Potential exergy storage capacity of salt caverns in the Cheshire basin using adiabatic compressed air energy storage

As the number of renewable energy sources connected to the grid has increased, the need to address the intermittency of these sources becomes essential. One solution to this problem is to install energy storage technologies on the grid to provide a buffer between supply and demand. One such energy storage technology is Compressed Air Energy Storage (CAES), which is suited to large-scale, long-term energy storage. Large scale CAES requires underground storage caverns, such as the salt caverns situated in the Cheshire Basin, UK. This study uses cavern data from the Cheshire Basin as a basis for performing an energy and exergy analysis of 10 simulated CAES systems to determine the exergy storage potential of the caverns in the Cheshire Basin and the associated work and power input and output. The analysis revealed that a full charge of all 10 caverns could store 25.32 GWh of exergy, which can be converted to 23.19 GWh of work, which requires 43.27 GWh of work to produce, giving a round trip efficiency of around 54%. This corresponds to an input power of 670.07 GW and an output power of 402.74 GW. The Cheshire Basin could support around 100 such CAES plants, giving a potential total exergy storage capacity of 2.53 TWh and a power output of 40 TW. This is a significant amount of storage which could be used to support the UK grid. The total exergy destroyed during a full charge, store, and discharge cycle for each cavern ranged from 299.02 MWh to 1600.00 MWh

Modelling, real-time simulation and control of automotive windscreen wiper systems for electronic control unit development

In recent years there has been a growth in the automotive industry, coupled with a growth in the amount of electronic components and systems in a modern vehicle. The higher amount of electronics has led to an increased amount of Electronic Control Units (ECU) in a vehicle which require advanced simulation based testing procedures throughout their development process. One such method is Hardware in the Loop (HIL) simulation in which a real ECU is connected to simulation models of its environment via a real-time simulator. This project is concerned with developing a plant model of a windscreen wiper system for use in the development of Jaguar Land Rover’s (JLR) body electronics ECU. The system is divided into four parts which are modelled separately: Wiper motor, linkages, arm and blades, and the windscreen environment. The wiper motor and mechanical elements models are derived and implemented using the physical modelling tools SimScape and SimMechanics. A dynamic friction model describing the interaction between the wiper blades and the windscreen is developed, based on results presented in the literature. A simple aerodynamic model describing the forces on the wiper blades is also established. The parameters of the models are derived using three sequential optimisation methods: Transfer function parameter identification, Genetic Algorithms (GA) and a nonlinear least squares local optimiser. A transfer function relating the motor current to the voltage was derived for step one, and a bespoke GA has been developed for step two. The parameters were successfully identified. Following this, Artificial Neural Networks (ANN) were used to convert the physical models into real-time capable models suitable for HIL simulation. Finally, adaptive control systems are designed in order to maintain the motor at a constant velocity. The models are presented in a Simulink library and graphical user interface modelling tool for ease of use

A new scroll-type air motor with magnetic spirals

The scroll-type air motor, also named the scroll expander, has been widely used for different applications due to its characteristics of compact structure and high energy conversion efficiency. However, the leakage and the friction result in non-negligible energy losses. This paper presents the recent work on developing a new scroll-type air motor with mounted permanent magnetic spirals and investigates its potential in leakage reduction and efficiency improvement, especially at low-pressure air supply conditions. A method for the implementation of the magnetic scroll air motor is proposed. A prototype is manufactured, and initial experimental tests are conducted to study the generalized torque distribution. A mathematical model for the magnetic scroll air motor is developed, and a corresponding simulation study is presented. The study shows that the proposed magnetic scroll air motor structure is feasible in terms of manufacturing and has the potential to reduce the air leakage and, thus, to improve the energy efficiency by a maximum of around 15% at a supply pressure of 2 × 10 5 Pa, with a flank leakage clearance reference of 0.06 mm

Feasibility study of a simulation software tool development for dynamic modelling and transient control of adiabatic compressed air energy storage with its electrical power system applications

The field of large-scale electrical energy storage is growing rapidly in both academia and industry, which has driven a fast increase in the research and development on adiabatic compressed air energy storage. The significant challenge of adiabatic compressed air energy storage with its thermal energy storage is in the complexity of the system dynamic characteristics arising from the multi-physical (pneumatic, thermal, mechanical and electrical) processes. This has led to a strong demand for simulation software tools specifically for dynamic modelling and transient control of relevant multi-scale components, subsystems and whole systems with different configurations. The paper presents a feasibility study of a simulation tool development implemented by the University of Warwick Engineering team to achieve this purpose. The developed tool includes a range of validated simulation models from the fields of pneumatics, thermodynamics, heat transfer, electrical machines and power grids. The structure of the developed tool is introduced and a component library is built up on the Matlab/Simulink platform. The mathematical descriptions of key components are presented, which precedes a presentation of four case studies of different applications. The case studies demonstrate that the simulation software tool can be used for dynamic modelling of multi-scale adiabatic compressed air energy storage components and systems, real performance analysis, dynamic control strategy implementation and feasibility studies of applications of adiabatic compressed air energy storage integrated with power grids. The paper concludes that the continued development and use of such a tool is both feasible and valuable

Potential and distribution of transplanted hematopoietic stem cells in a nonablated mouse model

