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All-wheel-drive (AWD) multimotor electric powertrains offer greater potential for system performance, efficiency, and reliability improvements. In this article, a new AWD electric powertrain that can increase the overall powertrain efficiency and battery lifetime is introduced. The proposed powertrain is based on a compact and efficient flywheel-based kinetic energy recovery system (KERS) that overcomes most of the shortcomings of the conventional electric KERS. Here, a significant part of the mechanical power transfer takes place without conversion to electrical power. Therefore, a selectable fraction of the recoverable kinetic energy is processed by power electronics. Thus, no energy exchange is necessary between the battery and the powertrain during acceleration and deceleration, resulting in a reduced battery power rating. This article compares the proposed powertrain with a conventional AWD electric powertrain. Mathematical modeling and simulations based on the space vector method were used for both powertrains that show the advantage of the proposed powertrain over the conventional one. The experimental data are also presented from our proof of the concept laboratory setup.

Four-wheel-drive (4WD) full-electric powertrains offer great potential for vehicle performance and efficiency improvements. This study introduces a novel 4WD electric powertrain that significantly increases the overall powertrain performance and battery lifespan. The proposed powertrain benefits from a new compact and highly efficient flywheel-based kinetic energy recovery system (KERS) that enables us to overcome most of the shortcomings of the conventional battery-based KERS. The utilized KERS is capable of capturing or providing much higher mechanical power than its electrical power ratings. Meaning that, without overloading, the powertrain can capture more mechanical power than traction motors’ nominal values. Moreover, since a significant part of the energy exchange takes place in mechanical form, only a portion of the initial kinetic energy (slip energy) needs to be converted into electrical form and be processed electrically. In the proposed powertrain, there is no energy exchange necessary between the battery and the powertrain during each accelerations or braking event, thus also reducing the battery power rating. Mathematical modeling and simulations were performed using space vector modeling method for the proposed powertrain. The results prove the functionality of the proposed 4WD powertrain. Experimental results are also presented for the proof of the concept.

Freight wagons typically do not have an electrical train supply and state-of-the-art auxiliary energy generation systems as, e.g. axle generators on freight wagons lack the possibility for a cost-effective retrofit. However, emerging applications, as, e.g. anti-lock braking systems for freight trains or condition monitoring systems for the loaded goods, require electric power in the watt range. Therefore, a non-invasive auxiliary energy supply system with 22 W/dm 3 (360 mW/in 3 ) based on a non-coaxial eddy-current coupling is described and analysed in this study. It is a kinetic energy recovery system, which can extract power directly from the motion of a freight wagon's wheel. An air gap of 10 mm between the wheel and a permanent magnet rotor is set during operation, making the system a non-invasive one. A model for the transfer efficiency of the system is established and verified by measurements. The prototype including an optimised generator and an integrated active rectifier for generating a DC-output voltage is built and an electric power of 8 W can be extracted from a steel wheel moving with a surface speed of 22 m/s.

The active electromagnetic slip coupling kinetic energy recovery system (KERS), introduced in this paper, is potentially a cost effective, yet efficient method of energy transfer between a vehicle and a lightweight flywheel. The transferred torque, as well as the coupling status, is determined by controlling its windings currents. The proposed system can work at any slip safely, including negative and positive values, between the primary and the secondary shafts as the slip power is converted into electrical power, and thus can be recovered. The proposed KERS may be less costly and less complicated than flywheel batteries as it needs only one electric machine and one power electronic converter. Moreover, it is capable of capturing much more mechanical power than its electrical ratings. Furthermore, since a great part of the energy exchange takes place in mechanical form, only a fraction of the captured energy needs to be processed by the power electronic converter. In this paper, mathematical modeling and simulations are performed using the space vector modeling method. Also, for the proof of the concept prototype of the system has been built, tested, and the results are verified.

