ChrisCooper
Established Member
A large amount of the electricity the railways use is not for traction purposes, it's things like signalling and heating and lighting buildings. These are areas where savings can easily be made, and are being, for example low energy lighting (both in terms of "domestic" lighting and also LED signals) and more energy efficient buildings. As an example, the domestic energy cost for a new control centre is going to be quite a bit lower than for all the drafty old signal boxes it replaces. There are also moves to make new buildings energy neutral by fitting solar panels, wind turbines etc.
As has been said, backup power supplies are not perfect. For a start they can and do fail when required. Safety critical backups will be regularly tested and often backed up themselves, but others often are only tested when they are needed, infact there have been cases where backup systems have been unavailable for some time without anyone even caring until the mains goes off. I remember a situation where a backup generator started but cut out after a few mins because it ran out of fuel. Backup supplies are also usually only good for a limited time, even safety critical backups (in the event of a longer term outage alternative sources will often be needed), sometimes an hour or less. Another problem is that if a power outage is preceeded by a surge it can trip breakers so even if backup is available and works then power might not be restored instantly anyway. On quite a few systems even a very short interuption to power (for example caused by a backup generator being slow to come on line, or a breaker tripping) can lead to a long delay to get everything working again (a railway example might be a signalling system that can't reset until the line is clear of trains). Power restoration also often has to be staged to prevent big surges if power is restored all at once.
As has been said, backup power supplies are not perfect. For a start they can and do fail when required. Safety critical backups will be regularly tested and often backed up themselves, but others often are only tested when they are needed, infact there have been cases where backup systems have been unavailable for some time without anyone even caring until the mains goes off. I remember a situation where a backup generator started but cut out after a few mins because it ran out of fuel. Backup supplies are also usually only good for a limited time, even safety critical backups (in the event of a longer term outage alternative sources will often be needed), sometimes an hour or less. Another problem is that if a power outage is preceeded by a surge it can trip breakers so even if backup is available and works then power might not be restored instantly anyway. On quite a few systems even a very short interuption to power (for example caused by a backup generator being slow to come on line, or a breaker tripping) can lead to a long delay to get everything working again (a railway example might be a signalling system that can't reset until the line is clear of trains). Power restoration also often has to be staged to prevent big surges if power is restored all at once.
