Diesel vs Electric

[DaveNewcastle]

That's right, but much more so for nuclear fuelled stations than coal. You just can't "throttle back" - the thermal energy takes hours to dissipate even when you drop all the rods. That energy just has to go somewhere. As a consequence, in Belgium, they lit all the motorways to provide a useful load for off-peak nuclear generation. In Scotland, they used the turbines in reverse to pump water back up to the header reservoirs. This was all good "joined-up" planning of the network while the UK was actively developing more nuclear stations (the 1970s and 80s), the hyrdo-electric schemes at Cruachan and Foyers operate in that way.

Sadly, we don't have a joined-up industry any more. In fact there's hardly any investment in power generation. The newest hydro power station on Loch Ness does not have the capability of working in reverse (to use overnight nuclear power energy to pump water back up). Maybe that doesn't matter now, while our nuclear stations are idle, but if we resume their construction which seems likely, then what are we to do with their night time energy?
That's another of the joys of privatisation and fragmentation of an industry.

 

[90019]

They can be especially useful (there's some in Wales, and a couple more beside Cruachan in Scotland I'm pretty sure) at times such as the end of Eastenders (when lots of kettles go on- no joke) as they spin up very quickly, whilst the thermal stations take longer to respond.

I think there's only 2 in Scotland; Cruachan and Foyers.

IIRC, Cruachan can go be started up and be at maximum capacity in about 2 minutes (or, if the turbines are running, about 30 seconds).

 

[DaveNewcastle]

(or, if the turbines are running, about 30 seconds).

That's about right, on average. Its all down to the "art" of synchronising the phases of the turbines with the phases on "the grid". Could be almost instananeous - could take a little jiggling with the big heavy spinning hardware over a minute or so.

So, yes, its helpful to have some advance knowledge of peaks in demand if we're to avoid voltage dips.
Unfortunately for us on here, many consumer electrical products are comparitively immune to modest voltage variations, but electric railway traction will be affected immediately.
Up to a point, drivers will be oblivious as they'll draw whatever power they require from momment to momment, but when they're demanding full power, and the network (for all its auto transformers) simply hasn't got the low impedance source of the power to deliver what they expect, then we'll have reductions in performance.
That was one of teh difficulties often experienced in some European low voltage DC OHLE networks. The most quoted example being around Amsterdam Centraal.

 

[142094]

As I understand it, a lot of dams pump water uphill during times of low power demand, increasing the potential energy stored behind it. I have to wonder where the energy for that comes from.

This mostly happens at night when demand for electricity on the grid is lower, and therefore prices are lower. Water is moved from the lower reservoir into the upper. Come peak time (such as everyone switching on the kettle after Coronation Street or World Cup), this water can then be used to create electricity quicker to meet the demand. Same reason why we sometimes have to import electricity from northern France in peak times. Think the one in Wales is Dinorwic (not sure on spelling).

 

[LE Greys]

This is interesting, and makes sense. I suppose it would also help with fluctuations in renewable power (high winds/low winds, sunny days/dark nights, etc). Most of what I know about nuclear power comes from ship-scale power plants, and so I hadn't really considered startup time, which is less than fifteen minutes on the USS Enterprise (eight small reactors).

I wonder if microgeneration would make it better or worse. Quite a few watermills are installing generators, and I suppose they could use some sort of self-regulation system to account for local fluctuations (millponds fill up fairly quickly). However, personal wind turbines and solar panels can't do this, so they might end up having to use accumulators to do something similar. I'm trying to decide whether to install a wind turbine or not at the moment. Good idea, yes or no?

 

[brad465]

in retrospect people just talk about energy power sources, and forget some of the unoticed factors

 

[DaveNewcastle]

Most of what I know about nuclear power comes from ship-scale power plants, and so I hadn't really considered startup time, which is less than fifteen minutes on the USS Enterprise (eight small reactors).

