Energy Map Research Articles

Catalytic/photocatalytic oxidative desulfurization activities of heteropolyacid immobilized on magnetic polythiophene nanocatalyst

Herein, Keggin-type heteropolyacid (SiMo12) supported on magnetic polythiophene nanocomposite has been successfully synthesized. The obtained Fe3O4@SiO2@PT\\SiMo12 magnetic nanocomposite has been characterized by XRD, FESEM and the relating XEDS energy mapping, UV–vis DRS, ICP-MS, and VSM. The catalytic and photocatalytic oxidative desulfurization (ODS) activities of the synthesized nanocatalysts were studied with T, BT, and DBT as the model sulfur compounds. Results showed that the Fe3O4@SiO2@PT\\SiMo12 nanocatalyst exhibited significantly higher catalytic and photocatalytic ODS activities than pure SiMo12, PT, and Fe3O4@SiO2@PT at the same experimental conditions. In general, Fe3O4@SiO2@PT\\SiMo12 showed higher photocatalytic ODS (under visible light) activity (97.2%, 99% and 99.7%) than catalytic ODS (87%, 89.6% and 96.2%) for T, BT, and DBT respectively after 45 min. Also, the Fe3O4@SiO2@PT\\SiMo12 nanocatalyst possessed excellent stability after five reaction cycles.

Extending the luminescence properties of zinc gallogermanate via co-doping with cost-effective metals ions (Cr3+/Mg2+, Cr3+/Ca2+, and Cr3+/Sr2+)

The huge applications of red-light-emitting materials paying the research attention to reduce the cost of production and raw materials. Therefore, abundant cations of alkaline-earth metals, e.g., Mg2+, Ca2+, and Sr2+ were successfully incorporated with Cr3+: Zn3Ga2Ge2O10 (Cr-ZGGO) as co-activators via simple solid-state method. The X-ray diffraction results of all samples confirmed the formation of zinc gallogermanate superstructure with two cubic phases ZnGa2O4 and Zn2GeO4. The particle imaging of Cr-ZGGO and Ca@Cr-ZGGO via field emission scanning electron microscopy reveals a significant change in morphology and particle size by Ca2+ co-doping. Meanwhile, the energy dispersive X-ray spectroscopic analysis and mapping techniques elucidate the exact chemical composition of the calculated stoichiometric substitution and illustrate the equal distribution of all elements over the whole sample. Optical bandgap energy of Mg2+, Ca2+, and Sr2+ co-doped phosphors are lower than Cr-ZGGO. The Sr@Cr-ZGGO displays the most intense photoluminescence peak and the broadest emission in the near-infrared region as a result of increasing light traps and generation of new paths between the energy levels of trapping centers.

RETRACTED: Geospatial mapping of micro-wind energy for district electrification in Ghana

The present study provides an assessment of micro-wind energy potential within the 170 districts in Ghana with more focus on a distributed electricity system for district household electrification. The wind resource is assessed based on three main potentials, the theoretical, the geographical and the technical; these included an assessment of localised wind power densities, necessary environmental conditions of the terrain suitable for wind turbine installation as well as the energy generated by the turbine within the districts. The study was done using wind speed data at a hub of 50 m and then interpolated to a 1 km by 1 km grid cell to enhance granularity and localisation of the geospatial assessment of results. All input datasets were interpolated to this effect. The study is based on a single turbine model; V52/850 and used its power curve to determine the maximum energy output per grid cell. Results of the analysis are visualised using high resolution maps. Results of the analysis show that, areas along the coast and the middle belt areas show high potential with annual production more than a 2,000 GWhy−1 per square kilometre.

A Top-Down Digital Mapping of Spatial-Temporal Energy Use for Municipality-Owned Buildings: A Case Study in Borlänge, Sweden

Urban energy mapping plays a crucial role in benchmarking the energy performance of buildings for many stakeholders. This study examined a set of buildings in the city of Borlänge, Sweden, owned by the municipality. The aim was to present a digital spatial map of both electricity use and district heating demand in the spatial–temporal dimension. A toolkit for top-down data processing and analysis was considered based on the energy performance database of municipality-owned buildings. The data were initially cleaned, transformed and geocoded using custom scripts and an application program interface (API) for OpenStreetMap and Google Maps. The dataset consisted of 228 and 105 geocoded addresses for, respectively, electricity and district heating monthly consumption for the year 2018. A number of extra parameters were manually incorporated to this data, i.e., the total floor area, the building year of construction and occupancy ratio. The electricity use and heating demand in the building samples were about 24.47 kWh/m2 and 268.78 kWh/m2, respectively, for which great potential for saving heating energy was observed. Compared to the electricity use, the district heating showed a more homogenous pattern following the changes of the seasons. The digital mapping revealed a spatial representation of identifiable hotspots for electricity uses in high-occupancy/density areas and for district heating needs in districts with buildings mostly constructed before 1980. These results provide a comprehensive means of understanding the existing energy distributions for stakeholders and energy advisors. They also facilitate strategy geared towards future energy planning in the city, such as energy benchmarking policies.

