Smarter mobility through V2X communication: energy, thermal and environmental opportunities and engineering challenges

Abstract

Vehicle-to-Everything (V2X) communication is widely credited with reducing the energy demand and emissions of road transport, but the supporting literature reports its benefits almost exclusively as percentage fuel savings, without an explicit energy balance and without resolving where the avoided energy would otherwise have gone. This paper re-expresses the environmental case for V2X as a thermal and energy accounting problem. Three dissipation pathways are quantified: the chemical energy not released as fuel, the mechanical energy not dissipated as heat in the friction brakes, and the electrical energy continuously dissipated by the communication hardware itself. In a signalised urban corridor, a single avoided stop removes 104 kJ (73–144) from the friction brake and raises the front discs by 15.4 K (10.3–22.8), a rise that accumulates over successive stops. Because brake wear and the evaporation–condensation formation of ultrafine particles are temperature-governed, this heat reduction converts into a non-exhaust particulate benefit that fuel-based accounting does not capture: 0.18 mg km−1 (0.10–0.30) of PM10 and 0.06 mg km−1 (0.04–0.11) of PM2.5. Conditioning all pathways on the communication reliability actually achievable, and on the measured share of mileage over which the advisory is available, reduces the fuel–energy benefit from 12.4 to 3.8 MJ per 100 km against an urban baseline of 234 MJ per 100 km. All quantities are reported with uncertainty propagated by Monte Carlo over their published parameter ranges. The results indicate that the environmental case for V2X is real but substantially smaller than commonly reported, and that its non-exhaust particulate component—thermally driven, and currently unregulated—has been overlooked.