From a “tank to wheel” (TTW) point of view, a BEV, or a PHEV running in electric mode do not produce either pollutant or greenhouse gases while the emissions of pollutant and CO 2 in the WTW processes depend on the primary source and the technology used to generate electric energy at the grid. Generally speaking, the environmental impact of an ecologic vehicle has to be determined with a “well to wheel” (WTW) approach. The particular operating strategy employed in this kind of vehicles significantly influences the component attributes and the value of the PHEV technology ( Gonder et al. The study of Simpson, 2006 underlined that from the economic point of view, the PHEVs can become a competitive technology is the cost of petroleum will continue to increase and the cost of the batteries will decrease.īecause of different characteristics of multiple energy sources, the fuel economy and the environmental impact of hybrid vehicles mainly depend on a proper power management strategy. vehicles containing enough useable energy stored in their battery to run more than 20 mi (32 km) on the UDDS cycle in electric mode according to the previous definition of AER). In particular, reductions higher than 45% in the petroleum consumption can be achieved using designs of PHEV20 or higher (i.e. On the basis of his model, Simpson found that PHEVs can reduce per-vehicle petroleum consumption. Simpson, 2006 presented a comparison of the costs (vehicle purchase costs and energy costs) and benefits (reduced petroleum consumption) of PHEVs relative to HEVs and conventional vehicles. PHEVs require fewer fill-ups at the gas station than conventional cars and have the advantage, over HEV, of home recharging.īEVs, HEVs, and PHEVs have also the capability of partially recovering energy from brakes by inverting the energy flow from batteries to wheels through the electric machine. A vehicle is classified as PHEVXY if it has an AER of XY miles. The size of the battery influences the All Electric Range (AER), an important design parameters of PHEVs that is defined as the number of miles they vehicle can run in pure electric mode on the UDDS cycle. They are characterized by the use of much larger battery pack when compared with standard HEVs. PHEVs can be considered either as BEVs that can be run in hybrid mode when the state of the charge (SOC) of the batteries is low or as HEVs with batteries that can be recharged from the electricity grid. Moreover, the engine can be turned off when the vehicle is arrested (e.g., at traffic lights) or the power request is very low (reduction of the idle losses). The main advantages of HEVs are: the flexibility in the choice of engine operating point that allows the engine to be run in its high efficiency region and the possibility of downsizing the ICE and so obtaining a higher average efficiency. HEVs have no limitation of range with respect to conventional vehicle and use the existing distribution infrastructure. Hybrid electric vehicles are characterized by the presence of two different typologies of energy storage systems: usually a battery and a gasoline or diesel fuel tank. Thus, they are not to be considered as a viable way for eco-mobility in the next future ( German, 2003). They add to the problems of a BEV, the use of a very light gaseous fuel that has severe limitations in terms of producing process, storing system, safety and distribution infrastructure. Vehicles using fuel cell (FCV) a very clean fuel conversion system, have technologic drawback even higher. Moreover, they have an unsatisfactory life cycle and require long recharging times. They are still too expensive, too bulky and heavy (due to their low energy density). The main drawback of BEVs resides in the batteries. However, they are still unable to penetrate the market for several technological limitations. Moreover, gasoline and diesel fuels have an established infrastructure of distribution that is difficult and very expensive to replicate for other energy sources.Įnvironmental issues, energy crises, concerns regarding peaking oil consumption and the expected increase of number of cars in developing countrieshave eventually encouraged research into alternative energy sources. Their main advantage over both gas engines and Battery Electric Vehicles (BEVs) is the very high energy density of liquid fuel that allows long driving ranges with small (and light-weight) storage tanks and safe and fast refueling processes. Since early 1900s, gasoline and diesel internal combustion engines have represented the most successful automotive powering systems despite their low efficiency, their emissions issues and the increasing cost of fuel.