Increasingly, allogeneic and even more often autologous bone marrow transplants are being done to correct a wide variety of diseases. In addition, autologous marrow transplants potentially provide an opportune means of delivering genes in transfected, engrafting stem cells. However, despite its widespread clinical use and promising gene therapy applications, relatively little is known about the mechanisms of engraftment in marrow transplant recipients. This is especially so in the nonablated recipient setting. Our data show that purified lineage negative rhodamine 123/Hoechst 33342 dull transplanted hematopoietic stem cells engraft into the marrow of nonablated syngeneic recipients. These cells have multilineage potential, and maintain a distinct subpopulation with stem cell characteristics. The data also suggests a spatial localization of stem cell niches to the endosteal surface, with all donor cells having a high spatial affinity to this area. However, the level of stem cell engraftment observed following a transplant of stem cells was significantly lower than that expected following a transplant of the same number of unseparated marrow cells from which the purified cells were derived, suggesting the existence of a nonstem cell facilitator population, which is required in a nonablated syngeneic transplant setting

Study on the cleaning and cooling of solar photovoltaic panels using compressed airflow

Solar photovoltaics (PV) are becoming one of the main sources of renewable energy to reduce carbon emissions of electricity supply. It is well recognised that dust accumulation and high temperatures result in a dramatic reduction in the performance of PV panels. To improve the efficiency of solar PV panels, a compressed air-based regulation method which can simultaneously clean and cool PV panels is studied and tested. A modelling study of the dust adhesion and detachment mechanism is conducted and the temperature variation caused by the air blowing process is analysed. Dynamic models of the compressed air release are derived which can be used to guide the design of the regulation system for increasing PV power output. A test system is developed for verifying various design and system parameters. The test results are used to validate the suitability of the modelling and illustrate how the inefficiency arising from soiling and high temperatures can be mitigated with the regulated compressed airflow. PV arrays serving in an arid region are adopted for this study and the increased energy yield arising from the cleaning and cooling effects is evaluated via the experimental test. The relationship between the airflow duration, various sizes of particles cleaning from the surface and power generation efficiency improvement is investigated to maximise the net power output increase from the PV panel. The results of this study can contribute to improving PV efficiency and help to realise decarbonisation in energy industry

Cells Capable of Bone Production Engraft from Whole Bone Marrow Transplants in Nonablated Mice

Allogeneic and autologous marrow transplants are routinely used to correct a wide variety of diseases. In addition, autologous marrow transplants potentially provide opportune means of delivering genes in transfected, engrafting stem cells. However, relatively little is known about the mechanisms of engraftment in transplant recipients, especially in the nonablated setting and with regard to cells not of hemopoietic origin. In particular, this includes stromal cells and progenitors of the osteoblastic lineage. We have demonstrated for the first time that a whole bone marrow transplant contains cells that engraft and become competent osteoblasts capable of producing bone matrix. This was done at the individual cell level in situ, with significant numbers of donor cells being detected by fluorescence in situ hybridization in whole femoral sections. Engrafted cells were functionally active as osteoblasts producing bone before being encapsulated within the bone lacunae and terminally differentiating into osteocytes. Transplanted cells were also detected as flattened bone lining cells on the periosteal bone surface

Techno-economic analysis of bulk-scale compressed air energy storage in power system decarbonisation

Although the penetration of renewable energy in power systems has been substantially increased globally in the last decade, fossil fuels are still important in providing the essential flexibility required to reliably maintain the system balance. In 2019, more than one quarter of power generation in Europe and over 40% of the UK’s electricity generation was from fossil fuels (mainly gas). For achieving the net-zero greenhouse gas emission target around the middle of this century, these fossil fuels have to be decarbonised in the coming decades. Bulk-scale energy storage has been recognised as a key technology to overcome the reduced dispatchability associated with the decrease of fossil fuels in generation. Taking the UK power system as a case study, this paper presents an assessment of geological resources for bulk-scale compressed air energy storage (CAES), and an optimal planning framework for CAES in combination with solar and wind to replace fossil fuels in the power generation system. The analysis reveals up to 725 GWh of ready-to-use capacity by utilising existing underground salt caverns in the UK. These potential CAES sites with added solar and wind generation equal to the generation from fossil fuels in 2018 can reduce carbon emissions by 84% with a cost increase by 29%, compared to the system in 2018. The results indicate the plausibly achievable cost-effectiveness of CAES as bulk-scale energy storage for power system decarbonisation in countries the geological resources are available

Mathematical modelling of a system for solar PV efficiency improvement using compressed air for panel cleaning and cooling

The efficiency of solar photovoltaic (PV) panels is greatly reduced by panel soiling and high temperatures. A mechanism for eliminating both of these sources of inefficiencies is presented by integrating solar PV generation with a compressed air system. High-pressure air can be stored and used to blow over the surface of PV panels, removing present dust and cooling the panels, increasing output power. A full-system mathematical model of the proposed system is presented, comprised of compressed air generation and storage, panel temperature, panel cleaning, and PV power generation. Simulation results indicate the benefit of employing compressed air for cleaning and cooling solar PV panels. For a fixed volume of compressed air, it is advantageous to blow air over the panels early in the day if the panel is soiled or when solar radiation is most abundant with the highest achievable flow rate if the panel is clean. These strategies have been shown to achieve the greatest energy captures for a single PV panel. When comparing the energy for air compression to the energy gain from cleaning a single PV over a two-week period, an energy ROI of 23.8 is determined. The system has the potential to eliminate the requirement for additional manual cleaning of solar PV panels