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Fast Sizing Methodology and Assessment of Energy Storage Configuration on the Flight Time of a Multirotor Aerial Vehicle
Apr 2023
Publication
Urban air mobility (UAM) defined as safe and efficient air traffic operations in a metropolitan area for manned aircraft and unmanned aircraft systems is being researched and developed by industry academia and government. This kind of mobility offers an opportunity to construct a green and sustainable sub-sector building upon the lessons learned over decades by aviation. Thanks to their non-polluting operation and simple air traffic management electric vertical take-off and landing (eVTOL) aircraft technologies are currently being developed and experimented with for this purpose. However to successfully complete the certification and commercialization stage several challenges need to be overcome particularly in terms of performance such as flight time and endurance and reliability. In this paper a fast methodology for sizing and selecting the propulsion chain components of an eVTOL multirotor aerial vehicle was developed and validated on a reduced-scale prototype of an electric multirotor vehicle with a GTOW of 15 kg. This methodology is associated with a comparative study of energy storage system configurations in order to assess their effect on the flight time of the aerial vehicle. First the optimal pair motor/propeller was selected using a global nonlinear optimization in order to maximize the specific efficiency of these components. Second five energy storage technologies were sized in order to evaluate their influence on the aerial vehicle flight time. Finally based on this sizing process the optimized propulsion chain gross take-off weight (GTOW) was evaluated for each energy storage configuration using regression-based methods based on propulsion chain supplier data.
Assessment of Hydrogen Gas Turbine-fuel Cell Powerplant for Rotorcraft
Jul 2023
Publication
Conventional turboshaft engines are high power density movers suffering from low efficiency at part power operation and producing significant emissions. This paper presents a design exploration and feasibility assessment of a hybrid hydrogen-fueled powerplant for Urban Air Mobility (UAM) rotorcraft. A multi-disciplinary approach is devised comprising models for rotorcraft performance tank and subsystems sizing and engine performance. The respective trade-offs between payload-range and mission level performance are quantified for kerosene-fueled and hybrid hydrogen tilt-rotor variants. The effects of gas turbine scaling and fuel cell pressurization are evaluated for different hybridization degrees. Gas turbine scaling with hybridization (towards the fuel cell) results in up to 21% benefit in energy consumption relative to the non-scaled case with the benefits being more pronounced at high hybridization degrees. Pressurizing the fuel cell has shown significant potential as cell efficiency can increase up to 10% when pressurized to 6 bar which translates to a 6% increase in overall efficiency. The results indicate that current fuel cells (1 kW/kg) combined with current hydrogen tank technology severely limit the payload range capability of the tilt-rotor. However for advanced fuel cell technology (2.5 kW/kg) and low ranges hybrid powerplant show the potential to reduce energy consumption and reduce emissions footprint.
Techno-Economic Assessment of Power-to-Liquids (PtL) Fuels Production and Global Trading Based on Hybrid PV-Wind Power Plants
Nov 2016
Publication
This paper introduces a value chain design for transportation fuels and a respective business case taking into account hybrid PV-Wind power plants electrolysis and hydrogen-to-liquids (H2tL) based on hourly resolved full load hours (FLh). The value chain is based on renewable electricity (RE) converted by power-to-liquids (PtL) facilities into synthetic fuels mainly diesel. Results show that the proposed RE-diesel value chains are competitive for crude oil prices within a minimum price range of about 79 - 135 USD/barrel (0.44 – 0.75 €/l of diesel production cost) depending on the chosen specific value chain and assumptions for cost of capital available oxygen sales and CO2 emission costs. A sensitivity analysis indicates that the RE-PtL value chain needs to be located at the best complementing solar and wind sites in the world combined with a de-risking strategy and a special focus on mid to long-term electrolyser and H2tL efficiency improvements. The substitution of fossil fuels by hybrid PV-Wind power plants could create a PV-wind market potential in the order of terawatts.
