Applications & Pathways

Pursued climate goals require reduced greenhouse gas emissions by substituting fossil fuels with energy from renewable sources in all energy-consuming processes. On a large-scale this can mainly be achieved through electricity from wind and sun which are subject to intermittency. To efficiently integrate this variable energy a coupling of the power sector to the residential transport industry and commercial/trade sector is often promoted called sector coupling (SC). Nevertheless our literature review indicates that SC is frequently misinterpreted and its scope varies among available research from exclusively considering the use of excess renewable electricity to a rather holistic view of integrated energy systems including excess heat or even biomass sources. The core objective of this article is to provide a thorough understanding of the SC concept through an analysis of its origin and its main purpose as described in the current literature. We provide a structured categorization of SC derived from our findings and critically discuss its remaining challenges as well as its value for renewable energy systems. We find that SC is rooted in the increasing use of variable renewable energy sources and its main assets are the flexibility it provides for renewable energy systems decarbonization potential for fossil-fuel-based end-consumption sectors and consequently reduced dependency on oil and gas extracting countries. However the enabling technologies face great challenges in their economic feasibility because of the uncertain future development of competing solutions.

To meet the climate targets set forth in the International Maritime Organization’s Initial GHG Strategy the maritime transport sector needs to abandon the use of fossil-based bunker fuels and turn toward zero-carbon alternatives which emit zero or at most very low greenhouse gas (GHG) emissions throughout their lifecycles. This report “The Potential of Zero-Carbon Bunker Fuels in Developing Countries” examines a range of zero-carbon bunker fuel options that are considered to be major contributors to shipping’s decarbonized future: biofuels hydrogen and ammonia and synthetic carbon-based fuels. The comparison shows that green ammonia and green hydrogen strike the most advantageous balance of favorable features due to their lifecycle GHG emissions broader environmental factors scalability economics and technical and safety implications. Furthermore the report finds that many countries including developing countries are very well positioned to become future suppliers of zero-carbon bunker fuels—namely ammonia and hydrogen. By embracing their potential these countries would be able to tap into an estimated $1+ trillion future fuel market while modernizing their own domestic energy and industrial infrastructure. However strategic policy interventions are needed to unlock these potentials.

This report illustrates what a reliable resilient decarbonised electricity supply system could look like in 2035 and the steps required to achieve it. It provides new insights and new advice on how such a system can be achieved by 2035 using real weather data and hourly analysis of Great Britain’s power system (Northern Ireland is part of the all-Ireland system). It also looks at the implications for hydrogen.

Hydrogen fuel cell tractors are emerging as a new power source for tractors. Currently there is no mature energy management control method available. Existing methods mostly rely on engineers’ experience to determine the output power of the fuel cell and the power battery resulting in relatively low energy utilization efficiency of the energy system. To address the aforementioned problems a power optimization method for the energy system of hydrogen fuel cell wheel-driven electric tractor was proposed. A dynamic model of tractor ploughing conditions was established based on the system dynamics theory. From this based on the equivalent hydrogen consumption theory the charging and discharging of the power battery were equivalent to the fuel consumption of the hydrogen fuel cell forming an equivalent hydrogen consumption model for the tractor. Using the state of charge (SOC) of the power battery as a constraint and with the minimum equivalent hydrogen consumption as the objective function an instantaneously optimized power allocation method based on load demand in the energy system is proposed by using a traversal algorithm. The optimization method was simulated and tested based on the MATLAB simulation platform and the results showed under ploughing conditions compared with the rule-based control strategy the proposed energy system power optimization method optimized the power output of hydrogen fuel cells and power batteries allowing the energy system to work in a high-efficiency range reducing the equivalent hydrogen consumption of the tractor by 7.79% and solving the energy system power distribution problem.

