Publications

The European Commission recently proposed requirements for the production of renewable fuels as these are required to decarbonize the hard-to-electrify parts of the industrial and heavy transport sectors. Power-to-X (P2X) energy hubs enable efficient synergies between energy infrastructures production facilities and storage options. In this study we explore the optimal operation of an energy hub by leveraging the flexibility of P2X including hydrogen methanol and ammonia synthesizers by analyzing potential revenue streams such as the day-ahead and ancillary services markets. We propose EnerHub2X a mixed-integer linear program that maximizes the hub’s profit based on current market prices considering the technical constraints of P2X such as unit commitment and non-linear efficiencies. We investigate a representative Danish energy hub and find that without price incentives it mainly sells renewable electricity and produces compressed hydrogen. A sufficient amount of renewable ammonia and methanol is only produced by adding a price premium of about 50% (0.16 e/kg) to the conventional fuel prices. To utilize production efficiently on-site renewable energy sources and P2X must be carefully aligned. We show that renewable power purchase agreements can provide flexibility while complying with the rules set by the European Commission.

Among the numerous envisioned applications for hydrogen in the decarbonization of the energy system seasonal energy storage is usually regarded as one of the most likely options. Although long-term energy storage is usually considered at grid-scale level given the increasing diffusion of distributed energy systems and the expected cost reduction in hydrogen related components some companies are starting to offer residential systems with PV modules and batteries that rely on hydrogen for seasonal storage of electrical energy. Such hydrogen storage systems are generally composed by water electrolysers hydrogen storage vessels and fuel cells.<br/>The aim of this work is to investigate such systems and their possible applications for different geographical conditions in Italy. On-grid and off-grid systems are considered and compared to systems without hydrogen in terms of self-consumption ratio size of components and economic investment. Each different option has been assessed from a techno-economic point of view via MESS (Multi Energy Systems Simulator) an analytical programming tool for the analysis of local energy systems.<br/>Results have identified the optimal sizing of the system's components and have shown how such systems are not in general economically competitive for a single dwelling although they can in some cases ensure energy independence.

The present research work deals with prediction of hydrogen consumption of a fuel cell in an energy storage system. Due to the fact that these kind of systems have a very nonlinear behaviour the use of traditional techniques based on parametric models and other more sophisticated techniques such as soft computing methods seems not to be accurate enough to generate good models of the system under study. Due to that a hybrid intelligent system based on clustering and regression techniques has been developed and implemented to predict the necessary variation of the hydrogen flow consumption to satisfy the variation of demanded power to the fuel cell. In this research a hybrid intelligent model was created and validated over a dataset from a fuel cell energy storage system. Obtained results validate the proposal achieving better performance than other well-known classical regression methods allowing us to predict the hydrogen consumption with a Mean Absolute Error (MAE) of 3.73 with the validation dataset.

A Lagrangian-based one-dimensional approach has been developed using Cantera to study the dynamics of spherically expanding flames. The detailed reaction model USC-Mech II has been employed to examine flame propagating in hydrogen-air mixtures. In the first part our approach has been validated against laminar flame speed and Markstein number data from the literature. It was shown that the laminar flame speed was predicted within 5% on average but that discrepancies were observed for the Markstein number especially for rich mixtures. In the second part a detailed analysis of the thermo-chemical dynamics along the path of Lagrangian particles propagating in stretched flames was performed. For mixtures with negative Markstein lengths it was found that at high stretch rates the mixture entering the reaction-dominated period is less lean with respect to the initial mixture than at low stretch rate. This induces a faster rate of chemical heat release and of active radical production which results in a higher flame propagation speed. Opposite effects were observed for mixtures with positive Markstein lengths for which slower flame propagation was observed at high stretch rates compared to low stretch rates."

In order to wrap Season 3 of EAH appropriately we are honored to have our most popular EAH guest back with us Alicia Eastman President and Co-Founder of Intercontinental Energy is here to help us review the big hydrogen happenings of 2022 and preview some of the most important predictions and expectations for the sector coming for 2023.

