Sweden

Hydrogen has become a strong candidate to be a future energy storage medium but there are technological challenges both in its production and storage. For storage a search for lightweight abundant and non-toxic materials is on the way. An abundant natural material such as wood cellulose would make an ideal storage medium from a sustainability perspective. Here using a combination of static DFT calculations and ab initio molecular dynamics simulations at different temperatures it is shown that wood cellulose has the ability to uptake H2 via a physisorption mechanism based on dispersion interactions of the van der Waals type involving the O-atoms of the d-glucose rings. The absorption causes little to no disturbances on the cellulose structure and H2 is highly mobile in the material. At an external pressure of H2(g) of 0.09 atm and T = 25 °C cellulose has a theoretical gravimetric density of hydrogen storage of ≈1%.

Efficient and robust control strategies can greatly contribute to the reliability of fuel cell systems and a stable output voltage is a key criterion for evaluating a fuel cell system's reliability as a power source. In this study a polymer electrolyte fuel cell (PEFC) system model is developed and its performances under different operating conditions are studied. Then two different novel controllers—a proportional integral derivative (PID) controller and a model predictive control (MPC) controller—are proposed and applied in the PEFC system to control its output voltage at a desired value by regulating the hydrogen and air flow rates at the same time which features a multi‐input and single‐output control problem. Simulation results demonstrate that the developed PEFC system model is qualified to capture the system's behaviour. And both the developed PID and MPC controllers are effective at controlling the PEFC system's output voltage. While the MPC controller presents superior performance with faster response and smaller overshoot. The proposed MPC controller can be easily employed in various control applications for fuel cell systems.

Bioenergy with carbon capture and storage (BECCS) is one of the prevailing negative carbon emission technologies. Ensuring a hydrogen economy is essential to achieving the carbon-neutral goal. In this regard the present study contributed by proposing a carbon negative process for producing high purity hydrogen from the organic fraction of municipal solid waste (OFMSW). This integrated process comprises anaerobic digestion pyrolysis catalytic reforming water-gas shift and pressure swing adsorption technologies. By focusing on Sweden the proposed process was developed and evaluated through sensitivity analysis mass and energy balance calculations techno-economic assessment and practical feasibility analysis. By employing the optimum operating conditions from the sensitivity analysis 72.2 kg H2 and 701.47 kg negative CO2 equivalent emissions were obtained by treating 1 ton of dry OFMSW. To achieve these results 6621.4 MJ electricity and 325 kg of steam were utilized during this process. Based on this techno-economic assessment of implementing the proposed process in Stockholm when the negative CO2 equivalent emissions are recognized as income the internal rate of return and the discounted payback period can be obtained as 26% and 4.3 years respectively. Otherwise these values will be 13% and 7.2 years.

Wind power is rapidly growing in the Finnish grid and Finland’s electricity consumption is low in the summer compared to the winter. Hence there is a need for storage that can absorb a large amount of energy during summer and discharge it during winter. This study examines one such storage technology geological hydrogen storage which has the potential to store energy on a GWh scale and also over longer periods of time. Finland’s electricity generation system was modelled with and without hydrogen storage using the LEAP-NEMO modeling toolkit. The results showed about 69% decline in carbon dioxide emissions as well as a decline in the fossil fuel-based power accompanied with a higher capability to meet demand with less imports in both scenarios. Finally a critical analysis of the Finnish electricity mix with and without hydrogen storage is presented.

With the move to a hydrogen-based primary steel production envisioned for the near future in Europe existing regional industrial clusters loose major assets. Such a restructuring of industries may result in a new geographical distribution of the steel industry and also to another quality of vertical integration at sites. Both implications could turn out as drivers or barriers to invest in new technologies and are thus important in respect to vertical integration of sites and to regional policy. This paper describes an approach to model production stock invest for the steel industries in North-Western Europe. Current spatial structures are reproduced with capacity technical and energy efficiency data on the level of single facilities like blast furnaces. With the model developed both investments in specific technologies and at specific production sites can be modelled. The model is used to simulate different possible future scenarios. The case with a clear move to hydrogen-based production is compared to a reference scenario without technological shift. The scenarios show that existing trends like movement of production to the coast may be accelerated by the new technology but that sites in the hinterland can also adapt to a hydrogen economy. Possible effects of business cycles or a circular economy on regional value chains are explored with a Monte-Carlo analysis.