Much longer for commercial power generation - especially the thermal inertia which slows the reduction in energy production when the load begins to drop. Perhaps more to the point, its just not effectively viable to operate reactors at anything other than optimum heat generation (no easing off the power overnight), hence the "marriage" of nuclear and hydro plants where the hydro-plants can use unsold energy to back-pump water into the header at night.

I'm trying to decide whether to install a wind turbine or not at the moment. Good idea, yes or no?

Every case is different. Of course, much would depend on the actual energy costs you believe might be reduced.
But how would you get a realistic estimate of the power you could generate over any given period? What would be the losses in storing that energy until you needed it? What are the maintenance costs of the turbine?
You even get different answers depending on what loads you have to use. If you can use applicances designed for whatever storeage system you use (e.g. DC battery storeage will power DC applicances much, much more efficiently than AC appliances, where there would be great losses in the inverters. The most wasteful is in converting DC to 240v AC, only then to power appliances which convert it back to low v. DC!)).

I'm eager to see the outcome of the energy plan for "Strata" the new residential tower in Elephant & Castle (London) visible from London Bridge with 3 big wind turbines on top. Some estimates suggested that they might provide 13% of the building's requirement - other estimates are lower. They have to be shut down in high wind! And they're still being commissioned.
The sums will be much more complex than just reading a meter, as much of this thread illustrates - viability depends on how many of the actual factors we take into account and which we ignore.

 

[jrhilton]

The shining example as far as electrification, especially in picturesque landscape, has to be the Swiss railways: 3641 out of 3,652 km (2,262 out of 2,269 mi) of the standard gauge and 1,353 out of 1,383 km (841 out of 859 mi) of the narrow gauge network is electrified.

I am surprised the non-electrified millage is that high! Agreed a picturesque country, with equally plesent people.


Now back on the subject, can I add, for people living along railway lines, it is quieter to have an EMU go past than a similar size/weight DMU at the same speed, I talk from experience on this one.

Electric traction allows the use of regenerative braking which should really be used across the UK network more than it is at the moment given how long the tech has been around.

Also electric motors tend to have low maintenance, ABB motors that are in lots of trains around the world for example are designed so that very little maintenance is needed over the whole life cycle of the motor. Most diesel engines as far as I am aware are designed with the intention that a major overhaul will take place after xxxx k miles.

The good argument that diesel has is it can go on lines that are not electrified, but change the question to compare like for like and ask it again.

So here goes - you have a network that is 100% electrified, all capital costs of doing this have been written off etc, you have no trains at all and need to buy some, which would you now choose, diesel trains, or electric...

Answer – 100% electric. If the UK network was fully electrified, I doubt you would see any diesel trains carrying passengers.

 

[brad465]

So here goes - you have a network that is 100% electrified, all capital costs of doing this have been written off etc, you have no trains at all and need to buy some, which would you now choose, diesel trains, or electric...

Answer – 100% electric. If the UK network was fully electrified, I doubt you would see any diesel trains carrying passengers.

Right on there if you ask me

 

[krus_aragon]

Think the one in Wales is Dinorwic (not sure on spelling).

Yes, that's the one, near Llanberis. It's spelt Dinorwig these days, but in the days of the slate quarry the Dinorwic spelling was prevalent. The power station is marketed to the public as Electric Mountain, regardless.

 

[142094]

Been few years since I visited on a field trip. Quite an interesting place.

 

[jopsuk]

I'm trying to decide whether to install a wind turbine or not at the moment. Good idea, yes or no?

As far as I understand it, home-scale wind turbines are a waste of money and resources. If you live in any settlement, the wind is too gusty and unreliable to make it worth it- you'd need a much bigger turbine on a much taller pole to get the power the manufacturers will claim with any reliability.

Wind power works best with relatively uninterrupted wind- that's why the big developments are on moorland, on fenland and (especially) out at sea- the developments that are due for in the midst of the North Sea are mind-blowing- in the region of 3000 turbines on the Dogger Bank being just one farm. We've got a rather tedious poster on the internal window of the office (giving us some privacy) showing the current and planned wind energy installations across Europe.

