High-Energy Electrode Investigation For Plug-In Hybrid Electric Vehicles

While various high-energy-density electrode materials for lithium-ion (Li-ion) batteries<!–[if supportFields]> XE “battery” <![endif]–><!–[if supportFields]><![endif]–> exist, Lu et al. (2011) suggest that other engineering approaches, such as electrode optimization, be considered to meet the energy requirements for plug-in hybrid<!–[if supportFields]> XE “hybrid” <![endif]–><!–[if supportFields]><![endif]–> electric vehicles (PHEVs). The authors investigate the impact of the electrode thickness on the energy density of Li-ion batteries, although their findings show that the electrode thickness would affect the battery’s “integrity, electrochemical performance, and cycleability.” That is why it is important to find both an appropriate and practical thickness of the electrode for high-energy batteries. The authors also found that the hybrid pulse power characterization (HPPC) test indicates that the electrode resistance is “inversely proportional” to the electrode thickness. This allows for the use of thicker electrodes, practical thickness measuring around 100 µm, in Li-ion batteries to meet standard PHEV power requirements. The authors also find that cycle performance shows that cells with a “higher loading density have a similar capacity retention to cells with a lower loading density.” —Laura Silverberg

Lu et al. assess high-energy electrode density levels for the purpose of meeting the energy requirements for PHEVs. In fiscal year 2009, the Department of Energy (DOE) began its pledge to enable the development of PHEVs with a 40-mile all-electric range. However, along with other challenges regarding Li-ion batteries<!–[if supportFields]>XE “battery” <![endif]–><!–[if supportFields]><![endif]–> in the HEV application, the issue of cycle life, as well as providing sufficient energy within the weight and volume requirements of PHEVs became apparent. Currently, there is no commercially available high-energy material to meet the needs of the proposed 40-mile PHEV. However, this issue can be addressed by engineering approaches. Thus far, various possibilities have been investigated for experimental and modeling techniques including electrode porosity and inactive additives. Both of these possibilities can be utilized to improve the energy density.
Lu et al. examine a series of cathode and anode electrodes with varying thicknesses and porosities that were prepared using a small laboratory coater. Both lithium half-cells and fuel cells were created in an “inert atmosphere glove box with an oxygen level of less than 5 ppm.” Additionally, the results of the electrochemical performance of coin cells, investigated using the HPPC profile, were also used in the study to determine thickness effects.
While no commercially available electrode materials currently exist to meet the weight and volume requirements of a 40-mile PHEV, it is important to consider battery<!–[if supportFields]> XE “battery” <![endif]–><!–[if supportFields]><![endif]–> structure optimization to increase battery energy density, for example, by increasing electrode thickness. Using a battery design model based on PHEV energy requirements, the authors experiment with various cathode and anode electrode thicknesses. They found that the cathode electrode should be thicker than 130 µm if only 70% of the total battery energy will be utilized and that the “battery weight reduction rate levels off when the electrode thickness is greater than 100 µm.” This is due to less weight and volume from the current collector and separator. The authors also evaluate the relationship between the electrode thickness and coating weight before and after calendering. Electrode integrity gets worse when the electrode thickness reaches above 100 µm. Thicker electrodes, however, do not affect the useable capacity of the NCA cathode material at a low cycling rate, although it is affected by the electrode thickness at a higher discharge rate. Due to this, better binder strength must be developed which will allow for thicker electrodes and volume expansion. The authors determine that within the relationship between the deliverable capacity and discharge rate of NCA half-cells, the usable capacity will drop significantly when the discharge rate increases.
Power performance of the NCA half-cells with varying electrode thicknesses also utilized the HPPC test. Area specific impedance (ASI) of the half-cells decreases as the electrode thickness increases and levels off according to the results from the half-cell and full-cell. Lu et al. clarify that “[t]his does not necessarily mean that the cell with the thicker electrode always has a higher power capability,” thus confirming that thicker electrode cells must be discharged at a higher current density. This process can offset the lower impedance. However, this combination can cause tension on the transport of lithium ions in the electrolyte, limiting its rate capability. The last test regards the assessment of capacity fading of cells with various electrode-loading densities. No obvious difference was observed for the full-cells under this condition.
The authors conclude that while the HPPC test results indicate that the electrode impedance is “inversely proportional” to the electrode thickness, this is will allow for good power capability of the Li-ion battery<!–[if supportFields]>XE “battery” <![endif]–><!–[if supportFields]><![endif]–> with a higher loading density in the future. Higher loading densities have similar capacity retention as lower loading densities.