The podcast can be found on their website.

There is increasing interest in migrating to a carbon-neutral power system that relies on renewable energy due to concerns about greenhouse gas emissions energy shortages and global warming. However the increasing share of renewable energy has added volatility and uncertainty to power system operations. Introducing new devices and using flexible resources may help solve the problem but expanding the domain of the problem can be another solution. Sector coupling which integrates production consumption conversion and storage by connecting various energy domains could potentially meet the needs of each energy sector. It can also reduce the generation of surplus energy and unnecessary carbon emissions. As a result sector coupling an integrated energy system increases the acceptance of renewable energy in the traditional power system and makes it carbon neutral. However difficulties in large-scale integration low conversion efficiency and economic feasibility remain obstacles. This perspective paper discusses the background definition and components of sector coupling as well as its functions and examples in rendering power systems carbon-neutral. The current limitations and outlook of sector coupling are also examined.

Fossil resources are unevenly distributed on the earth and are finite primary energy which is widely used in the fields of industry transportation and power generation etc.<br/>Primary energies that can replace fossil resources include renewable energy and nuclear energy. Hydrogen has the potential to be secondary energy that can be widely used in industry for various purposes. Nuclear energy can be used for producing hydrogen; it is becoming more important to convert this primary energies into hydrogen. This paper describes the roles of nuclear energy as a primary energy in hydrogen production from the viewpoint of the basics of energy form conversion.

Decarbonising economies and improving environment can be enhanced through circular economy energy and environmental systems integrating electricity water and gas utilities. Hydrogen production can facilitate intermittent renewable electricity through reduced curtailment of electricity in periods of over production. Positioning an electrolyser at a wastewater treatment plant with existing sludge digesters offers significant advantages over stand-alone facilities. This paper proposes co-locating electrolysis and biological methanation technologies at a wastewater treatment plant. Electrolysis can produce oxygen for use in pure or enhanced oxygen aeration offering a 40% reduction in emissions and power demand at the treatment facility. The hydrogen may be used in a novel biological methanation system upgrading carbon dioxide (CO2)in biogas from sludge digestion yielding a 54% increase in biomethane production. A 10MW electrolyser operating at 80% capacity would be capable of supplying the oxygen demand for a 426400 population equivalent wastewater treatment plant producing 8500 tDS/a of sludge. Digesting the sludge could generate 1409000 m 3 CH4/a and 776000 m 3 CO2/a. Upgrading the CO2 to methane would consume 22.2% of the electrolyser generated hydrogen and capture 1.534 ktCO2e/a. Hydrogen and methane are viable advanced transport fuels that can be utilised in decarbonising heavy transport. In the proposed circular economy energy and environment system sufficient fuel would be generated annually for 94 compressed biomethane gas (CBG) heavy goods vehicles (HGV) and 296 compressed hydrogen gas fuel cell (CHG) HGVs. Replacement of the equivalent number of diesel HGVs would offset approximately 16.1 ktCO2e/a.

The integrated energy system with electric vehicles can realize multi-energy coordination and complementarity and effectively promote the realization of low-carbon environmental protection goals. However the temporary change of vehicle travel plan will have an adverse impact on the system. Therefore a multi-layer coordinated optimization strategy of electric-thermal-hydrogen integrated energy system including vehicle to grid (V2G) load feedback correction is proposed. The strategy is based on the coordination of threelevel optimization. The electric vehicle charging and discharging management layer comprehensively considers the variance of load curve and the dissatisfaction of vehicle owners and the charging and discharging plan is obtained through multi-objective improved sparrow search algorithm which is transferred to the model predictive control rolling optimization layer. In the rolling optimization process according to the actual situation selectively enter the V2G load feedback correction layer to update V2G load so as to eliminate the impact of temporary changes in electric vehicle travel plans. Simulation results show that the total operating cost with feedback correction is 4.19% lower than that without feedback correction and tracking situation of tie-line planned value is improved which verifies the proposed strategy.

