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Investigation of an Intensified Thermo-Chemical Experimental Set-Up for Hydrogen Production from Biomass: Gasification Process Integrated to a Portable Purification System—Part II
Jun 2022
Publication
Biomass gasification is a versatile thermochemical process that can be used for direct energy applications and the production of advanced liquid and gaseous energy carriers. In the present work the results are presented concerning the H2 production at a high purity grade from biomass feedstocks via steam/oxygen gasification. The data demonstrating such a process chain were collected at an innovative gasification prototype plant coupled to a portable purification system (PPS). The overall integration was designed for gas conditioning and purification to hydrogen. By using almond shells as the biomass feedstock from a product gas with an average and stable composition of 40%-v H2 21%-v CO 35%-v CO2 2.5%-v CH4 the PPS unit provided a hydrogen stream with a final concentration of 99.99%-v and a gas yield of 66.4%.
Study of Attenuation Effect of Water Droplets on Shockwaves from Hydrogen Explosion
Sep 2021
Publication
The increasing demand for renewable energy storage may position hydrogen as one of the major players in the future energy system. However to introduce such technology high level of safety must be offered. In particular for the accident scenarios with combustion or explosion of the unintendedly released hydrogen in partially or fully confined volumes such as e.g. road tunnel the effective countermeasures preventing or reducing the risk of equipment damages and person injuries should be established. A mitigation strategy could be the use of existing fire suppression system which can inject water as a spray. The shock waves resulted from hydrogen explosion could be weakened by the water droplets met on the shock path. In the presented work an attenuation effect of water droplets presence on the strength of the passing shock was studied. The analysis of the different attenuation mechanisms was performed and estimation of the effect of spray parameters such as droplet size and spray density on the shock wave was carried out. For the quantitative evaluation of the attenuation potential a numerical model for the COM3D combustion code was developed. The novel model for the droplet behavior accounting for the realistic correlations for the fluid (water) particle drag force linked with the corresponding droplet breakup model describing droplet atomization is presented. The model was validated against literature experimental data and was used for the blind simulations of the hydrogen test facility in KIT.
An Extensive Review of Liquid Hydrogen in Transportation with Focus on the Maritime Sector
Sep 2022
Publication
The European Green Deal aims to transform the EU into a modern resource-efficient and competitive economy. The REPowerEU plan launched in May 2022 as part of the Green Deal reveals the willingness of several countries to become energy independent and tackle the climate crisis. Therefore the decarbonization of different sectors such as maritime shipping is crucial and may be achieved through sustainable energy. Hydrogen is potentially clean and renewable and might be chosen as fuel to power ships and boats. Hydrogen technologies (e.g. fuel cells for propulsion) have already been implemented on board ships in the last 20 years mainly during demonstration projects. Pressurized tanks filled with gaseous hydrogen were installed on most of these vessels. However this type of storage would require enormous volumes for large long-range ships with high energy demands. One of the best options is to store this fuel in the cryogenic liquid phase. This paper initially introduces the hydrogen color codes and the carbon footprints of the different production techniques to effectively estimate the environmental impact when employing hydrogen technologies in any application. Afterward a review of the implementation of liquid hydrogen (LH2 ) in the transportation sector including aerospace and aviation industries automotive and railways is provided. Then the focus is placed on the maritime sector. The aim is to highlight the challenges for the adoption of LH2 technologies on board ships. Different aspects were investigated in this study from LH2 bunkering onboard utilization regulations codes and standards and safety. Finally this study offers a broad overview of the bottlenecks that might hamper the adoption of LH2 technologies in the maritime sector and discusses potential solutions.