RD&D Cooperation for the Development of Fuel Cell, Hybrid, and Electric Ve-hicles within the International Energy Agency

The rising level of CO2 emissions is becoming more concerning for a growing population dependent on roadway mobility. Fuel cell vehicles, hereafter FCVs, can provide a significant alternative and sustainable form of transport that combines “energy efficiency<!–[if supportFields]> XE “energy efficiency” <![endif]–><!–[if supportFields]><![endif]–>, emissions reductions, and reduced petroleum use.”  This paper summarizes the report of Annex XIII in 2010 by compiling “an up-to date, neutral, and comprehensive assessment of current trends in fuel cell vehicle technology and related policy.” Telias et al. (2010) include a review of the most current components of the fuel cell battery<!–[if supportFields]> XE “battery” <![endif]–><!–[if supportFields]><![endif]–> stack, batteries, and hydrogen storage with commentary on the successful results of fuel cell vehicle demonstrations projects worldwide. —Laura Silverberg
Telias, G., Day, K., Dietrich, P. 2010. RD&D Cooperation for the Development of Fuel Cell, Hybrid, and Electric Vehicles within the International Energy Agency. 2010. World Battery, Hybrid and Fuel Cell Electric Vehicle Symposium & Exhibition, 1–6.

 Telias et al. assess two applications of fuel cell technology, a system that can be seen as a power converter unit providing “electricity and heat and therefore provid[ing] an analogous function in combination with an electric machine as the internal combustion engine<!–[if supportFields]> XE “engine” <![endif]–><!–[if supportFields]><![endif]–> in a conventional vehicle.” The first system functions as an energy converter, used in conjunction with an electric motor to propel the vehicle. The second application of the system analyzes its auxiliary units where power may not be needed at all times, particularly when the vehicle is not in motion. Generally with FCVs, the auxiliaries are significantly lower than that of the demands of the vehicle propulsion.  In both applications of the system, the fuel cell can be directly linked with an electric motor, creating a pure fuel cell power train. It is only when the powertrain is combined with an energy storage system that the powertrain becomes a hybrid<!–[if supportFields]> XE “hybrid” <![endif]–><!–[if supportFields]><![endif]–>. Pure FCVs, systems that can manage with the dynamic power demands of the vehicle, require maximum power; the power demand of the car matches the maximum output power of the fuel cell system. The production of power from the fuel cell system has to react instantaneously since there is no energy storage system within the vehicle. This is dynamic power adaptation. In addition, the fuel cell starting time must be in the same range as an internal combustion engine or battery<!–[if supportFields]> XE “battery” <![endif]–><!–[if supportFields]><![endif]–> electric vehicle. Finally, the power output of a fuel cell system, while temperature-dependent (the power output of the fuel cell may be reduced at a lower temperatures), must not be overly-reduced at the ambient temperatures at which it is expected to operate.
Telias et al. briefly evaluate two configurations of hybrid<!–[if supportFields]> XE “hybrid” <![endif]–><!–[if supportFields]><![endif]–> FCVs. The conventional hybrid contains batteries<!–[if supportFields]>XE “battery” <![endif]–><!–[if supportFields]><![endif]–> that store collected braking energy and supply peaking power, or as an alternative, use a supercapacitor for short-term peak power demands. The plug-in hybrid system can be used with or without a connection to the electricity storage grid—it can be charged from the fuel cell system, or charged with electricity. This allows the user to drive moderate distances using grid-supplied electricity.
FCVs require technologically advanced components that are not found in conventional vehicles today. The major components of a typical FCV include: fuel cell system power electronics (consisting of a fuel cell stack offering significant potential for cost-effective production based on economy of scale, and a motor controller, DC/DC converter, and inverter), fuel processor, current inverters and conditioners, and a heat recovery system), electric machines (use alternating current to provide traction to the wheels of the vehicle, therefore enabling propulsion; an energy storage system, and a hydrogen storage system.
Polymer electrolyte fuel cells, hereafter PEFCs, are typically applied for automotive use. Low-temperature fuel cells show good performance regarding nominal power, cold temperature performance, and service life. High-temperature PEFCs have substantial advantages regarding water management and CO<!–[if supportFields]>XE “CO” <![endif]–><!–[if supportFields]><![endif]–>-tolerance, but function slightly less well under low-temperature conditions. Generally, PEFCs can be operated at low pressure with more simple auxiliaries, which result in less power demand for the air compression. In this scenario, humidity control is needed. In a high-pressure scenario, power density can be increased, allowing the water volume for humidity control to be reduced with the addition of a compressor unit. The majority of FCVs today take advantage of high power, high energy, and long cycle life energy storage devices to improve system performance. These energy storage devices can provide assistance to the fuel cell system during events in which temperature and fuel delivery to the fuel cell stack result in voltage drops during high-load demands. Currently, energy storage systems available for use in FCVs include “lithium-ion, nickel-metal hydride, and lead-acid batteries<!–[if supportFields]>XE “battery” <![endif]–><!–[if supportFields]><![endif]–>, as well as ultra capacitors.” Onboard hydrogen storage systems are also required for FCVs. The development of an onboard system to store hydrogen fuel still remains an inhibiting factor for the widespread commercialization of hydrogen. Research and development of additional technologies is still being conducted.
Worldwide, various FCV demonstration projects have been used as a basis for development of future hydrogen infrastructure performance. These demonstrations offer the opportunity to “gather valuable data—including fuel economy, and other factors—that can be used in working towards creative solutions to technical barriers facing hydrogen fuel cell technology in automobiles.” Telias et al. highlight select results of “notable passenger vehicle demonstrations” from around the world including: North America, the European Union, and Japan. Over the next decade, these project committees will focus on infrastructure development and preparing the market for the introduction of their vehicle models in the transportation sector worldwide. Additionally, the authors assess the international trends in funding for RD&D activities regarding fuel cell and hydrogen technologies for transport applications and the policies that provide the framework of development for these activities. In the United States, the Fuel Cell Technologies Program is responsible for the research and development of: hydrogen production and delivery, hydrogen storage, fuel cell stack components, as well as various aspects of the safety standards, technology, marketing, transportation, and distribution of fuel cells. In the European Union, the Multi-Annual Implementation Plan of the “Fuel Cells and Hydrogen Joint Technology Initiative” is responsible for the research and development of: transport and refueling infrastructure, hydrogen production and distribution, stationary power generation and combined heat and power<!–[if supportFields]> XE “combined heat and power (CHP)” <![endif]–><!–[if supportFields]><![endif]–>, early markets, and cross-cutting issues. In Japan, The “Cool Earth – Innovative Energy Technology Program” gives “priority to 21 technologies based on their potential to reduce CO2emissions and to deliver substantial performance improvement, cost reduction, and increased diffusion as well as technologies where Japan could have the global lead.” In this program, the development for FCVs foresees cost reduction through technology development and improvement of durability and cruising distance over the next decade.

