Applications & Pathways

Rapid urbanization and globalization are causing a rise in the energy demand within the residential sector. Currently majority of the energy demand for the residential sector being supplied from fossil fuels these sources account for greenhouse gas emissions responsible for anthropogenic-driven climate change. About 85 % of the world’s energy demands are being met by non-renewable sources of energy. An immediate need to shift towards renewable energy sources to generate electricity is the need of the hour. These long-standing renewable energy sources including solar hydropower and wind energy have been crucial pillars of sustainable energy for years. However as their implementation has matured we are increasingly recognizing their limitations. Issues such as the scarcity of suitable locations and the significant carbon footprint associated with constructing renewable energy infrastructure are becoming more apparent. Hydrogen has been found to play a vital role as an energy carrier in framing the energy picture in the 21st century. Currently about 1 % of the global energy demands are being met by hydrogen energy harnessed through renewable methods. Its low carbon emissions when compared to other methods lower comparative production costs and high energy efficiency of 40–60 % make it a suitable choice. Integrating hydrogen production systems with other renewable source of energy such as solar and wind energy have been discussed in this review in detail. With the concepts of green buildings or net zero energy buildings gaining attraction integration of hydrogen-based systems within residential and office sectors through the use of devices such as micro–Combined Heat and Power devices (mCHP) have proven to be effective and efficient. These devices have been found to save the consumed energy by 22 % along with an effective reduction in carbon emissions of 18 % when used in residential sectors. Using the rejected energy from other processes these mCHP devices can prove to be vital in meeting the energy demands of the residential sector. Through the support of government schemes mCHP devices have been widely used in countries such as Japan and Finland and have benefitted from the same. Hydrogen storage is critical for efficient operation of the integrated renewable systems as improper storage of the hydrogen produced could lead to human and environmental disasters. Using boron hydrides or ammonia (121 kg H2/m3 ) or through organic carriers hydrogen can be stored safely and easily regenerated without loss of material. A thorough comparison of all the renewable sources of energy that are used extensively is required to evaluate the merits of using hydrogen as an energy carrier which has been addressed in this review paper. The need to address the research gap in application of mCHP devices in the residential sector and the benefits they provide has been addressed in this review. With about 2500 GW of energy ready to be harnessed through the mCHP devices globally the potential of mCHP systems globally are discussed in detail in this paper. This review discusses challenges and solutions to hydrogen production storage and ways to implement hydrogen technology in the residential sector. This review allows researchers to build a renewable alternative with hydrogen as a clean energy vector for generating electricity in residential systems.

An energy systems comparison of grid-electricity derived liquid hydrogen (LH2) and liquid ammonia (LNH3) is conducted to assess their relative potential in a low-carbon future. Under various voyage weather conditions their performance is analysed for use in cargo transport energy vectors for low-carbon electricity transport and fuel supply. The analysis relies on literature projections for technological development and grid decarbonisation towards 2050. Various voyages are investigated from regions such as North America (NA) Europe (E) and Latin America (LA) to regions projected to have a higher electricity and fuel grid carbon intensity (CI) (i.e. Asia Pacific Africa the Middle-East and the CIS). In terms of reducing the CI of electricity and fuel at the destination port use of LH2 is predicted to be favourable relative to LNH3 whereas LNH3 is favourable for low-carbon transport of cargo. As targeted by the International Maritime Organisation journeys of LNH3 cargo ships originating in NA E and LA achieve a reduction in volumetric energy efficiency design index (kg-CO2/m3 -km) of at least 70% relative to 2008 levels. The same targets can be met globally if LH2 is supplied to high CI regions for production of LNH3 for cargo transport. A future shipping system thus benefits from the use of both LH2 and LNH3 for different functions. However there are additional challenges associated with the use of LH2. Relative to LNH3 1.6 to 1.7 times the number of LH2 ships are required to deliver the same energy. Even when reliquefaction is employed their success is reliant on the avoidance of rough sea states (i.e. Beaufort Numbers >= 6) where fuel depletion rates during a voyage are impractical.

