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3 EVALUATIONS OF INDIVIDUAL TECHNOLOGY AREAS
Pages 29-60

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From page 29...
... VEHICLE SYSTEMS The Vehicle Systems section of the plan attempts to define the requirements for subsystems of the overall vehicle system necessary to meet the OAAT goals and objectives. The proposed approach involves computer modeling of the overall vehicle system, based on the development and validation of subsystem models incorporated into the overall vehicle system models.
From page 30...
... In contrast to conventional power trains, which have a single power source, hybrid power trains have a primary power source and a secondary power source that provides onboard energy storage. With a hybrid configuration, the primary
From page 31...
... vehicles should not be excluded at this time, particularly in light of the cost constraints described in the OAAT goal (advanced technology vehicles will have to be competitively priced compared with conventional vehicles.) The need for two power sources in a hybrid vehicle is likely to increase the overall cost and complexity of the power plant compared to conventional power plants.
From page 32...
... Compression-Ignition Direct-Injection Engines The OAAT plan for R&D on advanced automotive piston engines involves working with the U.S. automotive industry to solve the major technical barriers associated with the CIDI engine.
From page 33...
... One aspect of the OAAT plan that needs to be clarified is the basis for the technical targets for the performance of CIDI diesel engines. Targets for peak efficiency, peak power, specific power, emissions, and power density are given in the vehicle systems section.
From page 34...
... Many of the CIDI engine technical tasks in the OAAT plan for example, R&D on CIDI fuel systems, spark-ignited combustion, advanced integrated emission control, and technology validation are already being pursued by industry independently. Therefore, it is not clear to the committee why the government should be a partner in these activities.
From page 35...
... No clear research directions are defined in the OAAT plan for making the engine lighter, thereby increasing its specific power. Nor is there a discussion of the candidate materials, such as compacted cast iron, spheroidized cast iron, and aluminum alloys, that might meet the requirements for castability, damping, recycling, and cost, as well as weight reduction.
From page 36...
... Four major technical barriers are identified: efficiency, especially at part load; cost, especially in ceramic component fabrication; durability and reliability, especially for ceramic components; and NOX emissions, especially for cold starts and transients. The goal of the materials R&D program related to gas turbines is the development of durable, high temperature, high strength ceramic materials and associated manufacturing technologies.
From page 37...
... Six of the seven technical barriers to the development of gas turbines and engine system materials are entirely or primarily associated with ceramic components, and seven of the eight technical tasks are entirely or primarily associated with the development and manufacture of ceramic components. The implication is that overcoming problems with ceramics would all but eliminate the technical barriers to a hybrid vehicle turbine.
From page 38...
... The following objectives and tasks should be added to the plan: · address other areas where costs may be unacceptably high, such as compressors, burners, control systems, bearings, and housings · establish a more definitive approach to achieving very high efficiencies at 25 percent power · establish a more definitive approach to reducing NOx levels, if necessitated by increased combustion temperatures · define an approach to developing a high efficiency, low cost alternator · establish criteria for acceptable engine life FUEL CELLS Fuel cells are being investigated as a potential alternative to the internal combustion engine in automobiles. Fuel cell vehicles offer the potential of higher energy efficiency than vehicles powered by internal combustion engines because they use a near isothermal electrochemical reaction as opposed to a combustion process.
From page 39...
... Nevertheless, the power density and start-up time for PEM fuel cells are poor when compared to internal combustion engines. The OAAT program (like most other fuel cell vehicle development programs around the world)
From page 40...
... Questions to be addressed include whether, when using natural gas, the onboard fuel processor and compressed gas storage tank would be too bulky to fit in the vehicle and would render vehicle efficiency targets extremely difficult to achieve because of the extra weight. Systems studies to clarify performance and cost goals for fuel cell vehicle components should be continued and expanded, especially to compare alternative fuels and fuel processors and to compare fuel cells to other power plants.
From page 41...
... The plan should include a discussion of the hybrid vehicle configurations in which the high power energy storage devices would be used and should confirm that hybrid vehicles would meet all OAAT objectives. High Power Batteries High power batteries for hybrid vehicles must have high specific power with power-to-energy ratios greater than 10 kW/kWh.
From page 42...
... However, major technical problems for high power batteries remain, many of which are addressed in the OAAT R&D plan. The OAAT plan for high power batteries is explicitly aimed at satisfying requirements for a hybrid vehicle with a slow-response engine.
From page 43...
... Nevertheless, in the committee' s view, nickelmetal hydride and lithium-ion technologies are the most promising battery options for meeting high power energy storage requirements for hybrid vehicles. The choice of either nickel-metal hydride or lithium-ion batteries will probably be made in the marketplace.
From page 44...