Friction energy map for sliding wear of Al2O3-TiO2 and Cr2O3-TiO2 coatings

The present study deals with the development of friction energy map for plasma sprayed Al2O3-TiO2 and Cr2O3-TiO2 coatings. Al2O3-TiO2 and Cr2O3-TiO2 coatings were deposited by atmospheric plasma spray technique. The structural and mechanical properties of coatings were studied using Scanning Electron Microscopy (SEM), x-ray Diffraction (XRD) and Vickers macro and micro hardness test. Sliding wear tests were performed on coated specimens over a range of sliding speed and load using pin on disc test apparatus. The analysis of worn surface and wear debris was carried by SEM, XRD and Raman Spectroscopy. Cr2O3-TiO2 coating showed higher hardness and elastic modulus and relatively lower fracture toughness than Al2O3-TiO2 coating. Al2O3-TiO2 coatings exhibited 1.8 times better wear resistance and 11%–30% lower friction coefficient, as compared to Cr2O3-TiO2 coating, depending upon the wear test conditions. The reduction in friction coefficient and wear rate at higher sliding speed was due to the formation of tribofilms on worn surface. A good correlation was observed between friction energy and contact severity; which incorporates mechanical properties of coatings. Friction energy map was used to rationalize wear rates of Al2O3-TiO2 and Cr2O3-TiO2 coatings, for the identification of various wear regimes and failure modes of the coating.

The Perturbed Free-Energy Landscape: Linking Ligand Binding to Biomolecular Folding.

The effects of ligand binding on biomolecular conformation are crucial in drug design, enzyme mechanisms, the regulation of gene expression, and other biological processes. Descriptive models such as "lock and key", "induced fit", and "conformation selection" are common ways to interpret such interactions. Another historical model, linked equilibria, proposes that the free-energy landscape (FEL) is perturbed by the addition of ligand binding energy for the bound population of biomolecules. This principle leads to a unified, quantitative theory of ligand-induced conformation change, building upon the FEL concept. We call the map of binding free energy over biomolecular conformational space the "binding affinity landscape" (BAL). The perturbed FEL predicts/explains ligand-induced conformational changes conforming to all common descriptive models. We review recent experimental and computational studies that exemplify the perturbed FEL, with emphasis on RNA. This way of understanding ligand-induced conformation dynamics motivates new experimental and theoretical approaches to ligand design, structural biology and systems biology.

Cathode luminescence analysis of Cu(In,Ga)Se2 solar cells treated with thiourea solution

Cross-sectional cathode luminescence (CL) was performed on working Cu(In,Ga)Se2 (CIGS) solar cells to clarify the mechanism behind the performance improvement of solar cells subjected to a thiourea treatment. The low panchromatic CL intensity at the depletion zone demonstrates that the existent electric field sweeps the carriers nearby, lowering their possibility of non-radiative and radiative recombination. Accordingly, the low CL intensity at grain boundaries are not necessarily caused by high non-radiative recombination rate if band bending is present. The photon energy mapping showed an emission distribution according to the double-graded bandgap profile. A blue shift in photon emission at the minimum bandgap area was observed for the thiourea-treated sample. We presume that S ions provided by the thiourea solution passivate subgap defects such as donor-type Se vacancies, resulting in radiative transitions with higher energies and higher net carrier density that eventually contributed to the higher fill-factor and higher open-circuit voltage.

