Next Steps for Hydrogen - physics, technology and the future

Hydrogen has been proposed as a future energy carrier for more than 40 years. In recent decades, impetus has been given by the need to reduce global greenhouse gas emissions from vehicles. In addition, hydrogen has the potential to facilitate the large-scale deployment of variable renewables in the electricity system. Despite such drivers, the long-anticipated hydrogen economy is proving to be slow to emerge. This report stresses the role that physics and physics-based technology could play in accelerating the large-scale deployment of hydrogen in the energy system. Emphasis is given to the potential of cryogenic liquid hydrogen and the opportunities afforded by developments in nanoscience for hydrogen storage and use. The use of low-temperature liquid hydrogen opens up a technological opportunity separate from, but complementary with, energy applications. The new opportunity is the ability to cool novel materials into the superconducting state without the need to use significant quantities of expensive liquid helium. Two of the authors have previously coined the term “hydrogen cryomagnetics” for when liquid hydrogen is utilised in high-field and high-efficiency magnets. The opportunity for liquid hydrogen to displace liquid helium may be a relatively small business opportunity compared to global transport energy demands, but it potentially affords an opportunity to kick-start the wider commercial use of hydrogen. The report considers various important factors shaping the future for hydrogen, such as competing production methods and the importance of safety, but throughout it is clear that science and engineering are of central importance to hydrogen innovation and physics has an important role to play

Energy Storage Technology for Decentralised Energy Management: Future Prospects

The chapter provides a comparison of energy storage technologies in decentralised energy systems for energy management. The various costs, advantages and disadvantages of the storage technologies will be considered. System dynamics modelling will be used to analyse energy management within the decentralised renewable and storage systems. Additionally, the integration of hydrogen storage technology and the use of hydrogen as an energy carrier in a decentralised airport scenario will be highlighted and the arising advantages of a decentralised airport using novel electric planes powered by hydrogen are discussed

Heat extraction from HTS tape stacks applied in a superconducting motor in different cooling conditions

Abstract The heat is generated inside the stack of superconducting tapes mounted on the surface of the electrical machine rotor during its operation and magnetization. Cooling of such stack presents challenges because of the layered structure of both tape, and stack. Moreover, the tapes should be electrically isolated to minimize the AC losses, that assumes gluing them, rather than soldering. The calculations consider a conductive heat dissipation also through the rotor iron. Results show that: liquid nitrogen provides an effective cooling; the temperature of the stack shows complex distribution patterns with the gaseous coolant. Additional preventive measures were analyzed to keep the stack operational in vacuum conditions.</jats:p

Frequency-dependent demagnetisation rate of a shielded HTS tape stack

Abstract This work presents results of investigation of crossed-field demagnetization in 2G high temperature superconducting stacks at temperatures in the range of 77 - 20 K and in a variable frequency, corresponding to the particular rotor application. We propose a method to reduce the demagnetization rate for a given stack configuration necessary for the superconducting rotor operating at a cryogenic temperature. This technique involves 3-D wrapping the stack of tapes with perpendicular layers of similar superconducting properties. Previous ‘proof of concept’ studies documented some improvements in flux demagnetisation reduction for basic configuration. In the present study a more advanced approach based on magnetic flux shielding is adopted. The presented results provide an important contribution to development for design solutions that aim to increase the operational time before remagnetisation of the stacks would be required.</jats:p

Field cooling magnetization and losses of an improved architecture of trapped-field superconducting rotor for aircraft applications

A hybrid electric configuration for aircraft propulsion can yield several advantages, reducing fuel consumption and take-off distance, improving control and decreasing emissions. For such a benign scenario to occur, advances destined to increase the power-to-weight ratio of actual electric motors must be developed. Superconducting technology offers the prospect of achieving such performance, but at the cost of increasing design and constructive complexity. In that sense, stacks consisting of piling up layers of high temperature superconductor have proven to trap high value current vortexes and thus can provide a source of magnetic flux density for torque production, without the need of current leads or other equipment in the rotor. However, these macroscopic currents must be induced prior to operation and then maintained undisturbed by any variation of the magnetic flux density in the airgap, which cause heating and demagnetization. This work presents the result of novel numerical computations on a new rotor architecture developed within the ASuMED project with the aim of facilitating the magnetization of the stacks from a superconducting stator and prevent their demagnetization during torque production. The performance of the machine is assessed, and the expected survivability of the stacks compared with laboratory measurements.EPSRC grant EP/P000738/

A methodology for techno-economic evaluation of asymmetric energy storage systems: A nuclear energy case study

This paper discusses a novel methodology for the analysis of energy storage system. This methodology combines engineering and economic modelling to assess the relative economic performance of plant designs within a simulated UK electricity market. It presents a case study that explores whether a nuclear power plant can be combined with a liquid air energy storage plant to allow the resultant hybrid plant to provide a load-following electricity supply. The approach adopted is distinct from much of the work on conventional load following nuclear power plant operations, as in our case the underlying nuclear energy production does not vary. The methodology expands the previous literature by performing market-led system optimisation to best design the output profile of the hybrid plant to improve economic performance in the UK electricity grid. Whilst this combined modelling approach has been demonstrated in the context of a specific plant design, this methodology might be applied to any asymmetric energy storage system to assess its economic viability. This work is both contrasting and complementary to the levelized cost of storage approach. Rather than providing the price at which energy must be sold to make a storage system economically viable, this approach considers how volatile the electricity spot market would have to become to make such a system profitable. The ability to explore different market conditions is a major omission from the existing literature on energy storage systems