While there has been significant development of battery<!–[if supportFields]> XE “battery” <![endif]–><!–[if supportFields]><![endif]–> electric vehicles and plug-in hybrid<!–[if supportFields]> XE “hybrid” <![endif]–><!–[if supportFields]><![endif]–> electric vehicles, manufacturers are continuing research efforts on FCVs. The list of shortcomings of FCVs has been reduced dramatically, although improvements regarding investment costs of the powertrain and installation of the proper fueling infrastructure need further development. Telias et al. suggest learning from the compressed natural gas infrastructure network for fueling stations or introducing the fuel cell system as a “range extender” in combination with a driving battery plugged or unplugged. While the authors anticipate competition over the technologies of the pure battery electric vehicle and the FCV, the favored outcome of the two systems will be based in its superior “combination of costs and convenience.

A Web-based Light Electric Vehicle for Homecare Use—A Pilot Study

With the rapid increase in biomedical technology, the mortality rate of elderly people in economically developed areas has decreased. However, according to a recent public health survey, problems associated with the aging community in Taiwan have become particularly severe. In this paper, authors Cheng et al. (2010) present an economically viable light electric vehicle design for the homecare of elderly. User needs, application feedbacks, and human factors are taken into account and incorporated into their web-based interactive platform. The goal for this project is to develop a light electric vehicle that can be used for easing the mobility of the elderly both indoors and outdoors. Within their one-year integration project, supported by the National Science Council of TAIWAN, the authors propose and analyze various innovative platforms. These platforms include: “industrial design, biomedical engineering [for healthcare monitoring and vehicle safety checking], mechanical design, power electronics [for green energy development of solar cells], communication technology [for both indoor and outdoor wireless positioning], and information management [regarding computer technology of a built-in health monitoring system].” The authors conclude that their proposed vehicle can provide multiple positive functions for homecare use. —Laura Silverberg
Cheng, K., Liang, T., Lu, C., Shih, D., Cai, D., Hsu, M., Huang, J., 2010. A Web-based Light Electric Vehicle for Homecare Use – A Pilot Study. 2010 International Conference on Computational Aspects of Social Networks, 175–178.