With the urbanization construction and the advancement of the carbon peaking and carbon neutrality goals urban energy systems are characterized by coupling multi-energy networks and a high proportion of renewable energy. Urban energy systems need to improve the quality of energy use as well as to achieve energy conservation and emission reduction. Inter-seasonal heat technology has satisfactory engineering application prospects in promoting renewable energy consumption and the energy supply of urban multi-energy systems. Considering inter-seasonal heat storage and electric hydrogen production a joint optimization method of planning and operation is proposed for the urban multi-energy flow system. First the operation framework of inter-seasonal heat storage and electric hydrogen production system is established which clarifies the energy flow of the urban multi-energy system. Secondly aiming at the goals of minimizing the equipment’s annual investment cost and the multi-energy system annual operation cost combined with the time series period division method a planning operation model has been established considering multi-objectives. Through case study it is shown that the proposed model can promote the renewable energy consumption and reduce the operation cost of the whole system.

Several countries have revised their targets in recent years to reach net-zero CO2 emissions across all sectors by 2050 and the transport sector is responsible for a significant share of these emissions. This study compares possible pathways to decarbonise the transport sector through electrification including passenger cars light commercial vehicles and heavy commercial vehicles. To do so we explore 125 scenarios by varying the share of battery and hydrogen-based fuel cell electric vehicles in each of the three categories above independently. We further model the decarbonisation of the industrial hydrogen demand using electrolysers with hydrogen storage. To explore the potential role of electric and hydrogen transport as well as their trade-offs we use GRIMSEL an open-source sector coupling energy system model of Switzerland which includes the residential commercial industrial and transport sectors with four energy carriers namely electricity heat hot water and hydrogen. The total costs are minimised from a social planner perspective. We find that the full electrification of the transport sector could lead on average to a 12% increase in costs by 2050 and 1.3 MtCO2/year which represents a 90% CO2 emissions reduction for the whole sector. Second the transport energy self-sufficiency (i.e. the share of domestic electricity generation in final transport demand) may reach up to 50% for the scenarios with the largest share of battery electric vehicles mainly due to a smaller energy demand than with hydrogen vehicles. Third more than three quarters of the industrial hydrogen production is met by local photovoltaic electricity coupled with battery at minimum costs i.e. green hydrogen. Finally the use of hydrogen as an energy carrier to store electricity over a long period is not cost-optimal.

Green hydrogen is likely to play an important role in meeting the net-zero targets of countries around the globe. One potential option for green hydrogen production is to run electrolysers directly from offshore wind turbines with no grid connection and hence no expensive cabling to shore. In this work an innovative proof of concept of a wind farm control methodology designed to reduce variability in wind farm active power output is presented. Smoothing the power supplied by the wind farm to the battery reduces the size and number of battery charge cycles and helps to increase battery lifetime. This work quantifies the impact of the wind farm control method on battery lifetime for wind farms of 1 4 9 and 16 wind turbines using suitable wind farm battery and electrolyser models. The work presented shows that wind farm control for smoothing wind farm power output could play a critical role in reducing the levelised cost of green hydrogen produced from wind farms with no grid connection by reducing the damaging load cycles on batteries in the system. Hence this work paves the way for the design and testing of a full implementation of the wind farm controller.

Proton-exchange membrane fuel cells (PEMFCs) are low-temperature fuel cells that have excellent starting performance due to their low operating temperature can respond quickly to frequent load fluctuations and can be manufactured in small packages. Unlike existing studies that mainly used hydrogen as fuel for PEMFCs in this study methane is used as fuel for PEMFCs to investigate its performance and economy. Methane is a major component of natural gas which is more economically competitive than hydrogen. In this study methane gas is reformed by the steam reforming method and is applied to the following five gas post-treatment systems: (a) Case 1—water– gas shift only (WGS) (b) Case 2—partial oxidation reforming only (PROX) (c) Case 3—methanation only (d) Case 4—WGS + methanation (e) Case 5—WGS + PROX. In the evaluation the carbon monoxide concentration in the gas did not exceed 10 ppm and the methane component which has a very large greenhouse effect was not regenerated in the post-treated exhaust gas. As a result Case 5 (WGS and PROX) is the only case that satisfied both criteria. Therefore we propose Case 5 as an optimized post-treatment system for methane reforming gas in ship PEMFCs.