Transmotor-based flywheel energy exchange is a low-cost yet highly efficient method of energy transfer between vehicle wheels and a lightweight flywheel. This method utilizes one dual-rotor electric machine that enables us to overcome some of the shortcomings of the conventional electric kinetic energy recovery systems (KERS).The proposed system is capable of capturing far more mechanical power than its electrical power ratings. Furthermore, since a significant part of the energy exchange takes place in mechanical form, only a small fraction of the initial kinetic energy needs to be processed by the electrical energy storage device and the power electronic drive system. In this paper, the proposed Transmotor-based KERS has been compared with the conventional electric KERS. Mathematical modeling and simulations were performed using a space vector modeling method for both conventional electric KERS and the proposed system. Results show that the proposed system is capable of capturing a great part of kinetic energy of a vehicle during deceleration and storing it in a lightweight flywheel to be used for the next acceleration while keeping the electrical ratings of the KERS relatively low. Experimental results are also presented for the proof of the concept.

This paper describes a holistic development and testing approach for a battery electric vehicle (BEV) prototype based on a self-supporting body platform originating from a vehicle powered by an internal combustion engine. The topic was investigated in relation to the question of whether conversion of existing vehicle platforms is a viable approach in comparison to designing a new vehicle ab initio. The scope of work consisted of the development stage, followed by laboratory and on-road testing to verify the vehicle’s performance and driveability. The vehicle functionality targeted commercial daily use on urban routes. Based on the assumed technical requirements, the vehicle architecture was designed and components specified that included various sub-systems: electric motor powertrain, electronic control unit (ECU), high-voltage battery pack with battery management system (BMS), charging system, high and low voltage wiring harness and electrically driven auxiliary systems. Electric sub-systems were integrated into the existing vehicle on-board controller area network (CAN) bus by means of enhanced algorithms. The test methodology of the prototype electric vehicle included the vehicle range and energy consumption measurement using the EU legislative test cycle. Laboratory testing was performed at different ambient temperatures and for various characteristics of the kinetic energy recovery system. Functional and driveability testing was performed on the road, also including an assessment of overall vehicle durability. Based on the results of testing, it was determined that the final design adopted fulfilled the pre-defined criteria; benchmarking against competing solutions revealed favorable ratings in certain aspects.

Energy is the main driving force of an economy. Due to which many advancements in renewable energy technology have been witnessed over the decade. However, not all countries have efforts in the same direction and have continued using coal-based technology. These old technologies have a sizable energy wastage in the form of fuel thermal energy (Kinetic Energy). The said wastage can be harnessed by using a specifically designed recovery turbine deployed in the industrial stack. Keeping in mind the same, this research focuses on a mathematical model to develop the best-suited design for the utmost augmentation of the kinetic energy. A Convergent-Divergent nozzle with varying ratios of entry to the throat area (Aent/A*) and exit to the throat area (Ae/A*) were subjected to mathematical formulations. The combinations of Aent/A* and Ae/A* tested were (a)1.489 and 1.256 (b) 1.78 and 1.97 respectively. The results indicate that the combination “b” is a better option owing to the largest velocity augmentation. The maximum velocity at the throat was noted at 3.9 times the inlet velocity, which would result in a larger power output by the turbine positioned there. Post analysis of the Mach number (Ma), it was also concluded that the flow is incompressible, and no shockwaves were seen. The development of such a novel technology would result not only in financial saving for the industries but also reducing the environmental impact due to non-renewable sources of energy.

In this two-part work, an electric kinetic energy recovery system (e-KERS) for internal combustion engine vehicle (ICEV) is presented and its performance evaluated through numerical simulations. The KERS proposed is based on the use of a supercapacitor as energy storage, interfaced to a brushless machine through a properly designed power converter. In Part 1, the system is described and analysed, and the mathematical model used for the simulations is presented. For each component of the KERS, the real efficiency and the power or energy limitations are adequately considered. In Part 2, the energetic and economic advantages attainable by the proposed KERS are evaluated using MATLAB Simulink, considering a widely diffused passenger car and two reference driving cycles (ECE-15 and Artemis urban). Energy savings of the order of 20% were found, with a slight increase in vehicle weight (+2%) and with an overall commercial cost that would be compensated in 5 years thanks to the fuel economy improvement, to which corresponds an equal reduction of CO2 emissions. The low complexity of the system, never proposed for ICEV, the moderate weight of its components, and their availability on the market, make the solution presented ready for the introduction in current vehicle production.