Water electrolysis is a process which converts electricity into hydrogen and is seen as a key technology in enabling a net-zero compatible energy system. It will enable the scale-up of renewable electricity as a primary energy source for heating transport and industry. However displacing the role currently met by fossil fuels might require a price of hydrogen as low as 1 $/kg whereas renewable hydrogen produced using electrolysis is currently 10 $/kg. This article explores how mass manufacturing of proton exchange membrane (PEM) electrolysers can reduce the capital cost and thus make the production of renewable power to hydrogen gas (PtG) more economically viable. A bottom up direct manufacturing model was developed to determine how economies of scale can reduce the capital cost of electrolysis. The results demonstrated that (assuming an annual production rate of 5000 units of 200 kW PEM electrolysis systems) the capital cost of a PEM electrolysis system can reduce from 1990 $/kW to 590 $/kW based on current technology and then on to 431 $/kW and 300 $/kW based on the an installed capacity scale-up of ten- and one-hundred-fold respectively. A life-cycle costing analysis was then completed to determine the importance of the capital cost of an electrolysis system to the price of hydrogen. It was observed that based on current technology mass manufacturing has a large impact on the price of hydrogen reducing it from 6.40 $/kg (at 10 units units per year) to 4.16 $/kg (at 5000 units per year). Further analysis was undertaken to determine the cost at different installed capacities and found that the cost could reduce further to 2.63 $/kg and 1.37 $/kg based on technology scale-up by ten- and one hundred-fold respectively. Based on the 2030 (and beyond) baseline assumptions it is expected that hydrogen production from PEM electrolysis could be used as an industrial process feed stock provide power and heat to buildings and as a fuel for heavy good vehicles (HGVs). In the cases of retrofitted gas networks for residential or industrial heating solutions or for long distance transport it represents a more economically attractive and mass-scale compatible solution when compared to electrified heating or transport solutions.

To abate climate change and ameliorate the air quality in urban areas innovative solutions are required to reduce CO2 and pollutant emissions from traffic. Alternative fuels made from biomass or CO2 and hydrogen can contribute to these goals by substituting fossil gasoline or diesel in combustion engines. Using a conjoint analysis approach the current study investigates preferences of laypeople (n = 303) for fuel production facilities in terms of siting location plant size raw material used in the production and raw material transport. The location was most decision-relevant followed by raw material transport whereas plant size and type of raw material played a less prominent role for the preference choice. The best-case scenario from the point of view of acceptance would be the installation of a rather small bio-hybrid fuel production plant in an industrial area (instead of an agricultural or pristine environment). No transport or transport via underground pipeline were preferred over truck/tank car or overground pipeline. The findings can be used as a basis for planning and decision-making for designing production networks for new fuel types.

Hydrogen direct reduction has been proposed as a means to decarbonize primary steelmaking. Preferably the hydrogen necessary for this process is produced via water electrolysis. A downside to electrolysis is the large electricity demand. The electricity cost of water electrolysis may be reduced by using a hydrogen storage to exploit variations in electricity price i.e. producing more hydrogen when the electricity price is low and vice versa. In this paper we compare two kinds of hydrogen storages in the context of a hydrogen direct reduction process via simulations based on historic Swedish electricity prices: the storage of gaseous hydrogen in an underground lined rock cavern and the storage of hydrogen chemically bound in methanol. We find the methanol-based storages to be economically advantageous to lined rock caverns in several scenarios. The main advantages of methanol-based storage are the low investment cost of storage capacity and the possibility to decouple storage capacity from rate capacity. Nevertheless no storage option is found to be profitable for historic Swedish electricity prices. For the storages to be profitable electricity prices must be volatile with relatively frequent high peaks which has happened rarely in Sweden in recent years. However such scenarios may become more common with the expected increase of intermittent renewable power in the Swedish electricity system.