Top-down spatially-explicit probabilistic estimation of building energy performance at a scale

Achieving the energy-related and environmental targets for nations and municipalities is largely dependent on the existing built stock. It plays a pivotal role in the accomplishment of these targets through the implementation of energy efficiency and flexibility programs, involving the deployment of distributed energy resource management technologies, refurbishment of building envelopes and upgrading of indoor environmental control equipment. Spatial awareness about urban energy use enables to prioritise the areas where these solutions will be most effective and balanced with the plans for new constructions. Large-scale building energy mapping, however, must cope with heterogeneity of buildings within the built stock, absence of detailed information and multiple sources of uncertainty that stem from the complex and dynamic properties of the phenomenon at a building level. One of the key challenges in the discipline is to account for these uncertainties while maintaining the rational model complexities and data needs. This study, therefore, suggests a parsimonious top-down probabilistic modelling recipe to enable geospatial energy mapping and analysis. Under such modelling principles, an inverse propagation of uncertainties is carried out from the status quo of the built stock. The proposed framework is based on probabilistic sampling with prior parametric univariate density estimation and statistical hypothesis testing. Consolidation with the exogenous influencing factors is facilitated through the measure of statistically significant difference. This approach is exemplified with the data from two sources: the cadastral system and the energy performance certificates registry. A case study developed for Trondheim (Norway) quantified the central tendency and dispersion in the distributions of the simulated bulk total annual energy use by buildings per 1×1km grid cell over the urban territory. The results suggest that best estimates of these values vary between 11MWh·y-1 and 141GWh·y-1 depending on the grid cell. A measure of dispersion in the simulated results is highly correlated with these estimates. Robust handling of uncertainties and the possibility to accommodate a variety of modelling objectives make this approach practical for energy mapping with a flexible spatial resolution that may facilitate numerous applications in energy planning. A collection of methods for univariate density estimation discussed in this study together with the empirical data are accessible through Built Stock Explorer:https://builtstockexplorer.indecol.ntnu.no. This open web application for knowledge discovery in building energy data enables to reproduce some of the results presented in the article.

Atomistic Simulation of the Polymerization Reaction by a (Pyridylamido)hafnium(IV) Catalyst: Counteranion Influence on the Reaction Rate and the Living Character of the Catalytic System.

Atomistic simulation of the 1-octene polymerization reaction by a (pyridylamido)Hf(IV) catalyst was conducted on the basis of Red Moon (RM) methodology, focusing on the effect of the counteranions (CAs), MeB(C6F5)3-, and B(C6F5)4-, on the catalyst activity and chain termination reaction. We show that RM simulation reasonably reproduces the faster reaction rate with B(C6F5)4- than with MeB(C6F5)3-. Notably, the initiation of the polymerization reaction with MeB(C6F5)3- is comparatively slow due to the difficulty of the first insertion. Then, we investigated the free energy map of the ion pair (IP) structures consisting of each CA and the cationic (pyridylamido)Hf(IV) catalyst with the growing polymer chain (HfCatPn+), which determines the polymerization reaction rates, and found that HfCatPn+-MeB(C6F5)3- can keep forming "inner-sphere" IPs even after the polymer chain becomes sufficiently bulky, while HfCatPn+-B(C6F5)4- forms mostly "outer-sphere" IPs. Finally, we further tried to elucidate the origin of the broader molecular weight distribution (MWD) of the polymer experimentally produced with B(C6F5)4- than that with MeB(C6F5)3-. Then, through the trajectory analysis of the RM simulations, it was revealed that the chain termination reaction would be more sensitive to the IP structures than the monomer insertion reaction because the former involves a more constrained structure than the latter, which is likely to be a possible origin of the MWDs dependent on the CAs.

Dynamic recrystallization behavior during hot deformation of as-cast 4Cr5MoSiV1 steel

The dynamic recrystallization behavior of as-cast 4Cr5MoSiV1 steel was studied by hot compression tests conducted at various temperatures (900–1150 °C) and strain rates (0.01–10 s−1). Flow stress curves and microstructural observation were employed to experimentally identify the various flow mechanisms during deformation. A revised Sellars’ constitutive equation was adopted to construct the thermal activation energy map, which considered the effects of deformation temperature and strain rate on the material variables. The Johnson–Mehl–Avrami-Kolmogorov (JMAK) type equation $$X_{D} = 1 - \exp [ - k(\frac{{\varepsilon - \varepsilon_{c} }}{{\varepsilon_{p} }})^{m} ],(\varepsilon \ge \varepsilon_{c} )$$ was applied to characterize the evolution of dynamic recrystallization (DRX) volume fraction. The nucleation of DRX was performed by the bulging, sub-grain swallowing. The presence of dendrite segregation would affect the DRX to a large extent that the segregated alloying elements and carbide precipitates inhibited the migration of boundaries. The thermal activation energy varied from 4310 to 470 kJ/mol and the thermal activation energy increased sharply at temperature below 1000 °C due to the dendrite segregation. By further analysis of the true stress–strain curves, the material constant $$m$$ in JMAK type equation was determined to be 1.29366, indicating the DRX was difficult.

