Energy Vector Research Articles

Energy-Economic Assessment of Islanded Microgrid with Wind Turbine, Photovoltaic Field, Wood Gasifier, Battery, and Hydrogen Energy Storage

Island energy systems are becoming an important part of energy transformation due to the growing needs for the penetration of renewable energy. Among the possible systems, a combination of different energy generation technologies is a viable option for local users, as long as energy storage is implemented. The presented paper describes an energy-economic assessment of an island system with a photovoltaic field, small wind turbine, wood chip gasifier, battery, and hydrogen circuit with electrolyzer and fuel cell. The system is designed to satisfy the electrical energy demand of a tourist facility in two European localizations. The operation of the system is developed and dynamically simulated in the Transient System Simulation (TRNSYS) environment, taking into account realistic user demand. The results show that in Gdansk, Poland, it is possible to satisfy 99% of user demand with renewable energy sources with excess energy equal to 31%, while in Agkistro, Greece, a similar result is possible with 43% of excess energy. Despite the high initial costs, it is possible to obtain Simple Pay Back periods of 12.5 and 22.5 years for Gdansk and Agkistro, respectively. This result points out that under a high share of renewables in the energy demand of the user, the profitability of the system is highly affected by the local cost of energy vectors. The achieved results show that the system is robust in providing energy to the users and that future development may lead to an operation based fully on renewables.

Nanotubular g-C3N4 confining AuPd particle for the improved catalytic reactivity in hydrogen production from formic acid

Hydrogen is a promising energy vector that provides an alternative to carbon fuels. Catalytic dehydrogenation of formic acid is an efficient solution to produce hydrogen, as formic acid can store hydrogen economically. In this study, novel AuPd supported by nanotubular T-g-C3N4 was synthesized using a chemical wet impregnation and reduction method. The graphene, bulk B-g-C3N4, and nanosheet-like S-g-C3N4 were also employed as AuPd supports for comparison. It was observed that the AuPd nanoparticles on carbon nitrides have higher dispersion and activity than those on graphene, due to the anchoring and electron donation effects of nitrogen. The reactivity of AuPd nanocatalyst was related to the geometry of g-C3N4 support. The T-g-C3N4 possesses the lowest surface area, which induced the lower dispersion of supported AuPd, as compared to B-g-C3N4 and S-g-C3N4. However, the AuPd/T-g-C3N4 delivered the highest catalytic activity, attributed to the confinement effect of the nanotubular geometry.

Performance assessment of the co-gasification for sustainable management of municipal solid waste: Moroccan Case

In the quest of virtuous energy system, clean energy production poses important environmental, social, and financial challenges. Among the potentially useful energy carriers, hydrogen emerges as a serious alternative to fossil fuels. Hydrogen is a clean energy vector whose use is likely to undergo significant development in the medium and long term. This article describes the current situation of municipal solid waste generation and management in Morocco. Additionally, a co-gasification plant model for hydrogen production from municipal solid waste and biomass blends was developed in Aspen Plus. A parametric analysis was carried out to study the effect of various parameters such as the temperature of gasification and the steam to feedstock ratio on syngas composition. The main findings show an increase in hydrogen molar fractions for higher temperatures (optimal values being achieved for ∼750 °C) and steam to feedstock ratios ≥1.2. The present model of the co-gasification plant could be further improved by adding a water–gas-shift reactor. This process intensification technique can contribute to the production of sustainable alternatives to the actual predominant fossil-based fuels.

Hydrogen Production from Surplus Electricity Generated by an Autonomous Renewable System: Scenario 2040 on Grand Canary Island, Spain

The electrification of final energy uses is a key strategy to reach the desired scenario with zero greenhouse gas emissions. Many of them can be electrified with more or less difficulty, but there is a part that is difficult to electrify at a competitive cost: heavy road transport, maritime and air transport, and some industrial processes are some examples. For this reason, the possibility of using other energy vectors rather than electricity should be explored. Hydrogen can be considered a real alternative, especially considering that this transition should not be carried out immediately because, initially, the electrification would be carried out in those energy uses that are considered most feasible for this conversion. The Canary Islands’ government is making considerable efforts to promote a carbon-free energy mix, starting with renewable energy for electricity generation. Still, in the early–mid 2030s, it will be necessary to substitute heavy transport fossil fuel. For this purpose, HOMER software was used to analyze the feasibility of hydrogen production using surplus electricity produced by the future electricity system. The results of previous research on the optimal generation MIX for Grand Canary Island, based exclusively on renewable sources, were used. This previous research considers three possible scenarios where electricity surplus is in the range of 2.3–4.9 TWh/year. Several optimized scenarios using demand-side management techniques were also studied. Therefore, based on the electricity surpluses of these scenarios, the optimization of hydrogen production and storage systems was carried out, always covering at least the final hydrogen demand of the island. As a result, it is concluded that it would be possible to produce 3.5 × 104 to 7.68 × 104 t of H2/year. In these scenarios, 3.15 × 105 to 6.91 × 105 t of water per year would be required, and there could be a potential production of 2.8 × 105 to 6.14 × 105 t of O2 per year.

