Applications & Pathways

With the growth of aviation traffic and the demand for emission reduction alternative fuels like the so-called electrofuels could comprise a sustainable solution. Electrofuels are understood as those that use renewable energy for fuel synthesis and that are carbon-neutral with respect to greenhouse gas emission. In this study five potential electrofuels are discussed with respect to the potential application as aviation fuels being n-octane methanol methane hydrogen and ammonia and compared to conventional Jet A-1 fuel. Three important aspects are illuminated. Firstly the synthesis process of the electrofuel is described with its technological paths its energy efficiency and the maturity or research need of the production. Secondly the physico-chemical properties are compared with respect to specific energy energy density as well as those properties relevant to the combustion of the fuels i.e. autoignition delay time adiabatic flame temperature laminar flame speed and extinction strain rate. Results show that the physical and combustion properties significantly differ from jet fuel except for n-octane. The results describe how the different electrofuels perform with respect to important aspects such as fuel and air mass flow rates. In addition the results help determine mixture properties of the exhaust gas for each electrofuel. Thirdly a turbine configuration is investigated at a constant operating point to further analyze the drop-in potential of electrofuels in aircraft engines. It is found that electrofuels can generally substitute conventional kerosene-based fuels but have some downsides in the form of higher structural loads and potentially lower efficiencies. Finally a preliminary comparative evaluation matrix is developed. It contains specifically those fields for the different proposed electrofuels where special challenges and problematic points are seen that need more research for potential application. Synthetically-produced n-octane is seen as a potential candidate for a future electrofuel where even a drop-in capability is given. For the other fuels more issues need further research to allow the application as electrofuels in aviation. Specifically interesting could be the combination of hydrogen with ammonia in the far future; however the research is just at the beginning stage.

With the gradual popularization of hydrogen fuel cell vehicles (HFCVs) the construction and planning of hydrogen refueling stations (HRSs) are increasingly important. Taking operational HRSs in China’s coastal and major cities as examples we consider the main factors affecting the site selection of HRSs in China from the three aspects of economy technology and society to establish a site selection evaluation system for hydrogen refueling stations and determine the weight of each index through the analytic hierarchy process (AHP). Then combined with fuzzy comprehensive evaluation (FCE) method and artificial neural network model (ANN) FCE method is used to evaluate HRS in operation in China's coastal areas and major cities and we used the resulting data obtained from the comprehensive evaluation as the training data to train the neural network. So an intelligent site selection model for HRSs based on fuzzy comprehensive evaluation and artificial neural network model (FCE-ANN) is proposed. The planned HRSs in Shanghai are evaluated and an optimal site selection of the HRS is obtained. The results show that the optimal HRSs site selected by the FCE-ANN model is consistent with the site selection obtained by the FCE method and the accuracy of the FCE-ANN model is verified. The findings of this study may provide some guidelines for policy makers in planning the hydrogen refueling stations

Europe has built up one of the best gas distribution infrastructures in the world. There’s one problem though. It distributes natural gas a fuel that we will hardly be able to use if we’re to reach our net zero targets. Can we use the infrastructure instead for clean hydrogen – either blended with natural gas as a stepping stone or with pure hydrogen in the future? In this episode we put aside discussion on the extent to which we should do this – and focus on whether or not we can do this and what’s involved in doing so.

Jon Slowe is joined by Eva Hennig Head of Department for EU Energy Policy at Thüga an alliance of German municipal energy companies (as well as chair of Eurogas’s distribution committee); Keith Owen Head of Systems Development and Energy Strategy at Northern Gas Networks in the UK; and Delta-EE expert Rob Castek.  

With the development of technologies in recent decades and the imposition of international standards to reduce greenhouse gas emissions car manufacturers have turned their attention to new technologies related to electric/hybrid vehicles and electric fuel cell vehicles. This paper focuses on electric fuel cell vehicles which optimally combine the fuel cell system with hybrid energy storage systems represented by batteries and ultracapacitors to meet the dynamic power demand required by the electric motor and auxiliary systems. This paper compares the latest proposed topologies for fuel cell electric vehicles and reveals the new technologies and DC/DC converters involved to generate up-to-date information for researchers and developers interested in this specialized field. From a software point of view the latest energy management strategies are analyzed and compared with the reference strategies taking into account performance indicators such as energy efficiency hydrogen consumption and degradation of the subsystems involved which is the main challenge for car developers. The advantages and disadvantages of three types of strategies (rule-based strategies optimization-based strategies and learning-based strategies) are discussed. Thus future software developers can focus on new control algorithms in the area of artificial intelligence developed to meet the challenges posed by new technologies for autonomous vehicles.

