Standalone and hybridised flywheels for frequency response services: a techno-economic feasibility study

Frequency response services are one of the key components used by major electrical networks worldwide, acting to help control the frequency within set boundaries. Battery Energy Storage Systems (BESSs) are commonly deployed for this purpose; however, their potential is limited by susceptibility to cycle-based degradation and widely reported safety incidents. Flywheel Energy Storage Systems (FESSs) do not share these weaknesses and hence could be a potential candidate for longer-term participation in frequency response markets. This study presents the most in-depth and wide-ranging techno-economic analysis of the feasibility of FESSs for frequency response to date. Standalone FESSs are shown to be economically viable across a range of different specifications, achieving a positive Net Present Value (NPV) under varying economic conditions. At a capital cost of 500 GBP/kW with a discount rate of 4%, a 5C FESS can achieve an NPV of GBP 38,586 as a standalone unit. The complex trade-offs when considering hybridising FESSs and BESSs for this application are also investigated in-depth for the first time, again showing positive changes to NPV under various scenarios. Conversely, under some conditions, hybridisation can have a significant negative impact, showcasing the optimisation needed when considering hybrid systems. The impact of introducing a hybrid BESS varies from a low of decreasing the NPV of the system by GBP 97,955 to a high of increasing the NPV by GBP 119,621 depending on the configuration chosen. This comprehensive work provides the foundations for future research into FESS deployment for frequency response services and shows for the first time the circumstances under which deployment for this application would be both technically and economically viable

Sensitivity analysis of a wind farm with integrated flywheel energy storage

Integration of quick response energy storage with wind-based generation sites has the potential to enhance the performance of these sites. Flywheel Energy Storage Systems (FESSs) are ideally placed to be utilized in this way due to their long lifetime and high cyclability. The effectiveness of this integration is dependent on a set of variables and constraints. A sensitivity analysis has been conducted to investigate the effect of changing system variables on output metrics using a mathematical simulation model

Optimal compression of vibration data with lifting wavelet transform and context-based arithmetic coding

Publication in the conference proceedings of EUSIPCO, Kos island, Greece, 201

Sintering Kinetics of Plasma-Sprayed Zirconia TBCs

A model of the sintering exhibited by EB-PVD TBCs, based on principles of free energy minimization, was recently published by Hutchinson et al. In the current paper, this approach is applied to sintering of plasma-sprayed TBCs and comparisons are made with experimental results. Predictions of through-thickness shrinkage and changing pore surface area are compared with experimental data obtained by dilatometry and BET analysis respectively. The sensitivity of the predictions to initial pore architecture and material properties are assessed. The model can be used to predict the evolution of contact area between overlying splats. This is in turn related to the through-thickness thermal conductivity, using a previously-developed analytical model

Bosons in a Toroidal Trap: Ground State and Vortices

We study the Bose-Einstein condensate (BEC) in a 3-D toroidal Mexican hat trap. By changing the parameters of the potential, or the number of bosons, it is possible to modify strongly the density profile of the BEC. We consider the ground state properties for positive and negative scattering length and calculate the spectrum elementary excitations. We also discuss the macroscopic phase coherence and superfluidity of the BEC by analyzing vortex states and their stability.Comment: 15 pages + 4 figures, to be published in Phys. Rev.

Cost-benefits and environmental impact of the no-biopsy approach for the diagnosis of coeliac disease in adults

Objective: Recent evidence suggests that adult patients with IgA tissue transglutaminase levels of ≥10× the upper limit of normal could be accurately diagnosed with coeliac disease without undergoing endoscopy and biopsy. We aimed to evaluate the cost-benefits and the environmental impact of implementing the no-biopsy approach for diagnosing coeliac disease in clinical practice. Design: We calculated the overall direct and indirect costs of the conventional serology-biopsy approach and the no-biopsy approach for the diagnosis of coeliac disease based on the national average unit costs and the Office of National Statistics data. We further estimated the environmental impact of avoiding endoscopy based on the estimated greenhouse gas emissions from endoscopy. Results: Approximately 3000 endoscopies for suspected coeliac disease could be avoided each year in the UK. Implementing the no-biopsy approach for the diagnosis of coeliac disease in adults could save the National Health Service over £2.5 million in direct and indirect costs per annum and reduce endoscopy carbon footprint by 87 tonnes of CO2 per year, equivalent to greenhouse gas emissions from driving 222 875 miles, carbon emissions from charging over 10 million smartphones and the carbon sequestrated by 1438 trees grown for 10 years. Conclusion: The implementation of this non-invasive green approach could be an essential first step in the ‘Reduce’ strategy advocated by the British Society of Gastroenterology and other international endoscopy societies for sustainable endoscopy practice

Effect of alloy treatment and coiling temperature on microstructure and bending performance of ultra-high strength strip steel

Two different high strength B-containing microalloyed steel strips produced in industrial processing conditions, one treated with Ti and the other treated with Al, processed by controlled rolling, accelerated cooling and coiling in two different temperatures ranges [723 K to 733 K (450 °C to 460 °C)] and [633 K to 653 K (360 °C to 380 °C)] were subjected to bend testing. The Ti treated steel coiled at the higher temperature 733 K (460 °C) showed the best bending performance. The relatively softer (tensile strength of and even {112} in the sub-surface region as well as uniformity of through thickness texture of the rolled sheet improve the bendability. In the presence of crack initiators, like coarse and brittle TiN particles found in the Ti treated steel, a harder microstructure and the presence of Cube and Goss texture in the sub-surface layer, seen for the lower coiling temperature can cause local transgranular cleavage cracking. Finally the post-uniform elongation obtained from tensile testing and bendability follow a good correlation

Natural Orbitals and BEC in traps, a diffusion Monte Carlo analysis

We investigate the properties of hard core Bosons in harmonic traps over a wide range of densities. Bose-Einstein condensation is formulated using the one-body Density Matrix (OBDM) which is equally valid at low and high densities. The OBDM is calculated using diffusion Monte Carlo methods and it is diagonalized to obtain the "natural" single particle orbitals and their occupation, including the condensate fraction. At low Boson density, $na^3 < 10^{-5}$, where $n = N/V$ and $a$ is the hard core diameter, the condensate is localized at the center of the trap. As $na^3$ increases, the condensate moves to the edges of the trap. At high density it is localized at the edges of the trap. At $na^3 \leq 10^{-4}$ the Gross-Pitaevskii theory of the condensate describes the whole system within 1%. At $na^3 \approx 10^{-3}$ corrections are 3% to the GP energy but 30% to the Bogoliubov prediction of the condensate depletion. At $na^3 \gtrsim 10^{-2}$, mean field theory fails. At $na^3 \gtrsim 0.1$, the Bosons behave more like a liquid $^4$He droplet than a trapped Boson gas.Comment: 13 pages, 14 figures, submitted Phys. Rev.