This paper addresses the design of a bi-directional DC/DC power converter to interface a supercapacitor bank and a motor-generator unit. The design is based on an interleaved six legs topology in which the current is shared among six inductors to minimize their weight and cost, allowing, besides, a low switching frequency to lessen switching losses. The converter is conceived to be employed in an electric Kinetic Energy Recovery System for Internal Combustion Engine Vehicles. The system makes use of a supercapacitor as a storage system, and a motorgenerator unit connected to the drive shaft for vehicle acceleration and braking. The system uses available commercial devices, thus obtaining a cheap and high-efficiency conversion chain. It is shown how the design criteria differ from traditional interleaved converters. The same topology allows minimizing the input and output ripple and improving the reliability in case of fault as well. Losses are reduced both by sharing the currents and by a suitable control strategy, which allows more converters to be connected in parallel to increase the delivered power. Results, given in simulation, assess the stability and dynamic performance of the conversion circuit, showing a low current and voltage ripple in all operating conditions. © 2020, European Association for the Development of Renewable Energy, Environment and Power Quality (EA4EPQ). All rights reserved.

In recent studies, the dynamic response of a passenger car to a gyrostat was investigated for a series of driving manoeuvres, but the gyrostat was assumed to be rigidly supported, thus neglecting t...

Objectives: In this paper, design of the mechanical system and the kinematic analysis of the regenerative braking have been presented. The mechanism has been proposed to store brake energy in a spiral spring and release it back to the vehicle transmission. Methods/Statistical Analysis: First, the mechanism was modelled in Autodesk Inventor software package and the model then imported to Solid-Works Motion for kinematic analysis. The kinematic simulation was carried out for all the three modes of operation, viz. the idle mode, braking mode and the energy recovery mode. The analysis results were as per the desired output. Once the model was established, the individual components were transferred to ANSYS Static Structural to evaluate and optimize the design. Finally, the spiral spring being the main energy storing device was analyzed for variation in moment and deflection with its thickness and width. Findings: This concept of low-cost Kinetic Energy Recovery System (KERS) can store energy that is lost during braking in a spiral spring and release it smoothly to the vehicle whenever required. The paper presents the simple and lucid design of the mechanism that uses the combinations of planetary gear and one-way clutch. The system can be implemented on bicycle where use of other energy recovery techniques is restricted due to their various limitations. A sample calculation on amount of energy to be stored has been performed to find out the spring parameters so that the calculation can be replicated and the system can be customized for each vehicle. Application/Improvements: The designed setup is flexible and can be installed with ease on a wheel hub. This system will assist the driver during acceleration and thus will improve the overall performance of the vehicle. Keywords: Energy Harvesting, Flat Spiral Spring, Mechanism Design, Mechanical KERS, Regenerative Braking System

In this work, the authors evaluate the energetic and economic advantages connected to the implementation of an electric Kinetic Energy Recovery System (e-KERS) on an internal combustion engine vehicle (ICEV). The e-KERS proposed is based on the use of a supercapacitor (SC) as energy storage element, a brushless motor generator unit (MGU) for the conversion of the vehicle kinetic energy into electric energy (and vice versa), and a power converter properly designed to manage the power transfer between SC and MGU. The low complexity of the system proposed, the moderate volume and weight of the components selected for its assembly, together with their immediate availability on the market, make the solution presented ready for the introduction in current vehicle production. A widely diffused passenger car, endowed of a gasoline fuelled spark ignition engines, was selected for the evaluation of the advantage connected to the implementation of the e-KERS. The attainable energy saving, together with the related fuel economy, were evaluated on the basis of standard driving cycles by means of simulation performed using MatLab Simulink employing a model properly developed by the authors. It was found that the proposed KERS could allow substantial energy savings, to which correspond important fuel economy improvement together with a reduction of CO2 emissions. The achievable fuel economy and the cost of the KERS components allowed also to estimate the economic advantage of its implementation.

