What did Mr. Fletcher mean by “clean”? Was he talking about NOx and other chemical compounds that are directly harmful to our health and environment? Or, was he talking about CO2, which is said to be causing global warming?
“Modern low emission ICE” – If he is talking about CO2, he must be talking about small displacement engines. The amount of CO2 emission is directly related to the amount of fuel burned. For example, a car that goes 100km on 10 litres of gas emits 100 percent more CO2 than a car that goes 100km on 5 litres of gas. There is no magic here. Cat converters cannot reduce the amount of CO2.
Any car with a set of the same parameters such as mass, Cd, frontal area and tire rolling resistance requires the same amount of energy, be it derived from gas or electricity, to go from point A to B under the same speed map. So, the question is which car burns more fossil fuel to go a certain distance.
ICE car and ICE+electric motor hybrid – Comparison easy. Just compare the amount of fuel needed to go a certain distance. Knowing that the thermal efficiency of ICEs is about 25%, if a hybrid requires about 50 percent less fuel to go a certain distance than a similar size ICE only car (Prius vs Carolla, for example), we can presume the hybrid is in effect about 50 percent efficient thermally.
Electric car – Situation is rather complicated. There are CO2 emitting power plants such as coal- or natural gas-fired plant and there are no CO2 emitting power plants such as hydro, nuke, wind and solar. All these plants are connected to the grid.
Suppose an EV is charged with energy generated only by coal- or natural gas-fired plants, although the thermal efficiency of the latest combined cycle plant is as high as 60 percent (thermal energy input vs. electrical energy output) I would guess the average efficiency of all the plants on the grid is 40 percent at best. Taking the loss in the transmission and charging the battery into consideration, we are talking about 35 percent or so of EV’s overall thermal efficiency, which is worse than the abovementioned hybrid example. So, EV causes more global warming than hybrid if on coal- and natural gas- fired plants only.
If an EV is charged with energy generated by hydro plants (British Columbia and Quebec) and nuke plants, the EV wins of course. The real situation is somewhere in-between, but I do not think the overall grid thermal efficiency is as high as hybrid’s 50 percent.
To complicate the situation BC and Quebec are not totally CO2 emission free. Since output of hydro plants is relatively easy to reduce or shut down during off-peak hours these provinces are buying cheap surplus electricity from other jurisdictions (as far away as California) by reducing output of their hydro plants (saves water). During off-peak hours BC and Quebec are causing CO2 emissions elsewhere.