This paper presents the application of a multidisciplinary approach for the preliminary design and evaluation of the potential improvements in performance and environmental impact through the utilization of compressed (CGH2) and liquefied (LH2) hydrogen fuel for a civil tilt-rotor modelled after the NASA XV-15. The methodology deployed comprises models for rotorcraft flight dynamics engine performance flight path analysis hydrogen tank and thermal management system sizing. Trade-offs between gravimetric efficiency energy consumption fuel burn CO2 emissions and cost are quantified and compared to the kerosene-fuelled rotorcraft. The analysis carried out suggests that for these vehicle scales gravimetric efficiencies of the order of 13% and 30% can be attained for compressed and liquid hydrogen storage respectively leading to reduced range capability relative to the baseline tilt-rotor by at least 40%. At mission level it is shown that the hydrogen-fuelled configurations result in increased energy consumption by at least 12% (LH2) and 5% (CGH2) but at the same time significantly reduced life-cycle carbon emissions compared to the kerosene counterpart. Although LH2 storage at cryogenic conditions has a higher gravimetric efficiency than CGH2 (at 700 bar) it is shown that for this class of rotorcraft the latter is more energy efficient when the thermal management system for fuel pressurization and heating prior to combustion is accounted for.

Political decarbonisation commitments and outcompeting renewable electricity costs are disrupting energy systems. This foresight study prepares stakeholders for this dynamic reactive change by examining visions that constitute a probable plausible and possible component of future energy systems. Visions were extrapolated through an expert review of energy technologies and Australian case studies. ‘Probable–Abundant’ envisages a high penetration of solar and wind with increased value of balancing services: batteries pumped hydro and transmission. This vision is exemplified by the South Australian grid where variable and distributed sources lead generation. ‘Plausible–Traded’ envisages power and power fuel exports given hydrogen and high-voltage direct-current transmission advances reflected by public and private sector plans to leverage rich natural resources for national and intercontinental exchanges. ‘Possible–Zero’ envisages the application of carbon removal and nuclear technologies in response to the escalating challenge of deep decarbonisation. The Australian critical minerals strategy signals adaptations of high-emission industries to shifting energy resource values. These visions contribute a flexible accessible framework for diverse stakeholders to discuss uncertain energy systems changes and consider issues from new perspectives. Appraisal of preferred futures allows stakeholders to recognise observed changes as positive or negative and may lead to new planning aspirations.

Today in the field of energy the main goal is to reduce emissions with 7 the aim of maintaining a clean environment. To reduce energy consumption 8 from fossil fuels new tools for micro-grids have been proposed. In the context 9 of multi-vector energy management systems the present work proposes an 10 optimal scheduler based on genetic algorithms to manage flexible assets in the 11 energy system such as energy storage and manageable demand. This tool is 12 applied to a case study for a Spanish technology park (360 kW consumption 13 peak) with photovoltaic and wind generation (735 kW generation peak) 14 hydrogen production (15 kW) and electric and fuel cell charging stations. 15 It provides an hourly day-ahead scheduling for the existing flexible assets: 16 the electrolyser the electric vehicle charging station the hydrogen refuelling 17 station and the heating ventilation and air conditioning system in one 18 building of the park. 19 A set of experiments is carried out over a period of 14 days using real 20 data and performing computations in real time in order to test and validate 21 the tool. The analysis of results show that the solution maximises the use of 22 local renewable energy production (demand is shifted to those hours when 23 there is a surplus of generation) which means a reduction in energy costs 24 whereas the computational cost allows the implementation of the tool in real 25 time.