Carbon Footprint and Energy Transformation Analysis of Steel Produced via a Direct Reduction Plant with an Integrated Electric Melting Unit
Aug 2022
Publication
The production of fat steel products is commonly linked to highly integrated sites which include hot metal generation via the blast furnace basic oxygen furnace (BOF) continuous casting and subsequent hot-rolling. In order to reach carbon neutrality a shift away from traditional carbon-based metallurgy is required within the next decades. Direct reduction (DR) plants are capable to support this transition and allow even a stepwise reduction in CO2 emissions. Nevertheless the implementation of these DR plants into integrated metallurgical plants includes various challenges. Besides metallurgy product quality and logistics special attention is given on future energy demand. On the basis of carbon footprint methodology (ISO 14067:2019) diferent scenarios of a stepwise transition are evaluated and values of possible CO2equivalent (CO2eq) reduction are coupled with the demand of hydrogen electricity natural gas and coal. While the traditional blast furnace—BOF route delivers a surplus of electricity in the range of 0.7 MJ/kg hot-rolled coil; this surplus turns into a defcit of about 17 MJ/ kg hot-rolled coil for a hydrogen-based direct reduction with an integrated electric melting unit. On the other hand while the product carbon footprint of the blast furnace-related production route is 2.1 kg CO2eq/kg hot-rolled coil; this footprint can be reduced to 0.76 kg CO2eq/kg hot-rolled coil for the hydrogen-related route provided that the electricity input is from renewable energies. Thereby the direct impact of the processes of the integrated site can even be reduced to 0.15 kg CO2eq/ kg hot-rolled coil. Yet if the electricity input has a carbon footprint of the current German or European electricity grid mix the respective carbon footprint of hot-rolled coil even increases up to 3.0 kg CO2eq/kg hot-rolled coil. This underlines the importance of the availability of renewable energies.
A Model for Cost- and Greenhouse Gas Optimal Material and Energy Allocation of Biomass and Hydrogen
Nov 2022
Publication
BENOPT an optimal material and energy allocation model is presented which is used to assess cost-optimal and/or greenhouse gas abatement optimal allocation of renewable energy carriers across power heat and transport sectors. A high level of detail on the processes from source to end service enables detailed life-cycle greenhouse gas and cost assessments. Pareto analyses can be performed as well as thorough sensitivity analyses. The model is designed to analyse optimal biomass and hydrogen usage as a complement to integrated assessment and power system models
A Study on Green Hydrogen-based Isolated Microgrid
Oct 2022
Publication
This paper assesses the techno-economic feasibility of a green hydrogen-based microgrid for a remote Australian island. Hydrogen can be used to provide clean energy in areas where large-scale renewable energy sources are not feasible owing to geography government regulations or regulatory difficulties. This study not only identifies the appropriate component size for a hydrogen-based microgrid but also provides an economic perspective of decarbonising Thursday Island in Torres Straits Queensland Australia. Due to geographical constraints the green hydrogen production system needs to be distinct from the electrical network. This research shows how to produce green hydrogen transport it and generate power at a low cost. The study was performed utilising the HOMER simulation platform to find the least cost solution. The simulation results demonstrate an AU$0.01 reduction in Levelised Cost of Energy compared to the present electricity generation cost which is AU$0.56. The inclusion of a green hydrogen system will potentially minimise CO2 emissions by 99.6% while ensuring almost 100% renewable penetration. The results of this study will also serve as a guide for the placement of hydrogen-based microgrids in similar remote locations around the world where numerous remote energy systems are located close to each other.
Two-stage Model Predictive Control for a Hydrogen-based Storage System Paired to a Wind Farm Towards Green Hydrogen Production for Fuel Cell Electric Vehicles
Jul 2022
Publication
This study proposes a multi-level model predictive control (MPC) for a grid-connected wind farm paired to a hydrogen-based storage system (HESS) to produce hydrogen as a fuel for commercial road vehicles while meeting electric and contractual loads at the same time. In particular the integrated system (wind farm + HESS) should comply with the “fuel production” use case as per the IEA-HIA report where the hydrogen production for fuel cell electric vehicles (FCEVs) has the highest unconditional priority among all the objectives. Based on models adopting mixed-integer constraints and dynamics the problem of external hydrogen consumer requests optimal load demand tracking and electricity market participation is solved at different timescales to achieve a long-term plan based on forecasts that then are adjusted at real-time. The developed controller will be deployed onto the management platform of the HESS which is paired to a wind farm established in North Norway within the EU funded project HAEOLUS. Numerical analysis shows that the proposed controller efficiently manages the integrated system and commits the equipment so as to comply with the requirements of the addressed scenario. The operating costs of the devices are reduced by 5% which corresponds to roughly 300 commutations saved per year for devices.