Cross-field demagnetization of stacks of tapes: 3D modelling and measurements

Stacks of superconducting (SC) tapes can trap much higher magnetic fields than conventional magnets. This makes them very promising for motors and generators. However, ripple magnetic fields in these machines present a cross-field component that demagnetizes the stacks. At present, there is no quantitative agreement between measurements and modeling of cross-field demagnetization, mainly due to the need for a 3D model that takes the end effects and real micron-thick SC layer into account. This article presents 3D modeling and measurements of cross-field demagnetization in stacks of up to 5 tapes and initial magnetization modeling of stacks of up to 15 tapes. 3D modeling of the cross-field demagnetization explicitly shows that the critical current density, J$_{c}$, in the direction perpendicular to the tape surface does not play a role in cross-field demagnetization. When taking the measured anisotropic magnetic field dependence of J$_{c}$ into account, 3D calculations agree with measurements with less than a 4% deviation, while the error of 2D modeling is much higher. Then, our 3D numerical methods can realistically predict cross-field demagnetization. Due to the force-free configuration of part of the current density, J, in the stack, better agreement with experiments will probably require measuring the J$_{c}$ anisotropy for the whole solid angle range, including J parallel to the magnetic field

Distribution of Trapped Magnetic Flux in Superconducting Stacks Magnetised by Angled Field

Abstract: Some novel energy applications require the use of complex shapes of stacks of superconducting tapes as trapped-flux magnets. A trapped-flux magnet magnetised in a superconducting motor may experience an angled magnetising field rather than a field normal to its surface. This will affect the trapped magnetic flux distribution. This work presents the results of the numerical and experimental analyses of the stacks magnetised in an angled magnetic field. The finite element model using H-formulation is developed to compute the induced superconducting currents. The measurements are performed on stacks with different thicknesses and with different orientations against a magnetising field. The resulting distribution of the magnetic flux as well as the electric currents is computed, presented and discussed in details. The importance of the observed distribution patterns is assessed in the context of the implementation of such stacks in a fully superconducting electric motor

Inkjet Printing Infiltration of the Doped Ceria Interlayer in Commercial Anode-Supported SOFCs.

Single-step inkjet printing infiltration with doped ceria Ce0.9Ye0.1O1.95 (YDC) and cobalt oxide (CoxOy) precursor inks was performed in order to modify the properties of the doped ceria interlayer in commercial (50 × 50 × 0.5 mm3 size) anode-supported SOFCs. The penetration of the inks throughout the La0.8Sr0.2Co0.5Fe0.5O3-δ porous cathode to the Gd0.1Ce0.9O2 (GDC) interlayer was achieved by optimisation of the inks' rheology jetting parameters. The low-temperature calcination (750 °C) resulted in densification of the Gd-doped ceria porous interlayer as well as decoration of the cathode scaffold with nanoparticles (~20-50 nm in size). The I-V testing in pure hydrogen showed a maximum power density gain of ~20% at 700 °C and ~97% at 800 °C for the infiltrated cells. The latter effect was largely assigned to the improvement in the interfacial Ohmic resistance due to the densification of the interlayer. The EIS study of the polarisation losses of the reference and infiltrated cells revealed a reduction in the activation polarisations losses at 700 °C due to the nano-decoration of the La0.8Sr0.2Co0.5Fe0.5O3-δ scaffold surface. Such was not the case at 800 °C, where the drop in Ohmic losses was dominant. This work demonstrated that single-step inkjet printing infiltration, a non-disruptive, low-cost technique, can produce significant and scalable performance enhancements in commercial anode-supported SOFCs

Experimental characterization and elementary reaction modeling of solid oxide electrolyte direct carbon fuel cell

A detailed mechanistic model for solid oxide electrolyte direct carbon fuel cell (SO-DCFC) is developed while considering the thermo-chemical and electrochemical elementary reactions in both the carbon bed and the SOFC, as well as the meso-scale transport processes within the carbon bed and the SOFC electrode porous structures. The model is validated using data from a fixed bed carbon gasification experiment and the SO-DCFC performance testing experiments carried out using different carrier gases and at various temperatures. The analyzes of the experimental and modeling results indicate the strong influence of the carrier gas on the cell performance. The coupling between carbon gasification and electrochemical oxidation on the SO-DCFC performance that results in an unusual transition zone in the cell polarization curve was predicted by the model, and analyzed in detail at the elementary reaction level. We conclude that the carbon bed physical properties such as the bed height, char conversion ratio and fuel utilization, as well as the temperature significantly limit the performance of the SO-DCFC.National Natural Science Foundation (China) (20776078)National Natural Science Foundation (China) (51106085)Low Carbon Energy University Alliance (LCEUA) (Seed Funding