Fuel cell electric vehicles (FCEV) currently have the challenge of high CAPEX mainly associated to the fuel cell. This study investigates strategies to promote FCEV deployment and overcome this initial high cost by combining a detailed simulation model of the passenger transport sector with an energy system model. The focus is on an energy system with 95% CO2 reduction by 2050. Soft-linking by taking the powertrain shares by country from the simulation model is preferred because it considers aspects such as car performance reliability and safety while keeping the cost optimization to evaluate the impact on the rest of the system. This caused a 14% increase in total cost of car ownership compared to the cost before soft-linking. Gas reforming combined with CO₂ storage can provide a low-cost hydrogen source for FCEV in the first years of deployment. Once a lower CAPEX for FCEV is achieved a higher hydrogen cost from electrolysis can be afforded. The policy with the largest impact on FCEV was a purchase subsidy of 5 k€ per vehicle in the 2030–2034 period resulting in 24.3 million FCEV (on top of 67 million without policy) sold up to 2050 with total subsidies of 84 bln€. 5 bln€ of R&D incentives in the 2020–2024 period increased the cumulative sales up to 2050 by 10.5 million FCEV. Combining these two policies with infrastructure and fuel subsidies for 2030–2034 can result in 76 million FCEV on the road by 2050 representing more than 25% of the total car stock. Country specific incentives split of demand by distance or shift across modes of transport were not included in this study.

Citizens’ emotional responses to energy technology projects influence the success of the technology’s implementation. Contrary to popular belief these emotions can have a systematic base. Bringing together insights from appraisal theory and from technology acceptance studies this study develops and tests hypotheses regarding antecedents of anger fear joy and pride about a local hydrogen fuel station (HFS). A questionnaire study was conducted among 271 citizens living near the first publicly accessible HFS in the Netherlands around the time of its implementation. The results show that anger is significantly explained by (from stronger to weaker effects) perceived procedural and distributive unfairness and fear by distributive unfairness perceived safety procedural unfairness gender and prior awareness. Joy is significantly explained by perceived environmental outcomes and perceived usefulness and pride by prior awareness perceived risks trust in industry and perceived usefulness. The study concludes that these predictors are understandable practical and moral considerations which can and should be taken into account when developing and executing a project.

Scaling up renewables to meet the 1.5ºC climate goal

As global economies aim to become carbon neutral competitive hydrogen produced with renewables has emerged as a key component of the energy mix. Falling renewable power costs and improving electrolyser technologies could make ""green"" hydrogen cost competitive by 2030 this report finds.

Green hydrogen can help to achieve net-zero carbon dioxide (CO₂) emissions in energy-intensive hard-to-decarbonise sectors like steel chemicals long-haul transport shipping and aviation. But production costs must be cut to make it economical for countries worldwide. Green hydrogen currently costs between two and three times more than ""blue"" hydrogen which is produced using fossil fuels in combination with carbon capture and storage (CCS).

This report from the International Renewable Energy Agency (IRENA) outlines strategies to reduce electrolyser costs through continuous innovation performance improvements and upscaling from megawatt (MW) to multi-gigawatt (GW) levels.

Among the findings:

• Electrolyser design and construction: Increased module size and innovation with increased stack manufacturing have significant impacts on cost. Increasing plant size from 1 MW (typical in 2020) to 20 MW could reduce costs by over a third. Optimal system designs maximise efficiency and flexibility.
• Economies of scale: Increasing stack production with automated processes in gigawatt-scale manufacturing facilities can achieve a step-change cost reduction. Procurement of materials: Scarcity of materials can impede electrolyser cost reduction and scale-up.
• Efficiency and flexibility in operations: Power supply incurs large efficiency losses at low load limiting system flexibility from an economic perspective.
• Industrial applications: Design and operation of electrolysis systems can be optimised for specific applications in different industries. Learning rates: Based on historic cost declines for solar photovoltaics (PV) the learning rates for fuel cells and electrolysers – whereby costs fall as capacity expands – could reach values between 16% and 21%.
• Ambitious climate mitigation: An ambitious energy transition aligned with key international climate goals would drive rapid cost reduction for green hydrogen. The trajectory needed to limit global warming at 1.5oC could make electrolysers an estimated 40% cheaper by 2030.

Heating and cooling accounts for almost half of global energy consumption. With most of this relying fossil fuels however it contributes heavily to greenhouse gas emissions and air pollution. In parts of the world lacking modern energy access meanwhile inefficient biomass use for cooking also harms people’s health damages the environment and reduces social well-being.