Cheng et al. assess their project from three perspectives: from a technological viewpoint to “build an integration innovation of multiple technologies”; from the industry viewpoint, to “develop an add-on value of the culture electric vehicle for elderly use”; and from the welfare viewpoint, to “promote the humanity of devices.” The project was divided into six research groups focusing on the innovative platforms described above, in order to best develop the proposed light electric vehicle. However, since the research groups are located at varying distant sites, a web-based interactive platform was developed to alleviate discussion and communication problems among the groups. Cheng et al. make note of the importance of collaboration between the varying research groups. In order for one research group to incorporate specific design elements into the light electric vehicle, it is up to another research group to develop that design. This partnership is important for the success of the vehicle.
Industrial design, power control and management, health monitoring and safety checking, information integration, and management are analyzed. Industrial design consists of the survey users’ needs for utilizing the light electric vehicle, the size and design of the vehicle, and the proposal of its conceptual design. The authors provide various views of the proposed light electric vehicle for outdoor use and its detachable chair for indoor use. The authors design a power control and management system to meet the needs of the vehicle. A figure outlining the power supply system is included in the paper. A health monitoring system measuring the ECG signal for vital signs has also been incorporated into the design of the light electric vehicle. Seat pressure and declined level are measured for safety checking. Additionally, a blockdiagram of the system and an image of the developed circuit board that controls the measurement of the ECG signal are provided. The authors integrate a computer screen shot of the management system of the light electric vehicle into their assessment.
The authors conclude that while the interaction information platform may provide a slight solution for communication problems, it is still difficult to discuss the innovative platforms among the participating research groups. However, that is not to say that the future design and implementation of the light electric vehicle is incapable of providing various beneficial functions for homecare use. 

Future Vehicle Society Based on Electric Motor. Capacitor and Wireless Power Supply

Over the past decade, various international conferences on electric vehicles have focused on the discussion of the rise of developing automobile technologies to make the shift from internal combustion engine<!–[if supportFields]> XE “engine” <![endif]–><!–[if supportFields]><![endif]–> vehicles (ICVs) to pure electric vehicles, hereafter EVs. In the future, EVs will be connected to the existing electric powertrain infrastructure, and supercapacitors, rather than conventional batteries<!–[if supportFields]> XE “battery” <![endif]–><!–[if supportFields]><![endif]–>, will function in charging these vehicles. Supercapacitors have a “long operating life, large current density, and environmentally friendly composition.” With this power, EVs powered by supercapacitors can operate for more than twenty minutes, even after a charge of only thirty seconds. In this scenario, the efficiency of these EVs increase, and the recharge time is reduced. Hori discusses a wireless power transfer system based on magnetic resonance and the efficiency in power transfer it enables. Equipped with an electric motor, EVs have three major advantages for traction control systems, antilock braking, motion control, and estimation of road surface conditions: quick and accurate motor torque generation—a motor can be attached to each wheel, and motor torque can be estimated precisely. Hori concludes that EVs that utilize electric motors, supercapcitors, and wireless power transfer, eliminate the need for engines, high performance lithium ion batteries, and large charging stations.—Laura Silverberg
Hori, Yoichi, 2010. Future Vehicle Society Based on Electric Motor, Capacitor and Wireless Power Supply. The 2010 International Power Electronics Conference, 2930–2934.

Hori presents a plug-in hybrid<!–[if supportFields]> XE “hybrid” <![endif]–><!–[if supportFields]><![endif]–> electric vehicle, hereafter PHEV, as the transitional state between ICVs and EVs. With PHEVs, users can utilize nighttime generated electricity during the day and can utilize daytime electricity after a half-day’s charge in the evening. The excess of daytime electricity will prove to be beneficial for electric power companies. Hori hopes that PHEVs will lead to a progressive reduction in gasoline<!–[if supportFields]> XE “gasoline” <![endif]–><!–[if supportFields]><![endif]–> usage and familiarize users with a pure EV lifestyle. By eliminating the requirement of gasoline engines and complex hybrid control systems, the purchase and maintenance costs of the vehicle will be reduced.
As a replacement for conventional batteries<!–[if supportFields]> XE “battery” <![endif]–><!–[if supportFields]><![endif]–>, Hori presents the supercapacitor model, also known as an electric double layer capacitor, hereafter EDLC, as a physical battery needed to run EVs. In comparison to the conventional model, supercapacitors have long operating lives, extremely high power densities, and use environmentally friendly materials in their make-up. The EDLC energy density, on the other hand, is rather low; improvements for increasing energy density will require a significant amount of time. However, that is not to say that the current amount of energy density is insufficient for operating EVs. In fact, when the capacitors utilize anywhere between 50 and 100 Volts, more than 75% of the charged energy can be used. This is not the case for conventional batteries. Additionally, with a short charging time for these capacitors, EDLC-operated EVs can function for longer than twenty minutes on thirty seconds worth of charging. Hori presents the “Capacitor Car,” a concept first utilized by buses in Shanghai, as a suitable and potential transport system for the majority of large cities. Hori details the ubiquity of electric consents and suggests the revamping of vehicle range and infrastructure to apply EV technology to larger scale electric pursuits.
Hori highlights the three main advantages of EVs and the ways in which ICVs are incomparable to their highly sophisticated model: quick torque response of motors, distributed motor installation, and tractable motor torque. The torque response of electric motors is 100 times faster than that of engines. The only energy losses result from the friction between the tire and road surface. With the application of adhesion control, the tire would evade the problem of friction losses. Hori explains that “[t]he most important advantage of these EVs is motion control.” In regard to motor installation, a single EV motor can be “divided into 4 and installed into the wheels of the EV without any significant cost increase, which is not the case with cars.” This is entirely different from conventional 4-wheel drive or 4-wheel steering, which are based on “driving force distribution using differential gear.” Motor torque can be determined from motor current. In EVs, force is transferred from the tire to the road by using “the driving force observer.” Running sensors in the vehicle can inform the driver of road surface conditions, significantly improving driving safety.
Hori proposes a wireless power transfer system for supplying energy to moving objects. In this system, capacitor batteries<!–[if supportFields]> XE “battery” <![endif]–><!–[if supportFields]><![endif]–> will play an important role as a buffer system. This will reduce the dependence on gasoline<!–[if supportFields]> XE “gasoline” <![endif]–><!–[if supportFields]><![endif]–> stations, thereby reducing the costs affiliated with charging gasoline-operated vehicles. Hori mentions the most recent experimental results of wireless power transfer using approximately 10 MHz frequency. The total efficiency of the energy transfer between the two antennas is over 90%. Good robustness of the wireless power transfer system against gap variation and antenna displacement is presented.
Hori mentions that fuel cell vehicles, FCVs, are no longer a viable choice for the future of automobile technology, as they use 100 g Pt per vehicle. Instead, he suggests that FCV vehicle range can be reduced. He concludes that enhancing vehicle technology with the usage of electricity from a power network can revolutionize daily commutation.

