Publications

We combine previously separate models of Northern European power markets local district heating and cooling (DHC²) systems and biomass supply in a single modelling framework to study local and system level impacts of bioenergy technologies in phasing out fossil fuels from a DHC system of the Finnish capital. We model multiple future scenarios and assess the impacts on energy security flexibility provision economic performance and emissions. In the case of Helsinki heat only boiler is a robust solution from economic and climate perspective but reduces local electricity self-sufficiency. Combined heat and power solution is more valuable investment for the system than for the city indicating a conflict of interest and biased results in system level models. Bringing a biorefinery near the city to utilize excess heat would reduce emissions and increase investment's profitability but biomass availability might be a bigger limiting factor. Our results show that the availability of domestic biomass resources constrains bio-based technologies in Southern Finland and further highlights the importance of considering both local and system level impacts. Novel option to boost biorefinery's production with hydrogen from excess electricity is beneficial with increasing shares of wind power.

The hydrogen economy has received resurging interest in recent years as more countries commit to net-zero CO₂ emissions around the mid-century. “Blue” hydrogen from natural gas with CO₂ capture and storage (CCS) is one promising sustainable hydrogen supply option. Although conventional CO₂ capture imposes a large energy penalty advanced process concepts using the chemical looping principle can produce blue hydrogen at efficiencies even exceeding the conventional steam methane reforming (SMR) process without CCS. One such configuration is gas switching reforming (GSR) which uses a Ni-based oxygen carrier material to catalyze the SMR reaction and efficiently supply the required process heat by combusting an off-gas fuel with integrated CO₂ capture. The present study investigates the potential of advanced La-Fe-based oxygen carrier materials to further increase this advantage using a gas switching partial oxidation (GSPOX) process. These materials can overcome the equilibrium limitations facing conventional catalytic SMR and achieve direct hydrogen production using a water-splitting reaction. Results showed that the GSPOX process can achieve mild efficiency improvements relative to GSR in the range of 0.6–4.1%-points with the upper bound only achievable by large power and H₂ co-production plants employing a highly efficient power cycle. These performance gains and the avoidance of toxicity challenges posed by Ni-based oxygen carriers create a solid case for the further development of these advanced materials. If successful results from this work indicate that GSPOX blue hydrogen plants can outperform an SMR benchmark with conventional CO₂ capture by more than 10%-points both in terms of efficiency and CO₂ avoidance.

The increasing ambition of climate targets creates a major role for hydrogen especially in achieving carbon-neutrality in sectors presently difficult to decarbonise. This work examines to what extent the currently carbon-intensive hydrogen production in Europe could be replaced by water electrolysis using electricity from renewable energy resources (RES) such as solar photovoltaic onshore/offshore wind and hydropower (green hydrogen). The study assesses the technical potential of RES at regional and national levels considering environmental constraints land use limitations and various techno-economic parameters. It estimates localised clean hydrogen production and examines the capacity to replace carbon-intensive hydrogen hubs with ones that use RES-based water electrolysis. Findings reveal that -at national level- the available RES electricity potential exceeds the total electricity demand and the part for hydrogen production from electrolysis in all analysed countries. At regional level from the 109 regions associated with hydrogen production (EU27 and UK) 88 regions (81%) show an excess of potential RES generation after covering the annual electricity demand across all sectors and hydrogen production. Notably 84 regions have over 50% excess RES electricity potential after covering the total electricity demand and that for water electrolysis. The study provides evidence on the option to decarbonize hydrogen production at regional level. It shows that such transformation is possible and compatible with the ongoing transition towards carbon–neutral power systems in the EU. Overall this work aims to serve as a tool for designing hydrogen strategies in harmony with renewable energy policies.

It is well-documented experimentally that the influence of hydrogen on the mechanical properties of structural alloys like austenitic stainless steels nickel superalloys and carbon steels strongly depends on temperature. A typical curve plotting any hydrogen-affected mechanical property as a function of temperature gives a temperature THEmax where the degradation of this mechanical property reaches a maximum. Above and below this temperature the degradation is less. Unfortunately the underlying physico-mechanical mechanisms are not currently understood to the level of detail required to explain such temperature effects. Though this temperature effect is important to understand in the context of engineering applications studies to explain or even predict the effect of temperature upon the mechanical properties of structural alloys could not be identified. The available experimental data are scattered significantly and clear trends as a function of chemistry or microstructure are difficult to see. Reported values for THEmax are in the range of about 200–340 K which covers the typical temperature range for the design of structural components of about 230–310 K (from −40 to +40 °C). That is the value of THEmax itself as well as the slope of the gradient might affect the materials selection for a dedicated application. Given the current lack of scientific understanding a statistical approach appears to be a suitable way to account for the temperature effect in engineering applications. This study reviews the effect of temperature upon hydrogen effects in structural alloys and proposes recommendations for test temperatures for gaseous hydrogen applications

Modern arc processes such as the modified spray arc (Mod. SA) have been developed for gas metal arc welding of high-strength structural steels with which even narrow weld seams can be welded. High-strength joints are subjected to increasingly stringent requirements in terms of welding processing and the resulting component performance. In the present work this challenge is to be met by clarifying the influences on hydrogen-assisted cracking (HAC) in a high-strength structural steel S960QL. Adapted samples analogous to the self-restraint TEKKEN test are used and analyzed with respect to crack formation microstructure diffusible hydrogen concentration and residual stresses. The variation of the seam opening angle of the test seams is between 30° and 60°. To prevent HAC the effectiveness of a dehydrogenation heat treatment (DHT) from the welding heat is investigated. As a result the weld metals produced at reduced weld opening angle show slightly higher hydrogen concentrations on average. In addition increased micro- as well as macro-crack formation can be observed on these weld metal samples. On all samples without DHT cracks in the root notch occur due to HAC which can be prevented by DHT immediately after welding.

