The move to using electric vehicles has been slow. A recent US analysis suggests that the widespread use of advanced hybrid electric vehicles (PHEVs), which plug directly into the electricity grid, will be delayed unless social and infrastructural barriers are addressed, in addition to technological obstacles.

Road transport is expected to grow. Even with improved technology to reduce vehicle emissions, this will lead to an increase in pollution. But if half the vehicles in the US in 2007 had been PHEVs, it has been estimated that greenhouse gas (GHG) emissions would have been reduced by 27 percent.

The main reason for these GHG savings is that generating electricity for vehicles from a relatively small number of power plants is more efficient than the petrol production (conversion from crude oil) and combustion process.

Air quality could also improve drastically, with estimated reductions of 93 per cent for VOCs and 98 per cent for carbon monoxide, for example.

Widespread use of PHEVs could also reduce dependence on imports of oil and act as a buffer against fluctuating oil prices. Hybrid electric vehicles (HEVs) combine a traditional internal combustion (IC) engine with a battery-powered electric motor. They produce fewer emissions than standard vehicles and there are several popular models on the market. PHEVs are HEVs with larger batteries and a plug-in recharger.

Prototypes of these vehicles currently travel at speeds of 30-100km on electricity alone. However, currently there are no commercially viable PHEVs on the market. Overcoming technical barriers will make PHEVs more commercially viable. Vehicle-to-grid (V2G) technology, also known as 'mobile energy' or 'smart charging', is a key means of achieving this, according to the analysis.

V2G technology would see 'intelligent' recognition between the electric grid and vehicles. So, for example, vehicles would 'know' when to draw electricity from the grid at off-peak periods and store it for later usage. V2G thus helps lower the cost of electric vehicles for the consumer and help overcome social resistance to electric vehicles.

The high cost of the vehicles and their batteries are widely considered the biggest barriers to uptake. However, the researchers suggest that, even with V2G technology, PHEVs will never be in widespread use unless wider social and infrastructural barriers are removed. It has been found that consumers expect unrealistically short times - less than 5 months - to recover their investment in electric vehicles.

Many owners also drive too aggressively. This can decrease the efficiency of an HEV by 30 per cent. Poor driving of IC vehicles also decreases their efficiency, but by just 5-10 per cent. These extra variables affect the payback of a vehicle and complicate purchasing decisions.

Consumers generally prefer to stick with the comfortable and familiar. PHEVs are typically marketed as new and exciting, but such approaches are unlikely to appeal to the mass market. To be attractive to the consumer, PHEVs must be easy to use and not appear to alter the lifestyle and behaviour to which consumers have become accustomed to. It has also been found that there is a social stigma attached to electric vehicles.

US studies have found that PHEVs are considered 'cheap', 'light' and 'small'. The researchers also describe infrastructural barriers. They suggest many players in the existing transport system could oppose PHEVs. Oil companies and vehicle manufacturers have invested heavily in the infrastructure for a fossil fuel driven economy. Associated businesses such as repair and maintenance companies and fuel stations would be affected, as electric vehicles do not have the same service requirements as an IC vehicle.

Furthermore, electric utility companies could see extensive use of V2G technology as a threat to their role as primary producers of electricity and may try to place restrictive conditions on its use, even though such companies could operate more efficiently if electricity was also drawn during off- peak times.

Source: Sovacool, B.K. and Hirsh, R.F. (2009). Beyond batteries: An examination of the benefits and barriers to plug-in hybrid electric vehicles (PHEVs) and a vehicle-to-grid (V2G) transition. bsovacool@nus.edu.sg �or richard@vt.edu