Underutilization of waste as a resource: bottom-up approach to waste management and its energy implications in Lagos, Nigeria

ABSTRACT The inadequate and improper waste management strategies adopted in Lagos state has led to significant levels of negative externalities with deterrent impact on the health, wellbeing and environment of its residents. This study utilizes a bottom-up approach, which is informed by the knowledge and opinions of over 200 residents in Lagos, which was obtained from the direct administration of a survey questionnaire. The sampling method utilized is critical case sampling due to the exploratory nature of this study. The findings highlight the poor status of the waste management services and the need for public awareness on proper waste disposal strategy. The main challenges revealed from this study is the insufficient or lack of waste collection and separation infrastructures and the inadequate operations of waste collection services. These challenges currently deter the potential for waste to energy solutions as observed in the energy map constructed. The improvement strategies include the development of regulatory infrastructures for guiding the waste sector, improvement of financing to the waste sector by government investment or increasing waste fees levied, raising awareness on sustainable and proper waste management practices, and investing in appropriate technologies, infrastructures and manpower to enable adequate operation of waste collection and recycling facilities.

Development of a novel microfluidic device to study metal geochemistry in situ using X-ray fluorescence microprobe spectroscopy.

The study of in situ microscale biogeochemical processes represents a major challenge in the environmental sciences. The combination of microfluidic devices with X-ray fluorescence microprobe spectroscopy may address this need, but typical materials used in these devices attenuate the X-rays needed to analyze key elements of interest, such as Fe or As. In this work, a method is presented for fabricating an etched silicon microfluidic device that is sealed with a 30 µm thin glass window that is sufficiently transparent for X-ray fluorescence microprobe spectroscopy. The capabilities of these devices for X-ray microprobe spectroscopy are demonstrated using an Fe (hydr)oxide solid that is loaded with As and then infused with sulfide, on beamline 4-BM at NSLS-II, resulting in time-variant Fe precipitation reactions and As sorption. Key results include insitu X-ray fluorescence time-series maps of Fe, As and a Br flow tracer, as well as spot XANES at both the Fe K edge and As K edge. Additionally, multiple energy mapping is used to examine the spatial speciation of As over time. The results of this work clearly demonstrate the capabilities of this novel microfluidic system that can be analyzed using X-ray fluorescence microprobe spectroscopy and can be made to study a wide range of complex microscale geochemical systems.

Individual dosimetry system for targeted alpha therapy based on PHITS coupled with microdosimetric kinetic model

BackgroundAn individual dosimetry system is essential for the evaluation of precise doses in nuclear medicine. The purpose of this study was to develop a system for calculating not only absorbed doses but also EQDX(α/β) from the PET-CT images of patients for targeted alpha therapy (TAT), considering the dose dependence of the relative biological effectiveness, the dose-rate effect, and the dose heterogeneity.MethodsA general-purpose Monte Carlo particle transport code PHITS was employed as the dose calculation engine in the system, while the microdosimetric kinetic model was used for converting the absorbed dose to EQDX(α/β). PHITS input files for describing the geometry and source distribution of a patient are automatically created from PET-CT images, using newly developed modules of the radiotherapy package based on PHITS (RT-PHITS). We examined the performance of the system by calculating several organ doses using the PET-CT images of four healthy volunteers after injecting 18F-NKO-035.ResultsThe deposition energy map obtained from our system seems to be a blurred image of the corresponding PET data because annihilation γ-rays deposit their energies rather far from the source location. The calculated organ doses agree with the corresponding data obtained from OLINDA 2.0 within 20%, indicating the reliability of our developed system. Test calculations by replacing the labeled radionuclide from 18F to 211At suggest that large dose heterogeneity in a target volume is expected in TAT, resulting in a significant decrease of EQDX(α/β) for higher-activity injection.ConclusionsAs an extension of RT-PHITS, an individual dosimetry system for nuclear medicine was developed based on PHITS coupled with the microdosimetric kinetic model. It enables us to predict the therapeutic and side effects of TAT based on the clinical data largely available from conventional external radiotherapy.

