A comparison of high-speed flywheels, batteries, and ultracapacitors on the bases of cost and fuel economy as the energy storage system in a fuel cell based hybrid electric vehicle

Fuel cells aboard hybrid electric vehicles (HEVs) are often hybridized with an energy storage system (ESS). Batteries and ultracapacitors are the most common technologies used in ESSs aboard HEVs. High-speed flywheels are an emerging technology with traits that have the potential to make them competitive with more established battery and ultracapacitor technologies in certain vehicular applications. This study compares high-speed flywheels, ultracapacitors, and batteries functioning as the ESS in a fuel cell based HEV on the bases of cost and fuel economy. In this study, computer models were built to simulate the powertrain of a fuel cell based HEV where high-speed flywheels, batteries, and ultracapacitors of a range of sizes were used as the ESS. A simulated vehicle with a powertrain using each of these technologies was run over two different drive cycles in order to see how the different ESSs performed under different driving patterns. The results showed that when cost and fuel economy were both considered, high-speed flywheels were competitive with batteries and ultracapacitors.     

Development of lithium batteries for energy storage and EV applications

The results of the Japanese national project of R&D on large-size lithium rechargeable batteries by Lithium Battery Energy Storage Technology Research Association (LIBES), as of fiscal year (FY) 2000 are reviewed. Based on the results of 10 Wh-class cell development in Phase I, the program of Phase II aims at further improvement of the performance of large-size cells and battery modules, and the formulation of roadmaps toward worldwide dissemination of large-size lithium secondary batteries. In addition to the above R&D programs, a new target was presented particularly for the near-term practical application of several kWh-class battery modules in FY 1998.

For the large-size battery modules, two types of 2 and 3 kWh-class battery modules have been developed for stationary device and electric vehicle applications, respectively. The battery modules for both types have achieved most of the targets other than cycle life. Currently, further improvements in the cycle life of the cells themselves are being pursued. For this purpose, the materials for cathodes and anodes, the shapes and structures for batteries and the methods for cell connection are being re-investigated.

The development of middle-size battery systems for mini-size electric vehicles (EVs), as well as for demand-side stationary device applications is under way. These battery systems have been fabricated and their fundamental performance confirmed. They are now being subjected to field tests.     

Lithium polymer batteries and proton exchange membrane fuel cells as energy sources in hydrogen electric vehicles

This paper deals with the application of lithium ion polymer batteries as electric energy storage systems for hydrogen fuel cell power trains. The experimental study was firstly effected in steady state conditions, to evidence the basic features of these systems in view of their application in the automotive field, in particular charge-discharge experiments were carried at different rates (varying the current between 8 and 100 A). A comparison with conventional lead acid batteries evidenced the superior features of lithium systems in terms of both higher discharge rate capability and minor resistance in charge mode. Dynamic experiments were carried out on the overall power train equipped with PEM fuel cell stack (2 kW) and lithium batteries (47.5 V, 40 Ah) on the European R47 driving cycle. The usage of lithium ion polymer batteries permitted to follow the high dynamic requirement of this cycle in hard hybrid configuration, with a hydrogen consumption reduction of about 6% with respect to the same power train equipped with lead acid batteries.     

Improved dynamic performance of hybrid PEM fuel cells and ultracapacitors for portable applications

Transient power demand fluctuations and maintaining high energy density are important for many portable devices. Small fuel cells are potentially good candidates as alternative energy sources for portable applications. Hybrid power sources have some inherent properties which may be effectively utilized to improve the efficiency and dynamic response of the system. In this paper, an improved dynamic model considering the characteristics of the temperature and equivalent internal resistance is presented for proton exchange membrane (PEM) fuel cells. The dynamic behavior of a system with hybrid PEM fuel cells and an ultracapacitor bank is simulated. The hybrid PEM fuel cell/ultracapacitor bank system is used for powering a portable device (such as a laptop computer). The power requirement of a laptop computer varies significantly under different operation conditions. The analytical models of the hybrid system with PEM fuel cells and an ultracapacitor bank are designed and simulated by developing a detailed simulation software using Matlab, Simulink and SimPowerSystems Blockset for portable applications.     

