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This study investigates the impact of including (or neglecting) the variable efficiency of hydrogen electrolyzers as a function of operating power in the modelling of green hydrogen produced from variable renewable energy sources. Results show that neglecting the variable electrolyzer efficiency, as is commonly done in studies of green hydrogen, leads to significant overestimation of hydrogen production in the range of 5–24%. The effects of the time resolution used in models are also investigated, as well as the impact of including the option for the electrolyzer to switch to stand-by mode instead of powering down and electrolyzer ramp rate constraints. Results indicate that these have a minor effect on overall hydrogen production, with the use of hour resolution data leading to overestimation in the range of 0.2–2%, relative to using 5-min data. This study used data from three solar farms and three wind in Australia, from which it is observed that wind farms produced 55% more hydrogen than the solar farms. The results in this study highlight the critical importance of including the variable efficiency of electrolyzers in the modelling of green hydrogen production. As this industry scales, continuing to neglect this effect would lead to the overestimation of hydrogen production by tens of megatonnes. • Variable efficiency electrolyzers are compared to fixed efficiency electrolyzers. • Fixed efficiency can lead to overestimation in hydrogen production by up to 24%. • Low fidelity time resolution has a modest impact on modelling hydrogen production. • Fixed efficiency electrolyzers underestimate the optimal size of hydrogen plant. • Results are validated using data from six renewable energy sites in Australia. [ABSTRACT FROM AUTHOR]

Hydrogen gas can provide baseload energy as society decarbonizes through the energy transition. Underground Hydrogen Storage (UHS) will be secure, convenient and scalable to accommodate excess hydrogen production or compensate temporary shortfalls in energy supply. Hydrogen is a gas under all viable subsurface conditions, so is invasive, mobile and low-density. Methane and CO 2 are also stored underground but storage parameters differ for each, affecting the balance of geological storage risks. UHS in Australia is most likely to utilise conventional sedimentary reservoir rocks bound by conventional trapping closures. Hydrogen energy density will affect the competitiveness of UHS against purpose-built surface storage or solution-mined salt cavities. This study presents an overview of key considerations when screening for UHS opportunities and evaluates them for five Australian sedimentary basins. A threshold storage depth mapped across them reveals that the most prospective UHS basins will have to function as integrated energy fluid resource systems. [Display omitted] • Underground Hydrogen Storage (UHS) is necessary to facilitate the role of green hydrogen in our future energy mix. • Australian sedimentary basins will have a major role to play throughout the Energy Transition. • Existing Australian petroleum basins provide a clear, technically feasible opportunity for UHS. • Most UHS in Australian basins will operate in reservoir systems deeper than a kilometre underground. [ABSTRACT FROM AUTHOR]

A dedicated grid-tied offshore hybrid energy system for hydrogen production is a promising solution to unlock the full benefit of offshore wind and solar energy and realize decarbonization and sustainable energy security targets in electricity and other sectors. Current knowledge of these offshore hybrid systems is limited, particularly in the integration, component control, and allocation aspects. Therefore, a grid-integrated analytical model with a power dispatch allocation strategy between the grid and electrolyzer for the co-production of hydrogen from the offshore hybrid energy system is developed in this paper. While producing hydrogen, the proposed offshore hybrid energy system supplies a percentage of its capacity to the onshore grid facility, and the amount of the electricity is quantified based on the electricity market price and available total offshore generation. The detailed controls of each component are discussed. A case study considers a hypothetical hybrid offshore energy system of 10 MW situated in a potential offshore off the NSW of Australia based on realistic metrological data. A grid-scale proton-exchange membrane electrolyzer stack is used and a model predictive power controller is implemented on the distributed hydrogen generation scheme. The model is helpful for the assessment or optimization of both the economics and feasibility of the dedicated offshore hybrid energy farm for hydrogen production systems. • Modeling of a grid-integrated analytical model of an OHES for hydrogen co-production. • Development of a power dispatch allocation strategy for the proposed OHES. • Development of detailed controls of each component used in the proposed OHES. • Demonstrations of a case study considering 10 MW OHES situated in offshore off the NSW of Australia. [ABSTRACT FROM AUTHOR]

This study uses an online quasi-experiment with a national sample from Australia to evaluate public acceptance of hydrogen exports. It explores the complex communications environment that messaging about hydrogen exports is typically encountered in. We find that acceptance of green hydrogen exports is significantly higher than blue or brown hydrogen exports, and acceptance of blue hydrogen exports higher than brown hydrogen exports. Additionally, results show economic-framed benefit messages are associated with lesser public acceptance when encountered in communication contexts that outline differently-focused environmental downsides (competing contexts), but not same-focused economic downsides (conflicting contexts). In contrast, environment-framed benefit messages are associated with lesser public acceptance when presented in communication contexts that outline same-focused environmental downsides (conflicting contexts), but not differently-focused economic downsides (competing contexts). Overall, the study indicates message framing can impact acceptance of hydrogen exports, and that organisations should consider the informational context within which their communications will be received. • Public acceptance of green hydrogen exports higher than blue or brown hydrogen exports. • Environment-benefit framing leads to marginally higher acceptance than economic-benefit. • Conflicting and competing informational contexts affect acceptance of hydrogen exports. [ABSTRACT FROM AUTHOR]

