The results suggest that it is possible to control and avoid significant H2 production in dark fermentation. Minimizing H2 production can be useful in preparation of organic feed for other bio-fuel production processes, such as methanogenic processes and bio-electrochemical H2 production.

scholarly journals Catalytic Conversion of n-C7 Asphaltenes and Resins II into Hydrogen Using CeO2-Based Nanocatalysts

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1301
Author(s):  
Oscar E. Medina ◽  
Jaime Gallego ◽  
Sócrates Acevedo ◽  
Masoud Riazi ◽  
Raúl Ocampo-Pérez ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Low Temperatures ◽  
Gaseous Mixture ◽  
H2 Production ◽  
The Other ◽  
Hydrogen Release ◽  
Catalytic Gasification ◽  
Three Samples ◽  
Main Decomposition ◽  
Catalytic Capacity

This study focuses on evaluating the volumetric hydrogen content in the gaseous mixture released from the steam catalytic gasification of n-C7 asphaltenes and resins II at low temperatures (<230 °C). For this purpose, four nanocatalysts were selected: CeO2, CeO2 functionalized with Ni-Pd, Fe-Pd, and Co-Pd. The catalytic capacity was measured by non-isothermal (from 100 to 600 °C) and isothermal (220 °C) thermogravimetric analyses. The samples show the main decomposition peak between 200 and 230 °C for bi-elemental nanocatalysts and 300 °C for the CeO2 support, leading to reductions up to 50% in comparison with the samples in the absence of nanoparticles. At 220 °C, the conversion of both fractions increases in the order CeO2 < Fe-Pd < Co-Pd < Ni-Pd. Hydrogen release was quantified for the isothermal tests. The hydrogen production agrees with each material’s catalytic activity for decomposing both fractions at the evaluated conditions. CeNi1Pd1 showed the highest performance among the other three samples and led to the highest hydrogen production in the effluent gas with values of ~44 vol%. When the samples were heated at higher temperatures (i.e., 230 °C), H2 production increased up to 55 vol% during catalyzed n-C7 asphaltene and resin conversion, indicating an increase of up to 70% in comparison with the non-catalyzed systems at the same temperature conditions.

Bifunctional single-atomic Mn sites for energy-efficient hydrogen production

Nanoscale ◽  
2021 ◽  
Author(s):  
Xianyun Peng ◽  
Junrong Hou ◽  
Yuying Mi ◽  
Jiaqiang Sun ◽  
Gaocan Qi ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Energy Saving ◽  
Hydrogen Evolution Reaction ◽  
Energy Efficient ◽  
Low Cost ◽  
Clean Energy ◽  
H2 Production ◽  
Energy Technology ◽  
Highly Active ◽  
Clean Energy Technology

Electrocatalytic hydrogen evolution reaction (HER) for H2 production is essential for future renewable and clean energy technology. Screening energy-saving, low-cost, and highly active catalysts efficiently, however, is still a grand...

scholarly journals Exergy analysis of a biomass-based multi-energy system

2019 ◽  
Vol 113 ◽  
pp. 02017
Author(s):  
Mariagiovanna Minutillo ◽  
Alessandra Perna ◽  
Alessandro Sorce
Keyword(s):  
Exergy Analysis ◽  
Energy System ◽  
H2 Production ◽  
Operating Conditions ◽  
Processing Unit ◽  
Storage Unit ◽  
Fuel Processing ◽  
Fuel Processor ◽  
Energy Processes ◽  
And Storage

This paper focuses on a biofuel-based Multi-Energy System generating electricity, heat and hydrogen. The proposed system, that is conceived as refit option for an existing anaerobic digester plant in which the biomass is converted to biogas, consists of: i) a fuel processing unit, ii) a power production unit based on the SOFC (Solid Oxide Fuel Cell) technology, iii) a hydrogen separation, compression and storage unit. The aim of this study is to define the operating conditions that allow optimizing the plant performances by applying the exergy analysis that is an appropriate technique to assess and rank the irreversibility sources in energy processes. Thus, the exergy analysis has been performed for both the overall plant and main plant components and the main contributors to the overall losses have been evaluated. Moreover, the first principle efficiency and the second principle efficiency have been estimated. Results have highlighted that the fuel processor (the Auto-Thermal Reforming reactor) is the main contributor to the global exergy destruction (9.74% of the input biogas exergy). In terms of overall system performance the plant has an exergetic efficiency of 53.1% (it is equal to 37.7% for the H2 production).

