Above – tram wires strung from the Vienna Grand Opera House
Various Notes from various contributors:
Remember, people walking in and around cities rarely look up above the shop name on a shopfront. The see the rails and think permanence and that’s where the trams run, but never look up at the overhead wires. In some European cities, OLE head-spans are attached to medieval cathedrals and no-one notices (or cares).
At the Manchester Light Rail conference, I asked Brad Read after his presentation, what the overall efficiency was of the hydrogen cycle, including electrolysis, compression and fuel cell. He said that for electrolysis and the fuel cell it was 48%, but he didn’t give a figure for compression. As 350Bar is used (about 5,000psi!), I imagine it’s quite large. Ian Walmsley in Modern Railways puts the overall efficiency at about 30%. The hydrogen proponents say this doesn’t matter, as “surplus” energy from wind farms at night is used! Where is this surplus in practice? With all cars being electrified and charged at night, it’s quite likely this will be the new peak on the grid!
At a time of concern about global warming, we should be doing all we can to use energy efficiently, and “straight” electric traction is the best way to do it. With rail systems, one conductor already exists, and the vehicle takes a known path, so It should be a relatively simple task (it used to be!) to install a simple overhead line, and achieve an efficiency of around 90%. The rating and size of this could be greatly reduced by the use of relatively small energy storage on the vehicle to smooth out demand. I would go for super-capacitors for this, they don’t have the life limitations of batteries, and are more efficient, as electrical energy is stored directly.
In Croydon the overhead wires were not taken down until several weeks after the trams ceased to run in April 1951, and the Croydon Advertiser carried out a public survey one Saturday in North End, a busy shopping street, asking pedestrians what was different in the street compared with the previous week. Only three persons out of about forty interviewed even noticed that the tram wires had been taken down since the previous week. (J H Price, “Tramway London – Background to the abandonment of London’s trams 1931-1952”, LRTA, 1993). People probably didn’t notice them either when they were put back up in Croydon town centre.