The aim of this work is to discuss the possibility to store energy on board electric vehicles by means of flywheels as alternative to common batteries. A detailed optimization of the power storage system for the mini-car Icar0 ZD-1 with a target autonomy of 50 km in urban context is carried out. A preliminary designed is then made considering the power consumption in urban context accounting for the full power-train energetic model. Material, geometry and motor have been selected to fit all the vehicle space requirements considering also that flywheels operate in vacuum environment. In particular, attention is focused on some critical aspects like the effect of vibrations transmitted to the flywheel. For this reason, induced gyroscopic effects are considered both in straight and during turns. Finally, a possible bearing configuration is presented.

Electric mobility can represent a game changing technology for the long-term sustainability of the transportation sector. Pursuing this target, a model to simulate an Electric Vehicle (EV) for Formula SAE Electric competition is herein proposed: all the subsystems of the EV and the hybrid storage of the Li-ion batteries and Ultra-Capacitors (UCs) are implemented, in order to store the kinetic energy of the regenerative braking in the storage system through the Kinetic Energy Recovery System (KERS). A bidirectional DC-DC resonant converter is herein applied to the KERS to manage the UC pack. The operational limits of the proposed system, keeping the soft-switching properties, are discussed, and the results show the capability of the converter to operate under resonant mode in both boost and buck mode. A drawback is the presence of high current peaks in the resonant inductor. The use of more than one converter in interleaving and the adoption of a suitable capability factor ensure the proper operation of the system.

Reaction wheel systems (RWSs) are beneficial in improving bipedal walking stability, and theoretical work has shown that they can also improve the efficiency of preplanned walking motions. This work provides the first demonstration of RWS-related efficiency improvements on a physical robot and identifies the energy-saving paradigm. Gaits for a five-link planar biped are generated via trajectory optimization with and without reaction wheels. Comparisons of the resulting system behavior show a 5–10% efficiency advantage for robots with an RWS under typical walking conditions and a larger advantage near regions of marginal dynamic feasibility. The savings are mainly accomplished by enabling trajectories with better joint motor utilization, not by minimizing impact losses or acting as a kinetic energy recovery system. The RWS also improves centroidal angular momentum regulation, with the reduction in centroidal angular momentum amplitude reaching 30% at high speeds. Simulations and experiments with a five-link planar biped validate the efficiency improvements seen in optimization. This demonstrates the viability of using efficient inertial actuators to improve the efficiency of complex walking robots.

The new challenge in the reduction of CO₂ emissions by heavy duty trucks is leading to a technological evolution in powertrain efficiency. Towards this objective, the European Union (EU) has funded in the frame of the 7th framework program the project GASTONE: a collaborative project between several private and public companies and institutions: CRF, FTP, Continental, GENTHERM, MAGNA and Universitate Politecnica de Valencia, targeting the development of a new powertrain concept based on the integration of electric generation, energy recovery and storage with engine system and control strategies. The main features of this compressed natural gas (CNG) engine concept are: (1) The energy recovery from the exhaust gases heat with a cascade approach thanks to the adoption of an advanced thermoelectric generator and a turbo-generator. (2) The integration of a smart kinetic energy recovery system to substitute the alternator with a smarter electrical machine. (3) The electrification of the main auxiliaries (coolant and oil pumps, auxiliary e-supercharger and air conditioning compressor). The electrification process is supported by an improvement of the performance of the CNG engine (the actual average value is about 38%): this number is expected to rise by 4% thanks to the engine control strategy improvement, by 1% due to the introduction of the water charge air cooler, by 2% from the reduction of the belt drive and gear losses, by 1% from the system strategy and management optimization and by 7% from the exhaust heat recovery (thermo-electric generator plus turbo-generator). This paper presents the details of the new powertrain concept design, the simulation tool developed to support the design and optimize the system and a cost per function tool to perform an economic analysis in the hypothesis to introduce the system in the market. The obtained benefits are expressed in terms of fuel saving for a target real driving cycle and effects related to the new devices are developed and tested. The project is in the design phase and the paper collects a first estimation of results based on the design, strategy and control improvement.