A Multi-Level Perspective on the Introduction of Hydrogen and Battery-Electric Vehicles

Battery-electric and hydrogen vehicles have the ability to change a significant number of challenges present in the current automobile sector. These changes pertain to internal combustion engines, hereafter ICEs, by targeting the rise of global climate change, deterioration of air quality, high fuel prices, and the security of energy supplies. Van Bree et al. attempt to address all questions regarding the transition to these alternative vehicles, particularly focusing on the relationship between car manufacturers and consumers and the developments that could interfere. As environmental issues become more urgent, the likelihood of adopting new alternatives becomes more likely.  While it is made clear that neither alternative automobile technology is considered superior to the other or to conventional vehicles, only with technical progress can an answer be provided on the futures of the technologies. The authors divide their paper into six sections. Beginning in section two with an explanation of their methodology, the authors give an overview of the relationships between technology and society. Sections 3–5 describe the automobile within the current system of personal transportation. Section 6 describes two scenarios that could aid in the transition to alternative fuel vehicles, hereafter AFVs. Section 7 discusses the implications of these scenarios in the context of the current economic situations and the role policy makers place in supporting technology. The authors conclude that the development of technology of the coming years “will lay the foundation for the dynamics of the coming transition” to both fuel cell and battery electric vehicles.—Laura Silverberg
Van Bree, B., Verbong, G.P.J., Kramer, G.J., 2010. A Multi-Level Perspective on the Introduction of Hydrogen and Battery Electric Vehicles. Technological Forecasting & Social Change 77, 529–540.