Development and analysis of tool wear and energy consumption maps for turning of titanium alloy (Ti6Al4V)

Machine tools are the main source of electric power consumption in industrial operations. Thus, in manufacturing, energy-efficient and cleaner production methods are preferred to mitigate production costs. Titanium alloys are known for their poor machinability and are generally characterized by low tool life, high energy consumption and poor surface quality due to its unique physical and mechanical properties. This research aims to evaluate the tool wear rate (R) and the specific cutting energy (SCE) at varying cutting conditions by developing tool wear and energy maps using unified cutting tests. Uncoated H13A tools were used during single-point turning of Ti-6Al-4V alloy by employing Full Factorial Design of Experiments. Based on experimental data, comprehensive process maps were developed for monitoring wear and energy data. These maps showed regions of (low moderate and high) wear and specific energy consumption. It was observed that while machining Ti-6Al-4V alloy the recommended cutting condition (V=100 m/min and f =0.16 mm/rev) enhances the tool life and reduces energy consumption together with high material removal rate. It was also deduced that instead of low speed, using a higher speed of 125 m/min will increase MRR by 127 % and SCE by 16 %, which is more feasible in a production environment. From tool-chip contact length and chip morphology analysis, a strong correlation indicated the reason behind the occurrence of various zones on the maps. It has been found that high wear and energy zone occurred due to the larger contact length and higher chip compression ratio when machining at high speed. The developed maps can be used to help the manufacturers achieve the economic and energy-efficient goal of machining.

Energy map and effective metric in an effective-one-body theory based on the second-post-Minkowskian approximation

Effective-one-body (EOB) theory was originally proposed based on the post-Newtonian (PN) approximation and plays an important role in the analysis of gravitational wave signals. Recently, the post-Minkowskian (PM) approximation has been applied to the EOB theory. The energy map and the effective metric are the two key building blocks of the EOB theory, and in PN approximation radial action variable correspondence is employed to construct the energy map and the effective metric. In this paper, we employ the PM approximation up to the second order, and use the radial action variable correspondence and the precession angle correspondence to construct the energy map and the effective metric. We find that our results based on the radial action variable correspondence, are exactly the same with those obtained based on the precession angle correspondence. Furthermore, we compare the results obtained in this work to the previous existing ones.

ТРОМБОЗЫ МАГИСТРАЛЬНЫХ ВЕН В ПРАКТИКЕ ВРАЧА ИНТЕНСИВНОЙ ТЕРАПИИ

Purpose. To draw the attention of specialists to the question of incidence of catheterassociated and catheter-induced thrombosis in patients in intensive care units. To assess methods of visualization and monitoring of the great veins state using ultrasound. To evaluate various links in the pathogenesis of thrombus formation and the possibilities of prevention and treatment. Materials and methods. More than 3500 ultrasound examinations have been performed in over 850 patients, both in the ICU and after the transfer of patients to specialized departments. The study included children aged from 1,5 months to 18 and adults, with one or more central venous catheters (CVCs). In the absence of contraindications, patients received prophylactic anticoagulant therapy (heparin at a dose of 50-100 U/kg/day). Ultrasound was performed with a frequency of 4 to 85 times in one patient, depending on the detection and severity of CAT. The studies were carried out in B-mode using color and/or energy mapping on ultrasound scanners Philips HD 11 (Philips, USA), SonoSite MicroMaxx (USA), Logiq E8 (GE, USA), Mindrey M 7 (Mindrey, China), Samsung HM 70 (Samsung, South Korea) using linear multi-frequency sensors 10-16 MHz. The patients underwent a complex ultrasound examination of the superior or inferior vena cava (depending on the assumed main vein thrombosis (TMV) localization), as well as the main veins of the extremities. Conclusions. The multifactorial nature of TMV development in ICU patients requires increased alertness to this complication, which necessitates ultrasound monitoring of the great veins in patients in intensive care units with installed CVCs. It should be noted that, despite the ongoing prophylaxis of TMV (including the use of anticoagulants), there is still a high risk of their development.

