Why has there never been...

[EM2]

...a solar powered train?
It's only a half-serious question, because obviously it wouldn't work in the dark but maybe the solar panels could charge on-board batteries during the day to use after sunset and there's been battery railcars before.
There's all that space on carriage roofs going spare, it would save on all the OHLE posts and cables, and would be ideal for short branchlines, like the Thames Valley (e.g Maidenhead - Marlow).

Thoughts?

 

[90019]

Because photovoltaic cells are currently pretty inefficient and expensive.

 

[me123]

Also, we don't get much sunlight in the UK if you haven't noticed :razz:

In all seriousness, I don't see why solar panels on trains couldn't be used in the future. Not as a main power source, of course, but reducing the power sucked from the cables must be a good thing. As 90019 said, though, the price is a barrier to this happening in the foreseeable future.

 

[EM2]

What got me thinking was I went on holiday recently with a load of friends. We stayed at a manor house that had twelve panels on the roof (they would easily have fitted on the roof of a 159, say). Now, they had eight apartments with space for 34 people, a swimming pool, TVs, DVD players and appliances in all eight apartments and a games room, and *all* their electricity came from those panels.
So I'm sure that number of panels could run a train over a short branch...

 

[DaveNewcastle]

...a solar powered train?
It's only a half-serious question, because obviously it wouldn't work in the dark . . .

As 90019 said, they're not efficient.
If you look at the figures then we're out by a factor of 10,000 or so.
An electric loco can demand 5MegaWatts. The domestic consumer products you mention could all come off a 13Amp socket poss with capacity to spare - they may reach as much as 2 kiloWatt.
Frankly, whether its sunlight or moonlight on some photvoltaic cells isn't going to make much impact on moving a few thousand tons of metal.

There are benefits in using solar power on remote sigange (at level crossings for example), but its not to reduce the consumption from more efficient power stations, its to reduce the cost of installing (and maintaing) the supply line.

 

[90019]

Also, we don't get much sunlight in the UK if you haven't noticed :razz:

The photoelectric effect only requires light, not direct sunlight, to work.
It will work better in direct sunlight, as there will be more energy, but it won't stop if it clouds over.

 

[Dennis]

Actually, the figures are not as bad as previously implied, taking a 4 car EMU as an example, each car 20m long and with 2m of available roof width, thats 160m2 of available area.

Solar panels are rated typically in the region of 150W/m2 so 24kW of power is available. A class 455 unit is rated at 750kW so solar power can supply 3% of the maximum power required.

Also, the unit will not be on maximum power continuously and energy can be recovered by regenerative braking and stored when idle using batteries. So, even with current technology, solar power can provide a useful proportion of the power needed to run a train, probably in the region of 5% or more.

However, why carry the solar panels around, there is a lot of surface area available around the tracks to put them. Cost and other enviormental implications (the most common panel types contain arsenic) are significant barriers to this idea.

 

[The_Stig]

Solar panels and their required batteries are rather heavy are they not?

If trains were required to carry the extra weight around they would just cancel out the good they were doing perhaps.

 

[bengley]

If this is combined with regenerative braking, wind turbines on top of the trains and regenerative door motors, you can almost definitely power a train!

 

[Dennis]

Solar panels and their required batteries are rather heavy are they not?

If trains were required to carry the extra weight around they would just cancel out the good they were doing perhaps.

Which is why I suggested trackside might be a better location rather than carrying around the weight.

 

[generalvegitable]

Which is why I suggested trackside might be a better location rather than carrying around the weight.

so just use renewable energies to power them?

 

[Oswyntail]

so just use renewable energies to power them?

You mean wind-powered trains? Sails? Or tidal flows through the Severn Tunnel could make for a dramatic ride. Sorry - attack of the facetious there.

 

[Sir_Clagalot]

I notice a lot of lineside equipment boxes are getting either Solar panels or small wind turbines.
Given the spread of LED signal heads, could a secure radio link be used to transmit the aspect? And have a wind turbine and a decent set of batteries (say the leisure type found in Caravans etc), with the consequent reduction in the amount of copper cable, and therefore cable theft...

 

[krus_aragon]

I notice a lot of lineside equipment boxes are getting either Solar panels or small wind turbines.
Given the spread of LED signal heads, could a secure radio link be used to transmit the aspect? And have a wind turbine and a decent set of batteries (say the leisure type found in Caravans etc), with the consequent reduction in the amount of copper cable, and therefore cable theft...

Copper may be liable to theft, but radio is very liable to interference. Why not just wait until ERTMS solves all our woes?