Better than eighteen months ago, Volvo Car Group started a project that was meant to start a spiral of increasing fuel economy, starting with the electrical system.
The heart of the project is a new lithium-based supercapacitor, which is just 1mm thick, and can be integrated into body panels and vehicle structural members. A hood, for example, could be made of one of these lightweight carbon-fiber supercapacitors, but how could this make for better fuel economy? First of all, think about weight for a minute. According to the US Environmental Protection Agency [EPA], every extra 100 pounds your vehicle carries translates up to a 2% loss in fuel economy. The first part of the spiral begins with lighter body panels and structural members, carbon fiber being some of the lightest available.
What about the next part of the fuel economy spiral? Recall these panels are embedded with supercapacitors. If enough supercapacitor-bearing panels are mounted on the vehicle, perhaps the hood, trunk lid, roof, even the upper suspension crossbar, it would eliminate the need for heavy sealed lead acid [SLA] batteries. The typical conventional automobile today carries an SLA battery that weighs 20lb to 40lb. Following the logic from the EPA, eliminating the SLA battery alone could save about 1% fuel economy, but it doesn’t stop there.
The fuel economy spiral simply started with removing the SLA battery and some heavier steel or aluminum body panels and replacing them with lighter supercapacitors embedded in carbon-fiber. Other parts of the vehicle can be replaced with lighter parts as well. Volvo estimates that they could save up to 15% of a vehicle’s weight by getting rid of heavy panels and structural members, replacing them with carbon-fiber and supercapacitors. This alone, according to the EPA, could boost the fuel economy of the Volvo V60 Diesel PHEV, already 120MPG, to 135MPG!
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