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Blending Hydrogen from Electrolysis into the European Gas Grid
Jan 2022
Publication
In 2020 the European Commission launched a hydrogen strategy for a climate-neutral Europe setting out the conditions and actions for mainstreaming clean hydrogen along with targets for installing renewable hydrogen electrolysers by 2024 and 2030. Blending hydrogen alongside other gases into the existing gas grid is considered a possible interim first step towards decarbonising natural gas. In the present analysis we modelled electrolytic hydrogen generation as a process connecting two separate energy systems (power and gas). The analysis is based on a projection of the European power and gas systems to 2030 based on the EUCO3232.5 scenario. Multiple market configurations were introduced in order to assess the interplay between diverse power market arrangements and constraints imposed by the upper bound on hydrogen concentration. The study identifies the maximum electrolyser capacity that could be integrated in the power and gas systems the impact on greenhouse gas emissions and the level of price support that may be required for a broad range of electrolyser configurations. The study further attempts to shed some light on the potential side effects of having non-harmonised H2 blending thresholds between neighbouring Member States.
Recent Progress in Catalysts for Hydrogen-Chlorine Regenerative Fuel Cells
Oct 2020
Publication
The increasing energy demand and the subsequent climate change consequences are supporting the search for sustainable alternatives to fossil fuels. In this scenario the link between hydrogen and renewable energy is playing a key role and unitized hydrogen-chlorine (H2-Cl2) regenerative cells (RFCs) have become promising candidates for renewable energy storage. Described herein are the recent advances in cell configurations and catalysts for the different reactions that may take place in these systems that work in both modes: electrolysis and fuel cell. It has been found that platinum (Pt)-based catalysts are the best choice for the electrode where hydrogen is involved whereas for the case of chlorine ruthenium (Ru)-based catalysts are the best candidates. Only a few studies were found where the catalysts had been tested in both modes and recent advances are focused on decreasing the amount of precious metals contained in the catalysts. Moreover the durability of the catalysts tested under realistic conditions has not been thoroughly assessed becoming a key and mandatory step to evaluate the commercial viability of the H2-Cl2 RFC technology.
Techno-economic Assessment of Offshore Wind-to-hydrogen Scenarios: A UK Case Study
Jan 2023
Publication
The installed capacity electricity generation from wind and the curtailment of wind power in the UK between 2011 and 2021 showed that penetration levels of wind energy and the amount of energy that is curtailed in future would continue to rise whereas the curtailed energy could be utilised to produce green hydrogen. In this study data were collected technologies were chosen systems were designed and simulation models were developed to determine technical requirements and levelised costs of hydrogen produced and transported through different pathways. The analysis of capital and operating costs of the main components used for onshore and offshore green hydrogen production using offshore wind including alternative strategies for hydrogen storage and transport and hydrogen carriers showed that a significant reduction in cost could be achieved by 2030 enabling the production of green hydrogen from offshore wind at a competitive cost compared to grey and blue hydrogen. Among all scenarios investigated in this study compressed hydrogen produced offshore is the most cost-effective scenario for projects starting in 2025 although the economic feasibility of this scenario is strongly affected by the storage period and the distance to the shore of the offshore wind farm. Alternative scenarios for hydrogen storage and transport such as liquefied hydrogen and methylcyclohexane could become more cost-effective for projects starting in 2050 when the levelised cost of hydrogen could reach values of about £2 per kilogram of hydrogen or lower.
