Electric Plugin Hybrid Cars Environment Friendly City Switch

Not sure how practical that is - as far as I know PHEVs have a relatively short fully electric range - often only a few tens of miles (as the additional weight of the engine limits the amount of battery it can carry), so the ICE will be needed to cut in automatically when the battery becomes low - whether your in a low emission zone or not. So while some people could run without the ICE for 100% of the time inside the LEV, many others could only manage 80% or 60% or 40% or less (say those who do a decent daily mileage within the zone or visit multiple zones in the same day). Even those that mostly manage 100% could be caught out occasionally (e.g. during cold weather where the heating drains the battery faster than usual). So where could you draw a line between grant and no grant? Or have some massive administrative system to  pro-rata things?

I see PHEVs are a short term thing anyway - they're only a quick fix to give additional range to EVs - and are a bit of a botch - having to carry the additional weight of a useless engine around in electric mode and the extra weight of the batteries in IC mode - it's never going to be an efficient solution. As better batteries and more charge points appear, range anxiety is becoming a thing of the past anyway, so I see PHEVs fading away over the next decade or so. Not much point in building a huge system that would be obsolete soon after it was completed.

   - Andy.

AJJewsbury said:

I see PHEVs are a short term thing anyway - they're only a quick fix to give additional range to EVs - and are a bit of a botch - having to carry the additional weight of a useless engine around in electric mode and the extra weight of the batteries in IC mode - it's never going to be an efficient solution.

On the better PHEVs, they don't have an IC mode as such, once the battery has been discharged to a minimum level they switch into hybrid mode, maintaining a minimum state of charge on the battery and continuing to shut off the engine and using the motors when running at low speeds, or low throttle positions. The battery is still used to support the engine to optimise efficiency etc by either assisting or recharging as the engine moves between efficient operating points and during regenerative braking. On some PHEVs the aircon and heating is electric, powered by the HV traction supply and battery, so this continues running even when stationary with the engine off fed from the battery, so overall the battery is always in use.

Also, the battery is always needed on many PHEVs because they operate their engines slightly differently to regular cars, hybrids typically have engines that can operate in a form of Atkinson cycle, adjusting their air intake and fueling, to optimise compression and expansion to improve the thermal efficiency. The engines deliver better efficiency, but produce less power and torque, so rely on the hybrid motors to support the engine under different driving conditions.

Ultimately they can never match the lower carbon footprint of an EV powered by low carbon electricity, but they're actually a pretty impressive piece of engineering. Unfortunately I don't think the marketing divisions of the car manufacturer's do a good job of communicating the benefits and how they actually work.

Andy Millar said:

There's a really good way to reduce particulate and other emissions in cities, which is to improve public transport... (I know people can say "you would say that, you work in the rail industry". I would turn that round and say that I work in the rail industry because I feel it's potentially beneficial to society.)

The difficulty in Britain is the cost, clean electrified mass transit like trams and rail are so expensive to build, either new or expansion of existing networks, that they pretty much rule themselves out due to being unaffordable everywhere except our largest cities. 

Perhaps the hope lies in electric buses, as these become more affordable with falling battery costs and keep the need for new infrastructure to a minimum.

AJJewsbury said:

I see PHEVs are a short term thing anyway - they're only a quick fix to give additional range to EVs - and are a bit of a botch - having to carry the additional weight of a useless engine around in electric mode and the extra weight of the batteries in IC mode - it's never going to be an efficient solution.

On the better PHEVs, they don't have an IC mode as such, once the battery has been discharged to a minimum level they switch into hybrid mode, maintaining a minimum state of charge on the battery and continuing to shut off the engine and using the motors when running at low speeds, or low throttle positions. The battery is still used to support the engine to optimise efficiency etc by either assisting or recharging as the engine moves between efficient operating points and during regenerative braking. On some PHEVs the aircon and heating is electric, powered by the HV traction supply and battery, so this continues running even when stationary with the engine off fed from the battery, so overall the battery is always in use.

Also, the battery is always needed on many PHEVs because they operate their engines slightly differently to regular cars, hybrids typically have engines that can operate in a form of Atkinson cycle, adjusting their air intake and fueling, to optimise compression and expansion to improve the thermal efficiency. The engines deliver better efficiency, but produce less power and torque, so rely on the hybrid motors to support the engine under different driving conditions.

Ultimately they can never match the lower carbon footprint of an EV powered by low carbon electricity, but they're actually a pretty impressive piece of engineering. Unfortunately I don't think the marketing divisions of the car manufacturer's do a good job of communicating the benefits and how they actually work.

Andy Millar said:

There's a really good way to reduce particulate and other emissions in cities, which is to improve public transport... (I know people can say "you would say that, you work in the rail industry". I would turn that round and say that I work in the rail industry because I feel it's potentially beneficial to society.)

The difficulty in Britain is the cost, clean electrified mass transit like trams and rail are so expensive to build, either new or expansion of existing networks, that they pretty much rule themselves out due to being unaffordable everywhere except our largest cities. 

Perhaps the hope lies in electric buses, as these become more affordable with falling battery costs and keep the need for new infrastructure to a minimum.