David Bradley ) gurgled happily, sounding much
like they were saying :

Please explain further. In my book a trolleybus IS zero polluting.

Your book is - at best - skimpy.

Where does the electricity come from?

As a former CEGB / NGC employer I can answer that question in
exceptional detail. In can see where you are coming from by
suggesting that the production of electricity is sometimes less than
enviromental friendly but equally can be derived from renewable
sources such as wind power or hydro sources.

And what percentage of UK grid electricity is?

http://www.dti.gov.uk/energy/inform/...ity/dukes05_5_
6.xls

2004 -
Coal - 36.9%
Oil - 1.34%
Gas - 34.24%
Nuclear - 21.49%
Renewable Thermals - 3.34% (Burning biofuels and non-biodegradable
waste)
Other Thermals - 1.83% (Coke oven gas, Blast furnace gas, Waste products
from chemical processes)
Hydro - Natural Flow - 0.5%
Hydro - Pumped Storage - 0.27%
Other Non-Thermal - 0.2% (Wind, Wave, Solar)

So somewhere in the region of sod all. Or, to put a number on it,
renewables make 4.31% of the UK's electricity.

A lot better than I expected, I will admit. But still not much.
Especially as any ramp-up in demand will be met by the non-renewables,
as the renewables are stretched to provide the current amount.

The power might even have been provided from another country but
however it was produced, and where ever it originated from, the
product does not come with any kind of labelling for your average user
to be able to determine its source.

Indeed. So it's not quite right to say it's "zero-polluting", is it?

The right combination of circumstances can therefore have a trolleybus
operating on a fuel that can be considered to be entirely zero
polluting and to suggest that can't happen is bunkum.

Indeed.

However, to suggest that it's *likely* to happen is equally bunkum.

In any event I would certainly prefer a trolleybus service running
past my front, especially at night, rather than the cleanest of
diesel buses.

Ah, the "I don't live next door to a powerstation, so they don't
matter" NIMBY line.