Van Bree et al., in an effort to tackle the problems regarding the transition to AFVs, clarify that the transition itself is based in the joint development of technology and society. In order to fully comprehend the transition, the authors state that a multi-level perspective, hereafter MLP, should be embraced. In the MLP, three levels are examined: the middle level, the socio-technical regime consisting of the socio-technical system, actors, and rules regarding typical behavioral patterns in the carmaker-consumer relationship, which comprises all elements pertaining to production, distribution, and use of technology; the top level, landscape developments, developments meant to put pressure on the regime and can open a “window of opportunity” for breakthrough technologies; the bottom level, technological niches, the location for new technology development that have the means to be protected from market pressures.
Colleagues Geels and Schot provide an extension of the patterns that describe the transitions in the MLP in four pathways, all differing in the types of timing of multi-level interactions: transformation, regarding moderate landscape pressure; de-alignment and re-alignment, addressing sudden and diverse landscape pressure; technological substitution, presenting fully developed niche technology; and reconfiguration, similar to the transformation pathway with moderate landscape pressure, though with the addition of subsequent adoptions of symbiotic elements of niche technologies “lead[ing] to changes in the basic architecture of the system.”  In the event that “no niche-innovation has sufficiently developed, a competition between niche technologies may result, from which one winner emerges, as in the de-alignment and re-alignment pathway.”  Regardless, the pathways system is simply meant to provide further guidance to the scenarios that delineate a possible transition to AFVs.
The third section of the paper focuses solely on the socio-technical system for land-based road transportation. The automobile, “its cultural and symbolic meaning, markets and user practices, and the production system and industry structure” are all examined. The most central actors present in this system include car manufacturers, consumers and fuel providers. Other groups, namely non-governmental organizations, attempt to influence the system. The purchasing process is an important place to begin the study, in that it helps to describe how the car market works and how consumer preferences play a role in the carmaker-consumer relationship. Van Bree et al. gather that “safety, reliability, and comfort are the most important criteria for the buyers of any vehicle. Together with price, they can be considered the primary [purchasing] decision criteria.” Additionally, with rising fuel prices, the most sensible response for consumers is to “switch to more fuel-efficient cars, rather than opting for driving less.” The authors also assess the variety of automobile models that have reached the market over the last decades and the competition that arises between car manufacturers, the increasing modularity of car design, and the relevance of vehicle upgrades to users, all enabled by “consumer expectations and car-manufacturers’ drive to increase profitability.”
The fourth section considers two niche-innovations, battery-electric vehicles, hereafter BEVs, and fuel cell vehicles, hereafter FCVs, and the barriers that they face. These barriers include “the chicken and the egg problem,” “mismatch with consumer preferences,” and “high cost.” The authors disregard hydrogen from these barriers, although they do assess hydrogen as a technological-niche, since it takes place “in a highly protected environment and…[its] stability is low, i.e. a standard technical solution has not been decided on yet.” The electricity-niche is also evaluated.
In the fifth section, Van Bree et al. describe three relevant landscape developments: fuel prices, supply security of fossil fuels, and environmental stresses. The authors’ most important observation is that “supply, relative to demand, will be more constrained in the future.” Imbalances between supply and demand will cause oil prices to increase, particularly due to limited reserves. It is up to local governments to combat the effects of fossil fuel combustion by tightening emission standards.
The sixth section focuses on the segments of the transition process in the MLP. Linkages, otherwise known as “transition seeds,” present between various levels of the transition trajectory, have the potential to trigger change within market dynamics, particularly between consumer and carmaker behaviors, and can lead to new development. The authors assess two sets of scenarios as a means to accept the transition to AFVs. In the first set, tightening emissions regulations influences carmakers to scale up their vehicles and commercialize their products. The second set of scenarios pertains to rising fuel prices. This encourages carmakers to implement plug-in versions of their vehicles, and later with battery-electric and fuel cell vehicles. These two sets of scenarios provide different implications for the actors and infrastructure involved. The authors determine that while both FCVs and BEVs can coexist in a competitive market, the adoption of the BEVs would require more changes.
Van Bree et al. conclude their paper in section 7, reinforcing the potential that the institutionalized relationship between carmakers and consumers has to shape the transition from ICEs to BEVS and FCVs. While the economic collapse has severely affected the United States, the authors, suggesting the first set of scenarios, find it necessary to restructure the car industry. Products should be more fuel-efficient and plug-in hybrid electric vehicles should be implemented on a mass scale, starting with the public push for the Chevrolet Volt as the foundation. 

The Economics of Using Plug-in Hybrid Electric Vehicle Battery Packs For Grid Storage

In order to increase market acceptance for purchasers of plug-in hybrid electric vehicles, hereafter PHEVs, legislation passed in 2008 provided a subsidy as tax credits for said consumers. PHEVs have the potential to provide services to the electricity sector (vehicle-to-grid, hereafter V2G), in the form of “…peak load shifting, smoothing variable generation from wind and other renewables, and providing distributed grid-connected storage as a reserve against unexpected outages.” One of the most advantageous properties of electricity markets is the lack of cost-effective storage. In the absence of energy storage, meeting peak demand becomes difficult and investments in generators and transmission lines must be made. Because of this, the difference between daily peak and off-peak costs can vary significantly within a year.
In regard to V2G services, the authors believe that this system will be more profitable for grid support than the capital cost of batteries that must be remunerated for grid use. In addition to quick battery reaction times, V2G energy has the ability to stabilize or slow fluctuations from sporadic sources, particularly wind or solar sources, and eradicate the need for ‘raid ramping’ of generators to “match variable power sources.” Ramping can also lead to the increase in pollution. Peterson et al. evaluate the net revenue, “the net of avoided grid energy purchases from using the energy stored in the vehicle battery pack,” of V2G energy sales to determine the ‘attractive incentive’ for future owners in three separate categories: an organized market, as energy sales to the grid, or capturing values by running the meter slower.  While the first two options hold transaction and grid costs, the third option does not. Based on the implications of stored grid electricity, energy arbitrage is examined and potential sale prices of electricity, as well as other pertinent data, are collected from Boston, Massachusetts, Rochester, New York and Philadelphia, Pennsylvania. Each city’s hourly electricity markets differed considerably. Based on the authors’ findings, profits derived from battery purchases are not incentive enough for vehicle owners to use the battery pack for electricity storage and off-vehicle use.—Laura Silverberg
Peterson, Scott B., Whitacre, J.F., Apt, Jay, 2010. The Economics of Using Plug-In Hybrid Electric Vehicle Battery Packs for Grid Storage. Journal of Power Sources 195, 2377–2384.