Energetic evaluations of an electrochemical hydrogen compressor

Hydrogen has been considered as the energy vector that could narrow the gap in the transition towards less polluting energy production. However, it faces compression and storage as technological challenges. Electrochemical hydrogen compression (EHC) is an interesting alternative since it demands low power consumption and could even separate hydrogen from a gas mixture. Therefore, it is necessary to conduct an energetic evaluation of the EHC related to its working conditions to establish the optimal ones in terms of efficiency. This work presents the evaluation and comparison of galvanostatic and potentiostatic operation modes of an EHC with a 50-bar pressure target. During the development of the experimental work, the values of the main overpotentials that affect an EHC were obtained: diffusion voltage, membrane voltage, activation overpotential, and contact overpotential. The highest actual work and power values were achieved at 0.215 V and 0.5 A/cm2 (potentiostatic and galvanostatic mode), while the lowest were obtained at 0.072 V and 0.1 A/cm2. This trend is reversed for voltage efficiency, reaching a maximum of 69.7 % for 0.072 V and a minimum of 19.9 % for 0.5 A/cm2. The calculated flow efficiency values were, for all cases, higher than 94 %, with a maximum efficiency of 99 % at operating conditions of 0.5 A/cm2 and 0.215 V. The global efficiencies of the EHC were also calculated, being more efficient when working in a potentiostatic mode, presenting values of 66 % at 0.072 V against 52 % at 0.1 A/cm2.

Projecting the levelized cost of large scale hydrogen storage for stationary applications

Hydrogen as an energy vector is considered to be an attractive solution for sustainable energy systems - provided, of course, that the energy is from renewable resources. As for all energy systems, this would require energy storage to alleviate the supply and demand disparity within the energy value chain. Despite a great deal of effort to reduce the cost of hydrogen generation, there has been relatively little attention paid to the cost of hydrogen storage. This article determines the levelized cost of hydrogen storage (LCHS) for seven technologies based on the projected capital expenditure (CapEx), operational expenditure (OpEx), and decommissioning cost. Our analysis quantitatively demonstrates the impact of different storage cycle lengths on storage system economics, with LCHS dramatically increasing for long-term storage despite a radical decrease in OpEx cost. For example, the LCHS of above-ground compressed gaseous storage for a daily and 4-monthly storage cycle length is ∼$0.33 and ∼$25.20 per kg of H2, respectively. On the other hand, globally, most green hydrogen is produced by low-carbon electricity primarily based on intermittent solar and wind, and the average levelized cost of hydrogen production ranges from ∼$3.2 to ∼$7.7 per kg of H2. Thus, the storage costs are much higher than the generation cost for long-term storage. Storage in salt caverns exhibits the lowest LCHS at ∼$0.14/kg of H2 for daily storage, followed by above-ground compressed gaseous storage. On the other hand, ammonia has the highest LCHS ∼$3.51/kg of H2, followed by methanol ∼$2.25/kg of H2. These costs are expected to stay relatively high; our CapEx prediction suggests that by 2050 the LCHS of ammonia and methanol could decrease by 20–25%. Furthermore, storage efficiency for ammonia is the lowest at ∼42%, followed by methanol at ∼50%, while compressed gaseous shows the highest storage efficiency, at ∼92%. Overall the analysis shows that the cost of hydrogen storage would need to be significantly reduced for applications in long-term storage or if ammonia/methanol are used (due to, for example, compatibility with existing infrastructure). These insights could increase transparency around the future competitiveness of stationary storage technologies and help to guide research, policy, and investment activities to ensure cost-efficient deployment in a low-emission economy.