This paper describes a renewable energy system incorporating a hydrogen production unit to address the imbalance between energy supply and demand. The system utilizes renewable energy and hydrogen production energy to release energy to fill the power gap during peak demand power supply for demand peaking and valley filling. The system is optimized by analyzing marine predator behavioral logic and optimizing the system for maximum operational efficiency and best economic value. The results of the study show that after the optimized scheduling of the hydrogen production coupled renewable energy integrated energy system using the improved marine predator optimization algorithm the energy distribution of the whole energy system is good with the primary energy saving rate maintained at 24.75% the CO2 emission reduction rate maintained at 42.32% and the cost saving rate maintained at 0.78%. In addition this paper uses the Adaboost-BP prediction model to predictively analyze the system. The results show that as the price of natural gas increases the advantages of the combined hydrogen production renewable integrated energy system proposed in this paper become more obvious and the cumulative cost over three years is better than other related systems. These research results provide an important reference for the application and development of the system.

Hydrogen fuel has shown promise as a clean alternative fuel aiding in the reduction of fossil fuel dependence within the transportation sector. However hydrogen refueling stations and infrastructure remains a barrier and are a prerequisite for consumer adoption of low-cost and low-emission fuel cell electric vehicles (FCEVs). The costs for FCEV fueling include both station capital costs and operation and maintenance (O&M) costs. Contributing to these O&M costs unscheduled maintenance is presently more costly and more frequent than for similar gasoline fueling infrastructure and is asserted to be a limiting factor in achieving FCEV customer acceptance and cost parity. Unscheduled maintenance leads to longer station downtime therefore causing an increase in missed fueling opportunities which forces customers to seek refueling at other operable stations that may be significantly farther away. This research proposes a framework for a hydrogen station prognostics health monitoring (H2S PHM) model that can minimize unexpected downtime by predicting the remaining useful life for primary hydrogen station components within the major station subsystems. The H2S PHM model is a data-driven statistical model based on O&M data collected from 34 retail hydrogen stations located in the U.S. The primary subcomponents studied are the dispenser compressor and chiller. The remaining useful life calculations are used to decide whether or not maintenance should be completed based on the prediction and expected future station use. This paper presents the background method and results for the H2S PHM model as for a means for improving station availability and customer confidence in FCEVs and hydrogen infrastructure

This article presents a comprehensive description of the safety system of a real installation that comprises PV panels lithium-ion batteries an electrolyzer H2 storage a fuel cell and a barium chloride/ammonia thermochemical prototype for heat recovery and cooling production. Such a system allows for the increase of the overall efficiency of the H2 chain by exploiting the waste heat and transforming it into a cooling effect particularly useful in tropical regions like French Polynesia. The study provides a great deal of detail regarding practical aspects of the system implementation and a consistent reference to the relevant standards and regulations applicable to the subject matter. More specifically the study covers the ATEX classification of the site the safety features of each component the electrical power distribution the main safety instrumented system fire safety and the force ventilation system. The study also includes safety assessment and a section on lessons learned that could serve as guidance for future installations. In addition an extensive amount of technical data is readily available to the reader in repository (P&ID electrical diagrams etc.).

The shipping sector is facing increasing pressure to implement clean fuels and drivetrains. Especially hydrogen fuel cell drivetrains seem attractive. Although several studies have been conducted to assess the carbon footprint of hydrogen and its application in ships their results remain hard to interpret and compare. Namely it is necessary to include a variety of drivetrain solutions and different studies are based on various assumptions and are expressed in other units. This paper addresses this problem by offering a three-step meta-review of life cycle assessment studies. First a literature review was conducted. Second results from the literature were harmonized to make the different analyses comparable serving cross-examination. The entire life cycle of both the fuels and drivetrains were included. The results showed that the dominant impact was fuel use and related fuel production. And finally life-cycle hot spots have been identified by looking at the effect of specific configurations in more detail. Hydrogen production by electrolysis powered by wind has the most negligible impact. For this ultra-low carbon pathway the modes of hydrogen transport and the use of specific materials and components become relevant.

This study identifies supply options for sustainable urban energy systems which are robust to external system changes. A multi-criteria optimization model is used to minimize greenhouse gas (GHG) emissions and financial costs of a reference system. Sensitivity analyses examine the impact of changing boundary conditions related to GHG emissions energy prices energy demands and population density. Options that align with both financial and emission reduction and are robust to system changes are called “no-regret” options. Options sensitive to system changes are labeled as “potential-risk” options.<br/>There is a conflict between minimizing GHG emissions and financial costs. In the reference case the emission-optimized scenario enables a reduction of GHG emissions (-93%) but involves higher costs (+160%) compared to the financially-optimized scenario.<br/>No-regret options include photovoltaic systems decentralized heat pumps thermal storages electricity exchange between sub-systems and with higher-level systems and reducing energy demands through building insulation behavioral changes or the decrease of living space per inhabitant. Potential-risk options include solar thermal systems natural gas technologies high-capacity battery storages and hydrogen for buildiing energy supply.<br/>When energy prices rise financially-optimized systems approach the least-emission system design. The maximum profitability of natural gas technologies was already reached before the 2022 European energy crisis.