An Analysis on the Compressed Hydrogen Storage System for the Fast-Filling Process of Hydrogen Gas at the Pressure of 82 MPa
May 2021
Publication
During the fast-filling of a high-pressure hydrogen tank the temperature of hydrogen would rise significantly and may lead to failure of the tank. In addition the temperature rise also reduces hydrogen density in the tank which causes mass decrement into the tank. Therefore it is of practical significance to study the temperature rise and the amount of charging of hydrogen for hydrogen safety. In this paper the change of hydrogen temperature in the tank according to the pressure rise during the process of charging the high-pressure tank in the process of a 82-MPa hydrogen filling system the final temperature the amount of filling of hydrogen gas and the change of pressure of hydrogen through the pressure reducing valve and the performance of heat exchanger for cooling high-temperature hydrogen were analyzed by theoretical and numerical methods. When high-pressure filling began in the initial vacuum state the condition was called the “First cycle”. When the high-pressure charging process began in the remaining condition the process was called the “Second cycle”. As a result of the theoretical analysis the final temperatures of hydrogen gas were calculated to be 436.09 K for the first cycle of the high-pressure tank and 403.55 for the second cycle analysis. The internal temperature of the buffer tank increased by 345.69 K and 32.54 K in the first cycle and second cycles after high-pressure filling. In addition the final masses were calculated to be 11.58 kg and 12.26 kg for the first cycle and second cycle of the high-pressure tank respectively. The works of the paper can provide suggestions for the temperature rise of 82 MPa compressed hydrogen storage system and offer necessary theory and numerical methods for guiding safe operation and construction of a hydrogen filling system.
Novel Carbon-neutral Hydrogen Production Process of Steam Methane Reforming Integrated with Desalination Wastewater-based CO2 Utilization
Nov 2022
Publication
Steam methane reforming (SMR) process is facing serious greenhouse effect problems because of the significant CO2 emissions. To reduce pollution caused by gaseous emissions desalination wastewater can be used because it contains highly concentrated useful mineral ions such as Ca2+ Mg2+ and Na+ which react with carbonate ions. This study proposes a novel SMR process for carbon-neutral hydrogen production integrated with desalination wastewater-based CO2 utilization. A process model for the design of a novel SMR process is proposed; it comprises the following steps: (1) SMR process for hydrogen production; and (2) desalination wastewater recovery for CO2 utilization. In the process model the CO2 from the SMR process was captured using the Na+ ion and the captured ionic CO2 was carbonated using the Ca2+ and Mg2+ ions in desalination wastewater. The levelized cost of hydrogen (LCOH) was assessed to demonstrate the economic feasibility of the proposed process. Therefore 94.5 % of the CO2 from the SMR process was captured and the conversion of MgCO3 and CaCO3 was determined to be 60 % and 99 % respectively. In addition the CO2 emission via the proposed process was determined to be 0.016 kgCO2/kgH2 and the LCOH was calculated to be 2.6 USD/kgH2.
Exergy and Exergoeconomic Analysis for the Proton Exchange Membrane Water Electrolysis under Various Operating Conditions and Design Parameters
Nov 2022
Publication
Integrating the exergy and economic analyses of water electrolyzers is the pivotal way to comprehend the interplay of system costs and improve system performance. For this a 3D numerical model based on COMSOL Multiphysics Software (version 5.6 COMSOL Stockholm Sweden) is integrated with the exergy and exergoeconomic analysis to evaluate the exergoeconomic performance of the proton exchange membrane water electrolysis (PEMWE) under different operating conditions (operating temperature cathode pressure current density) and design parameter (membrane thickness). Further the gas crossover phenomenon is investigated to estimate the impact of gas leakage on analysis reliability under various conditions and criteria. The results reveal that increasing the operating temperature or decreasing the membrane thickness improves both the efficiency and cost of hydrogen exergy while increasing the gas leakage through the membrane. Likewise raising the current density and the cathode pressure lowers the hydrogen exergy cost and improves the economic performance. The increase in exergy destroyed and hydrogen exergy cost as well as the decline in second law efficiency due to the gas crossover are more noticeable at higher pressures. As the cathode pressure rises from 1 to 30 bar at a current density of 10000 A/m2 the increase in exergy destroyed and hydrogen exergy cost as well as the decline in second law efficiency are increased by 37.6 kJ/mol 4.49 USD/GJ and 7.1% respectively. The cheapest green electricity source which is achieved using onshore wind energy and hydropower reduces hydrogen production costs and enhances economic efficiency. The growth in the hydrogen exergy cost is by about 4.23 USD/GJ for a 0.01 USD/kWh increase in electricity price at the current density of 20000 A/m2. All findings would be expected to be quite useful for researchers engaged in the design development and optimization of PEMWE.
