In this paper we have selected and reviewed seven high-profile studies comparing hybrid, plug-in hybrid, battery electric and hydrogen fuel cell vehicles, and biofuels. Although the studies differ in terms of scope, data used and methods and hence their results are not strictly comparable, a coherent high-level story clearly emerges if they are considered in chronological order. In particular, the studies suggest that incremental improvements to internal combustion engine (ICE) vehicles have an important role to play in the short to medium term; however, in order to meet long-term policy targets, alternative fuels and powertrains will be necessary and strong policies will be required to promote their rapid development and uptake. Moreover, in the long run Plug-In Hybrid Electric Vehicles (PHEVs) may be constrained by the availability of sustainable biofuels, hence both battery electric Vehicles (BEVs) and hydrogen fuel cell vehicles (FCVs) are expected to play an important role. In particular, the latter technologies have been seen as largely antagonistic and mutually exclusive in earlier studies, while more recent studies argue that both BEVs and FCVs are needed as they will be serving different segments of the passenger car market. Our review of previous studies also suggests that, despite having generated and synthesised a tremendous amount of knowledge, they show some limitations which are potentially significant and which future studies could seek to address. In particular: a) the complexity of the passenger car market, consisting of many segments characterised by different requirements and use patterns, is not adequately represented; b) future changes in driving behaviour brought about by new policy and technology are generally not considered; c) different studies use different indicators, making results difficult to compare across studies and their interpretation difficult for the non-expert. In the remainder of the paper, we have sought to further explore the limitations of the studies reviewed by performing a Total Cost of Ownership (TCO) analysis which builds on previous work by the authors. In particular we have shown that, comparing alternative fuels and powertrains based on a single vehicle platform and using average driving patterns, future costs of all options are likely to be close and possible differences would be well within the error margin. In other words, using this method nothing conclusive can be said as to which one of them would be the least-cost option in 2030 or so. This result is in line with the findings of the most recent studies reviewed. However, building different vehicle segments and driving patterns into our TCO analysis, we found that costs start to diverge and that certain fuel and powertrain options are more competitive than others for given market segments. In particular, from a TCO perspective BEVs appear to be potentially at an advantage in the smaller vehicle segments, provided they are used on a low-energy driving cycle (e.g.: urban and low-speed extraurban) and that their utilisation (i. e.: total miles driven over the lifetime of the vehicle) is sufficiently high. FCVs and PHEVs (both FC and ICE) with relatively small batteries (i.e.: 5-15 kWh) would compete head to head in the other segments of the market, with ICE PHEVs potentially being the cheapest option of all but with non-zero tailpipe emissions. Moreover, PHEVs with downsized range extenders may offer significant savings to users who are prepared to sacrifice performance, particularly top speed. More analysis would be required in order to better explore markets segments were FCVs and PHEVs compete. However, the limited analysis performed in this paper is sufficient to clearly show the importance of taking into account the diversity of the passenger car market in future comparative studies. Moreover we demonstrated that taking into account possible future changes in driving behaviour can also alter the results of a comparative study quite significantly. So far, these studies have largely been based on today's driving patters and this is acceptable if the time horizon of the comparison is near, but almost certainly unacceptable if the comparison is projected into a more or less distant future. So, we suggest that behavioural change should be accounted for in future comparative studies. Finally, we recommend that more uniform indicators and metrics should be used when undertaking comparative studies in the future (be they "Well-to-Wheel" (WtW), TCO or societal cost analyses); it is also essential that the high uncertainty and hence explorative (as opposed to predictive) nature of the long-term studies is always made clear, for the benefit of the non-experts.
Battery electric vehicles, hydrogen fuel cells and biofuels. Which will be the winner?
Energy & Environmental Science ; 4 , 10 ; 3754-3772
2011
19 Seiten, 9 Bilder, 6 Tabellen, 57 Quellen
Aufsatz (Zeitschrift)
Englisch
Elektrofahrzeug , galvanische Batterie , Wasserstoffbrennstoffzelle , Biokraftstoff , Personenkraftwagen , Motor mit innerer Verbrennung , automatisches Getriebe , Wasserstoff , Fahrerverhalten , Fahrverhalten , Gesamtbetriebskosten , Marktsegment , Fahrzyklus , Kostenanalyse , Vergleichsuntersuchung , Vergleichstest