Hydrogen Production via Catalytic Autothermal Reforming of Desulfurized Jet-A Fuel

2016 ◽  
Author(s):  
Shuyang Zhang ◽  
Xiaoxin Wang ◽  
Peiwen Li
Keyword(s):  
Energy Efficiency ◽  
Hydrogen Production ◽  
Hydrogen Storage ◽  
Coke Formation ◽  
Autothermal Reforming ◽  
Operating Conditions ◽  
Hydrogen Yield ◽  
Fuel Conversion ◽  
Optimal Operating ◽  
Reaction Equilibrium

On-board hydrogen production via catalytic autothermal reforming is beneficial to vehicles using fuel cells because it eliminates the challenges of hydrogen storage. As the primary fuel for both civilian and military air flight application, Jet-A fuel (after desulfurization) was reformed for making hydrogen-rich fuels in this study using an in-house-made Rh/NiO/K-La-Ce-Al-OX ATR catalyst under various operating conditions. Based on the preliminary thermodynamic analysis of reaction equilibrium, important parameters such as ratios of H2O/C and O2/C were selected, in the range of 1.1–2.5 and 0.5–1.0, respectively. The optimal operating conditions were experimentally obtained at the reactor’s temperature of 696.2 °C, which gave H2O/C = 2.5 and O2/C = 0.5, and the obtained fuel conversion percentage, hydrogen yield (can be large than 1 from definition), and energy efficiency were 88.66%, 143.84%, and 64.74%, respectively. In addition, a discussion of the concentration variation of CO and CO2 at different H2O/C, as well as the analysis of fuel conversion profile, leads to the finding of effective approaches for suppression of coke formation.

scholarly journals Measurement of Air-Fuel Ratio Fluctuations Caused by Combustor Driven Oscillations

1998 ◽  
Author(s):  
Rajiv Mongia ◽  
Robert Dibble ◽  
Jeff Lovett
Keyword(s):  
Power Spectrum ◽  
Mole Fraction ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Premixed Combustion ◽  
Pollutant Emissions ◽  
Combustion Instabilities ◽  
Pressure Oscillations ◽  
Lean Premixed Combustion ◽  
Lean Premixed

Lean premixed combustion has emerged as a method of achieving low pollutant emissions from gas turbines. A common problem of lean premixed combustion is combustion instability. As conditions inside lean premixed combustors approach the lean flammability limit, large pressure variations are encountered. As a consequence, certain desirable gas turbine operating regimes are not approachable. In minimizing these regimes, combustor designers must rely upon trial and error because combustion instabilities are not well understood (and thus difficult to model). When they occur, pressure oscillations in the combustor can induce fluctuations in fuel mole fraction that can augment the pressure oscillations (undesirable) or dampen the pressure oscillations (desirable). In this paper, we demonstrate a method for measuring the fuel mole fraction oscillations which occur in the premixing section during combustion instabilities produced in the combustor that is downstream of the premixer. The fuel mole fraction in the premixer is measured with kHz resolution by the absorption of light from a 3.39 μm He-Ne laser. A sudden expansion combustor is constructed to demonstrate this fuel mole fraction measurement technique. Under several operating conditions, we measure significant fuel mole fraction fluctuations that are caused by pressure oscillations in the combustion chamber. Since the fuel mole fraction is sampled continuously, a power spectrum is easily generated. The fuel mole fraction power spectrum clearly indicates fuel mole fraction fluctuation frequencies are the same as the pressure fluctuation frequencies under some operating conditions.