Peterson et al. analyze the potential economic implications of utilizing vehicle batteries to “store grid electricity generated at off-peak hours for off-vehicle use during peak hours.” Hourly electricity prices in Boston, Rochester and Philadelphia were used to “arrive at daily profit values, while the economic losses associated with battery degradation were calculated based on data collected” from combined driving and off-vehicle electricity utilization. The authors calculated the revenue from energy arbitrage, degradation costs, and analyzed a sell-before-buy model as the basis for their study. In the revenue model, the authors assumed the PHEV owner was fixed under a real time pricing, hereafter RTP, tariff. With the addition of a transmission and distribution cost of 7¢kWh-1 to the “hourly nodal price” to estimate the RTP, the data resulted in the incentive for owners to use their PHEV for energy arbitrage. The degradation cost study was based on laboratory data from cycling lithium iron phosphate battery cells (LiFePO4) produced by A123 Systems. Using the Chevy Volt’s battery pack pricing as the framework for this degradation study, the authors concluded that by using a $5,000 replacement cost, a degradation cost of 4.2¢kWh-1 would operate. The sell-before-buy model entails a battery pack beginning on a day when it is fully charged. From 8 a.m. to 4:59 p.m., the authors designate time for driving exclusively and all other times are allocated for charging. The battery pack is charged at the lowest cost hours possible. In order to determine the amount of battery pack capacity a profit-driven consumer would choose to devote to energy arbitrage, the authors utilize two separate methods. The first method entails the consumer knowing the future TRP where they choose the most expensive locational marginal pricing, hereafter LMP, hour to use the battery pack for home energy use and the cheapest hour after to recharge. In this scenario, the vehicle is fully charged by 8 a.m. The second method calls for knowledge of previous RTPs to determine the hours least expensive to recharge the vehicle. While this method may mis-predict the cost of recharging since it is purely based on speculation, the battery pack energy can be used for home energy as well. The profit is calculated as the revenue cost from energy arbitrage, therefore doubling the incentive for consumers.
          Peterson et al. provide significant data resulting from their various studies. Using the three cities as the framework for examining electricity market costs, the maximum annual profit ($118) occurred in Philadelphia in 2008, whereas in Boston, the least profitable city, a consumer’s profit would only result in $12–48 based on a particular year’s market. Based on estimated profit analyses, the authors concluded that increased battery size would not increase the profit greatly due to the limitation of local circuit infrastructure in the three cities.
The authors presented sensitivity analyses on the effect of battery pack replacement cost on profit. Only if the battery pack replacement cost is set to zero, so too will be the cost of degradation. This would yield the maximum profit, particularly in Philadelphia. The difference between peak and off peak is higher in the Pennsylvania New Jersey Maryland Interconnection LLC, hereafter, PJM, than the other regional transition organizations, hereafter RTOs. In this scenario, Boston becomes more profitable than Rochester. The authors also discuss the interest of grid operators knowing when vehicle owners will make their energy available for sale on a given day. Philadelphia was found to be most profitable when PHEV consumers participated in energy arbitrage 56% of the days between the years 2003–2008. However, if the battery pack replacement cost is $10,000, this percentage decreases to 38%.
          The results indicate that vehicle owners are not likely to receive sufficient incentives from energy arbitrage to increase the use of car batteries for grid energy storage. The maximum annual profit is between $142–249 in all three cities due to the small variation present in LMPs. If degradation cost is included, the maximum annual profit would only range from $12–48 in perfect circumstances, although more realistically, it would range from $6–72. The authors suggest that if a large number of consumers decide to participate in energy arbitrage, the profit would decrease since the LMP spread would be lowered. Grid net social welfare benefits were also considered. The authors found that the increase of construction and use of peaking generators are similar in size to the energy arbitrage profit. Since there may only be $300–400 of annual net social welfare benefits that can be transferred to the owner of a PHEV, it is unlikely that large-scale usage of grid energy storage will be appealing to a large number of said vehicle owners. 