However everything I've read (admittedly mostly from "big wind" sources indicates micro generation using wind is for yachts and "off grid" locations. Unlike with PV, where the problem with making it viable for "on grid" generation was material, the problem is with the nature of urban wind. There's been lots of ideas using vertical turbines, but they just don't work well enough.


Photovoltaic solar is perhaps better, though it suffers at our latitudes of being less available when we use more energy- dark evenings, winter! The "free" panels are a bit of a con too- recent Guardian Money section article concluded that there's no point in getting PV on your roof unless you can raise the capital yourself- but that the pay off should be reasonably swift. With the "free" panels, the company that owns them makes money from your roof for the next quarter century, and whilst you save a little on your power, it isn't really worth it in the grand scheme of things. One interesting idea I've heard proposed though is to try and encourage, or even force, developers (especially of "eco" developments) to pretty much cover all appropriate roof surfaces in PV cells- turning housing estates into large power stations consisting of micro-generation units.

So, um, if you've got the cash and a suitable roof, go for PV, but don't waste your money on a turbine in the garden.

 

[LE Greys]

Every case is different. Of course, much would depend on the actual energy costs you believe might be reduced.
But how would you get a realistic estimate of the power you could generate over any given period? What would be the losses in storing that energy until you needed it? What are the maintenance costs of the turbine?
You even get different answers depending on what loads you have to use. If you can use applicances designed for whatever storeage system you use (e.g. DC battery storeage will power DC applicances much, much more efficiently than AC appliances, where there would be great losses in the inverters. The most wasteful is in converting DC to 240v AC, only then to power appliances which convert it back to low v. DC!)).

I'm eager to see the outcome of the energy plan for "Strata" the new residential tower in Elephant & Castle (London) visible from London Bridge with 3 big wind turbines on top. Some estimates suggested that they might provide 13% of the building's requirement - other estimates are lower. They have to be shut down in high wind! And they're still being commissioned.
The sums will be much more complex than just reading a meter, as much of this thread illustrates - viability depends on how many of the actual factors we take into account and which we ignore.

As far as I understand it, home-scale wind turbines are a waste of money and resources. If you live in any settlement, the wind is too gusty and unreliable to make it worth it- you'd need a much bigger turbine on a much taller pole to get the power the manufacturers will claim with any reliability.

Wind power works best with relatively uninterrupted wind- that's why the big developments are on moorland, on fenland and (especially) out at sea- the developments that are due for in the midst of the North Sea are mind-blowing- in the region of 3000 turbines on the Dogger Bank being just one farm. We've got a rather tedious poster on the internal window of the office (giving us some privacy) showing the current and planned wind energy installations across Europe.

However everything I've read (admittedly mostly from "big wind" sources indicates micro generation using wind is for yachts and "off grid" locations. Unlike with PV, where the problem with making it viable for "on grid" generation was material, the problem is with the nature of urban wind. There's been lots of ideas using vertical turbines, but they just don't work well enough.


Photovoltaic solar is perhaps better, though it suffers at our latitudes of being less available when we use more energy- dark evenings, winter! The "free" panels are a bit of a con too- recent Guardian Money section article concluded that there's no point in getting PV on your roof unless you can raise the capital yourself- but that the pay off should be reasonably swift. With the "free" panels, the company that owns them makes money from your roof for the next quarter century, and whilst you save a little on your power, it isn't really worth it in the grand scheme of things. One interesting idea I've heard proposed though is to try and encourage, or even force, developers (especially of "eco" developments) to pretty much cover all appropriate roof surfaces in PV cells- turning housing estates into large power stations consisting of micro-generation units.

So, um, if you've got the cash and a suitable roof, go for PV, but don't waste your money on a turbine in the garden.

Thanks for the input. I'd pretty much ruled it out anyway. However, I'll consider a turbine if I ever get a boat. Since everything runs of 12V d.c., recharging the batteries with wind energy would be a good idea, and windspeeds are generally higher than on land, certainly steadier. As for solar panels, the roof is at the wrong angle for them to work (although the streetlights are probably bright enough for them to work at night, how's that for wasted energy?).