In the Philippines, motorized tricycle was subjected to repetitive utilization of brakes due to traffic and road condition. To address the problem regarding the energy loss due to the application of brakes, Kinetic Energy Recovery System or KERS was introduced. KERS serves as the medium to recover and store the momentum of the vehicle. The study was aimed to design a mechanical interface of the kinetic energy recovery system applicable on motorized tricycles. This also aimed to determine the optimal dimensions and material of the flywheel that can maximize the recovery and storage of the lost kinetic energy of tricycles during braking. The triggering mechanism used was a combination of an actuator mechanism and a hand brake lever. The study was able to accomplish and design the appropriate triggering mechanism in order to utilize KERS. The group was able to prove the prototype’s cost- effectiveness of the system with the percent of fuel saved with the application of KERS. It is determined in the study that by utilizing the Flywheel KERS on the motorized tricycle, fuel savings of 2.93%, 4.28% and 5.93% were obtained for uniform velocities of 30 kph, 40 kph and 50 kph, respectively. In this study the group was able to design and fabricate a functional Flywheel Kinetic Energy Recovery system on a Motorized Tricycle.

In this two-part work, an electric kinetic energy recovery system (e-KERS) for internal combustion engine vehicle (ICEV) is presented, and its performance evaluated through numerical simulations. The KERS proposed is based on the use of a supercapacitor as energy storage, interfaced to a brushless machine through a properly designed power converter. In part 1, the system is described and analysed, and the mathematical model used for the simulations is presented. For each component of the KERS, the real efficiency, and the power or energy limitations are adequately considered. In part 2, the energetic and economic advantages attainable by the proposed KERS are evaluated using MATLAB Simulink, considering a widely diffused passenger car and two reference driving cycles (ECE-15 and Artemis Urban). Energy savings of the order of 20% were found, with a slight increase in vehicle weight (+2%) and with an overall commercial cost that would be compensated in 5 years thanks to the fuel economy improvement, to which corresponds an equal reduction of CO2 emissions. The low complexity of the system, never proposed for ICEV, the moderate weight of its components, and their availability on the market, make the solution presented ready for the introduction in current vehicle production.

Automotive industry consumes a lot of energy in the vehicle quality testing section. This kinetic energy is wasted during the acceleration and deceleration of the test rollers, which represents high costs of the fuel used to carry out the tests. The kinetic energy stored in the rollers has a usable energy potential to recover in a way that represented a secondary energy resource. This paper analyzes an alternative of a recovery system of kinetic energy based on an inertial flywheel, based on three stages, firstly, the analysis, design, and sizing of the flywheel. Secondly, modeling of the electromechanical system and sizing of the DC generator. Finally, as a third stage, the management of the energy recovered in a DC-DC converter for storing the energy.

This paper presents a comprehensive design of a controller for BLDC motor with maximal electric power around 1000W, using high-end components to provide high performance and more flexibility of the implemented algorithms at a low-level cost. The controller can drive a BLDC motor providing the possibility of rotating in both directions, create an electromagnetic brake and kinetic energy recovery system. The controller who has equipped a 500W electric scooter, and a 1000W electric motor cart and it proved to be reliable, performance and especially flexible and portable by parameterizing all the implemented software functions.

Reduction of energy consumption in manufacturing processes are becoming necessary due to the growing concern of industrial pollution and of electricity prices over time. Several factors such as raising of process automation, fluids consumption, process parameters selection and motion control influence the energy consumption. The consistent motion control on CNC machines are the most important for the machining process and are achievable by main drive control and auxiliary drive control. Positioning along lengths of travel can be linear (driven along a straight path) and rotary (driven along a circular path). Over the decades, mass of the machine tool is decreasing, and speeds are increasing what influence necessary kinetic energy for motion. Integrated Kinetic Energy Recovery System (KERS) on machine tools is one possible solution.