Concept Design and Energy Balance Optimization of a Hydrogen Fuel Cell Helicoptor for Unmanned Aerial Vehicle and Aerotaxi Applications
May 2023
Publication
In the new scenario where the transportation sector must be decarbonized to limit global warming fuel cellpowered aerial vehicles have been selected as a strategic target application to compose part of the urban fleet to minimize road transport congestion and make goods and personal transportation fast and efficient. To address the necessity of clean and efficient urban air transport this work consists of the conceptual development of a lightweight rotary-winged transport vehicle using a hydrogen-based fuel cell propulsion system and the optimization of its energy balance. For that purpose the methods for integrating the coupled aerodynamic and propulsion system sizing and optimization was developed with the aim of designing concepts capable of carrying 0 (unmanned aerial vehicle — Design 1) and 1 (Aerotaxi — Design 2) passengers for a distance of 300 km at a cruise altitude of 500 m with a minimum climbing rate capability of 6 m s−1 at 1000 m. The results show how these designs with the desired performance specifications can be obtained with a vehicle mass ranging from 416 to 648 kg depending on the application and with specific range and endurance respectively within 46.2–47.8 km/kg and 20.4–21.3 min/kg for design 1 and 33.3–33.8 km/kg and 12.5–13.9 min/kg for design 2.
Performance Assessment of a 25 kW Solid Oxide Cell Module for Hydrogen Production and Power Generation
Jan 2024
Publication
Hydrogen produced via water electrolysis from renewable electricity is considered a key energy carrier to defossilize hard-to-electrify sectors. Solid oxide cells (SOC) based reactors can supply hydrogen not only in electrolysis but also in fuel cell mode when operating with (synthetic) natural gas or biogas at low conversion (polygeneration mode). However the scale-up of SOC reactors to the multi-MW scale is still a research topic. Strategies for transient operation depending on electricity intermittency still need to be developed. In this work a unique testing environment for SOC reactors allows reversible operation demonstrating the successful switching between electrolysis (− 75 kW) and polygeneration (25 kW) modes. Transient and steady state experiments show promising performance with a net hydrogen production of 53 kg day− 1 in SOEL operation with ca. − 75 kW power input. The experimental results validate the scaling approach since the reactor shows homogenous temperature profiles.
The Cost of Clean Hydrogen from Offshore Wind and Electrolysis
Feb 2024
Publication
The decarbonization of industry heating and transportation is a major challenge for many countries’ energy transition. Hydrogen is a direct low-carbon fuel alternative to natural gas offering a higher flexibility in the range of possible applications yet currently most hydrogen is produced using carbonintensive steam methane reforming due to cost considerations. Therefore this study explores the economics of a prominent low-carbon method of hydrogen production comparing the cost of hydrogen generation from offshore wind farms with and without grid electricity imports to conventional hydrogen production methods. A novel techno-economic model for offshore electrolysis production costs is presented which makes hydrogen production fully dispatchable leveraging geological salt-cavern storage. This model determines the lifetime costs aportioned across the system components as well as the Levelized Cost of Hydrogen (LCOH). Using the United Kingdom as a case study LCOH from offshore wind power is calculated to be €8.68 /kgH2 using alkaline electrolysis (AEL) €10.49 /kgH2 using proton exchange membrane electrolysis (PEMEL) and €10.88 /kgH2 with grid electricity to backup the offshore wind power. A stochastic Monte-Carlo model is used to asses the uncertainty on costs and identify the cost of capital electrolyser and wind farm capital costs and cost of electricity as the most important drivers of LCOH across the different scenarios. Reducing the capital cost to comparative levels observed on today’s wind farms alone could see AEL LCOH fall to €5.32 /kgH2 near competitive with conventional generation methods.
Near-term Infrastructure Rollout and Investment Strategies for Net-zero Hydrogen Supply Chains
Feb 2024
Publication
Low-carbon hydrogen plays a key role in European industrial decarbonization strategies. This work investigates the cost-optimal planning of European low-carbon hydrogen supply chains in the near term (2025–2035) comparing several hydrogen production technologies and considering multiple spatial scales. We focus on mature hydrogen production technologies: steam methane reforming of natural gas biomethane reforming biomass gasification and water electrolysis. The analysis includes carbon capture and storage for natural gas and biomass-derived hydrogen. We formulate and solve a linear optimization model that determines the costoptimal type size and location of hydrogen production and transport technologies in compliance with selected carbon emission targets including the EU fit for 55 target and an ambitious net-zero emissions target for 2035. Existing steam methane reforming capacities are considered and optimal carbon and biomass networks are designed. Findings identify biomass-based hydrogen production as the most cost-efficient hydrogen technology. Carbon capture and storage is installed to achieve net-zero carbon emissions while electrolysis remains costdisadvantageous and is deployed on a limited scale across all considered sensitivity scenarios. Our analysis highlights the importance of spatial resolution revealing that national perspectives underestimate costs by neglecting domestic transport needs and regional resource constraints emphasizing the necessity for highly decarbonized infrastructure designs aligned with renewable resource availabilities.