scholarly journals High Pressure Photoreduction of CO2: Effect of Catalyst Formulation, Hole Scavenger Addition and Operating Conditions

Catalysts ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 430 ◽  
Author(s):  
Elnaz Bahadori ◽  
Antonio Tripodi ◽  
Alberto Villa ◽  
Carlo Pirola ◽  
Laura Prati ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Formic Acid ◽  
Gas Phase ◽  
Operating Conditions ◽  
Flame Spray ◽  
Co2 Solubility ◽  
Total Consumption ◽  
Solubility In Water ◽  
Hole Scavenger ◽  
Fuels And Chemicals

The photoreduction of CO2 is an intriguing process which allows the synthesis of fuels and chemicals. One of the limitations for CO2 photoreduction in the liquid phase is its low solubility in water. This point has been here addressed by designing a fully innovative pressurized photoreactor, allowing operation up to 20 bar and applied to improve the productivity of this very challenging process. The photoreduction of CO2 in the liquid phase was performed using commercial TiO2 (Evonink P25), TiO2 obtained by flame spray pyrolysis (FSP) and gold doped P25 (0.2 wt% Au-P25) in the presence of Na2SO3 as hole scavenger (HS). The different reaction parameters (catalyst concentration, pH and amount of HS) have been addressed. The products in liquid phase were mainly formic acid and formaldehyde. Moreover, for longer reaction time and with total consumption of HS, gas phase products formed (H2 and CO) after accumulation of significant number of organic compounds in the liquid phase, due to their consecutive photoreforming. Enhanced CO2 solubility in water was achieved by adding a base (pH = 12–14). In basic environment, CO2 formed carbonates which further reduced to formaldehyde and formic acid and consequently formed CO/CO2 + H2 in the gas phase through photoreforming. The deposition of small Au nanoparticles (3–5 nm) (NPs) onto TiO2 was found to quantitatively influence the products distribution and increase the selectivity towards gas phase products. Significant energy storage in form of different products has been achieved with respect to literature results.

Hydrogen Production via the Iron/Iron Oxide Looping Cycle

2011 ◽  
Author(s):  
A. Singh ◽  
F. Al-Raqom ◽  
J. Klausner ◽  
J. Petrasch
Keyword(s):  
Iron Oxide ◽  
Hydrogen Production ◽  
Gas Phase ◽  
Energy Content ◽  
Operation Conditions ◽  
Iron Oxide Reduction ◽  
Temperature Ranges ◽  
Iron Iron ◽  
Gas Phase Separation ◽  
Distinct Temperature

The iron/iron-oxide looping cycle has the potential to produce high purity hydrogen from coal or natural gas without the need for gas phase separation: Hydrogen is produced from steam oxidation of iron or Wustite yielding primarily Magnetite; Magnetite is then reduced back to iron/Wustite using syngas (CO+H2). A system model has been developed to identify favorable operation conditions and process configurations. Process configurations for three distinct temperature ranges, (i) 500–950 K, (ii) 950–1100 K, and (iii) 1100–1200 K have been developed. The energy content of high temperature syngas from conventional coal gasifiers is sufficient to drive the looping process throughout the temperature range considered. Temperatures around 1000 K are advantageous for both the hydrogen production step and the iron oxide reduction step. Simulations of a large number of subsequent cycles indicate that quasi-steady operation is reached after approximately 5 cycles. Comparison of simulations and experiments indicate that the process is currently limited by chemical kinetics at lower temperatures. Therefore, product recirculation should be used for a scaled-up process to increase reactant residence times while maintaining sufficient fluidization velocity.

Modelling of solid oxide steam electrolyser: Impact of the operating conditions on hydrogen production

2011 ◽  
Vol 196 (4) ◽  
pp. 2080-2093 ◽  
Author(s):  
J. Laurencin ◽  
D. Kane ◽  
G. Delette ◽  
J. Deseure ◽  
F. Lefebvre-Joud
Keyword(s):  
Hydrogen Production ◽  
Operating Conditions ◽  
Solid Oxide
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