Autoignition risk in initially non-premixed flowing systems such as premixing ducts must be assessed to help the development of low-NOx systems and hydrogen combustors. Such situations may involve randomly fluctuating inlet conditions that are challenging to model in conventional mixture-fraction-based approaches. A Computational Fluid Dynamics (CFD)-based surrogate modelling strategy is presented here for fast and accurate predictions of the stochastic autoignition behaviour of a hydrogen flow in a hot air turbulent co-flow. The variability of three input parameters i.e. inlet fuel and air temperatures and average wall temperature is first sampled via a space-filling design. For each sampled set of conditions the CFD modelling of the flame is performed via the Incompletely Stirred Reactor Network (ISRN) approach which solves the reacting flow governing equations in post-processing on top of a Large Eddy Simulation (LES) of the inert hydrogen plume. An accurate surrogate model namely a Gaussian Process is then trained on the ISRN simulations of the burner and the final quantification of the variability of autoignition locations is achieved by querying the surrogate model via Monte Carlo sampling of the random input quantities. The results are in agreement with the observed statistics of the autoignition locations. The methodology adopted in this work can be used effectively to quantify the impact of fluctuations and assist the design of practical combustion systems. © 2022 The Authors. Published by Elsevier Inc. on behalf of The Combustion Institute.

: In the last decade with the increased concerns about the global environment attempts have been made to promote the replacement of fossil fuels with sustainable sources. For transport which accounts for around a quarter of total greenhouse gas emissions meeting climate neutrality goals will require replacing existing fleets with electric or hydrogen-propelled vehicles. However the lack of adequate decision support approach makes the introduction of new propulsion technologies in the transportation sector a complex strategic decision problem where distorted non-optimal decisions may easily result in long-term negative effects on the performance of logistic operators. This research addresses the problem of transport fleet renewal by proposing a multi-criteria decision-making approach and takes into account the multiple propulsion technologies currently available and the objectives of the EU Green Deal as well as the inherent scenario uncertainty. The proposed approach based on the TOPSIS model involves a novel decision framework referred to as a generalized life cycle evaluation of the environmental and cost objectives which is necessary when comparing green and traditional propulsion systems in a long-term perspective to avoid distorted decisions. Since the objective of the study is to provide a practical methodology to support strategic decisions the framework proposed has been validated against a practical case referred to the strategic fleet renewal decision process. The results obtained demonstrate how the decision maker’s perception of the technological evolution of the propulsion technologies influences the decision process thus leading to different optimal choices.

The ‘deep’ decarbonization of the residential sector is a priority for meeting national climate change targets especially in countries such as the UK where natural gas has been the dominant fuel source for over half a century. Hydrogen blending and repurposing the national grid to supply low-carbon hydrogen gas may offer respective short- and long-term solutions to achieving emissions reduction across parts of the housing sector. Despite this imperative the social acceptance of domestic hydrogen energy technologies remains underexplored by sustainability scholars with limited insights regarding consumer perceptions and expectations of the transition. A knowledge deficit of this magnitude is likely to hinder effective policymaking and may result in sub-optimal rollout strategies that derail the trajectory of the net zero agenda. Addressing this knowledge gap this study develops a conceptual framework for examining the consumer-facing side of the hydrogen transition. The paper affirms that the spatiotemporal patterns of renewable energy adoption are shaped by a range of interacting scales dimensions and factors. The UK’s emerging hydrogen landscape and its actor-network is characterized as a heterogenous system composed of dynamic relationships and interdependencies. Future studies should engage with domestic hydrogen acceptance as a co-evolving multi-scalar phenomenon rooted in the interplay of five distinct dimensions: attitudinal socio-political community market and behavioral acceptance. If arrived to behavioral acceptance helps realize the domestication of hydrogen heating and cooking established on grounds on cognitive sociopolitical and sociocultural legitimacy. The research community should internalize the complexity and richness of consumer attitudes and responses through a more critical and reflexive approach to the study of social acceptance.

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.