Sustainable Ammonia Production Processes
Mar 2021
Publication
Due to the important role of ammonia as a fertilizer in the agricultural industry and its promising prospects as an energy carrier many studies have recently attempted to find the most environmentally benign energy efficient and economically viable production process for ammonia synthesis. The most commonly utilized ammonia production method is the Haber-Bosch process. The downside to this technology is the high greenhouse gas emissions surpassing 2.16 kgCO2-eq/kg NH3 and high amounts of energy usage of over 30 GJ/tonne NH3 mainly due to the strict operational conditions at high temperature and pressure. The most widely adopted technology for sustainable hydrogen production used for ammonia synthesis is water electrolysis coupled with renewable technologies such as wind and solar. In general a water electrolyzer requires a continuous supply of pretreated water with high purity levels for its operation. Moreover for production of 1 tonne of hydrogen 9 tonnes of water is required. Based on this data for the production of the same amount of ammonia through water electrolysis 233.6 million tonnes/yr of water is required. In this paper a critical review of different sustainable hydrogen production processes and emerging technologies for sustainable ammonia synthesis along with a comparative life cycle assessment of various ammonia production methods has been carried out. We find that through the review of each of the studied technologies either large amounts of GHG emissions are produced or high volumes of pretreated water is required or a combination of both these factors occur.
Low-Carbon Economic Dispatch of Integrated Energy Systems in Industrial Parks Considering Comprehensive Demand Response and Multi-Hydrogen Supply
Mar 2024
Publication
To address the increasing hydrogen demand and carbon emissions of industrial parks this paper proposes an integrated energy system dispatch strategy considering multi-hydrogen supply and comprehensive demand response. This model adopts power-to-gas technology to produce green hydrogen replacing a portion of gray hydrogen and incorporates a carbon capture system to effectively reduce the overall carbon emissions of the industrial park. Meanwhile incentive-based and price-based demand response strategies are implemented to optimize the load curve. A scheduling model is established targeting the minimization of procurement operation carbon emission and wind curtailment costs. The case study of a northern industrial park in China demonstrates that the joint supply of green and gray hydrogen reduces carbon emissions by 40.98% and costs by 17.93% compared to solely using gray hydrogen. The proposed approach successfully coordinates the economic and environmental performance of the integrated energy system. This study provides an effective scheduling strategy for industrial parks to accommodate high shares of renewables while meeting hydrogen needs and carbon reduction targets.
Dynamic Investigation and Optimization of a Solar‐Based Unit for Power and Green Hydrogen Production: A Case Study of the Greek Island, Kythnos
Nov 2022
Publication
The aim of the present work is the analysis of a solar‐driven unit that is located on the non‐interconnected island of Kythnos Greece that can produce electricity and green hydrogen. More specifically solar energy is exploited by parabolic trough collectors and the produced heat is stored in a thermal energy storage tank. Additionally an organic Rankine unit is incorporated to generate electricity which contributes to covering the island’s demand in a clean and renewable way. When the power cannot be absorbed by the local grid it can be provided to a water electrolyzer; therefore the excess electricity is stored in the form of hydrogen. The produced hydrogen amount is compressed afterward stored in tanks and then finally can be utilized as a fuel to meet other important needs such as powering vehicles or ferries. The installation is simulated parametrically and optimized on dynamic conditions in terms of energy exergy and finance. According to the results considering a base electrical load of 75 kW the annual energy and exergy efficiencies are found at 14.52% and 15.48% respectively while the payback period of the system is deter‐ mined at 6.73 years and the net present value is equal to EUR 1073384.