China aims to peak CO2 emissions before 2030 and to achieve carbon neutrality before 2060; hence industrial sectors in China are keen to figure out appropriate pathways to support the national target of carbon neutrality. The objective of this study is to explore near-zero emission pathways for the steel industry of China through a detailed technology assessment. The innovative technology development has been simulated using the AIM-China/steel model developed by including material-based technologies and optimal cost analysis. Six scenarios have been given in terms of different levels of production output emission reduction and carbon tax. Near-zero emission and carbon tax scenarios have shown that China’s steel industry can achieve near-zero emission using electric furnaces and hydrogen-based direct reduction iron technologies with policy support. Based on these technologies minimised production costs have been calculated revealing that the steel produced by these technologies is cost-effective. Moreover the feedstock cost can play a key role in these technology portfolios especially the cost of scrap iron ore and hydrogen. In addition the feedstock supply can have strong regional effects and can subsequently impact the allocation of steelmaking in the future. Therefore China can achieve near-zero emissions in the steel industry and electric furnace and hydrogen-based direct reduction iron technologies are crucial to achieving them.

With the development of the hydrogen fuel automobile industry higher requirements are put forward for the construction of hydrogen energy infrastructure the matching of parameters and the control strategy of hydrogen filling rate in the hydrogen charging process of hydrogen refueling stations. At present the technological difficulty of hydrogen fueling is mainly reflected in the balanced treatment of reducing the temperature rise of hydrogen and shortening the filling time during the fast filling process. Vehicle hydrogen storage cylinder (VHSC) is one of the important components of hydrogen fuel cell vehicles. This study proposed a theoretical model for calculating the temperature rise in the VHSC during the high pressure refueling process and revealed the hydrogen temperature rise during refueling. A hydrogen temperature rise prediction model was constructed to elucidate the relationship between filling parameters and temperature rise. The filling process of VHSC was analyzed from the theoretical method. The theoretical analysis results were consistent with the simulation and experimental analysis results which provided a theoretical basis for the current hydrogen temperature control algorithm of the gas source in the hydrogen refueling station and then reduced the energy consumption required for hydrogen cooling in the hydrogen refueling station.

The results shown in this paper extend our research group’s previous work which presents the theoretically achievable hydrogen engine-out NOeo x (H2-NOeo x ) Pareto front of a hydrogen hybrid electric vehicle (H2-HEV). While the Pareto front is calculated offline which requires significant computing power and time this work presents an online-capable algorithm to tackle the energy management of a H2-HEV with explicit consideration of the H2-NOeo x trade-off. Through the inclusion of realistic predictive data on the upcoming driving mission a model predictive control algorithm (MPC) is utilized to effectively tackle the conflicting goal of achieving low hydrogen consumption while simultaneously minimizing NOeo x . In a case study it is shown that MPC is able to satisfy user-defined NOeo x limits over the course of various driving missions. Moreover a comparison with the optimal Pareto front highlights MPC’s ability to achieve close-to-optimal fuel performance for any desired cumulated NOeo x target on four realistic routes for passenger cars.

