5. Modelos teóricos de la enseñanza de lenguaje
5.3 Enfoque comunicativo
Projecting the costs and retail prices of future vehicles and vehicle components has tended to be problematic even for conventional vehicles, and there is substantial controversy about how much hybrid vehicles will cost. Obvious problem areas for this analysis include:
1. Direct information on component prices to original equipment manufacturers is rarely available; the OEMs generally hold this information as confidential. In addition, the manufacturers treat the prices they pay to component manufacturers as confidential information. Another potential source of information, retail prices for particular components, may be available only in limited situations, because many components of interest are integral to the vehicle and are not separately priced. Even when prices are
available, they often do not reflect actual cost plus profit, but instead reflect the manufacturer’s estimate of how the market values the components. Thus, the existing price data are of limited help in supporting cost projections.
2. Hybrid engine costs are problematic for two reasons: first, they are extrapolations from larger, more powerful engines designed for CVs; and second, hybrid duty cycles are different from CV cycles, so the design of a purpose-built hybrid engine will be different from that of an engine built for a CV. In the Prius, for example, Toyota has restricted the rpm level of the engine and has been able to cut costs by using some lighter, less expensive components as a result.45
3. The electric drive components presently are built in small quantities at high prices that do not reflect savings associated with mass production. Further, there is a vigorous R&D program aiming at improving (altering) the designs for key components, further complicating the task of projecting costs and retail prices. The HEVCOST
methodology ignores current costs and estimates high volume costs by starting from the materials in the components, building in normal markups. However, uncertainties associated with changes in materials, production methods, and power densities (yielding reductions in materials) remain.46
4. Estimating fuel and electricity costs for both grid-independent and grid-dependent hybrids run into a number of problems. We have modeled HEV onroad fuel economy by multiplying the ADVISOR-estimated corporate average fuel economy (CAFE) values by the current EPA onroad degradation factor of 0.85 (we used a lower value, 0.80, as the degradation factor for conventional vehicles; this reflects the shift in driving to more congested conditions, a shift that will have less impact on HEVs). However, the 0.85 degradation factor was developed for vehicles with conventional drivetrains and is unlikely to be accurate for HEVs. We have adopted the 0.85
degradation factor as a default value for HEVs until better data are available. Another concern for grid-dependent HEVs is uncertainty about the percentage of energy use supplied by the grid.
3.3 References
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45Duleep, K.G., unpublished report to U.S. Department of Energy on Prius costs, 1998.
46As noted above, the new Prius battery back is much smaller and lighter than the previous version,
implying that cost estimates based on the previous pack’s power density and weight would be much too high.
Duleep, K.G., 1998, Briefing on Technology and Cost of Toyota Prius, Energy and Environmental Analysis, Inc., Arlington, Va.
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