ПОЛУЧЕНИЕ МАКРОМЕХАНИЧЕСКИХ ВЕЛИЧИН С ПОМОЩЬЮ КВАНТОВО-МЕХАНИЧЕСКИХ ДИФФЕРЕНЦИАЛЬНЫХ УРАВНЕНИЙ

The wave function Ψ satisfies the Schrödinger equation for a free particle. Formally, the Schrödinger equation generates the magnitude of mechanical motion of the zero order 0 p = mv 0 (in the sense that it is contained in the Schrödinger equation. Comparison of the wave function Ψ and its gradient implies a formal analogue of the Schrödinger equation, which generates the magnitude of mechanical motion of the first order 1 p = mv 1. From the comparison of the wave function and its time derivative yields a formal analogue of the Schrödinger equation, which generates the magnitude of mechanical motion of the second order 2 p = mv 2/2!. The values of mechanical motion of the zero, first, and second orders are known.Obviously, other formal analogs of the Schrödinger equation can generate mechanical motion of other orders.The aim of the work is to establish such quantities and related regularities that may be of interest, which makes the study relevant. hovering. Then the spatial derivatives will be one-dimensional. The magnitude of the mechanical movement of the third order is 3 p = mv 3/3!. This value is Umov's integral vector for kinetic energy. The magnitude of the mechanical movement minus the first order -1 p = mv -1 is a reverse impulse. The meaning of this quantity and its relevance is established by the theorem: in a hy- drogen-like atom, the quantity m v-1 is quantized. A fixed (unchanged) quantum is a quantity m v-1 correspond- e e 0 ing to the basic energy level. Almost all of the results obtained were a consequence of the use of quantum mechanical differential equations, however, the results themselves are predominantly macromechanical. The quantities of mechanical motion of various orders are generated by formal analogs of the Schrödinger equation. In all formal analogs of the Schrödinger equation, the orders of the partial derivatives differ by one. For quantities of motion with a positive degree of velocity, the order of the temporal derivatives is higher than that of the spatial ones. For quantities with a negative degree, the order of spatial derivatives is higher.

Fuel-lean ammonia/biogas combustion characteristics under the reacting swirl flow conditions

Ammonia has been identified as a viable energy vector for power generation. Using dual-fuel operation that mixes the ammonia with higher reactivity gaseous fuel can be vital in enhancing ammonia combustion. This study examined the fundamental swirl combustion characteristics of fuel-lean premixed ammonia/biogas via a numerical approach. The flame was established at an input thermal power of 7 kW and a global equivalence ratio of 0.8. The numerical model was validated with biogas emissions data acquired through experimental work. At 20 mm downstream the burner, increased carbon dioxide mass fraction in the biogas lowered the peak flame temperature by around 300 K. Moreover, the deformation of flame temperature radial profiles was also found aggravated as carbon dioxide concentration in the biogas elevated from 0 % to 40 %. The reduction in premixed reactant mixture reactivity not only initiated flame temperature profile deformation but also reduced the peak Damköhler number significantly. The peak Damköhler number was lowered by a factor of ∼ 1.5 when carbon dioxide dilution in the biogas elevated by 40 %. The premixed combustion was directed into the thin reaction flamelets zone with elevated carbon dioxide mass fraction, owing to the intensified flow fluctuation. This, in turn, elevates the normalised flame turbulent propagating speed, gas flow average velocities and turbulent kinetic energy, notwithstanding that heat release rate and averaged laminar flame speed declined. In all, the presence of carbon dioxide has been shown to lower the ammonia/methane mixture reactivity whilst escalating the reacting flow fluctuation.

Recovery of pyrolysis char from residual biomass in accordance with the principles of the circular economy

Millet and buckwheat husk are biomass residues from mills and are considered waste materials for which don't have identified alternative recovery currently. Pyrolysis can be an attractive option which is conducive to waste management – a key element of the circular economy. In view of this, chars were produced from millet and buckwheat husk through pyrolysis, followed by physical activation with either CO2 or steam. Then, chars or activated chars produced were implemented in order to compared their capacity to remove tar from syngas. The tests were carried out at 650 °C and the syngas was composed of H2, CH4, CO, CO2 and N2, with 40 g/Nm3 of ethylbenzene as tar surrogate. The results showed that biomasses with low ash content, but which contained particular species as K and Ca knowing to have a positive impact on the tar cracking, combined with high porosity performed better in syngas upgrading. The chars produced from buckwheat husk has both of this characteristic what allows them to be reactive to crack the tars. In this regard, steam activation appears to be a better option than CO2 activation since it was able to create higher porosity as well as micro and mesopore level, and mineral species such as K and Ca were preserved in the solid phase. The aim of this paper is to investigate the recovery of local agricultural residue for conversion into useful material and energy vectors in the context of the circular economy through the pyro-gasification of buckwheat and millet husk.