Electrochemical hydrogen storage: Opportunities for fuel storage,batteries, fuel cells,and supercapacitors

Solid-state storage of hydrogen is a possible breakthrough to realise the unique futures of hydrogen as a green fuel. Among possible methods, electrochemical hydrogen storage is very promising, as can be conducted at low temperature and pressure with a simple device reversibly. However, it has been overshadowed by the physical hydrogen storage in the literature, and thus, research efforts are not adequately connected to lead us in the right direction. On the other hand, electrochemical hydrogen storage is the basis of some other electrochemical power sources such as batteries, fuel cells, and supercapacitors. For instance, available hydrogen storage materials can build supercapacitors with exceptionally high specific capacitance in order of 4000 F g^?1. In general, electrochemical hydrogen storage plays a substantial role in the future of not only hydrogen storage but also electrochemical power sources. There are some vague points which have obscured our understanding of the corresponding system to be developed practically. This review aims to portray the entire field and detect those ambiguous points which are indeed the key obstacles. It is clarified that different materials have somehow similar mechanisms for electrochemical hydrogen storage, which is initiated by hydrogen dissociation, surface adsorption and probably diffusing deep within the bulk material. This mechanism is different from the insertion/extraction of alkali metals, though battery materials look similar. Based on the available reports, it seems that the most promising material design for the future of electrochemical hydrogen storage is a class of subtly designed nanocomposites of Mg-based alloys and mesoporous carbons.     

Multi-agent direct current systems using renewable energy sources and hydrogen fuel cells

Direct current provides accumulation of electricity and is therefore necessary when using renewable energy sources. Hydrogen energy storage devices in the form of fuel cells are the most effective and environmentally friendly way of energy storage and conservation. Shortcomings of electric power networks compared with DC networks in terms of stability, controllability, reliability and redundancy are noted. The necessity of transition from digitalization in the form of automated process control systems to smart grids, and subsequently to multi-agent DC networks with a high degree of redundancy, is revealed. Besides, the paper deals with application of distributed generation consisting of traditional and renewable energy sources, as well as accumulators and static converters. Characteristics of the above mentioned elements are given for simulating the modes in order to select the structure and control algorithms that provide increased power supply reliability.     

Characterization methods and modelling of ultracapacitors for use as peak power sources

This paper suggests both a methodology to characterize ultracapacitors and to model their electrical behaviour. Current levels, frequency intervals, and voltage ranges are adapted to ultracapacitors testing. Experimental data results in the determination of the ultracapacitors performances in terms of energy and power densities, the quantification of the capacitance dependence on voltage, and the modelling of the dynamic behaviour of the device. Then, an electric model is proposed taking into account the ultracapacitors characteristics and their future use as peak power source for hybrid and electric vehicles. After, the parameters identification procedure is explained. Finally, the model validation, both in frequency and time domains, proves the validity of this methodology and the performances of the proposed model.     

Potential use of geothermal energy sources for the production of lithium-ion batteries

The lithium-ion battery is one of the most promising technologies for energy storage in many recent and emerging applications. However, the cost of lithium-ion batteries limits their penetration in the public market. Energy input is a significant cost driver for lithium batteries due to both the electrical and thermal energy required in the production process. The drying process requires 45–57% of the energy consumption of the production process according to a model presented in this paper. The model is used as a base for quantifying the energy and temperatures at each step, as replacing electric energy with thermal energy is considered. In Iceland, it is possible to use geothermal steam as a thermal resource in the drying process. The most feasible type of dryer and heating method for lithium batteries would be a tray dryer (batch) using a conduction heating method under vacuum operation. Replacing conventional heat sources with heat from geothermal steam in Iceland, we can lower the energy cost to 0.008USD/Ah from 0.13USD/Ah based on average European energy prices. The energy expenditure after 15 years operation could be close to 2% of total expenditure using this renewable resource, down from 12 to 15% in other European countries. According to our profitability model, the internal rate of return of this project will increase from 11% to 23% by replacing the energy source. The impact on carbon emissions amounts to 393.4–215.1 g/Ah lower releases of CO₂ per year, which is only 2–5% of carbon emissions related to battery production using traditional energy sources.     