Residential Fuel Transition and Fuel Interchangeability in Current Self-Aspirating Combustion Applications: Historical Development and Future Expectations
May 2022
Publication
To reduce greenhouse gases and air pollutants new technologies are emerging to reduce fossil fuel usage and to adopt more renewable energy sources. As the major aspects of fuel consumption power generation transportation and industrial applications have been given significant attention. The past few decades witnessed astonishing technological advancement in these energy sectors. In contrast the residential sector has had relatively little attention despite its significant utilization of fuels for a much longer period. However almost every energy transition in human history was initiated by the residential sector. For example the transition from fuelwood to cheap coal in the 1700s first took place in residential houses due to urbanization and industrialization. The present review demonstrates the energy transitions in the residential sector during the past two centuries while portending an upcoming energy transition and future energy structure for the residential sector. The feasibility of the 100% electrification of residential buildings is discussed based on current residential appliance adoption and the analysis indicates a hybrid residential energy structure is preferred over depending on a single energy source. Technical considerations and suggestions are given to help incorporate more renewable energy into the residential fuel supply system. Finally it is observed that compared to the numerous regulations on large energy-consumption aspects standards for residential appliances are scarce. Therefore it is concluded that establishing appropriate testing methods is a critical enabling step to facilitate the adoption of renewable fuels in future appliances.
Batteries, Fuel Cells, or Engines? A Probabilistic Economic and Environmental Assessment of Electricity and Electrofuels for Heavy Goods Vehicles
Oct 2022
Publication
Uncertainty surrounding the total cost of ownership system costs and life cycle environmental impacts means that stakeholders may lack the required information to evaluate the risks of transitioning to low-carbon fuels and powertrains. This paper assesses the life cycle costs and well-to-wheel environmental impacts of using electricity and electrofuels in Heavy Good Vehicles (HGVs) whilst considering input parameter uncertainty. The complex relationship between electricity cost electrolyser capacity factor CO2 capture cost and electricity emissions intensity is assessed within a Monte Carlo based framework to identify scenarios where use of electricity or electrofuels in heavy goods vehicles makes economic and environmental sense. For vehicles with a range of less than 450 km battery electric vehicles achieve the lowest total cost of ownership for an electricity cost less than 100 €/MWh. For vehicles that require a range of up to 900 km hydrogen fuel cell vehicles represent the lowest long-term cost of abatement. Power-to-methane and power-to-liquid scenarios become economically competitive when low-cost electricity is available at high-capacity factors and CO2 capture costs for fuel synthesis are below 100 €/tCO2; these fuels may be more applicable to decarbonise shipping and aviation. Battery electric HGVs reduce greenhouse gas emissions by 50% compared to the diesel baseline with electricity emissions of 350 gCO2e/kWh. Electricity emissions less than 35 gCO2e/kWh are required for the power-to-methane and power-to-liquid scenarios to meet EU emissions savings criteria. High vehicle capital costs and a lack of widespread refuelling infrastructure may hinder initial uptake of low-carbon fuels and powertrains for HGVs.
A Study on the Prediction of the Temperature and Mass of Hydrogen Gas inside a Tank during Fast Filling Process
Dec 2020
Publication
The hydrogen compression cycle system recycles hydrogen compressed by a compressor at high pressure and stores it in a high-pressure container. Thermal stress is generated due to increase in the pressure and temperature of hydrogen in the hydrogen storage tank during the fast filing process. For the sake of safety it is of great practical significance to predict and control the temperature change in the tank. The hydrogen charging process in the storage tank of the hydrogen charging station was studied by experimentation and simulation. In this paper a Computational Fluid Dynamics (CFD) model for non-adiabatic real filling of a 50 MPa hydrogen cylinder was presented. In addition a shear stress transport (k-ω) model and real gas model were used in order to account for thermo-fluid dynamics during the filling of hydrogen storage tanks (50 MPa 343 L). Compared to the simulation results with the experimental data carried out under the same conditions the temperatures calculated from the simulated non-adiabatic condition results were lower (by 5.3%) than those from the theoretical adiabatic condition calculation. The theoretical calculation was based on the experimentally measured pressure value. The calculated simulation mass was 8.23% higher than the theoretical result. The results of this study will be very useful in future hydrogen energy research and hydrogen charging station developments.