The pressing global challenge of climate change necessitates a concerted effort to limit greenhouse gas emissions particularly carbon dioxide. A critical pathway is to replace fossil fuel sources by electrification including transportation. While electrification of light-duty vehicles is rapidly expanding the heavy-duty vehicle sector is subject to challenges notably the logistical drawbacks of the size and weight of high-capacity batteries required for range as well as the time for battery charging. This Perspective highlights the potential of hydrogen fuel-cell vehicles as a viable alternative for heavy-duty road transportation. We evaluate the implications of hydrogen integration into the freight economy energy dynamics and CO2 mitigation and envision a roadmap for a holistic energy transition. Our critical opinion presented in this Perspective is that federal incentives to produce hydrogen could foster growth in the nascent hydrogen economy. The pathway that we propose is that initial focus on operators of large fleets that could control their own fueling infrastructure. This opinion was formed from private discussions with numerous stakeholders during the formation of one of the awarded hydrogen hubs if they focus on early adopters that could leverage the hydrogen supply chain.

A wide range of aircraft propulsion technologies is being investigated in current research to reduce the environmental impact of commercial aviation. As the implementation of purely hydrogenpowered aircraft may encounter various challenges on the airport and vehicle side combined hydrogen and kerosene energy sources may act as an enabler for the first operations with liquid hydrogen propulsion technologies. The presented studies describe the conceptual design of such a dual-fuel regional aircraft featuring a retrofit derived from the D328eco under development by Deutsche Aircraft. By electrically assisting the sustainable aviation fuel (SAF) burning conventional turboprop engines with the power of high-temperature polymer-electrolyte fuel cells the powertrain architecture enables a reduction of SAF consumption. All aircraft were modeled and investigated using the Bauhaus Luftfahrt Aircraft Design Environment. A description of this design platform and the incorporated methods to model the hydrogen-hybrid powertrain is given. Special emphasis was laid on the implications of the hydrogen and SAF dual-fuel system design to be able to assess the potential benefits and drawbacks of various configurations with the required level of detail. Retrofit assumptions were applied particularly retaining the maximum takeoff mass while reducing payload to account for the propulsion system mass increase. A fuel cell power allocation of 20% led to a substantial 12.9% SAF consumption decrease. Nonetheless this enhancement necessitated an 18.1% payload reduction accompanied by a 34.5% increment in propulsion system mass. Various additional studies were performed to assess the influence of the power split. Under the given assumptions the design of such a retrofit was deemed viable.

Battery electric vehicles (BEVs) and fuel cell electric vehicles (FCEVs) whose exhaust pipes emit nothing are examples of zero-emission automobiles. FCEVs should be considered an additional technology that will help battery-powered vehicles to reach the aspirational goal of zero-emissions electric mobility particularly in situations where the customers demand for longer driving ranges and where using batteries would be insufficient due to bulky battery trays and time-consuming recharging. This study stipulates a current evaluation of the status of development and challenges related to (i) research gap to promote fuel-cell based HEVs (ii) key barriers of fuel-cell based HEVs (iii) advancement of electric mobility and their power drive (iv) electrochemistry of fuel cell technology for FCEVs (v) power transformation topologies communication protocols and advanced charging methods (vi) recommendations and future prospects of fuel-cell HEVs and (vii) current research trends of EVs and FCEVs. This article discusses key challenges with fuel cell electric mobility such as low fuel cell performance cold starts problems with hydrogen storage cost-reduction safety concerns and traction systems. The operating characteristics and applications of several fuel-cell technologies are investigated for FCEVs and FCHEVs. An overview of the fuel cell is provided which serves as the primary source of energy for FCHEVs along with comparisons and its electrochemistry. The study of power transformation topologies communication protocols and enhanced charging techniques for FCHEVs has been studied analytically. Recent technology advancements and the prospects for FCHEVs are discussed in order to influence the future vehicle market and to attain the aim of zero emissions.