... Double-layer ultracapacitor modules of up to 48 V with power densities of 1 kW/kg have been achieved in experimental cells. Despite this progress, the OAAT has concluded that double-layer ultracapacitor technology is fundamentally incapable of meeting the long-range, high power energy storage requirements for PNGV.
From page 45...
... One justification for selecting pseudocapacitors for future OAAT investment is credible technical evidence that energy storage based on electrochemical redox couples has the potential for higher energy density (although lower power density) than electrostatic charge separation, which is the basis for double-layer capacitor technology (Conway, 1991~.
From page 46...
... OAAT's R&D on flywheels is an enabling technology program primarily concentrated on overcoming the technical barrier of safety, especially on the problem of containment in case of rotor failure. The objectives include developing analytical models and standardized tests for rotor failure and containment systems, and the technical tasks are all directed toward overcoming the containment problem.
From page 47...
... In the absence of adequate vehicle systems studies, the committee is concerned that the flywheel energy storage system may not be a viable system for a highly efficient, cost competitive vehicle even if the containment barrier can be overcome. In addition, OAAT's technical targets for power-to-energy ratio, specific energy, energy density, cycle life, and production cost are all very far from current levels, and OAAT has no program for meeting these targets.
From page 48...
... The purpose of the aggressive PEBB program, which involves manufacturers of semiconductors, is to develop new power semiconductor devices and modules that integrate many of the inverter functions into low cost compact units with high power density. The OAAT plan also incorporates parallel multi-year materials R&D programs in both the electric machines and power electronics areas that will be defined at the end of 1997 based on the results of an ongoing assessment of the materials needed for hybrid vehicle power electronics and EVs.
From page 49...
... It appears that most of OAAT' s expenditures in the area of power electronics and electric machines will be devoted to R&D on power electronics rather than on electrical machines, although the proposed resource allocations are not stated. In the committee's view, a decision to focus R&D investments on power electronics is appropriate, given that, in general, the cost of power electronics today greatly exceeds the cost of electrical machines.
From page 50...
... The OAAT, as a stakeholder in the multi-agency PEBB program, should ensure that more program resources are devoted to reducing the cost of power electronics. ADVANCED AUTOMOTIVE MATERIALS Lightweight materials in the drivetrain, body, and chassis will be necessary for the OAAT to meet its goal of vehicle fuel economy.
From page 51...
... However, current vehicles contain substantial quantities of plain carbon steel and grey cast iron, materials that can be easily recycled and are eagerly sought as feedstock by mini-mills and foundries. If lightweight materials (high strength steels, Mg, Al, Ti, and composites)
From page 52...
... Alternative fuels have the potential to displace substantial amounts of petroleum, as well as to improve fuel efficiency and lower emissions, if the cost barriers associated with vehicles, fuels, and infrastructure can be overcome. These cost barriers vary depending on the fuel, but none of the alternatives is competitive with today's gasoline or diesel fuel.
From page 53...
... to be achieved within a short period of time and the relative priorities assigned to the technical barriers. Natural gas is one of the few alternative fuels that currently has an operating cost advantage over gasoline.
From page 54...
... If these targets are met by changing the design to increase the tank volume without decreasing vehicle cargo capacity, the proposed technical approach and costs should be described. The descriptions of technical tasks generally do not include descriptions of the technical approaches to overcoming barriers.
From page 55...
... Technical approaches to safety concerns raised by the increased use of natural gas should be included in the plan. Recommendation.
From page 56...
... Because the OAAT plan for ethanol does not address innovative, high-risk approaches to making ethanol commercially competitive with gasoline, the committee sees no need for government funding of the proposed R&D. The plan states that the successful resolution of the cold start problem with E85 technology "will allow research to progress to neat ethanol (Eg5~6 in the future, which would provide greater energy and emissions benefits." Almost all i5The physical properties of methanol are better for cold starts (4.6 psi, with a boiling point of 65°C)
From page 57...
... OAAT plans to use some ongoing work at the OHVT (Office of Heavy Vehicle
From page 58...
... The committee noted that the reduction in incremental vehicle cost of $1,500 to $600 indicated in the technical targets for DME does not appear to meet the OAAT goal of a vehicle that is "competitive with conventional vehicles." Recommendation Recommendation. The plan should state that DME is made from methanol and should include an analysis of the technical and economic trade-offs between using methanol and DME (made from methanol)
From page 59...
... OAAT must also explain how these costs will make EVs competitive with conventional vehicles. In the committee's opinion, the target cost will be difficult to attain, and the proposed technical approach for reducing cost is not adequately defined ("have each developer conduct ...
From page 60...
... 1996. Proceedings of the Sixth International Seminar on Double-Layer Capacitors and Similar Energy Storage Devices.


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