US: Study shows aluminium use in EVs can lower costs

A new study jointly conducted by the Aluminum Association and Ricardo concludes that opting for high-strength, low-weight aluminium over heavier steel structures for plug-in electric and hybrid vehicles can cut vehicle price overall by reducing the battery energy requirements and the associated costs. The purpose of the study was to evaluate the impact of vehicle weight reductions on electric vehicle performance, range and battery size. The majority of the vehicle simulations were done using the FTP75 drive cycle with a few highway drive cycles. Conclusions from the study include the following. •The driving range of the vehicles could be improved approximately equal to the mass saved. Reduce the mass of the vehicle 20%, go 20% further. One example vehicle had the range extended from 80 to 97 miles. •The heaviest vehicle in the study, at 1,822kg, consumed about 300Wh/mi, while the lightest at 627kg consumed about 146Wh/mi. •Regenerative braking could recover about 65% of the energy associated with the vehicle's momentum irrespective of the vehicle weight, but this was only about 15-20% of the total energy expended. •For the lightest vehicle, about 44% of the energy is lost to powertrain inefficiencies, with 33% of the energy used to overcome air resistance, and only 24% is used to move the vehicle. •As with conventional vehicles, lighter vehicles have faster acceleration. Michael Bull, director of Automotive Technology for Novelis, representing the Aluminum Association, notes: “As automakers gear up for a new generation of plug-in electric vehicles, the high cost of battery power remains a barrier. What this new report shows is that by upgrading from traditional steel to an advanced aluminium body structure, the vehicle's stored energy requirements can be cut by about 10%, which could save up to US$3,000 per vehicle since less power and energy is required to move the lighter vehicle." He continues: "Plug-in and hybrid electric cars contain precious little, and quite expensive, 'fuel' in the form of batteries. Therefore, every effort must be made to utilise this stored energy to the highest possible efficiency. The solution lies in lowering the vehicle's weight with aluminium as part of a holistic approach to also include advanced powertrains and batteries, enhanced thermal management, improved aerodynamics, and reduced rolling resistance."