The power capability of ultracapacitors and lithium batteries for electric and hybrid vehicle applications

There is much confusion and uncertainty in the literature concerning the useable power capability of batteries and ultracapacitors (electrochemical capacitors) for various applications. Clarification of this confusion is one of the primary objectives of this paper. The three approaches most often applied to determine the power capability of devices are (1) matched impedance power, (2) the min/max method of the USABC, and (3) the pulse energy efficiency approach used at UC Davis. It has been found that widely different power capability for batteries and ultracapacitors can be inferred using these approaches even when the resistance and open-circuit voltage are accurately known. In general, the values obtained using the energy efficiency method for EF = 90-95% are much lower than the other two methods which yield values corresponding to efficiencies of 70-75%. For plug-in hybrid and battery electric vehicle applications, the maximum useable power density for a lithium-ion battery can be higher than that corresponding to 95% efficiency because the peak power of the driveline is used less frequently and consequently charge/discharge efficiently is less important. For these applications, the useable power density of the batteries can be closer to the useable power density of ultracapacitors. In all cases, it is essential that a careful and appropriate measurement is made of the resistance of the devices and the comparisons of the useable power capability be made in a way appropriate for the application for which the devices are to be used.     

Preliminary experimental evaluation of a four wheel motors,batteries plus ultracapacitors and series hybrid powertrain

This paper reports the preliminary experimental evaluation of a four wheel motors series hybrid prototype equipped with an internal combustion engine coupled to a generator and an energy recovery system (batteries plus ultracapacitors). The paper analyses global efficiency (energy dissipated to overcome the dissipative forces on energy dissipated in fuel), autonomy in electric configuration, and the efficiency of the regenerative braking system. The tests were carried out in a test cell equipped with a chassis dynamometer. The tests were performed according to the current regulated procedures. A constant speed test was performed in order to evaluate the autonomy of the vehicle in the electric configuration. The results show that the real tank to wheels efficiency is about 30% for HOST as a series hybrid and 79% for HOST as an electric vehicle.     

On the comparison and the complementarity of batteries and fuel cells for electric driving

This paper considers different current and emerging power train technologies (ICE, BEV, HEV, FCEV and FC-RE) and provides a comparison within a techno-economic framework, especially for the architectures of range-extender power trains. The economic benefits in terms of Total Cost of Ownership (TCO) are based on forecasts for the major TCO-influencing parameters up to 2030: electric driving distances, energy (fuel, electricity, hydrogen) prices, batteries and fuel cell costs. The model takes into account functional parameters such as the battery range as well as daily trip segmentation statistics.     

Investigation of distributed power generation based on renewable energy sources and hydrogen batteries

The paper deals with investigation of distributed renewable power sources use efficiency by the example of solar power plant, wind farm and biogas power plants. The paper uses statistical data collection on weather conditions and solar radiation in different regions of the Russian Federation to assess effectiveness. It has been found out that arrangement of solar power plants and wind farms in the Republic of Bashkortostan is more profitable than their arrangement in other regions (Astrakhan, Vladivostok, Gorno-Altaisk, Makhachkala, St. Petersburg), and the use of biogas power plant is profitable in the region, where the production of biofuels is possible, including the Republic of Bashkortostan. Moreover, the paper presents a high-speed magnetoelectric generator for microturbines. In order to save and generate electric energy in accordance with consumer load curve, hydrogen batteries have been examined.     

Hydrogen and fuel cells: Towards a sustainable energy future

A major challenge—some would argue, the major challenge facing our planet today—relates to the problem of anthropogenic-driven climate change and its inextricable link to our global society's present and future energy needs [King, D.A., 2004. Environment—climate change science: adapt, mitigate, or ignore? Science 303, 176–177]. Hydrogen and fuel cells are now widely regarded as one of the key energy solutions for the 21st century. These technologies will contribute significantly to a reduction in environmental impact, enhanced energy security (and diversity) and creation of new energy industries. Hydrogen and fuel cells can be utilised in transportation, distributed heat and power generation, and energy storage systems. However, the transition from a carbon-based (fossil fuel) energy system to a hydrogen-based economy involves significant scientific, technological and socioeconomic barriers to the implementation of hydrogen and fuel cells as clean energy technologies of the future. This paper aims to capture, in brief, the current status, key scientific and technical challenges and projection of hydrogen and fuel cells within a sustainable energy vision of the future. We offer no comments here on energy policy and strategy. Rather, we identify challenges facing hydrogen and fuel cell technologies that must be overcome before these technologies can make a significant contribution to cleaner and more efficient energy production processes.     