Hydrogen has recently been proposed as a versatile energy carrier to contribute to archiving universal access to clean cooking. In hard-to-reach rural settings decentralized produced hydrogen may be utilized (i) as a clean fuel via direct combustion in pure gaseous form or blended with Liquid Petroleum Gas (LPG) or (ii) via power-to-hydrogen-to-power (P2H2P) to serve electric cooking (e-cooking) appliances. Here we present the first techno-economic evaluation of hydrogen-based cooking solutions. We apply mathematical optimization via energy system modeling to assess the minimal cost configuration of each respective energy system on technical and economic measures under present and future parameters. We further compare the potential costs of cooking for the end user with the costs of cooking with traditional fuels. Today P2H2P-based e-cooking and production of hydrogen for utilization via combustion integrated into the electricity supply system have almost equal energy system costs to simultaneously satisfy the cooking and electricity needs of the isolated rural Kenyan village studied. P2H2P-based e-cooking might become advantageous in the near future when improving the energy efficiency of e-cooking appliances. The economic efficiency of producing hydrogen for utilization by end users via combustion benefits from integrating the water electrolysis into the electricity supply system. More efficient and cheaper hydrogen technologies expected by 2050 may improve the economic performance of integrated hydrogen production and utilization via combustion to be competitive with P2H2P-based e-cooking. The monthly costs of cooking per household may be lower than the traditional use of firewood and charcoal even today when applying the current life-line tariff for the electricity consumed or utilizing hydrogen via combustion. Driven by likely future technological improvements and the expected increase in traditional and fossil fuel prices any hydrogen-based cooking pathway may be cheaper for end users than using charcoal and firewood by 2030 and LPG by 2040. The results suggest that providing clean cooking in rural villages could economically and environmentally benefit from utilizing hydrogen. However facing the complexity of clean cooking projects we emphasize the importance of embedding the results of our techno-economic analysis in holistic energy delivery models. We propose useful starting points for future aspects to be investigated in the discussion section including business and financing models.

The rapid expansion of renewable energies has the potential to decarbonize the electricity supply. This is more challenging in difficult-to-electrify sectors. The use of hydrogen provides a massive potential for this issue. However expanding hydrogen production increases electricity demand while providing additional flexibility to the electricity market. This paper mainly aims to analyze the economic effects of this sector coupling between the European electricity and national hydrogen markets. The developed energy market model jointly considers both markets to reach an overall welfare optimum. A novel modeling approach allows the interaction of these markets without the need for several iterative optimization runs. This allows for a detailed analysis of various market participants’ changes in consumer and producer surpluses. The optimization is conducted in 13 connected Central European countries to account for various power plant fleets generation mixes and electricity prices. Results show an overall welfare increase of EUR 4 to 28 billion in 2030 and an EUR 5 to 158 billion increase in 2040. However there is a surplus shift from consumers to producers. The consumer surplus is reduced by up to EUR 44 billion in 2030 and EUR 60 billion while producers benefit to achieve the overall welfare benefits. The reduction of consumer surplus changes if significant price peaks occur. Fuel cell applications can avoid these price peaks resulting in a surplus shift from thermal power plants to consumers. Hence consumer surplus can increase by up to EUR 146 billion in the respective 2040 scenarios. Pink hydrogen accounts for a sizable portion of total hydrogen production up to 58 percent in 2030 and up to 30 percent in 2040. As a result nuclear power plants that are nearly entirely allocated in France stand to benefit greatly from this sector coupling. Additional efforts could be made to address the link between hydrogen and natural gas prices. Furthermore the potential for cross-border hydrogen trade and the implementation of national legal and regulatory frameworks could be assessed.

In order to improve the consumption of renewable energy and reduce the carbon emissions of integrated energy systems (IESs) this paper proposes an optimal operation strategy for an integrated energy system considering the coordination of electricity and hydrogen in the context of carbon trading. The strategy makes full use of the traditional power-to-gas hydrogen production process and establishes a coupling model comprising cogeneration and carbon capture equipment an electrolytic cell a methane reactor and a hydrogen fuel cell. Taking a minimum daily operating cost and minimal carbon emissions from the system as objective functions a mixed-integer nonlinear optimal scheduling model is established. This paper designs examples based on MATLAB R2021b and uses the GUROBI solver to solve them. The results show that compared with the traditional two-stage operation process the optimization method can reduce the daily operation cost of an IES by 26.01% and its carbon emissions by 90.32%. The results show that the operation mode of electro-hydrogen synergy can significantly reduce the carbon emissions of the system and realize a two-way flow of electro-hydrogen energy. At the same time the addition of carbon capture equipment and the realization of carbon recycling prove the scheduling strategy’s ability to achieve a lowcarbon economy of the scheduling strategy.