As fuel consumption and emissions regulations for heavy goods vehicles (HGV) are getting stringent, it is becoming increasingly important to develop new technologies for next generation of HGVs. A new mechanical hybrid system is developed with Kinetic Energy Recovery System (KERS) to increase fuel economy. This system is compared with a conventional system by simulating for driving cycles on AVL CRUISE. A mechanical hybrid controller has been developed and its performance assessed by fuel consumption results on driving cycles of VECTO Long-Haul (Vehicle Energy Consumption Calculation Tool) and WHVC (World Harmonized Vehicle Cycle). Driving cycle simulation result provide an insight of target customer of the new technology.

This paper intends to explore the bidirectional DC/DC converter concept and super capacitor which are used in conversion of the kinetic energy in moving vehicles during braking into electrical energy and can be used again during the acceleration of a car. Three modes of Electrical Vehicle (EV) are examined. Power balance is guaranteed under fluctuations or ups and downs in load values. Implementation is carried out by MATLAB /Simulink software to show the feasibility of the presented control strategy. The simulation results indicate the amalgamation of the of bi-directional converters and assortment super capacitor show that the imposed cost of electrical energy generation can be decreased significantly by the proposed method, at the same time satisfaction of the EV user is also taken into account.

The paper discusses the modeling and control of a 800 metric tons servo mechanical forming press. The control objective is to actuate the kinetic energy recovery system so to minimize the amplitude of the oscillations on the Direct Current bus line. The paper describes and models all the components of the system from an energy standpoint. Measured data on an instrumented press validate the model. Two controllers are proposed: a perfect knowledge controller that requires knowledge of the working cycle and a nested causal closed loop controller. A detailed simulation study compares the two approaches, showing that both approaches successfully reduce the variance of the power. The analysis further confirms that the perfect knowledge control outperforms the closed loop controller in nominal conditions; the closed loop controller is on the other hand capable of guaranteeing a 3 kW peak to peak variation in a robust way.

Electric vehicle is one of the major technological innovations of this century which has already shown immense potential to change the course of human transportation system. This paper focuses mainly on the design and implementation of an electric speed booster which includes an ultra-capacitor bank, a regeneration system, a solar charging system and a traction system. In this paper, an ultra-capacitor bank is charged through both regeneration as well as the solar charging system to act as a surge power source for speed boosting. Necessary converters and rectifiers have been employed for conversion of the energy for charging the capacitor bank. The ultra-capacitor bank has been connected in conjunction with a battery bank, both of which are used to support the DC bus that electrically drives the drive train. A toggle switch is employed for initiating speed boost mechanism in the vehicle. The system operates such that the ultra-capacitor-battery combination works as a range extender when speed boost is switched off and as a speed booster when it is switched on. Such a system has shown to further improve the efficiency and performance of the system. Performance analysis is carried out and results are provided in the later section of this paper.

New generation hybrid and electric models of mail delivery vehicles (quadricycles) were analyzed in terms of their environmental emissions and energy consumption. The aims of the present work are to compare on an environmental and energy point of view two recharge modalities (electric vehicle with a range extender installed on a specific ground station and hybrid vehicle with on-board range extender) and to evaluate the performance of a KERS (kinetic energy recovery system) system for the employment of the quadricycles for the postal service.

Over the past few years Hybrid Electric and Electric propulsion systems have found significant attention as the most plausible substitute to fossil fuel based engines. Hybrid Electric Vehicles (HEV) have been around for more than a decade and extensive research has been taken out to make these vehicles more efficient. With advances in technology, manufacturers such as Tesla and Chevrolet have successfully launched a number of Electric Vehicles (EV) in the past 5 years. In despite of all this success, HEVs and EVs currently face challenges in energy storage systems (ESS) with regard to a variety of parameters and to overcome these issues research has been done on different types of ESS systems to extend the range of such vehicles. Flywheel Energy Storage Systems (FESS) have regained interest in the last decade and the application of kinetic energy recovery system (KERS) in the Formula 1 has reinforced the case of using FESS in HEV and EV. In this study, the integration of an FESS system within a hybrid electric propulsion and an electric propulsion system is considered and with the help of Bond-Graphs as a multidisciplinary modelling tool the impact of this integration is analyzed and compared with each other.

