Going further with smaller EVs: System-level battery range, emissions and charging infrastructure analysis

Abstract

Electric vehicles are a necessary part of a zero-carbon future. However, one in five motorists worldwide depend on small petrol motorcycles for their transport needs — vehicles for which no satisfactory low-carbon substitute exists. Meanwhile, the rise in electric car ownership is not reducing GHG emissions as much as often thought, due to the significant emissions from producing ever-larger batteries. Both problems can be solved by uncovering the mechanisms of long distance EV travel, beyond battery range, where the interaction with recharging infrastructure governs vehicle performance.This study develops a new model for journeys involving multiple run-recharge cycles and introduces a novel metric for EV performance — Day Range. Not only does this allow a direct comparison between a wide variety of vehicle and infrastructure options but, by further manipulating the formulae, high level trends can be observed and specific quantitative guidelines extracted.In vehicle design, a strong emphasis on efficiency and recharge rates can drastically reduce both in-use and embodied energy while matching the touring performance of a conventional, resource intensive, heavy battery car. Meanwhile, the recharging network can be developed to better support this lower energy use. Taking the example of the UK motorway network, charge rates up to only 100kW should be installed with the focus instead falling on reliably reducing chargepoint intervals at least as far as the existing target of 28 miles, and ideally much further. In doing so, required battery capacity can be reduced from the 60kWh+ currently seen as necessary to as little as 25kWh.The resulting vehicles not only consume less energy in motion but emit far less greenhouse gases during manufacture and will cost less to produce, allowing a much wider uptake of electric vehicles than possible under the existing, energy intensive battery vehicle touring paradigm.