The Role of Hydrogen Storage in an Electricity System with Large Hydropower Resources
Feb 2024
Publication
Hydrogen is considered one of the key pillars of an effective decarbonization strategy of the energy sector; however the potential of hydrogen as an electricity storage medium is debated. This paper investigates the role of hydrogen as an electricity storage medium in an electricity system with large hydropower resources focusing on the Swiss electricity sector. Several techno-economic and climate scenarios are considered. Findings suggest that hydrogen storage plays no major role under most conditions because of the large hydropower resources. More specifically no hydrogen storage is installed in Switzerland if today’s values of net-transfer capacities and low load-shedding costs are assumed. This applies even to hydrogen-favorable climate scenarios (dry years with low precipitation and dam inflows) and economic assumptions (high learning rates for hydrogen technologies). In contrast hydrogen storage is installed when net-transfer capacities between countries are reduced below 30% of current values and load-shedding costs are above 1000 EUR/MWh. When installed hydrogen is deployed in a few large-scale installations near the national borders.
Energy-exergy Evaluation of Liquefied Hydrogen Production System Based on Steam Methane Reforming and LNG Revaporization
Jul 2023
Publication
The research motivation of this paper is to utilize the large amount of energy wasted during the LNG (liquefied natural gas) gasification process and proposes a synergistic liquefied hydrogen (LH2) production and storage process scheme for LNG receiving station and methane reforming hydrogen production process - SMR-LNG combined liquefied hydrogen production system which uses the cold energy from LNG to pre-cool the hydrogen and subsequently uses an expander to complete the liquefaction of hydrogen. The proposed process is modeled and simulated by Aspen HYSYS software and its efficiency is evaluated and sensitivity analysis is carried out. The simulation results show that the system can produce liquefied hydrogen with a flow rate of 5.89t/h with 99.99% purity when the LNG supply rate is 50t/h. The power consumption of liquefied hydrogen is 46.6kWh/kg LH2; meanwhile the energy consumption of the HL subsystem is 15.9kWh/kg LH2 lower than traditional value of 17~19kWh/kg LH2. The efficiency of the hydrogen production subsystem was 16.9%; the efficiency of the hydrogen liquefaction (HL) subsystem was 29.61% which was significantly higher than the conventional industrial value of 21%; the overall energy efficiency (EE1) of the system was 56.52% with the exergy efficiency (EE2) of 22.2% reflecting a relatively good thermodynamic perfection. The energy consumption of liquefied hydrogen per unit product is 98.71 GJ/kg LH2.
A Review of Liquid Hydrogen Aircraft and Propulsion Technologies
Jan 2024
Publication
Sustainable aviation is a key part of achieving Net Zero by 2050 and is arguably one of the most challenging sectors to decarbonise. Hydrogen has gained unprecedented attention as a future fuel for aviation for use within fuel cell or hydrogen gas turbine propulsion systems. This paper presents a survey of the literature and industrial projects on hydrogen aircraft and associated enabling technologies. The current and predicted technology capabilities are analysed to identify important trends and to assess the feasibility of hydrogen propulsion. Several key enabling technologies are discussed in detail and gaps in knowledge are identified. It is evident that hydrogen propelled aircraft are technologically viable by 2050. However convergence of a number of critical factors is required namely: the extent of industrial collaboration the understanding of environmental science and contrails green hydrogen production and its availability at the point of use and the safety and certification of the aircraft and supporting infrastructure.