Storing energy in hydrogen deposits balances the operation of energy systems and is an effective tool in the process of energy transformation towards achieving Sustainable Development Goals. To assess the validity of its use as an alternative renewable energy carrier in dispersed energy systems of hybrid configuration a comprehensive review of scientific literature was conducted in this study based on bibliometric analysis. The bibliographic database used in the study was the international Web of Science database. This review contributes to a better understanding of the characteristics of the selected research area. The evolution of research trends implemented in the design of energy systems associated with hydrogen technologies is revealed clearly indicating that it is a developing field. In recent years there has been an increase in the number of publications although the territorial range of research (mainly simulation) conducted in the domain does not include areas with the most favourable infrastructural conditions. The analysis reveals weak cooperation between South American African East Asian and Oceanic countries. In the light of earlier thematically similar literature reviews several research gaps are also identified and proposals for future research are presented. They concern in particular the parallel implementation and optimization of the operation of hydrogen (HRES—Hybrid Renewable Energy System and HESS—Hybrid Energy Storage System) solutions in terms of economics ecology lifespan and work efficiency as well as their feasibility analysis. With the support of other researchers and those involved in the subject matter this review may contribute to the further development of hybrid hydrogen systems in terms of increasing competitiveness and promoting the implementation of these technologies.

Global supply chains must be decarbonised as part of meeting climate targets set by the United Nations and world leaders. Rail networks are vital infrastructure in passenger and freight transport however have not received the same push for decarbonisation as road transport. In this investigation we used real world data from locomotives operating on seven rail corridors to identify optimal battery capacity and hydrogen fuel cell (HFC) power in hybrid systems. We found that the required battery capacity is dependent on both the available regenerative braking energy and on the capacity required to buffer surpluses and deficits from the HFC. The optimal system for each corridor was identified however it was found that one 3.6 MWh battery and 860 kW HFC system could service six of the seven corridors. The optimal systems presented in this work suggest an average of around 5 h of battery storage for the HFC power which is larger than the 2 h previously reported in literature. This may indicate a gap between purely theoretical works that use only route topography and speed and those that employ real world locomotive data.

A direct drive wave power generation system (DDWPGS) has the advantages of a simple structure and easy deployment and is the first choice to provide electricity for islands and operation platforms in the deep sea. However due to the off-grid the source and load cannot be matched so accommodation is an important issue. Hydrogen storage is the optimal choice for offshore wave energy accommodation. Therefore aiming at the source-load mismatch problem of the DDWPGS an electric-hydrogen hybrid energy storage system (HESS) for the DDWPGS is designed in this paper. Based on the characteristics of the devices in the electric-hydrogen HESS a new dynamic power allocation strategy and its control strategy are proposed. Firstly empirical mode decomposition (EMD) is utilized to allocate the power fluctuations that need to be stabilized. Secondly with the state of charge (SOC) of the battery and the operating characteristics of the alkaline electrolyzer being considered the power assignments of the battery and the electrolyzer are determined using the rule-based method. In addition model predictive control (MPC) with good tracking performance is used to adjust the output power of the battery and electrolyzer. Finally the supercapacitor (SC) is controlled to maintain the DC bus voltage while also balancing the system’s power. A simulation was established to verify the feasibility of the designed system. The results show that the electric-hydrogen HESS can stabilize the power fluctuations dynamically when the DDWPGS captures instantaneous power. Moreover its control strategy can not only reduce the start-stop times of the alkaline electrolyzer but also help the energy storage devices to maintain a good state and extend the service life.