Fuel Cell Electrical Vehicles as Mobile Coupled Heat and Power Backup-Plant in Neighbourhoods
Apr 2022
Publication
Fuel cell electric vehicles (FCEVs) can be used during idle times to convert hydrogen into electricity in a decentralised manner thus ensuring a completely renewable energy supply. In addition to the electric power waste heat is generated in the fuel cell stack that can also be used. This paper investigates how the energy demand of a compiled German neighbourhood can be met by FCEVs and identifies potential technical problems. For this purpose energy scenarios are modelled in the Open Energy System Modelling Framework (oemof). An optimisation simulation finds the most energetically favourable solution for the 10-day period under consideration. Up to 49% of the heat demand for heating and hot water can be covered directly by the waste heat of the FCEVs. As the number of battery electric vehicles (BEVs) to be charged increases so does this share. 5 of the 252 residents must permanently provide an FCEV to supply the neighbourhood. The amount of hydrogen required was identified as a problem. If the vehicles cannot be supplied with hydrogen in a stationary way 15 times more vehicles are needed than required in terms of performance due to the energy demand.
Iron as Recyclable Energy Carrier: Feasibility Study and Kinetic Analysis of Iron Oxide Reduction
Oct 2022
Publication
Carbon-free and sustainable energy storage solutions are required to mitigate climate change. One possible solution especially for stationary applications could be the storage of energy in metal fuels. Energy can be stored through reduction of the oxide with green hydrogen and be released by combustion. In this work a feasibility study for iron as possible metal fuel considering the complete energy cycle is conducted. Based on equilibrium calculations it could be shown that the power-to-power efficiency of the iron/iron oxide cycle is 27 %. As technology development requires a more detailed description of both the reduction and the oxidation a first outlook is given on the kinetic analysis of the reduction of iron oxides with hydrogen. Based on thermogravimetric experiments using Fe2O3 Fe3O4 and FeO it could be shown that the reduction is a three-step process. The maximum reduction rate can be achieved with a hydrogen content of 25 %. Based on the experimental results a reaction mechanism and accompanied kinetic data were developed for description of Fe2O3 reduction with H2 under varying experimental conditions.
Reduction Kinetics of Hematite Powder in Hydrogen Atmosphere at Moderate Temperatures
Sep 2018
Publication
Hydrogen has received much attention in the development of direct reduction of iron ores because hydrogen metallurgy is one of the effective methods to reduce CO2 emission in the iron and steel industry. In this study the kinetic mechanism of reduction of hematite particles was studied in a hydrogen atmosphere. The phases and morphological transformation of hematite during the reduction were characterized using X-ray diffraction and scanning electron microscopy with energy dispersive spectroscopy. It was found that porous magnetite was formed and the particles were degraded during the reduction. Finally sintering of the reduced iron and wüstite retarded the reductive progress. The average activation energy was extracted to be 86.1 kJ/mol and 79.1 kJ/mol according to Flynn-Wall-Ozawa (FWO) and Starink methods respectively. The reaction fraction dependent values of activation energy were suggested to be the result of multi-stage reactions during the reduction process. Furthermore the variation of activation energy value was smoothed after heat treatment of hematite particles.