Practical Implementation of an Hybrid Electric-Fuel Cell Vehicle

Electric vehicles are becoming more popular in the consumer world, as the demand for high-performance vehicles continues along an upward trajectory. While the costs of fossil fuels and clean energy are on the rise, vehicles whose power sources operate together within an electric or hybrid framework continue to be in high demand. A major advance in hybrid vehicle research has focused on fuel cell technology. This technology has improved significantly over the past few years, with a major decrease in the cost, the volume and the weight of individual cells. In fact, medium power fuel cells are now available in medium-high efficiency. In order to develop a “competitive product…” “[h]igh performance fuel-cell power modules, batteries and the necessary power electronics …are required” and must be developed for greatest efficiency. Dominguez et al. introduce a hybrid vehicle, built from the commercial vehicle GEM eL by Global Electric Motorcars, where the battery stack of the commercial car is supported by a 4 kW fuel cell. The “fuel cell charges the batteries when they have low charge but it provides…power directly to the dc motor drive when it is required by the user.” Within the proposed hybrid system, Dominguez et al. divide the description of their system into the following subsections: the fuel cell device and the hydrogen storage system, the dc/dc power converter and the auxiliary converters, and the control and monitoring system. These three categories serve as the basis for analysis of the authors’ proposed hybrid vehicle. The proposed model has been “experimentally tested in the facilities of the National Institute of Aerospace Technology in Huelva, Spain, where two separate vehicle acceleration scenarios were tested.” In both of these scenarios, the authors observed that the fuel cell provides power whether or not the vehicle is in motion. The advantage to this system is that the vehicle range can be extended since the fuel cell module charges the batteries using hydrogen as fuel. The authors determine that after an analysis of their proposed hybrid vehicle system, their data demonstrate a “high robustness and reliability.”—Laura Silverberg
Dominguez, E., Leon, J.I., Montero, C., Marcos, D., Rodriguez, M., Bordons, C., Ridao, M.A., Fernandez, E., 2010. Practical Implementation of an Hybrid Electric-Fuel Cell Vehicle. IEEE Proceedings from the Annual Conference of IEEE, 3828-3833.

Dominguez et al. analyze a practical model of a proposed hybrid vehicle, powered by an array of batteries and a fuel cell. The authors section their data into three main systems that have been integrated into their vehicle design. The first subsection describes the fuel cell power module, the HyPM-XR, which is used in the hybrid vehicle. Like any other fuel cell, this powertrain emits nearly zero emissions other than byproducts such as water and oxygen-depleted air. The fuel cell module, suitable for a wide range of “transportation, stationary and portable applications,” is highly reliable due to its “modular design, fast dynamic response and high efficiency.” The second subsection, focusing on dc/dc boost power converters and auxiliary dc/dc converters, describes the make up of the power electronic system incorporated into the vehicle. The authors make a note of the design system’s weight and volume reduction and that the reliability of this model is achieved by the boost converter system located under the driver’s seat. The converter is also capable of switching frequencies, barely allowing any noise to emit from the vehicle as it comes to a rest, as well as obtaining a dc voltage output higher than its input. If said voltage ratios were higher, a double-boost system could be used. However, the main reason for utilizing the auxiliary dc/dc converter is “to generate the necessary voltage to supply the secondary power systems such as the selenoidal valve and a computer with a tactile screen (PC-car),” as well as provide “300 watts for 20 seconds in the start-up of the fuel cell system.” This PC-car monitoring system, using Labview technology, allows the user to control and monitor the system. This includes the vehicle’s status, “the hydrogen load, the hydrogen pressure, the dc voltage of the fuel cell…the battery stack…and possible warnings and errors.” By providing liberties to the user to manipulate their own hybrid system, the authors’ proposed hybrid electrical-fuel cell vehicle proves to be a good basis and testing platform for future technologies.
In the third and final subsection of the paper, Dominguez et al. describe the proposed vehicle’s control and monitoring system. Hydrogen, an important facet of the vehicle’s design, is stored in the back of the vehicle. The fuel cell uses hydrogen to produce the energy to charge the battery stack when it is needed. When a low battery charge is detected, at a level below 78 volts, the fuel cell injects current to increase the charge. Typically “when a battery charge is applied to a battery stack, its dc voltage increases almost immediately.” On the other hand, when the vehicle is in motion, the dv voltage of the battery stack fluctuates. If this is not taken into account, a simple acceleration of the vehicle could be considered a low battery warning. The authors clarify that as part of their proposed model, this is not a problem since the “controller provides the necessary current to charge the batteries or to drive the dc motor directly.” However, at the same time, there is current flowing from the fuel cell system to charge the batteries. This process can save energy because the battery stack is left unaware that the user “is demanding more power unless the maximum nominal current of the fuel cell system is achieved.” Once the maximum is achieved, the “current from the fuel cell system is saturated and the rest of the power is provided back to the battery stack.”
Dominguez et al. review two experimentally tested scenarios on their proposed hybrid system. In the first experiment, the vehicle “is moving continuously and the driver is accelerating and braking following a hilly path.” Since the fuel cell is providing continuous energy to the battery stack, the battery stack can transfer that energy to the dc motor. In the second experiment, the “vehicle is moving and suddenly…stops.” In this scenario, the fuel cell not only provides power as the vehicle accelerates, but also when the vehicle stops and a low battery level is detected; the fuel cell is prompted to continue providing power in order to charge the battery stack. The authors also found that the vehicle range can be increased from 40 kilometers to 100 kilometers, as the only limiting factor is the hydrogen capacity in the vehicle. Furthermore, all experiments were developed under “real weather conditions.” The authors conclude that in the future, natural park and tourism vehicles should take advantage of their proposed hybrid system.