Utilizing renewable energy sources (RESs) such as wind and solar to convert electrical energy into hydrogen energy can promote the accommodation of green electricity. This paper proposes an optimal capacity planning approach for an industrial electricity-hydrogen multi-energy system (EHMES) aimed to achieve the local utilization of RES and facilitate the transition to carbon reduction in industrial settings. The proposed approach models the EHMES equipment in detail and divides the system’s investment and operation into producer and consumer sides with energy trading for effective integration. Through this effort the specialized management for different operators and seamless incorporation of RES into industrial users can be achieved. In addition the variations in investment and operating costs of equipment across different installed capacities are considered to ensure a practical alignment with real-world scenarios. By conducting a detailed case study the influence of various factors on the capacity configuration outcomes within an EHMES is analyzed. The results demonstrate that the proposed method can effectively address the capacity configuration of equipment within EHMES based on the local accommodation of RES and variable unit cost sequence. Wind power serves as the primary source of green electricity in the system. Energy storage acts as crucial equipment for enhancing the utilization rate of RES.

This study investigates methods for reducing air pollution in the shipping sector particularly in port areas. The study examines the use of fuel cells as an alternative to diesel generators. Environmental pollution at ports remains a critical issue so using fuel cells as an alternative to conventional energy systems warrants further research. This study compares commercial fuel cell types that can be used on a case study very large crude carrier (VLCC) vessel specifically although the technology is applicable to other vessels and requirements. Seven different fuel cell types were ranked based on five criteria to accomplish this. The proton-exchange membrane cell type was found to be the most suitable fuel cell type for the case study vessel. Based on the input fuel ammonia-based hydrogen storage has been identified as the most promising option along with using an ammonia reforming unit to produce pure hydrogen. Furthermore this study provides an integrated fuel cell module and highlights the economic environmental and maintenance aspects of implementing the proton-exchange membrane fuel cell module for this case study. It also calculates the required space as a crucial constraint of implementing fuel cell technology at sea.

The cement industry is a building block of modern society and currently responsible for around 7% of global and 4% of EU CO2 emissions. While facing global competition and a challenging business environment the EU cement sector needs to decarbonise its production processes to comply with the EU’s ambitious 2030 and 2050 climate targets. This report provides a snapshot of the current cement production landscape and discusses future technologies that are being explored by the sector to decarbonise its processes describing the transformational change the industry faces. This report compiles the current projects and announcements to deploy breakthrough technologies which do require high capital investments. However with 2050 just one investment cycle away the sector needs to commercialise new low-CO2 technologies this decade to avoid the risk of stranded assets. As Portland cement production is highly CO2-intensive and EU plants are already operating close to optimum efficiency the industry appears to be focussing on carbon capture storage and utilisation technologies - while breakthroughs in alternative chemistries are still being explored - to reduce emissions. While the EU has played an important role in supporting early stage R&D for these technologies it is now striving to fill the funding gap for the commercialisation of breakthrough technologies. The recent momentum towards CO2-free cement provides the EU with the opportunity to be a frontrunner in creating markets for green cement.

The European aviation sector must substantially reduce climate impacts to reach net-zero goals. This reduction however must not be limited to flight CO2 emissions since such a narrow focus leaves up to 80% of climate impacts unaccounted for. Based on rigorous life-cycle assessment and a time-dependent quantification of non-CO2 climate impacts here we show that from a technological standpoint using electricity-based synthetic jet fuels and compensating climate impacts via direct air carbon capture and storage (DACCS) can enable climate-neutral aviation. However with a continuous increase in air traffic synthetic jet fuel produced with electricity from renewables would exert excessive pressure on economic and natural resources. Alternatively compensating climate impacts of fossil jet fuel via DACCS would require massive CO2 storage volumes and prolong dependence on fossil fuels. Here we demonstrate that a European climate-neutral aviation will fly if air traffic is reduced to limit the scale of the climate impacts to mitigate.