A skeletal chemical kinetic mechanism for ammonia/n-heptane combustion

Progressively stricter pollutant emission targets in international agreements have shifted the focus of combustion research to low carbon fuels. Ammonia is recognized as one of the promising energy vectors for next-generation power production. Due to the low flame speed and high auto-ignition temperature, ammonia is often burned with a high reactivity pilot fuel (e.g. diesel). However, chemical kinetic mechanisms describing the combustion of ammonia and large hydrocarbon fuels (such as n-heptane, a surrogate of diesel) are less developed. In this work, a skeletal chemical kinetic mechanism for n-heptane/ammonia blend fuels is proposed using a joint decoupling methodology and optimization algorithm. A sensitivity analysis of the ignition delay times of the ammonia/n-heptane mixture is performed to identify the dominant reactions. A genetic algorithm is used to optimize the mechanism further. The final skeletal mechanism is made up of 69 species and 389 reactions. The skeletal ammonia/n-heptane mechanism is validated against the experimental data for combustion of pure ammonia, ammonia/hydrogen and ammonia/n-heptane mixtures, including the global combustion characteristic parameters such as ignition delay times measured in shock tubes or rapid compression machines, laminar burning velocities measured in heat flux burners or spherical flame vessels, and species data measured in jet-stirred reactors. Comparing the results from the skeletal mechanism with those from other mechanisms from the literature is conducted to evaluate the mechanism further. The present skeletal mechanism can well predict the combustion processes for a wide range of conditions, and the mechanism is computationally efficient, showing good potential to model ammonia/n-heptane combustion with good accuracy and efficiency.

Electromagnetic modeling and experimental study of can-effect on a canned switched reluctance machine

This paper proposes a novel electromagnetic modelling method, with experimental study of the magnetic can-shield effect, based on a novel canned switched reluctance machine. Such model considers the characteristic electromagnetic coupling relation between magnetic flux and eddy current on cans, with harmonic analysis by analytical calculation in vector form. The model is structured with multiple concentrated layers in cylindrical coordinate and the main modeling process includes domain solution of the magnetic field, and an energy vector deduction for loss and energy. Comparative measurement with an indirect method demonstrates the electromagnetic features by the use of cans and meanwhile verifies the analytical model.

Energy Vector and Time Vector in the Dirac Theory

A sign operator of energy, analogous to the helicity operator, but in the direction of what we call energy vector has been introduced. It is possible that there may be physical phenomena where energy vector should be considered. However, to write a wave function this energy vector needs a time vector. But, unlike the energy vector the time vector has no physical meaning yet. To make physical senses of the components of the time vector, the time dilation in special relativity has been studied and also the components of the time vector have been related to the tunneling times when an electron crosses a potential barrier. Physical results for quantum tunneling time will not be limited to this study.

Hydrogen energy of mining waste waters: Extraction and analysis of solving issues

Billions liters of wastewater are created every day from industrial and domestic locations, and while wastewater is frequently regarded as a concern, it includes the potential to be regarded as a rich supply of energy and materials. The creation of hydrogen gas by electrolysis utilizing a solar system is an alternate method for treating this residual water. Wastewater has four to five times the energy necessary to its treatment and a good source of bio-hydrogen as a feedstock chemical, clean energy vector, and a fuel generally acknowledged to play a part in the energy system's decarburization. The goal of this research was to see how well wastewater might be used to produce anaerobic hydrogen. Synthetic wastewater with high- and ordinary strength organic loadings as real-time residential wastewater with(out) a combination of food waste was examined. Hydrogen generation during sewage sludge and mining residue suspensions coupled was measured using electro dialytic methods at 50 and 100 mA. Hydrogen purity has been reached at 33 % along the electro dialytic treat of sewage sludge. Hydrogen purity reached 71 percent and 34 percent, respectively, while adding sewage sludge or effluent as enhancers in waste solutions. The maximum extraction ratios of phosphorus (71 %) and tungsten (62 %), respectively, were obtained while the technique has been performed to waste suspensions mixed with sewage sludge. This study's findings could be used to develop onsite household energy and wastewater recovery systems.

