Research shows that approximately 80% of light duty vehicle journeys in Europe are less than 50 km, while 80% of light duty vehicle journeys in the US are les than 50 miles (80km). Although it is difficult to generalise, according to the European Commission’s statistics body Eurostat, apart from the 1:1.6 ratio increase in distances, the passenger mobility data for Europe are broadly similar to the US. A summary compiled by Eurostat in 2007 of the most recent national travel surveys found that people in most countries make on average three trips per day, totalling between 30 and 40 km across all modes of transport. These passenger kilometers are predominantly satisfied by the use of private cars: in the EU-25, close to 460 million citizens travel a daily average of 27 km by car. These trends in distribution of personal vehicle miles driven daily are illustrated in figure 13.
Figure13. Distribution of personal vehicle miles driven daily
(source: US Dept. of Transportation Federal Highway Administration)
This distribution of personal vehicle miles driven daily in the EU and the US has enormous implications for hybrid electric vehicles. It can be seen that for plug-in hybrid vehicles with a battery range of 30 miles (US) or 30 km (EU), electricity can fuel approximately 50% of total light duty vehicle miles driven daily.
Studies such as “"Plugged In: The End of the Oil Age” by WWF
(Dr. G. Kendall, 2008) show that given the current EU electricity generation mix, and conservative estimates about the efficiency of battery electric vehicles (BEV) compared to an ICE powered vehicle, W-T-W savings of over 57% CO2 emissions are possible when the plug-in hybrid is operating in EV mode (619g : 1460g / kWh).
When operating with the Libralato engine APU, a 10% decrease in CO2 emissions from the engine efficiency could be added to by a further 10% decrease from use of 20% blend biofuel, counteracted by an increase of 15% from electrical losses.
Therefore a plug-in hybrid electric vehicle equipped with a Libralato engine APU and with a battery range of 30km (PHEV30) could produce W-T-W CO2 savings of 33% and T-T-W savings of 53.5% compared to a conventional light duty vehicle. 500,000 of these vehicles per annum by 2020 replacing conventional vehicles, could reduce CO2 emissions in the EU by 594,000 tones per annum, equivalent to taking 165,000 cars off the road.
The engine is equally adaptable for use with blends of gasoline-ethanol. Indeed given the lower compression ratios involved, it may be that this is a less technically challenging solution to be achieved first. Through a lambda probe monitoring the exhaust gas, the digital engine management unit can alter the air-fuel ratio and spark timing to adjust for varying blends of biofuels, offering flex-fuel capability in addition to precision controlled fuel injection.
As described by Dr. Kendall, “The potential for grid-connected vehicles to decimate our demand for liquid hydrocarbon fuels should be clear. Freed from the psychological barriers which hinder widespread market acceptance of pure battery electric vehicles, plug-in hybrids with an all-electric capability of just fifty kilometres would slash liquid fuel consumption, since such a high proportion of journeys undertaken are well within this range. Beyond 50 km, a significant share of the ‘residual’ liquid demand may be met with next generation biofuels. Suddenly, the European Union’s target that renewable energy must meet 10% of transport fuel demand by 2020 which, up to now, has been widely considered as rather ambitious, may even prove somewhat conservative.”
The graph below compares the cost of a plug-in hybrid powertrain (based on a Libralato APU, combined with a lowcost 6 kWh battery pack) compared to a conventional gasoline engine.
Figure 14. Cost versus fuel Consumption Improvements for Powertrain Technologies
As put by Dr Kendall. “Automotive transport is ripe for transformation. We need to accelerate the
commercialisation of vehicles with diversified primary energy sources, high efficiency and compatibility with a sustainable, renewable energy future. The electrification of automotive transport offers a promising way to achieve this objective. Grid-connected vehicle technology – enabling all or part of every journey to be powered by electricity taken from the grid – is available based on existing infrastructure and current technology. Battery electric vehicles (BEVs) and plug-in hybrid electric vehicles (PHEVs) – supplemented by sustainable biofuels for range extension – can dramatically reduce the crude oil dependency of [and climate change caused by] automotive transport in an efficient and sustainable manner.”