Survive, Revive, Thrive: Chapter 4: Opening the Sails

Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso, Spanish painter/sculptor, 1881-1973 It’s Time To Look at the Horizon “Opening our sails” is a metaphor that the worst of the storm has passed or is passing, and it is time to get our-selves shipshape, making necessary repairs and preparations, and get back on course. As individuals, and certainly as SPE, we must be ready to cautiously open our sails. The pandemic may be at or near its peak, and despite relatively strong economic performance in most sec-tors, we know that the global economy remains fragile. As an industry, we don’t have the luxury of waiting. We must provide energy and feedstock in advance of global needs, so it is time to get busy and plan not for what was but for what will be. The energy map, meaning the needs, resources, economies, and priorities of the world, is changing. The oil and gas industry will continue to adapt, but as I have mentioned many times, the need for the service we provide is greater now than ever before. We need to be prepared for both increasing demand and public apathy for what we do. This is nothing new, and capital investments in oil and gas should begin to increase as we enter the new year. Perhaps not at the rates we saw during the “shale revolution,” but investors know how essential we are to a strong global economy and will act accordingly. I believe Picasso was right. We must develop the discipline to sacrifice for our passions completely, for what we are doing is too important to wait and too important to sleep. Person-ally, I have a compulsive need to serve and to create. The service part probably came from having older parents who came from, let’s say, very modest circumstances, and the creative part perhaps from the desire to take things apart and put them back together with the fewest possible parts left over. I mention this because each of us has an artist, a writer, an engineer, a doctor, and maybe even a mad scientist inside them. And each of us has our own compulsions. In the post-pandemic, we need to channel that same discipline that Picasso implies. Our passions are our compass, and our energy derives from our compulsion to fulfill those passions. My challenge to you, as an industry, is to align your passions. Someone recently told me that the pandemic had provided us the opportunity of a generation to realign our priorities. I believe it is the opportunity of a lifetime. We can choose to fear the future, or we can create it. It is that simple.

Radiofrequency Ablation Strategies for Intramural Ventricular Arrhythmias.

Catheter ablation is an established treatment strategy for ventricular arrhythmias. However, the presence of intramural substrate poses challenges with mapping and delivery of radiofrequency energy, limiting overall success of catheter ablation. Advances over the past decade have improved our understanding of intramural substrate and paved the way for innovative treatment approaches. Modifications in catheter ablation techniques and development of novel ablation technologies have led to improved clinical outcomes for patients with ventricular arrhythmias. In this review, we explore mapping techniques to identify intramural substrate and describe available radiofrequency energy delivery techniques that can improve overall success rates of catheter ablation.

Effect of heat treatment process on hardness and hot corrosion resistance of Fe-25Ni-18Cr-1Mo-2 W-1Nb-Cast austenitic stainless steel

Abstract This paper reports the effect of heat treatment process on hardness and hot corrosion resistance of Fe-25Ni-18Cr-1Mo-2 W-1Nb-cast austenite stainless steel. The steels were prepared by a process sequence of induction melting, hot rolled, solution treatment and aging. The solution treatment process carried out at a temperature of 975, 1025 and 1075 °C for 2 h and quench in the water and aging process carried out at 775 °C for 8, 16 and 24 h and quench in the air. The Optical Microscope (OM) observation and hardness micro Vickers test were carried out in the steels after process of heat treatment. Then, the steels were tested hot corrosion in the melting salt at a temperature of 800 °C for 4, 8, 12, 16 and 24 h. The weight loss of the steels due to hot corrosion test was calculated and analysis. The Scanning Electron Microscope (SEM), Energy Dispersive Spectrometry (EDS) and mapping of elements were used for analyses of corrosion products of the steels. The results show that the higher hardness value was found in solution treatment of 975 °C and aging for 16 h and the higher hot corrosion resistance was found in solution treatment of 1025 °C and aging 16 h.

Waste to Sustainable Biohydrogen Production Via Photo-Fermentation and Biophotolysis − A Systematic Review

Considering the environmental challenges humanity faces in the 21st century, it is obvious that there is an enormous need for change of the global energy map. Under these circumstances, new energy sources and intermediates must be considered as options to limit the greenhouse gases emissions and mitigate climate crisis. Biohydrogen production is one of the most appealing options, due to hydrogen's multiple applications and zero emissions as a fuel, to empower a future hydrogen circular economy. In this review article we focus on two methods that are not widely used at industrial scale but have many future possibilities and growth margins: (a) photo-fermentation and (b) bio photolysis. Both methods are light dependent and need photobioreactors to function and produce significant amounts of biohydrogen. Based on an extensive literature search and systemic analysis of the findings, presentation of the different reactants, operating conditions and biohydrogen productions, key factors and effecting parameters were discussed. Temperature, pH, light intensity and photobioreactor operation and design are some of the most significant factors that define the biohydrogen production rates and yields. Innovative solutions and approaches are presented including biotechnological and genetic engineering modifications to microorganisms, as well as combinations of some hybrid biohydrogen producing methods, especially dark and photo fermentation. For implementing a biohydrogen circular-economy, different wastes were explored as potential feedstocks, and overcoming of major bottlenecks that biophotolysis and photo-fermentation face in the transition to a sustainable biohydrogen economy, were discussed.