An Optimization-Based Model for A Hybrid Photovoltaic-Hydrogen Storage System for Agricultural Operations in Saudi Arabia
Apr 2023
Publication
Renewable energy technologies and resources particularly solar photovoltaic systems provide cost-effective and environmentally friendly solutions for meeting the demand for electricity. The design of such systems is a critical task as it has a significant impact on the overall cost of the system. In this paper a mixed-integer linear programming-based model is proposed for designing an integrated photovoltaic-hydrogen renewable energy system to minimize total life costs for one of Saudi Arabia’s most important fields a greenhouse farm. The aim of the proposed system is to determine the number of photovoltaic (PV) modules the amount of hydrogen accumulated over time and the number of hydrogen tanks. In addition binary decision variables are used to describe either-or decisions on hydrogen tank charging and discharging. To solve the developed model an exact approach embedded in the general algebraic modeling System (GAMS) software was utilized. The model was validated using a farm consisting of 20 greenhouses a worker-housing area and a water desalination station with hourly energy demand. The findings revealed that 1094 PV panels and 1554 hydrogen storage tanks are required to meet the farm’s load demand. In addition the results indicated that the annual energy cost is $228234 with a levelized cost of energy (LCOE) of 0.12 $/kWh. On the other hand the proposed model reduced the carbon dioxide emissions to 882 tons per year. These findings demonstrated the viability of integrating an electrolyzer fuel cell and hydrogen tank storage with a renewable energy system; nevertheless the cost of energy produced remains high due to the high capital cost. Moreover the findings indicated that hydrogen technology can be used as an energy storage solution when the production of renewable energy systems is variable as well as in other applications such as the industrial residential and transportation sectors. Furthermore the results revealed the feasibility of employing renewable energy as a source of energy for agricultural operations.
Operating Characteristics Analysis and Capacity Configuration Optimization of Wind-Solar-Hydrogen Hybrid Multi-energy Complementary System
Dec 2023
Publication
Wind and solar energy are the important renewable energy sources while their inherent natures of random and intermittent also exert negative effect on the electrical grid connection. As one of multiple energy complementary route by adopting the electrolysis technology the wind-solar-hydrogen hybrid system contributes to improving green power utilization and reducing its fluctuation. Therefore the moving average method and the hybrid energy storage module are proposed which can smooth the wind-solar power generation and enhance the system energy management. Moreover the optimization of system capacity configuration and the sensitive analysis are implemented by the MATLAB program platform. The results indicate that the 10-min grid-connected volatility is reduced by 38.7% based on the smoothing strategy and the internal investment return rate can reach 13.67% when the electricity price is 0.04 $/kWh. In addition the annual coordinated power and cycle proportion of the hybrid energy storage module are 80.5% and 90% respectively. The developed hybrid energy storage module can well meet the annual coordination requirements and has lower levelized cost of electricity. This method provides reasonable reference for designing and optimizing the wind-solar-hydrogen complementary system.
Benchmark of J55 and X56 Steels on Cracking and Corrosion Effects Under Hydrogen Salt Cavern Boundary Conditions
Feb 2024
Publication
Salt caverns have great potential to store relevant amounts of hydrogen as part of the energy transition. However the durability and suitability of commonly used steels for piping in hydrogen salt caverns is still under research. In this work aging effects focusing on corrosion and cracking patterns of casing steel API 5CT J55 and “H2ready” pipeline steel API 5L X56 were investigated with scanning electron microscopy and energy dispersive X-ray spectroscopy after accelerated stress tests with pressure/temperature cycling under hydrogen salt cavern-like conditions. Compared to dry conditions significant more corrosion by presence of salt ions was detected. However compared to X56 only for J55 an intensification of corrosion and cracking at the surface due to hydrogen atmosphere was revealed. Pronounced surface cracks were observed for J55 over the entire samples. Overall the results strongly suggest that X56 is more resistant than J55 under the conditions of a hydrogen salt cavern.