The emergence and diffusion of green and sustainable technologies is full of obstacles and has therefore become an important area of research. We are interested in further understanding the dynamics between entrepreneurial experimentation, market formation, and institutional contexts, together playing a decisive role for successful diffusion of such technologies. Accordingly, we study these processes by adopting a technological innovation system perspective focusing on actors, networks, and institutions as well as the functions provided by them. Using a qualitative case study research design, we focus on the high-speed flywheel energy storage technology. As flywheels are based on a rotating mass allowing short-term storage of energy in kinetic form, they represent an environmentally-friendly alternative to electrochemical batteries and therefore can play an important role in sustainable energy transitions. Our contribution is threefold: First, regarding the flywheel energy storage technology, our findings reveal two subsystems and related markets in which development took different courses. In the automotive sector, flywheels are developing well as a braking energy recovery technology under the influence of two motors of innovation. In the electricity sector, they are stagnating at the stage of demonstration projects because of two important system weaknesses that counteract demand for storage. Second, we contribute to the theory of technological innovation systems by better understanding the internal dynamics between different functions of an innovation system as well as between the innovation system and its (external) contextual structures. Our third contribution is methodological. According to our best knowledge, we are the first to use system dynamics to (qualitatively) analyze and visualize dynamics between the diverse functions of innovation systems with the aim of enabling a better understanding of complex and iterative system processes. The paper also derives important implications for energy scholars, flywheel practitioners, and policymakers., Highlights • In-depth analysis of the flywheel energy storage technology innovation and diffusion processes. • Systems analysis of technology development using technology innovation systems theory. • Comparing technology development in the automotive and power-grid related transitions. • First attempt to better understand clean storage in comparison to conventional storage (e.g. chemical batteries). • Detailed implications for practitioners – including market overview and outlook – and policy makers.

This paper presents the preliminary theoretical results obtained on a model of a kinetic energy recovery system for sailing yachts, based on the conversion of wave-induced boat oscillations (heave, pitch and roll) into electric energy by means of a linear generator. The recovery system is based on a linear generator, with a mass oscillating along the vertical axis and gaining kinetic energy: the resulting mechanical energy can be extracted (by means of electromagnetic damping) and converted into electricity. The oscillating mass incorporates permanent magnets which, moving in proximity of stator windings, generate electric power due to electromagnetic induction. The device aims at recovering as much kinetic energy as possible from the natural movements of a sailing yacht on the sea, therefore taking the view of a boat as a moving wave energy converter with energy harvesting capability. The boat's motions can be vertical oscillations due to the buoyancy in the presence of sea waves, both when the boat is still or sailing, and rolling and pitching motions originated both by sailing in wavy waters and by the normal boat dynamics due to the sails' propulsion. Linear generators will convert kinetic energy into electrical energy to be used as “green” electricity for any possible application on board. Preliminary calculations show that a properly configured system could be able to recover approximately 100 W under most sea conditions on an almost continuous basis, which can be an extremely attractive result since an electric energy availability of 1–2 kWh on a sailing yacht is of significant interest.

With the advent of flywheel-based kinetic energy recovery systems in automotive applications new safety issues arise as a consequence of the flywheel's high rotational speed. While the special structural safety requirements of the components are well discussed in the literature, there is still little research on the influence of gyroscopic effects on vehicle dynamics. The aim of this paper is to investigate the influence of a typical high-speed flywheel on the driving dynamics of an average passenger car. To this end the equations of motion of a gyroscope are derived, which relate the vehicle's roll, pitch and yaw rate with the transverse torque acting on the flywheel. These equations are implemented in a commercial vehicle dynamics simulation program in order to determine the reaction torques acting on the vehicle within a representative range of driving situations. Numerical simulations indicate that the gyroscopic effect can be considered insignificant in standard driving situations.

Continuously variable transmissions play an important role in mechanical kinetic energy recovery systems. In this work, a clutch based continuously variable transmission comprising two stages of three clutches is considered. A detailed mathematical model is derived and a control strategy for the load torque is given. The model covers losses in bearings, clutches and fixed transmissions as well as flywheel losses due to gas friction.