Lexus: The hybrid debate blog

Hybrids could make a significant contribution to the fight against climate change if they embraced plug-in technology on a large scale. However, this would depend on the UK government coming up with a sensible long-term strategy for energy generation.

Most hybrids available today obtain all their energy from a petrol engine. Their electrical systems are designed merely to save the energy used during braking, and to reuse it to boost acceleration (a process known as "regenerative braking"). This saves energy by balancing the load on the engine. However, a plug-in hybrid electric vehicle (PHEV) is much more efficient because, over short distances, it doesn’t need to use an internal combustion engine (ICE) at all.

If we could recharge our vehicles at night from the mains, most of the energy we used to propel ourselves during the day would come from power stations, and would therefore generate far less emissions in aggregate than an ICE-only fleet.

The problem with this scenario, of course, is that it depends on how the national grid generates its electricity going forward. And if the majority of drivers on UK roads were to drive PHEVs then we would need a lot more generating capacity.

Furthermore, a large fleet of PHEVs would come with significant practical problems. Not everyone has off-street parking, and the council would not take kindly to charging cables strewn along the pavement from motorists’ front doors to wherever they had been able to park. (Not forgetting that copper has a high scrap value, so cables might not last long in some areas without being stolen.)

A possible alternative would be a network of fast-charging stations, which would allow you to plug in your car, have a coffee and come back to a full charge. However, if you wanted to recharge a 20 kWh battery in five minutes (and this assumes the battery’s electrochemistry could take it, which is certainly not true of most current batteries) the cable and its connectors would need to be rated at well over 1,000 Amps - much the same size as the big orange electrical connections on the front of railway locomotives. Clearly, this is not the kind of apparatus you want to be handling while dressed for a wedding!