Effect of Carbon Concentration and Carbon Bonding Type on the Melting Characteristics of Hydrogen-reduced Iron Ore Pellets
Oct 2022
Publication
Decarbonization of the steel industry is one of the pathways towards a fossil-fuel-free environment. The steel industry is one of the top contributors to greenhouse gas emissions. Most of these emissions are directly linked to the use of a fossil-fuelbased reductant. Replacing the fossil-based reductant with green H2 enables the transition towards a fossil-free steel industry. The carbon-free iron produced will cause the refining and steelmaking operations to have a starting point far from today’s operations. In addition to carbon being an alloying element in steel production carbon addition controls the melting characteristics of the reduced iron. In the present study the effect of carbon content and form (cementite/graphite) in hydrogen-reduced iron ore pellets on their melting characteristics was examined by means of a differential thermal analyser and optical dilatometer. Carburized samples with a carbon content < 2 wt % did not show any initial melting at the eutectic temperature. At and above 2 wt % the carburized samples showed an initial melting at the eutectic temperature irrespective of the carbon content. However the absorbed heat varies with varied carbon content. The carbon form does not affect the initial melting temperature but it affects the melting progression. Carburized samples melt homogenously while melting of iron-graphite mixtures occurs locally at the interface between iron and carbon particles and when the time is not long enough melting might not occur to any significant extent. Therefore at any given carbon content > 2 wt % the molten fraction is higher in the case of carburized samples which is indicated by the amount of absorbed melting heat.
Feasibility Study of Vacuum Pressure Swing Adsorption for CO2 Capture From an SMR Hydrogen Plant: Comparison Between Synthesis Gas Capture and Tail Gas Capture
Dec 2021
Publication
In this paper a feasibility study was carried out to evaluate cyclic adsorption processes for capturing CO2 from either shifted synthesis gas or H2 PSA tail gas of an industrial-scale SMR-based hydrogen plant. It is expected that hydrogen is to be widely used in place of natural gas in various industrial sectors where electrification would be rather challenging. A SMR-based hydrogen plant is currently dominant in the market as it can produce hydrogen at scale in the most economical way. Its CO2 emission must be curtailed significantly by its integration with CCUS. Two Vacuum Pressure Swing Adsorption (VPSA) systems including a rinse step were designed to capture CO2 from an industrial-scale SMR-based hydrogen plant: one for the shifted synthesis gas and the other for the H2 PSA tail gas. Given the shapes of adsorption isotherms zeolite 13X and activated carbon were selected for tail gas and syngas capture options respectively. A simple Equilibrium Theory model developed for the limiting case of complete regeneration was taken to analyse the VPSA systems in this feasibility study. The process performances were compared to each other with respect to product recovery bed productivity and power consumption. It was found that CO2 could be captured more cost-effectively from the syngas than the tail gas unless the desorption pressure was too low. The energy consumption of the VPSA was comparable to those of the conventional MDEA processes.
Performance and Weight Parameters Calculation for Hydrogen and Battery-Powered Aircraft Concepts
May 2023
Publication
This article describes the creation of a program that would be useful for calculating mathematical models in order to estimate the weight of aircraft components. Using several parameters it can calculate other parameters of civil transport aircraft powered by batteries or fuel cells. The main goals of this research were to add the missing dimensions and parameters to the aircraft database create a simple but effective program for creating mathematical models and use this program to find technological barriers to battery or hydrogen fuel-cell-powered aircraft concepts. The article introduces the reader to the problem of calculating OEW (operating empty weight) using Breguet– Leduc equations. A calculation model was created for OEW calculation. The result of this work is the verification of a mathematical model for battery-powered electric aircraft of the CS-23 (European Aviation Safety Agency Certification Specification for Normal Utility Aerobatic and Commuter Category Aeroplanes) category by comparing the program’s outputs with real aircraft. Subsequently the results of mathematical models are shown in graphs that specify the space of possible concepts of aircraft powered by batteries or fuel cells sorted by the number of passengers and the range of the aircraft delimited by two or three criteria respectively.
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.