Performance analysis of a hybrid solar-hydrogen-retired EV batteries (REVB) energy system with thermal-electrical loops

Utilizing solar energy is an efficient method to provide hybrid renewable energy system with sufficient thermal/electrical energy. Meanwhile, the rapid development of electrical vehicles leads to an excess of retired electric vehicles. As a combination of the abovementioned two conceptions, this study proposed and examined a hybrid solar-hydrogen-retired electrical vehicle battery energy system to meet thermal and electrical loads for small-scale usage. The novelty of this research is delivered as follows: first of all, the proposed hybrid energy system supplies both thermal and electrical energy to small-scale end users; secondly, the retired electrical vehicle batteries are recycling to relieve the pressure of battery demand; thirdly, an energy management strategy to regulate the complicated hybrid energy system is designed. The results show that with assistance of fuel cell as an energy storage unit, solar energy can basically satisfy the annual thermal/electrical load with maximum monthly energy supplement of 1220.43 MJ and 1572.75 kWh, respectively. However, the solar radiation serving as single energy source is not very reliable for large-scale utilization. Although the state of charge does not fluctuate greatly, the small range charge/discharge between 59% and 63% can still guarantee the normal operation of the proposed hybrid energy system.     

Fuel cells,an alternative to standard sources of energy

Three E’s are the national energy policy drivers of any country of the world, Energy security, Economic growth and Environmental protection. A fuel cell is an energy conversion device that produces electricity by electrochemically combining fuel (hydrogen) and oxidant (oxygen from the air) gases through electrodes and across an ion conducting electrolyte. The principal characteristic of a fuel cell is its ability to convert chemical energy directly into electrical energy giving much higher conversion efficiencies than any conventional thermo-mechanical system thus extracting more electricity from the same amount of fuel, operate without combustion so they are virtually pollution free and have quieter operation since there are no moving parts. The emission of fuel cells running on hydrogen derived from a renewable source will be nothing but water vapour. Fuel cells are presently under development for a variety of power generation applications in response to the critical need for a cleaner energy technology. This paper reviews the existing or emerging fuel cells technologies, their design and operation, their limitations and their benefits in connection with energy, environment and sustainable development relationship. Few potential applications of fuel cell will be discussed.     

Design and optimization of radioisotope sources for betavoltaic batteries

A Monte Carlo source model using PENELOPE was developed to investigate different tritiated metals in order to design a better radioisotope source for betavoltaic batteries. The source model takes into account the self‐absorption of beta particles in the source which is a major factor for an efficient source design. The average beta energy, beta flux, source power output, and source efficiency were estimated for various source thicknesses. The simulated results for titanium tritide with 0° and 90° angular distributions of beta particles were validated with experimental results. The importance of the backscattering effect due to isotropic particle emission was analyzed. The results showed that the normalized average beta energy increases with the source thickness, and it reaches peak energy depending on the density and the specific activity of the source. The beta flux and power output also increase with increasing source thickness. However, the incremental increase in beta flux and power output becomes minimal for higher thicknesses, as the source efficiency decreases significantly at higher thicknesses due to the self‐absorption effect. Thus, a saturation threshold is reached. A low‐density source material such as beryllium tritide provided a higher power output with higher efficiency. A maximum power output of approximately 4 mW/cm³ was obtained for beryllium tritide with SiC. A form factor approach was used to estimate the optimum source thickness. The optimum source thickness was found near the thickness where the peak beta particle average energy occurs.     

Unveiling characteristics of dye-bearing microbial fuel cells for energy and materials recycling: Redox mediators

This study disclosed why and how some decolorized intermediates (e.g., 2-aminophenol) could act as electron-shuttling mediator(s) to enhance the capabilities of reductive decolorization and bioelectricity generation. It also selected several model auxochrome-containing compounds structurally associated to 2AP to explore how chemical structure influenced the feasibility of possible electron shuttles for power producing capabilities in microbial fuel cells (MFCs). The selection criteria of electron-shuttling mediators were suggested for optimal reductive decolorization and bioelectricity generation in MFCs for practical application.