Renewable green fuels (RGF) such as hydrogen are the global energy future. Air pollution is compounded with climate change as the emissions driving both development problems come largely from the same source of fossil fuel burning. As an energy exporter, Australian energy export dominates the total energy production and the RGF has become central to the current proposal of Australian government to reach net zero emission. The hydrogen production from solar panels only on 3% of Australia's land area could compensate 10 times of Germany's non-electricity energy consumption. In the unique geographic position, Australia's RGF export attracts significant costs for long distance onboard storage and shipping. While the cost reduction of RGF production relies on technological advancement which needs a long time, the storage and shipping costs must be minimised for Australia to remain competitive in the global energy market. The present review concentrates on Australian export pathways of lifecycles of liquid renewable green fuels including renewable liquified hydrogen (LH 2), liquified methane (LCH 4), ammonia (NH 3) and methanol (CH 3 OH) as liquid RGF have the advantages of adopting the existing infrastructure. This review compares the advantages and disadvantages of discussed renewable energy carriers. It is found that the cost of LH 2 pathway can be acceptable for shipping distance of up to 7000 km (Asian countries such as Japan) but ammonia (NH 3) or methanol (CH 3 OH) pathways may be more cost effective for shipping distance above 7000 km for European counties such as Germany. These observations suggest the proper fuel forms to fulfill the requirements to different customers, and hence will highlight Australia's position as one of major exporters of renewable energy in the future. Detailed techno-economic analysis is worth to be done for supplying more quantitative results. A review for Australian renewable green fuel export pathways. [Display omitted] • Australian export pathways of liquid renewable green fuels were investigated. • Different fuel forms should be chosen for different customers. • Australia's position as a major exporter of renewable energy is highlighted. [ABSTRACT FROM AUTHOR]

Hydrogen is considered a key energy vector and carrier for the decarbonization of global energy systems. However, the economics of green hydrogen systems hinder their widespread application. This paper presents a techno-economic analysis of a green hydrogen production system using high-temperature water electrolysis integrated with a concentrated solar power system (CSP-SOEC) for Western Australia. Real-time solar resource data with 30-min resolution for a typical meteorological year were used to assess the performance of the entire system. The intermittent nature of solar resources is accounted for by integrating the system with a thermal energy storage medium and performing the analysis in off-design mode. The validity of the electrolysis stack model is crucial for overall system performance, which was confirmed through experimental testing conducted on a 15-cell stack. The system was designed to generate a 1 MWe output, and the results showed that a field area of 29,000 m2 and thermal energy storage capacity of 382,500 kWh can fulfil the design criteria. The system generates 0.86 tonne/day of hydrogen at a cost of 8.87 US$/kg-H 2 with a solar-to-hydrogen efficiency of 13.80 %. The cost breakdown revealed that the storage medium has the most significant contribution. Moreover, the sensitivity of the system to the production capacity was analyzed, which showed that larger-scale hydrogen production systems have the potential to further reduce the cost. An 8 MWe system has the capacity to produce 7.18 tonne/day of hydrogen at a cost of 6.1 US$/kg-H 2. The molten salt is currently utilized only 39.3 % for the hydrogen production process. To optimize resource utilization, a cogeneration system is devised and assessed for simultaneous steam and hydrogen production. The results reveal that the cogeneration system can achieve an LCOH reduction of 9 % by reaching 8.07 US$/kg-H 2. These findings are invaluable for academic and industry stakeholders in making informed decisions and fostering the green hydrogen sector in Australia. • A techno economic assessment of green H 2 production for Australia is done. • The electrolysis model is corroborated using experimental results. • The cost of green H 2 for such system in Australia is 8.87 US$/kg-H 2. • Higher production capacity favors the system economics. • The cogeneration system reduces the cost by 9 %. [ABSTRACT FROM AUTHOR]

Large-scale hydrogen production will be required to provide sufficient hydrogen for planned applications. In Australia, and other countries, two main hydrogen productions methods have been proposed: hydrogen produced using renewables (green hydrogen) and hydrogen produced with fossil fuels and CCS (blue hydrogen). It is, to date, unclear how people think about the different attributes of these production methods and the extent to which the public's support for each approach influence downstream applications. Using an online survey instrument, this study explored how manipulating the hydrogen production method (green vs blue) influenced beliefs and public attitudes toward to production approach and various applications. The results revealed that beliefs differed depending on the production method presented but effect sizes were quite small overall. The effect was, however, more pronounced with those who more strongly endorse an environmental preservation attitude. The findings, overall, suggest that there is slightly stronger support for green hydrogen production, which is informed by the beliefs that blue hydrogen is a replaceable technology, will conflict with renewable electricity production and will have negative environmental impacts. The research emphasizes the importance of researchers and industry to show that blue hydrogen is a viable long-term option that will compliment, not conflict with, renewable electricity production. Additionally, the findings suggest that blue hydrogen projects will gain stronger support if they can demonstrate minimal local environmental impacts and limited carbon emissions. • Small differences in the perceived effects of blue vs green hydrogen production. • Acceptance of hydrogen applications are unaffected by the production method. • Blue hydrogen is seen as more replaceable and less environmentally friendly. • People who endorse environmental preservation are less accepting of blue hydrogen. • Industrial applications of hydrogen seen as more favourable than domestic uses. [ABSTRACT FROM AUTHOR]