In this paper a comparative analysis of direct operating costs between a 19-seat conventional and hydrogen-powered fuel cell aircraft is performed by developing a model to estimate direct operating costs and considering the evolution of costs over time from 2030 to 2050. However due to the technology being in its early stages of development and implementation there are still considerable uncertainties surrounding the direct operating costs of hydrogen aircraft. To address this the study considers high and low kerosene growth rates and optimistic and pessimistic development scenarios for hydrogen fuel cell aircraft while also considering the evolution of costs over time. The comparative analysis uses real flight and aircraft data for the airliner Trade Air. The results show that the use of 19-seat hydrogen fuel cell aircraft for air transportation is a viable option when compared to conventional aircraft. Additionally the study suggests potential policies and other measures that could accelerate the adoption of hydrogen fuel cell technology by considering their direct operating costs.

The supply storage and (international) transport of green hydrogen (H2) are essential for the decarbonization of the energy sector. The goal of this study was to assess the final cost-price and carbon footprint of imported green H2 in the market via maritime shipping of liquid organic hydrogen carriers (LOHCs) including dibenzyl toluene-perhydro-dibenzyltoluene (DBTPDBT) and toluene-methylcyclohexane (TOL-MCH) systems. The study focused on logistic steps in intra-European supply chains in different scenarios of future production in Portugal and demand in the Netherlands and carbon tariffs between 2030 and 2050. The case study is based on a formally accepted agreement between Portugal and the Netherlands within the Strategic Forum on Important Projects of Common European Interest (IPCEI). Under the following assumptions the results show that LOHCs are a viable technical-economic solution with logistics costs from 2030 to 2050 varying between 0.30-0.37 €/kg-H2 for DBT-PDBT and 0.28-0.34 €/kg-H2 for TOL-MCH. The associated CO2 emissions of these international H2 supply chains are between 0.46 and 2.46 kg-CO2/GJ (LHV) and 0.55-2.95 kg-CO2/GJ (LHV) for DBT-PDBT and TOL-MCH respectively.

The volatility and uncertainty of high-penetration renewable energy pose significant challenges to the stability of the power system. Current research often fails to consider the insufficient system flexibility during real-time scheduling. To address this issue this paper proposes a flexibility scheduling method for high-penetration renewable energy power systems that considers flexibility index constraints. Firstly a quantification method for flexibility resources and demands is introduced. Then considering the constraint of the flexibility margin index optimization scheduling strategies for different time scales including day-ahead scheduling and intra-day scheduling are developed with the objective of minimizing total operational costs. The intra-day optimization is divided into 15 min and 1 min time scales to meet the flexibility requirements of different time scales in the power system. Finally through simulation studies the proposed strategy is validated to enhance the system’s flexibility and economic performance. The daily operating costs are reduced by 3.1% and the wind curtailment rate is reduced by 4.7%. The proposed strategy not only considers the economic efficiency of day-ahead scheduling but also ensures a sufficient margin to cope with the uncertainty of intra-day renewable energy fluctuations.

This paper addresses the topic of the conceptual design of a regional aircraft with hybrid electric propulsion based on hydrogen fuel cells. It aims at providing an optimization-based method to design a hybrid propulsive system comprising two power sources (jet fuel and hydrogen) for the generation of the required propulsive power and at studying the impact of fuel cell technologies on the aircraft performances. Indeed by performing optimizations for two hybrid propulsive systems using either low temperature or high temperature Proton-exchange membrane fuel cells this study provides a preliminary assessment of the impact of the fuel cell operating temperature on the system design and the overall aircraft performance. First this paper gives a description of the baseline turboprop regional aircraft with a focus on its high speed and low speed flight performances which will serve as requirements for the design of the hybrid aircraft. Then the hybrid electric architecture and the sizing models of the propulsion system are presented. Finally optimizations are performed to design two parallel hybrid propulsive systems based on different fuel cells technologies and aimed at minimizing the block fuel per passenger over a mission of 200 nm. Results show how the proposed methodology and models lead to design two propulsive systems capable of reducing the fuel consumption per passenger by more than 30% compared to the baseline aircraft. The study also shows that the choice of fuel cell operating temperature has a first-order impact on the total mass of the propulsive system due to the higher cooling requirement of the low temperature fuel cells.