Improving Ecological Efficiency of Gas Turbine Power System by Combusting Hydrogen and Hydrogen-Natural Gas Mixtures
Apr 2023
Publication
Currently the issue of creating decarbonized energy systems in various spheres of life is acute. Therefore for gas turbine power systems including hybrid power plants with fuel cells it is relevant to transfer the existing engines to pure hydrogen or mixtures of hydrogen with natural gas. However significant problems arise associated with the possibility of the appearance of flashback zones and acoustic instability of combustion an increase in the temperature of the walls of the flame tubes and an increase in the emission of nitrogen oxides in some cases. This work is devoted to improving the efficiency of gas turbine power systems by combusting pure hydrogen and mixtures of natural gas with hydrogen. The organization of working processes in the premixed combustion chamber and the combustion chamber with a sequential injection of ecological and energy steam for the “Aquarius” type power plant is considered. The conducted studies of the basic aerodynamic and energy parameters of a gas turbine combustor working on hydrogen-containing gases are based on solving the equations of conservation and transfer in a multicomponent reacting system. A four-stage chemical scheme for the burning of a mixture of natural gas and hydrogen was used which allows for the rational parameters of environmentally friendly fuel burning devices to be calculated. The premixed combustion chamber can only be recommended for operations on mixtures of natural gas with hydrogen with a hydrogen content not exceeding 20% (by volume). An increase in the content of hydrogen leads to the appearance of flashback zones and fuel combustion inside the channels of the swirlers. For the combustion chamber of the combined-cycle power plant “Vodoley” when operating on pure hydrogen the formation of flame flashback zones does not occur.
Fuelling the Transition Podcast: How Will Hydrogen Heat and Safety in the Home?
Jan 2022
Publication
In this episode Angela Needle Director of Strategy at Cadent and John Williams Head of Hydrogen Expertise Cluster at AFRY Management Consulting join us to discuss a range of topics concerning hydrogen and the energy transition. This includes Cadent’s involvement in hydrogen through HyNet the role of hydrogen in heat safety and plans for the first hydrogen village. They also explore Angela’s role as co-founder of the Women’s Utilities Network a group focussed on helping women develop their skills within the energy space.
The podcast can be found on their website.
The podcast can be found on their website.
Fuelling the Transition Podcast: The Future of Electrolysers and Hydrogen in the UK
Nov 2021
Publication
ITM Power is a leading electrolyser manufacturer and is a globally recognised expert in hydrogen technologies. In this episode Graham Cooley Chief Executive Officer at ITM Power and John Williams Head of Hydrogen Expertise Cluster at AFRY Management Consulting join us to discuss ITM’s recent announcements. This includes raising £250 million to scale up its electrolyser manufacturing capacity to 5GW per annum by 2024 and forming a partnership with Linde to halve electrolyser manufacturing costs within five years. The episode also explores the UK hydrogen strategy how blue hydrogen compares with green hydrogen the role of electrolysers in hydrogen production and providing flexibility to power grids.
The podcast can be found on their website.
The podcast can be found on their website.
Global Demand Analysis for Carbon Dioxide as Raw Material from Key Industrial Sources and Direct Air Capture to Produce Renewable Electricity-based Fuels and Chemicals
Sep 2022
Publication
Defossilisation of the current fossil fuels dominated global energy system is one of the key goals in the upcoming decades to mitigate climate change. Sharp reduction in the costs of solar photovoltaics wind power and battery technologies enables a rapid transition of the power and some segments of the transport sectors to sustainable energy resources. However renewable electricity-based fuels and chemicals are required for the defossilisation of hard-to-abate segments of transport and industry. The global demand for carbon dioxide as raw material for the production of e-fuels and e-chemicals during a global energy transition to 100% renewable energy is analysed in this research. Carbon dioxide capture and utilisation potentials from key industrial point sources including cement mills pulp and paper mills and waste incinerators are evaluated. According to this study’s estimates the demand for carbon dioxide increases from 0.6 in 2030 to 6.1 gigatonnes in 2050. Key industrial point sources can potentially supply 2.1 gigatonnes of carbon dioxide and thus meet the majority of the demand in the 2030s. By 2050 however direct air capture is expected to supply the majority of the demand contributing 3.8 gigatonnes of carbon dioxide annually. Sustainable and unavoidable industrial point sources and direct air capture are vital technologies which may help the world to achieve ambitious climate goals.