It is now well established that electrochemical systems can optimally perform only within a narrow range of temperature. Exposure to temperatures outside this range adversely affects the performance and lifetime of these systems. As a result thermal management is an essential consideration during the design and operation of electrochemical equipment and can heavily influence the success of electrochemical energy technologies. Recently significant attempts have been placed on the maturity of cooling technologies for electrochemical devices. Nonetheless the existing reviews on the subject have been primarily focused on battery cooling. Conversely heat transfer in other electrochemical systems commonly used for energy conversion and storage has not been subjected to critical reviews. To address this issue the current study gives an overview of the progress and challenges on the thermal management of different electrochemical energy devices including fuel cells electrolysers and supercapacitors. The physicochemical mechanisms of heat generation in these electrochemical devices are discussed in-depth. Physics of the heat transfer techniques currently employed for temperature control are then exposed and some directions for future studies are provided.

It is a common belief that embedded expanding inclusions are subjected to an internal homogeneous compressive hydrostatic stress. Still cracks that appear in precipitates that occupy a larger volume than the original material are frequently observed. The appearance of cracks has since long been regarded as a paradox. In the present study it is shown that matrix materials that increases its volume even several percent during the precipitation process develop a tensile hydrostatic stress in the centre of the precipitate. This is the result of a complicated mechanical-chemical phase transformation process. The process is here studied using a Landau phase feld model. Before the material is transformed and incorporated in a precipitate it undergoes stretching beyond the elastic strain limit because of the presence of already expanded material. During the phase transformation the accompanying volumetric expansion cannot be fully accommodated which instead creates an internal compressive stress and adds tension in the surrounding material. As the growth of the precipitate proceeds a region with increasing tensile stress develops in the interior of the precipitate. This is suggested to be the most probable cause of the observed cracks. First the mechanics that lead to the tension is computed. The infuence of elastic-plastic properties is studied both for cases both with and without cracks. The growth history from microscopic to macroscopic precipitates is followed and the result is compared with observations of so called hydride blisters that are formed on surfaces of zirconium alloys in the presence of hydrogen. A common practical situation is when the zirconium is in contact with an object of lower temperature. Then the cooled spot attracts hydrogen that make the zirconium transform to a metal hydride with the shape of a blister. The simulations predicts a final size and position of the growing crack that compares well with the experimental observations.

A model for a fuel cell propelled 50 PAX hydrogen aircraft is developed. In terms of year 2045 Nordic air travel demand this aircraft is expected to cover 97% of travel distances and 58% of daily passenger volume. Using an ATR 42 as a baseline cryogenic tanks and fuel cell stacks are sized and propulsion system masses updated. Fuselage and wing resizing are required which increases mass and wetted area. Sizing methods for the multi-stack fuel cell and the cryogenic tanks are implemented. The dynamic aircraft model is updated with models for hydrogen consumption and tank pressure control. For the Multi-layer insulation (MLI) tank a trade study is performed. A ventilation pressure of 1.76 bar and 15 MLI layers are found to be optimal for the design mission. A return-without-refuel mission is explored where for a 10-hour ground hold 38.4% of the design range is retained out of the theoretically achievable 50%.

The investigation of the various heat management concepts using LH2 requires the development of a modeling environment coupling the cryogenic hydrogen fuel system with turbofan performance. This paper presents a numerical framework to model hydrogen-fueled gas turbine engines with a dedicated heat-management system complemented by an introductory analysis of the impact of using LH2 to precool and intercool in the compression system. The propulsion installations comprise Brayton cycle-based turbofans and first assessments are made on how to use the hydrogen as a heat sink integrated into the compression system. Conceptual tubular compact heat exchanger designs are explored to either precool or intercool the compression system and preheat the fuel to improve the installed performance of the propulsion cycles. The precooler and the intercooler show up to 0.3% improved specific fuel consumption for heat exchanger effectiveness in the range 0.5–0.6 but higher effectiveness designs incur disproportionately higher pressure losses that cancel-out the benefits.

Gaseous hydrogen for fuel cell electric vehicles must meet quality standards such as ISO 14687:2019 which contains maximal control thresholds for several impurities which could damage the fuel cells or the infrastructure. A review of analytical techniques for impurities analysis has already been carried out by Murugan et al. in 2014. Similarly this document intends to review the sampling of hydrogen and the available analytical methods together with a survey of laboratories performing the analysis of hydrogen about the techniques being used. Most impurities are addressed however some of them are challenging especially the halogenated compounds since only some halogenated compounds are covered not all of them. The analysis of impurities following ISO 14687:2019 remains expensive and complex enhancing the need for further research in this area. Novel and promising analyzers have been developed which need to be validated according to ISO 21087:2019 requirements.