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Because the grid in the United States is mature and the automotive industry reasonably saturated, the VDS Vision will be designed for a developing market in India, China or South America. To address variation in regional demand and infrastructure, six propulsion teams will work to develop a set of APU’s for the VDS Vision. Accordingly, the vehicle will be able to run on hydrogen, compressed natural gas, methane, ethanol, biodiesel, or straight electricity depending on the user’s choice of APU. This unit will be sized to propel the vehicle at cruising speeds on a highway. This modular characteristic will enable the vehicle to dynamically meet different load requirements and consumer demands. Perhaps more importantly, this set of generators meets the requirement that all VDS subsystem teams think about the independent significance of their work. In a world where the leading cause of childhood death is poor indoor air quality, small generators that could replace wood or dung as an energy source present an interesting auxiliary benefit, particularly if the fuel source is locally derived. In more developed regions where electricity is pervasive, coupling the debate over distributed versus grid-tied energy to that of personal mobility will enable focused progress on how to best clean up the electricity grid within the context of a diverse and sustainable energy future.
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The hybrid architecture selected for use in the VDS Vision will utilize an electric motor and an APU to maximize fuel efficiency and optimize vehicle performance. The increased fuel economy is achieved primarily through 3 mechanisms: a) Reducing wasted energy during idle/low output by utilizing the more efficient electric motor and turning off the APU; b) Recapturing waste energy (e.g. regenerative braking); and c) reducing the size and power of the APU unit, which often has 10x more power than required for nominal cruising conditions in order to meet acceleration requirements. The combination of the use of fluid fuels as well as smaller APUs results in significant weight savings in the propulsion system, which when combined with weight savings in other parts of a vehicle allow a smaller, more fuel efficient propulsion system to achieve similar performance to a much larger standalone internal combustion engine. The VDS hybrid architecture teams at UC Davis and the University of Waterloo will develop a parametric MatLab model to inform decision-making about size, runtime, and control of both the battery pack and the APU.
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| Plug-In Architecture for a Clean Electricity Grid |
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Vehicles are a leverage point for radical and systemic change. In the United States, 90% of all commuting activity has a range of 30 miles or less. To address this, the VDS Vision is designed as a two-mode vehicle with a design optimized for short and long distance transportation. Batteries will give the vehicle a 40-45 mile range without use of any APU (Auxiliary Power Unit), and the plug-in feature enables easy charging at home. A research group with the Union for Concerned Scientists, coordinated by Steven Bantz (Sr. Engineer, Clean Vehicles Program), will develop our model for true cost accounting of electricity as a fuel in cases where clean power is not generated on site. UCS will also advise on policy options and coordination with government. VDS sees this aspect of the Vision’s design as being a potential area of collaboration with partners interested policy options and leverage points associated with the Vision.
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VDS 2.0 