The Role of Direct Air Capture in EU’s Decarbonisation and Associated Carbon Intensity for Synthetic Fuels Production
May 2023
Publication
Direct air capture (DAC) is considered one of the mitigation strategies in most of the future scenarios trying to limit global temperature to 1.5 ◦C. Given the high expectations placed on DAC for future decarbonisation this study presents an extensive review of DAC technologies exploring a number of techno-economic aspects including an updated collection of the current and planned DAC projects around the world. A dedicated analysis focused on the production of synthetic methane methanol and diesel from DAC and electrolytic hydrogen in the European Union (EU) is also performed where the carbon footprint is analysed for different scenarios and energy sources. The results show that the maximum grid carbon intensity to obtain negative emissions with DAC is estimated at 468 gCO2e/kWh which is compliant with most of the EU countries’ current grid mix. Using only photovoltaics (PV) and wind negative emissions of at least −0.81 tCO2e/tCO2 captured can be achieved. The maximum grid intensities allowing a reduction of the synthetic fuels carbon footprint compared with their fossil-fuels counterparts range between 96 and 151 gCO2e/kWh. However to comply with the Renewable Energy Directive II (REDII) sustainability criteria to produce renewable fuels of non-biological origin the maximum stays between 30.2 to 38.8 gCO2e/kWh. Only when using PV and wind is the EU average able to comply with the REDII threshold for all scenarios and fuels with fuel emissions ranging from 19.3 to 25.8 gCO2e/MJ. These results highlight the importance of using renewable energies for the production of synthetic fuels compliant with the EU regulations that can help reduce emissions from difficult-to-decarbonise sectors.
A Flexible Techno-economic Analysis Tool for Regional Hydrogen Hubs - A Case Study for Ireland
Apr 2023
Publication
The increasing urgency with which climate change must be addressed has led to an unprecedented level of interest in hydrogen as a clean energy carrier. Much of the analysis of hydrogen until this point has focused predominantly on hydrogen production. This paper aims to address this by developing a flexible techno-economic analysis (TEA) tool that can be used to evaluate the potential of future scenarios where hydrogen is produced stored and distributed within a region. The tool takes a full year of hourly data for renewables availability and dispatch down (the sum of curtailment and constraint) wholesale electricity market prices and hydrogen demand as well as other user-defined inputs and sizes electrolyser capacity in order to minimise cost. The model is applied to a number of case studies on the island of Ireland which includes Ireland and Northern Ireland. For the scenarios analysed the overall LCOH ranges from V2.75e3.95/kgH2. Higher costs for scenarios without access to geological storage indicate the importance of cost-effective storage to allow flexible hydrogen production to reduce electricity costs whilst consistently meeting a set demand.
Potential Cost Savings of Large-scale Blue Hydrogen Production via Sorption-enhanced Steam Reforming Process
Jan 2024
Publication
As countries work towards achieving net-zero emissions the need for cleaner fuels has become increasingly urgent. Hydrogen produced from fossil fuels with carbon capture and storage (blue hydrogen) has the potential to play a significant role in the transition to a low-carbon economy. This study examined the technical and economic potential of blue hydrogen produced at 600 MWth(LHV) and scaled up to 1000 MWth(LHV) by benchmarking sorption-enhanced steam reforming process against steam methane reforming (SMR) autothermal gasheated reforming (ATR-GHR) integrated with carbon capture and storage (CCS) and SMR with CCS. Aspen Plus® was used to develop the process model which was validated using literature data. Cost sensitivity analyses were also performed on two key indicators: levelised cost of hydrogen and CO2 avoidance cost by varying natural gas price electricity price CO2 transport and storage cost and carbon price. Results indicate that at a carbon price of 83 £/tCO2e the LCOH for SE-SR of methane is the lowest at 2.85 £/kgH2 which is 12.58% and 22.55% lower than that of ATR-GHR with CCS and SMR plant with CCS respectively. The LCOH of ATR-GHR with CCS and SMR plant with CCS was estimated to be 3.26 and 3.68 £/kgH2 respectively. The CO2 avoidance cost was also observed to be lowest for SE-SR followed by ATR-GHR with CCS then SMR plant with CCS and was observed to reduce as the plant scaled to 1000 MWth(LHV) for these technologies.
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