Gas pipelines are exposed to operational loads combined with corrosive environment action during their long-term service. Complicated service conditions lead to a worsening of steel properties a reduction of serviceability of the whole object therefore a risk of its premature failure rises. Aware of the importance of the existing problem the aim of this study is the analysis of various mechanical properties of steels after their long-term operation on gas pipelines and detecting and evaluating fractographic signs of this degradation.<br/>Mechanical properties of operated pipe steels characterizing their brittle fracture resistance were significantly decreased. Delamination areas as one of a feature of brittle fracture were identified on the fracture surfaces of specimens after SSRT of the operated steels in corrosive environment. Fracture was initiated from the outer surface of the specimens along the boundaries of ferrite and pearlite grains with significant secondary cracking.<br/>The obvious texture in the steels affects noticeably the results of the impact tests. Higher KCV values for the specimens cut in the longitudinal direction relative to the pipe axis comparing with the specimens of transversal orientation were obtained. This was explained by different length of narrow pearlite strips alternated by wide ferrite bands and interrupted by individual ferrite grains depending on the orientation of the specimen fracture surface relative to the pipe axis. Thus a proper direction of specimen cutting to achieve the maximum sensitivity of KCV parameter to operational degradation of steels is discussed. The effect of specimen orientation on the results of the Charpy testing becomes much more pronounced with steel operation. Defects accumulated in steels during their service are preferentially oriented in the pipe axial direction along the boundaries between ferrite and pearlite strips. Analyzing the fracture surfaces of the Charpy specimens after their impact testing certain signs of embrittlement were found for long term operated steels in the form of delaminations varying in size and shape and some cleavage fragments. Furthermore their percentage of total fracture surface (generally formed by dimples) correlates well with a drop in the impact toughness. The established relationship could be the basis for the introduction of fractographic criteria of the steel serviceability.

Present work describes the failure analysis of cooling duct of a fighter aircraft. The analyzed chemical composition of cooling duct indicates that it is manufactured from Al-based alloy (AA 3003 or its equivalent). Microstructure of cooling duct displays the presence of two phases namely matrix and insoluble particles. The hardness values at different locations within damaged area of cooling duct reflect nearly same and consistent. The fracture surface of the cooling duct exhibits transgranular features and cracks with little branching. The analyzed hydrogen content in cooling duct is significantly higher (∼ 12 ppm) than the specified one (< 1 ppm). However the alloy used to fabricate cooling duct is not susceptible to typical hydrogen embrittlement. This shows hydrogen pick up during operation. The presence of cracks with branching does reflect features of hydrogen embrittlement. In addition striations indicative of fatigue features are also observed. It thus appears that the cooling duct has failed due to pick up of large amount of hydrogen as well as vibrational fatigue.

The realm of alkaline-based fuel cells has with the arrival of anionic exchange membrane fuel cells (AEMFCs) taken a great step to replace traditional liquid electrolyte alkaline fuel cells (AFCs). The following review summarises progress bottleneck issues and highlights the most recent research trends within the field. The activity of alkaline catalyst materials has greatly advanced however achieving long-term stability remains a challenge. Great AEMFC performances are reported though these are generally obtained through the employment of platinum group metals (PGMs) thus emphasising the importance of R&D related to non-PGM materials. Thorough design strategies must be utilised for all components to avoid a mismatch of electrochemical properties between electrode components. Lastly AEMFC optimisation challenges on the system-level will also have to be assessed as few application-size AEMFCs have been built and tested.

Keele University was chosen as the site for the HyDeploy project as it was seen as the site offered a high degree of control regarding safety functions high availability of operational data and minimal supply chain interfaces given that Keele University is the supplier transporter and distributer of natural gas at the site. The site was offered to the project as a living laboratory in line with the university's ambition to be at the forefront of energy innovation through the Smart Energy Network Demonstrator (SEND). Evidenced within this report is the supporting data that confirms the rationale for selecting Keele University and the necessary data to profile the section of the gas network which hydrogen will be injected into. The gas network at Keele University is segregated via the governor stations which regulate pressure within the network. The section of network which has been chosen for the HyDeploy project is the G3 network which is regulated by the G3 governor.

The widescale distribution of hydrogen through gas networks is promoted as a viable and cost-efficient option for optimising its application in heat industry and transport. It is a key step towards achieving decarbonisation targets in the UK. A key consideration before the injection of hydrogen into the UK gas networks is an assessment of the difference in hydrogen contaminants presence from different production methods. This information is essential for gas regulation and for further purification requirements. This study investigates the level of ISO 14687 Grade D contaminants in hydrogen from steam methane reforming proton exchange membrane water electrolysis and alkaline electrolysis. Sampling and analysis of hydrogen were carried out by the National Physical Laboratory following ISO 21087 guidance. The results of analysis indicated the presence of nitrogen in hydrogen from electrolysis and water carbon dioxide and particles in all samples analysed. The contaminants were at levels below or at the threshold limits set by ISO 14687 Grade D. This indicates that the investigated production methods are not a source of contaminants for the eventual utilisation of hydrogen in different applications including fuel cell electric vehicles (FCEV’s). The gas network infrastructure will require a similar analysis to determine the likelihood of contamination to hydrogen gas.