Hydrogen Production from the Air
Sep 2022
Publication
Green hydrogen produced by water splitting using renewable energy is the most promising energy carrier of the low-carbon economy. However the geographic mismatch between renewables distribution and freshwater availability poses a significant challenge to its production. Here we demonstrate a method of direct hydrogen production from the air namely in situ capture of freshwater from the atmosphere using hygroscopic electrolyte and electrolysis powered by solar or wind with a current density up to 574 mA cm−2 . A prototype of such has been established and operated for 12 consecutive days with a stable performance at a Faradaic efficiency around 95%. This so-called direct air electrolysis (DAE) module can work under a bone-dry environment with a relative humidity of 4% overcoming water supply issues and producing green hydrogen sustainably with minimal impact to the environment. The DAE modules can be easily scaled to provide hydrogen to remote (semi-) arid and scattered areas.
Decarbonisation Options for the Cement Industry
Jan 2023
Publication
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.
OIES Podcast - China and Hydrogen: A Tale of Three Cities
Apr 2023
Publication
China is by far the world’s largest producer and consumer of hydrogen mostly from coal and other fossil fuels and the country has an ambitious hydrogen strategy. In this podcast we dive into the provincial strategies on hydrogen in China and specifically discuss a recent paper published by the Institute entitled China’s hydrogen development: A tale of three cities. The paper looks at the experiences and plans of the pilot hydrogen clusters located in Datong Shanxi province Chengdu in Sichuan province and Zhangjiakou in the northern part of Hebei province which surrounds Beijing. In this podcast we are speaking with the paper’s author Arabella Miller-Wang recently an Aramco fellow at the Institute and also a Research Assistant at the Smith School of Enterprise and the Environment of The University of Oxford as well as with Michal Meidan director of the China Energy Programme at OIES and with Martin Lambert who heads hydrogen research at the OIES.
The podcast can be found on their website.
The podcast can be found on their website.
Thermodynamic Analysis of Methanol, Ammonia, and Hydrogen as Alternative Fuels in HCCI Engines
May 2023
Publication
The present study enters in the context of reducing harmful emissions of the marine fleet by using three of the most promising alternative fuels namely methanol ammonia and hydrogen. These fuels are to be examined from the perspective of both the first and second laws of thermodynamics when employed in turbocharged and intercooled Homogeneous Charge Compression Ignition Engines (HCCI) under various values of ambient temperature and equivalence ratio. Results showed that the highest engine performance values favour using ammonia as fuel followed in order by hydrogen and methanol. Furthermore most of the exergy destruction rates (65.26% ammonia to 84.02% for hydrogen) of the exergy destruction rate occurring in the engine take place in the HCCI engine.
The Impact of the Energy Crisis on the UK's Net Zero Transition
Mar 2023
Publication
Recent drastic increases in natural gas prices have brought into sharp focus the inherent tensions between net zero transitions energy security and affordability. We investigate the impact of different fuel prices on the energy system transition explicitly accounting for the increasingly coupled power and heating sectors and also incorporate the emerging hydrogen sector. The aim is to identify low-regret decisions and optimal energy system transitions for different fuel prices. We observe that the evolution of the heating sector is highly sensitive to the gas price whereas the composition of the power sector is not qualitatively impacted by gas prices. We also observe that bioenergy plays an important role in the energy system transition and the balance between gas price and biomass prices determines the optimal technology portfolios. The future evolution of the prices of these two resources is highly uncertain and future energy systems must be resilient to these uncertainties.
Boosting Hydrogen through a European Hydrogen Bank
Mar 2023
Publication
Hydrogen is indispensable to decarbonise European industry and reach the EU’s 2030 climate targets and 2050 climate neutrality. It is one of the key technologies of Europe’s Net Zero Industry Act. By scaling up its production we will reduce the use of fossil fuels in European industries and serve the needs of hard-to-electrify sectors.
Hydrogen Net Zero Investment Roadmap: Leading the Way to Net Zero
Apr 2023
Publication
This net zero investment roadmap summarises government’s hydrogen policies and available investment opportunities.
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