Techno-economic Modelling of Zero-emission Marine Transport with Hydrogen Fuel and Superconducting Propulsion System: Case Study of a Passenger Ferry
Mar 2023
Publication
This paper proposes a techno-economic model for a high-speed hydrogen ferry. The model can describe the system properties i.e. energy demand weight and daily operating expenses of the ferry. A novel aspect is the consideration of superconductivity as a measure for cost saving in the setting where liquid hydrogen (LH2) can be both coolant and fuel. We survey different scenarios for a high-speed ferry that could carry 300 passengers. The results show that despite higher energy demand compressed hydrogen gas is more economical compared with LH2 for now; however constructing large-scale hydrogen liquefaction plants make it competitive in the future. Moreover compressed hydrogen gas is restricted to a shorter distance while LH2 makes longer distances possible and whenever LH2 is accessible using a superconducting propulsion system has a beneficial impact on both energy and cost savings. These effects strengthen if the operational time or the weight of the ferry increases.
Smart Energy Management System: Design of a Smart Grid Test Bench for Educational Purposes
Apr 2022
Publication
The presented article aims to design an educational test bench setup for smart grids and renewable energies with multiple features and techniques used in a microgrid. The test bench is designed for students laboratory engineers and researchers which enables electrical microgrid system studies and testing of new advanced control algorithms to optimize the energy efficiency. The idea behind this work is to design hybrid energy sources such as wind power solar photovoltaic power hydroelectric power hydrogen energy and different types of energy storage systems such as batteries pumped storage and flywheel integrating different electrical loads. The user can visualize the state of the components of each emulated scenario through an open-source software that interacts and communicates using OPC Unified Architecture protocol. The researchers can test and validate new solutions to manage the energy behavior in the grid using machine learning and optimization algorithms integrated in the software in form of blocks that can be modified and improved and then simulate the results. A model-based system of engineering is provided which describes the different requirements and case studies of the designed test bench respecting the open-source software and the frugal innovation features in which there is use of low-cost hardware and open-source software. The users obtain the opportunity to add new sources and new loads change software platforms and communicate with other simulators and equipment. The students can understand the different features of smart grids such as defect classification energy forecasting energy optimization and basics of production transmission and consumption.
Recent Developments in State-of-the-art Hydrogen Energy Technologies – Review of Hydrogen Storage Materials
Jan 2023
Publication
Hydrogen energy has been assessed as a clean and renewable energy source for future energy demand. For harnessing hydrogen energy to its fullest potential storage is a key parameter. It is well known that important hydrogen storage characteristics are operating pressure-temperature of hydrogen hydrogen storage capacity hydrogen absorption-desorption kinetics and heat transfer in the hydride bed. Each application needs specific properties. Every class of hydrogen storage materials has a different set of hydrogenation characteristics. Hence it is required to understand the properties of all hydrogen storage materials. The present review is focused on the state-of– the–art hydrogen storage materials including metal hydrides magnesium-based materials complex hydride systems carbonaceous materials metal organic frameworks perovskites and materials and processes based on artificial intelligence. In each category of materials‘ discovery hydrogen storage mechanism and reaction crystal structure and recent progress have been discussed in detail. Together with the fundamental synthesis process latest techniques of material tailoring like nanostructuring nanoconfinement catalyzing alloying and functionalization have also been discussed. Hydrogen energy research has a promising potential to replace fossil fuels from energy uses especially from automobile sector. In this context efforts initiated worldwide for clean hydrogen production and its use via fuel cell in vehicles is much awaiting steps towards sustainable energy demand.
Main Trends and Research Directions in Hydrogen Generation Using Low Temperature Electrolysis: A Systematic Literature Review
Aug 2022
Publication
Hydrogen (H2 ) is the most abundant element in the universe and it is also a neutral energy carrier meaning the environmental effects of using it are strictly related to the effects of creating the means of producing of that amount of Hydrogen. So far the H2 generation by water electrolysis research field did not manage to break the efficiency barrier in order to consider H2 production as a technology that sustains financially its self-development. However given the complexity of this technology and the overall environmental impacts an up-to-date research and development status review is critical. Thus this study aims to identify the main trends achievements and research directions of the H2 generation using pure and alkaline water electrolysis providing a review of the state of the art in the specific literature. Methods: In order to deliver this a Systematic Literature Review was carried out using PRISMA methodology highlighting the research trends and results in peer review publish articles over more than two years (2020–2022). Findings: This review identifies niches and actual status of the H2 generation by water and alkaline water electrolysis and points out in numbers the boundaries of the 2020–2022 timeline research.
