kudu wrote:
Given the differences in train mileages and the differences in thermal efficiencies I would be amazed if the coal equivalent fuel consumption now for electric traction was remotely near what it was when we had 20,000-plus steam locos. Not quite sure what you mean by "towards the end of steam", though, as obviously coal consumption must have progressively fallen.
I'll let someone else answer your first question.
Kudu
Can't lay my hands on it immediately, but Roger Ford wrote an interesting piece on this topic in his Modern Railways column a few years back. First time around it contained the astonishing claim that 15% of all electricity generated "vanishes" through transmission losses in the grid - the proof reader hadn't noticed a missing decimal point (it's actually 1.5%)
giner wrote:What is the main energy source for generating electricity in the UK? If it's coal, then I wonder how the comparatives are in using coal for generating the electricity to run all current railways vis-a-vis using coal to fire all the steam locomotives that were in existence towards the 'end of steam'?
It is a frightningly long time since I was at university, but from what I remember the thermal efficiency of a typical superheated locomotive boiler is in the region of 10%. Once the various other inefficiencies of the locomotive are taken into account ( steam used for the blower, ejector, injectors etc. and mechanical losses) then the overall efficiency is less than 5%.
With a modern coal fired power station, the overall efficiency is in the region of 45%.
Even allowing for the losses in transmission and the copper losses in the traction motors and transformers of an electric locomotive, the overall efficiency of the system will be at least double that of a steam loco.
60041 wrote:It is a frightningly long time since I was at university, but from what I remember the thermal efficiency of a typical superheated locomotive boiler is in the region of 10%. Once the various other inefficiencies of the locomotive are taken into account ( steam used for the blower, ejector, injectors etc. and mechanical losses) then the overall efficiency is less than 5%.
With a modern coal fired power station, the overall efficiency is in the region of 45%.
Even allowing for the losses in transmission and the copper losses in the traction motors and transformers of an electric locomotive, the overall efficiency of the system will be at least double that of a steam loco.
Speaking from memory, which is often fallible, I think your figures sound about right. I believe Roger's numbers (once they'd been corrected to re-instate the AWOL decimal point) were 1.5% lost by the grid and a further 1.5% - but possibly of a smaller resulting total - lost by similar inefficiencies in the loco itself.
He also touched on issues like "What does it do if we turn the heating off?". That's an interesting one of course because during the winter quite a lot of a loco's steam would have been expended heating its train. Nowadays we do it differently though.
I was at Church Fenton this morning for SCOTS GUARDSMAN on "The Waverley",and two senior citizens wandered onto the platform,set up a tripod right on the edge,and not content with being in everyone's shot,one proceeded to lay down on his stomach to take his shot when GUARDSMAN passed!!No wonder we get called every bad word under the sun for partaking in our hobby!!!Can't imagine his shot being any good!!