Hydrogen is regarded as a promising fuel in the transition to clean energy. Nevertheless as the demand for hydrogen increases some microgrids equipped with P2H (MGH) will encounter the issue of primary energy deficiency. Meanwhile some microgrids (MGs) face the difficulty of being unable to consume surplus energy locally. Hence we interconnect MGs with different energy characteristics and then establish a collaborative scheduling model of multi-microgrids (MMGs). In this model a federated demand response (FDR) program considering predictive mean voting is designed to coordinate controllable loads of electricity heat and hydrogen in different MGs. With the coordination of FDR the users’ satisfaction and comfort in each MG are kept within an acceptable range. To further adapt to an actual working condition of the microturbine (MT) in MGH a power interaction method is proposed to maintain the operating power of the MT at the optimum load level and shave peak and shorten the operating periods of MT. In the solution process the sequence operation theory is utilized to deal with the probability density of renewable energy. A series of case studies on a test system of MMG demonstrate the effectiveness of the proposed method.

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.

This paper presents a day-ahead economic optimization scheduling model for Regional Electricity–Hydrogen Integrated Energy System (REHIES) with high penetration of renewable energies. The electricity–hydrogen coupling devices are modelled with energy storage units and Insensitive Electrical Load (ISEL). The proposed objective function is able to capture the maximum benefits for REHIES in terms of economic benefits and can be summarized as a Quadratic Programming (QP) problem. The simulation verification is performed by MATLAB/CPLEX solver. The simulation results show that the proposed optimization model adapts the market requirement by contributing flexible collaboration between electricity and hydrogen. Also the translational properties of ISEL can implement higher economic profits and more effective utilization of renewable energy.

Hydrogen will be a central cross-sectoral energy carrier in the decarbonization of the European energy system. This paper investigates how a large-scale deployment of green hydrogen production affects the investments in transmission and generation towards 2060 analyzes the North Sea area with the main offshore wind projects and assesses the development of an offshore energy hub. Results indicate that the hydrogen deployment has a tremendous impact on the grid development in Europe and in the North Sea. Findings indicate that total power generation capacity increases around 50%. The offshore energy hub acts mainly as a power transmission asset leads to a reduction in total generation capacity and is central to unlock the offshore wind potential in the North Sea. The effect of hydrogen deployment on power prices is multifaceted. In regions where power prices have typically been lower than elsewhere in Europe it is observed that hydrogen increases the power price considerably. However as hydrogen flexibility relieves stress in high-demand periods for the grid power prices decrease in average for some countries. This suggests that while the deployment of green hydrogen will lead to a significant increase in power demand power prices will not necessarily experience a large increase.

Decarbonisation will need a significant societal shift. The when why and how we travel is going to look very different within a decade. Joining us is Florentine Roy – a leading expert on electric vehicles and Innovation Project Lead at UK Power Networks and Matt Hindle - Head of Net Zero and Sustainability at Wales and West Utilities. Let’s talk about the energy system implications of this massive undertaking and how it can be enabled by innovation in a fair and just way.

The podcast can be found here.

The development of more sustainable and zero-emissions collective transport solutions could play a very important measure in the near future within smart city policies. This paper tries to give a contribution to this aim proposing a novel approach to fuel cell vehicle design and operation. Traditional difficulties experienced in fuel cell transient operation are in fact normally solved in conventional vehicle prototypes through the hybridization of the propulsion system and with the complete fulfillment of transients in road energy demand through a high-capacity onboard energy storage device. This makes it normally necessary to use Li-ion battery solutions accepting their restrictions in terms of weight costs energy losses limited lifetime and environmental constraints. The proposed solution instead introduces a partitioning of the hydrogen fuel cell (FC) and novel optimal power control strategy with the aim of limiting the capacity of the energy storage still avoiding FC transient operation. The limited capacity of the resulting energy storage systems which instead has to answer higher power requests makes it possible to consider the utilization of a high-speed flywheel energy storage system (FESS) in place of high energy density Li-ion batteries. The proposed control strategy was validated by vehicle simulations based on a modular and parametric model; input data were acquired experimentally on an operating electric bus in real traffic conditions over an urban bus line. Simulation results highlight that the proposed control strategy makes it possible to obtain an overall power output for the FC stacks which better follows road power demands and a relevant downsizing of the FESS device.