Hydrogen capacity for use in public transportation using the excess electricity generated by photovoltaics from rooftops in the urban area of Cuenca, Ecuador

The drawback of renewable technologies is the lack of coupling with energy demand, to reduce these drawbacks is by applying hydrogen as an energy vector. Hydrogen obtained from renewable energy sources could be stored and used when required, directly or in fuel cells. This work focuses on determining the hydrogen potential that can be obtained using photovoltaic plants in urban areas. In the city of Cuenca, with the renewal of the public transport vehicle fleet, it was reduced to 475 units, which emit 112 tons of CO2 and burn 11,175 gallons of diesel per day. The analysis determines the photovoltaic energy that is produced by implementing photovoltaic panels in the Historic Center of Cuenca, Ecuador. With this it is determined that the electrical energy produced is 5.5 times the demand of the study area. With the energy surplus, it was determined that energy would be available that would cover between 97% and 127% of the demand required to mobilize the total urban buses. There are advantages such as the reduction of emissions or the increase in the quality of life, but the economic and technological aspects could be barriers to the implementation of these in the medium or short term.

Tuning the Catalytic Activity of Bifunctional Cobalt Boride Nanoflakes for Overall Water Splitting over a Wide pH Range

The world is in the process of transitioning towards a more sustainable energy future, with green hydrogen considered an attractive energy vector that can replace fossil fuel consumption, meeting global energy demands. To date, the most advanced method to produce green hydrogen is through water electrolysis using the residual supply of renewable energy. The current state-of-the-art catalysts used in electrolyzers are platinum-based metals and ruthenium/iridium oxides. The scarceness of these elements, combined with their high price, make these catalysts not economically viable for largescale production of hydrogen through water electrolysis. This study presents cobalt boride nanoflakes as materials to be used in both the anode and the cathode of an electrolyzer for electrochemical water splitting over a wide pH range. The cobalt boride nanoflakes were synthesized by the chemical reduction of CoCl2 using NaBH4 at three different concentrations to obtain CoB and Co2B nanoflakes. CoB nanoflakes exhibited both a higher specific surface area and greatest disparity in charge between B and Co, in comparison to Co2B. It was demonstrated that by tuning the properties of the cobalt boride nanoflakes, higher catalytic activities for both the hydrogen and oxygen evolution reaction can be achieved, showing good overall stability.

Ectoine production from biogas: A sensitivity analysis. Effect of local commodity prices, economy of scale, market trends and biotechnological limitations

The utilization of methanotrophic haloalkaliphilic bacteria for the production of ectoine in waste treatment plants has demonstrated a great potential to upgrade the traditional use of biogas as energy vector and the current industrial routes for the production of this high added-value chemical (600–1000 €·kg−1). However, the influence of socio-economic aspects such as the location of the plant, the economy of scale and the market fluctuations on the profitability of the process remains unknown. A techno-economic and sensitivity analysis of the bioconversion of CH4 into ectoine in a bubble column bioreactor and the extraction and purification of ectoine via ionic exchange chromatography was herein conducted using Madrid as base-case scenario. The geographical assessment performed in 13 representative cities revealed high differences in the ectoine production costs, ranging from 158 to 231 €·kg−1. The economy of scale analysis evidenced a high dependence of the ectoine production costs towards the production scale, amounting to 782 and 164 €·kg−1 when manufacturing 0.1 and 89.6 t ectoine·y−1, respectively. The techno-economic study also showed a high robustness of CH4-ectoine profitability towards future market fluctuations, with all the scenarios analyzed guaranteeing internal rates of return >15% and payback periods <10 y. Finally, the sensitivity analysis identified the improvement of CH4 elimination capacity in bioreactors, the development of highly efficient microbial strains and the selection of the highest quality ionic exchange resins as key factors impacting the profitability of future biogas-to-ectoine biorefineries.

Planning of Multi-Vector Energy Systems with High Penetration of Renewable Energy Source: A Comprehensive Review

The increasing use of high shares of renewable energy sources (RESs) in the current electricity network introduces challenges to the design and management of the electricity network due to the variation and uncertainty nature of the RESs. Some existing energy infrastructures, such as heat, gas, and transport, all have some level of inbuilt storage capacity and demand response (DR) potentials that can be exploited in an energy system integration to give the electricity network some level of flexibility and promote an efficient transition to a low-carbon, resilient, and robust energy system. The process of integrating different energy infrastructure is known as multi-vector energy systems (MESs). This paper reviews different studies on the planning of MESs using the energy hubs (EHs) approach. The EHs model used in this paper links different energy vectors such as gas, electricity, and heat energy vectors in its planning model, as opposed to planning each energy vector independently, in order to provide more flexibility in the system, minimise total planning cost, and encourage high penetration of renewable energy source for future energy demands. In addition, different uncertainty modelling and optimization methods that have been used in past studies in planning of EH are classified and reviewed to ascertain the appropriate techniques for addressing RESs uncertainty when planning future EH. Numerical results show 12% reduction in the planning cost in the case of integrated planning with other energy vectors compared to independent planning.