The transition to renewable-based energy-efficient heating and cooling could follow several possible pathways depending on energy demand resource availability and the needs and priorities of each country or region. Broad options include electrification with renewable power renewable-based gases (including “green” hydrogen) sustainable bioenergy use and the direct use of solar and geothermal heat.



This report developed jointly by the International Renewable Energy Agency (IRENA) the International Energy Agency (IEA) and the Renewable Energy Policy Network for the 21st Century (REN21) outlines the infrastructure and policies needed with each transition pathway. This edition focused on renewable-based heating and cooling follows a broader initial study Renewable Energy Policies in a Time of Transition (IRENA IEA and REN21 2018).



The shift to renewables for heating and cooling requires enabling infrastructure (e.g. gas grids district heating and cooling networks) as well as various combinations of deployment integrating and enabling policies. The policy framework can demonstrate a country’s commitment to the energy transition level the playing field with fossil fuels and create the necessary enabling conditions to attract investments.



Along with highlighting country experiences and best practices the study identifies barriers and highlights policy options for renewable heating and cooling.



Key recommendations include:

• Setting specific targets and developing an integrated long-term plan for the decarbonisation of heating and cooling in all end-uses including buildings industry and cooking and productive uses in areas with limited energy access.
• Creating a level playing field by phasing out fossil-fuel subsidies and introducing other fiscal policies to internalise environmental and socio-economic costs.
• Combining the electrification of heating and cooling with increasingly cost-competitive renewable power generation scaling up solar and wind use and boosting system flexibility via energy storage heat pumps and efficient electric appliances.
• Harnessing existing gas networks to accommodate renewable gases such as biogas and green hydrogen.
• Introducing standards certification and testing policies to promote the sustainable use of biomass combining efficient systems and bioenergy solutions such as pellets briquettes bioethanol or anaerobic digestion.
• Reducing investment risks for geothermal exploration and scaling up direct use of geothermal heat.
• Improving district heating and cooling networks through energy efficiency measures and the integration of low-temperature solar thermal geothermal and other renewable-based heat sources.
• Supporting clean cooking and introducing renewable-based food drying in areas lacking energy access with a combination of financing mechanisms capacity building and quality standards aimed at improving livelihoods and maximising socio-economic benefits.

Environmental regulations have always been an essential component in the natural gas supply chain with recent and greater emphasis on shipping operations. Recently more stringent regulations have been imposed by the International Maritime Organization on global maritime shipping operations. This review explores the challenges and opportunities associated with substituting heavy fuel oils used for maritime transportation with relatively cleaner fuels. First the review considers the feasibility and environmental dimensions of different bunker fuels including liquefied natural gas hydrogen and ammonia. Also the operational viability and optimal conditions for these fuels are examined. Secondly the review considers the entire supply chain with an emphasis on how liquefied natural gas exporters can establish synergies across the supply chain to also deliver the end-product required by customers instead of delivering only liquefied natural gas. Finally measures that can support ship operators to comply with environmental regulations are suggested. The outcomes of this review supports the notion that the demand for alternative fuels will continue to increase as the transportation sector moves towards integrating cleaner fuels to comply with increasing environmental regulations.

The hydrogen economy refers to an economic and industrial structure that uses hydrogen as its main energy source replacing traditional fossil-fuel-based energy systems. In particular the widespread adoption of hydrogen fuel cell vehicles (HFCVs) is one of the key factors enabling a hydrogen economy and aggressive investment in hydrogen refuelling infrastructure is essential to make large-scale adoption of HFCVs possible. In this study we address the problem of effectively designing a hydrogen supply network for refuelling HFCVs in urban areas relatively far from a large hydrogen production site such as a petrochemical complex. In these urban areas where mass supply of hydrogen is not possible hydrogen can be supplied by reforming city gas. In this case building distributed hydrogen production bases that extract large amounts of hydrogen from liquefied petroleum gas (LPG) or compressed natural gas (CNG) and then supply hydrogen to nearby hydrogen stations may be a cost-effective option for establishing a hydrogen refuelling infrastructure in the early stage of the hydrogen economy. Therefore an optimization model is proposed for effectively deciding when and where to build hydrogen production bases and hydrogen refuelling stations in an urban area. Then a case study of the southeastern area of Seoul known as a commercial and residential center is discussed. A variety of scenarios for the design parameters of the hydrogen supply network are analyzed based on the target of the adoption of HFCVs in Seoul by 2030. The proposed optimization model can be effectively used for determining the time and sites for building hydrogen production bases and hydrogen refuelling stations.