Greased Lightning
It was extremely pleasant to drive, with more than adequate performance in city driving and a range of approximately 160km. Its only problem, like all pure electric vehicles, is that each re-fueling duration is six to eight hours, a far cry from the 10 minutes or so for a normal vehicle.
Despite great strides in battery technology, especially over the last three decades, the energy storage density of the best of its kind is still no match for the internal combustion engine’s liquid fuel.
The storage of portable electrical energy still requires large and heavy cells that totally destroy the vehicle’s power-to-weight ratio and space efficiency. This, of course, was the main impetus behind the development of hybrid vehicles like Toyota’s Prius and Honda’s Civic Hybrid! Insight, which as we know, combine an ‘electric motor with the conventional petrol engine (either of which can provide power for propulsion) – hence, requiring only a compact storage battery.
Conceptually, fuel cell vehicles (FCV) are the ideal solution because electricity is generated on board by “reverse electrolysis”, a process that does not consume fossil fuels or produce carbon dioxide. However, their powertrains are complex and expensive to produce, not least because of the high cost of the relatively new technology of fuel cells. So, an FCV is not the best commercially viable solution at the moment.
A simpler solution is used by General Motors in their soon-to-be launched Chevy Volt. It is not a hybrid because it is powered solely by a 120kW electric motor. The powertrain includes a 170kg lithium ion battery pack that can be charged by plugging into a 120V or 240V AC domestic power point.
By electric vehicle standards, the battery is compact and lightweight. Fully charged, the battery will take the Volt no more than 64km. But the car’s secret of survival on the roads beyond that is its on-board generator set, comprising a conventional 1.4-litre petrol-fuelled engine and an alternator to supply electrical energy either to the battery pack or directly to the motor. The engine has no mechanical link to the drivetrain, its sole function being to drive the alternator when the battery’s electrical power has been depleted. Essentially, this means the 64km range is extended, albeit with the assistance of liquid fuel. GM is readying the Volt for a 2010 launch. And while this much-awaited eco car is unlikely to prop GM back to being the largest carmaker in the world, it will go a long way in lifting GM’s hitherto lacklustre reputation for building high-tech motorcars.
Hot on the heels of the Chevy is an A-Class-size model from Daimler with similar extended-range capability. Unveiled at this year’s Frankfurt show, it is one of three versions based on the unique Mercedes-Benz Concept BlueZero Plus. The other two variants also based on the same sandwich floor platform/ chassis and sharing various drivetrain components are the types we described earlier: battery electric and fuel cell electric. All three BlueZero models will also share many of the electrical hardware, including the lithium-ion batteries and the 100kW electric motor. Notably, none of the three are hybrids – not even the model that houses a 1-litre turbocharged engine from the Smart city car. As in the Volt, the engine serves only to run an alternator to re-charge the battery and/or supply electricity directly to the electric motor.
The Volt and BlueZero (the one with an engine-driven alternator) are two of a new family of cars known as the extended-range electric vehicle or E- Rev. These cars are not zero-emission vehicles since there’s an engine on board. But the E- Rev scores because most urban commutes rarely exceed 60km. Besides, when the engine kicks in, effective range is nearly 400km. Though neither car is currently available at any dealership, Daimler and GM particularly are at an advanced near-series production stage of developing their E-Revs. They are nowhere as complex or costly as FCVs, and are far more useable than battery electric cars.
No doubt, other automakers are also in the game and we will know about their cars soon enough.
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