Favorable Start-Up Behavior of Polymer Electrolyte Membrane Water Electrolyzers
Nov 2022
Publication
Dynamically-operated water electrolyzers enable the production of green hydrogen for cross-sector applications while simultaneously stabilizing power grids. In this study the start-up phase of polymer electrolyte membrane (PEM) water electrolyzers is investigated in the context of intermittent renewable energy sources. During the start-up of the electrolysis system the temperature increases which directly influences hydrogen production efficiency. Experiments on a 100 kWel electrolyzer combined with simulations of electrolyzers with up to 1 MWel were used to analyze the start-up phase and assess its implications for operators and system designers. It is shown that part-load start-up at intermediate cell voltages of 1.80 V yields the highest efficiencies of 74.0 %LHV compared to heat-up using resistive electrical heating elements which reaches maximum efficiencies of 60.9 %LHV. The results further indicate that large-scale electrolyzers with electrical heaters may serve as flexible sinks in electrical grids for durations of up to 15 min.
Hydrogen Production from Methanol–Water Solution and Pure Water Electrolysis Using Nanocomposite Perfluorinated Sulfocationic Membranes Modified by Polyaniline
Oct 2022
Publication
In this work we report the preparation of Nafion membranes containing two different nanocomposite MF-4SC membranes modified with polyaniline (PANI) by the casting method through two different polyaniline infiltration procedures. These membranes were evaluated as a polymer electrolyte membrane for water electrolysis. Operating conditions were optimized in terms of current density stability and methanol concentration. A study was made on the effects on the cell performance of various parameters such as methanol concentration water and cell voltage. The energy required for pure water electrolysis was analyzed at different temperatures for the different membranes. Our experiments showed that PEM electrolyzers provide hydrogen production of 30 mL/min working at 160 mA/cm2 . Our composite PANI membranes showed an improved behavior over pristine perfluorinated sulfocationic membranes (around 20% reduction in specific energy). Methanol–water electrolysis required considerably less (around 65%) electrical power than water electrolysis. The results provided the main characteristics of aqueous methanol electrolysis in which the power consumption is 2.34 kW h/kg of hydrogen at current densities higher than 0.5 A/cm2 . This value is ~20-fold times lower than the electrical energy required to produce 1 kg of hydrogen by water electrolysis.
Hydrogen Sensing Properties of UV Enhanced Pd-SnO2 Nano-Spherical Composites at Low Temperature
Sep 2021
Publication
Metal oxide semiconductor (MOS) is promising in developing hydrogen detectors. However typical MOS materials usually work between 200-500°C which not only restricts their application in flammable and explosive gases detection but also weakens sensor stability and causes high power consumption. This paper studies the sensing properties of UV enhanced Pd-SnO2 nano-spherical composites at 80-360 ℃. In the experiment Pd of different molar ratios (0.5 2.5 5.0 10.0) was doped into uniform spherical SnO2 nanoparticles by a hydrothermal synthesis method. A xenon lamp with a filter was used as the ultraviolet excitation light source to examine the response of the spherical Pd- SnO2 nanocomposite to 50-1000 ppm H2 gas. The influence of different intensities of ultraviolet light on the gas-sensing properties of composite materials compared with dark condition was analyzed. The experiments show that the conductivity of the composites can be greatly stabilized and the thermal excitation temperature can be reduced to 180 ℃ under the effect of UV enhancement. A rapid response (4.4/ 17.4 s) to 200 ppm of H2 at 330 °C can be achieved by the Pd-SnO2 nanocomposites with UV assistance. The mechanism may be attributed to light motivated electron-hole pairs due to built-in electric fields under UV light illumination which can be captured by target gases and lead to UV controlled gas sensing performance. Catalytic active sites of hydrogen are provided on the surface of the mixed material by Pd. The results in this study can be helpful in reducing the response temperature of MOS materials and improving the performance of hydrogen detectors."
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