Sizing of a fuel cell–battery backup system for a university building based on the probability of the power outages length

Hydrogen is a bright energy vector that could be crucial to decarbonise and combat climate change. This energy evolution involves several sectors, including power backup systems, to supply priority facility loads during power outages. As buildings now integrate complex automation, domotics, and security systems, energy backup systems cause interest. A hydrogen-based backup system could supply loads in a multi-day blackout; however, the backup system should be sized appropriately to ensure the survival of essential loads and low cost. In this sense, this work proposes a sizing of fuel cell (FC) backup systems for low voltage (LV) buildings using the history of power outages. Historical data allows fitting a probability function to determine the appropriate survival of loads. The proposed sizing is applied to a university building with a photovoltaic generation system as a case study. Results show that the sizing of an FC–battery backup system for the installation is 7.6% cheaper than a battery-only system under a usual 330-minutes outage scenario. And 59.3% cheaper in the case of an unusual 48-hours outage scenario. It ensures a 99% probability of supplying essential load during power outages. It evidences the pertinence of an FC backup system to attend to outages of long-duration and the integration of batteries to support the abrupt load variations. This research is highlighted by using historical data from actual outages to define the survival of essential loads with total service probability. It also makes it possible to determine adequate survival for non-priority loads. The proposed sizing is generalisable and scalable for other buildings and allows quantifying the reliability of the backup system tending to the resilience of electrical systems.

Catalysis in Solid Hydrogen Storage: Recent Advances, Challenges, and Perspectives

Catalysis is at the core of previous energy transition. It has enabled the use of oil and natural gas as our primary energy sources in unprecedented ways and led to feedstocks enabling exceptionally high living standards in human history. In a decarbonized economy with hydrogen as the new energy vector, catalysis is already playing a key role in producing hydrogen. However, catalysts for the effective storage of hydrogen must be advanced. Many solid hydrogen storage materials such as magnesium‐based hydrides, alanates, and/or borohydrides display promising hydrogen densities far superior to the current state of compressed or liquid hydrogen. These solid materials have thermodynamic and kinetic barriers which severely hinder their practical hydrogen uptake and release. To date, most of these barriers for solid hydrides (especially boron or nitrogen compounds) are modified via catalysis; however, the catalytic species per se and their roles are obscure. Herein, a comprehensive overview of various catalysts for solid hydrogen storage materials, their catalytic roles, and the underpinning mechanisms is provided. The current state of knowledge is critically reviewed and gaps where further research intensification is needed to support rapid hydrogen generation and storage in solid materials for the emerging hydrogen economy are identified.

The hydrogen economy - Where is the water?

“Green hydrogen”, i.e. hydrogen produced by splitting water with a carbon “free” source of electricity via electrolysis, is set to become the energy vector enabling a deep decarbonisation of society and a virtuous water based energy cycle. If to date, water electrolysis is considered to be a scalable technology, the source of water to enable a “green hydrogen” economy at scale is questionable. Countries with the highest renewable energy potential like Australia, are also among the driest places on earth. Globally 380,000 GL/year of wastewater is available, and this is much more than the 34,500 GL/year of water required to produce the projected 2.3 Gt of hydrogen of a mature hydrogen economy. Hence the need to assess both technically and economically whether some wastewater treatment effluent, are a better source for green hydrogen. Analysis of Sydney Water's wastewater treatment plants alone shows that these plants have 37.6 ML/day of unused tertiary effluents, which if electrolysed would generate 420,000 t H2/day or 0.88 Mt H2/year, and cover ∼100% of Australia's estimated production by 2030. Furthermore, the production of oxygen as a by-product of the electrolysis process could lead to significant benefits to the water industry, not only in reducing the cost of the hydrogen produced for $3/kg (assuming a price of oxygen of $3–4 per kg), but also in improving the environmental footprint of wastewater treatment plants by enabling the onsite re-use of oxygen for the treatment of the wastewater. Compared to desalinated water that requires large investments, or stormwater that is unpredictable, it is apparent that the water utilities have a critical role to play in managing water assets that are “climate independent” as the next “golden oil” opportunity and in enabling a “responsible” hydrogen industry, that sensibly manages its water demands and does not compete with existing water potable water demand.