Using trains to store surplus renewable energy

[Will Crompton]

I hope this is of interest.

 

https://interestingengineering.com/energy-storage-trains-work-power-gravity

 

It is a news item about a concept called 'rail energy storage'. Basically you use surplus renewable energy to push a train up a hill. When the sun goes in, wind stops blowing etc you let the train roll back downhill and harvest the energy.

[The Johnster]

Sysiphus.  Google him.

 

I suspect you'd need a lot of storage trains to make much impact, and pumped hydro schemes are probably more efficient, but I like the idea.  Of course, if trains running down hills on the network can be energy harnessed in this way, and they probably could using the OLE, it might be worth doing; something like it already happens with regenerative braking.

[Mike Buckner]

Has to be more sensible/efficient to lay a pipe up a hill with turbines at top and bottom, and simply pump water up or let it flow down.

[Dagworth]

Amazing how many people comment on an article and the comments make it obvious that they haven't read it...

 

Andi

[jjb1970]

Is it just me that keeps seeing this as an A!se idea when I read the article?

[Davexoc]

All this surplus of renewable that gets spoken about is a little misleading. June has been a very poor for wind, and solar is very peaky anyway. Notice that no-one this year has released anything to say 'Look we haven't burnt coal for x hours', because we still are, even today.

The one scheme that should have gone ahead but got turnerd down was Swansea bay tidal. The tides are totally predicable and are always moving. But then if it doesn't pay back in three years, we don't seem to want it these days. Too much shorttermism....

 

Dave

[Corbs]

Strangely enough I've not seen this specific concept before but I was daydreaming about something similar the other day, except using a weight on a cable with a big reduction gear on the drum driving a generator. Maybe you could stick it on the mast of a wind turbine.

Edited July 1, 2018 by Corbs

[Gibbo675]

I hope this is of interest.

 

https://interestingengineering.com/energy-storage-trains-work-power-gravity

 

It is a news item about a concept called 'rail energy storage'. Basically you use surplus renewable energy to push a train up a hill. When the sun goes in, wind stops blowing etc you let the train roll back downhill and harvest the energy.

Hi Will,

 

You need to look up Nikola Tesla's Wardencliffe experiment and his scalar-wave energy transmission system based upon the Schumann resonance. This way you might get to find out what is actually going on in our universe that only actually appears to be physically made up from various forms of standing waves connected to the harmonic reciprocals of the speed of light.

 

 

Other interesting chaps are; Bruce Cathie and Randall Carlson.

 

Gibbo.

[ClikC]

All this surplus of renewable that gets spoken about is a little misleading. June has been a very poor for wind, and solar is very peaky anyway. Notice that no-one this year has released anything to say 'Look we haven't burnt coal for x hours', because we still are, even today.

The one scheme that should have gone ahead but got turnerd down was Swansea bay tidal. The tides are totally predicable and are always moving. But then if it doesn't pay back in three years, we don't seem to want it these days. Too much shorttermism....

 

Dave

 

That's because 'renewable' energy of almost every source has to be put through and inverter in order to be compatible with the national grid, this results in a 'stepped' equivalent of AC and not true sinusoidal power from power stations. This combination of renewable and, I'll use the term 'proper' power produces harmonics within the system which start drastically increasing heat in components and/or increased power usage.

 

Here in the sunny southwest, there are strict controls on how much solar can be fed into the grid for this reason.

 

Regards

 

Matt

[Ian J.]

Yes, but...

 

...it's using trains!

[Davexoc]

That's because 'renewable' energy of almost every source has to be put through and inverter in order to be compatible with the national grid, this results in a 'stepped' equivalent of AC and not true sinusoidal power from power stations. This combination of renewable and, I'll use the term 'proper' power produces harmonics within the system which start drastically increasing heat in components and/or increased power usage.

 

Here in the sunny southwest, there are strict controls on how much solar can be fed into the grid for this reason.

 

Regards

 

Matt

I know all about inverters, we use 0.18kW to 100kW on  loads of motors, and they stick harmonics back into the grid. Didn't realise solar was quite that bad at it. Maybe we need to start converting homes to DC, afterall, apart from cooking and the kettle, what needs more than 24v ?

 

As for the gravity train, you could make it more efficient by running it uphill unloaded and bringing something back down. Downside, where do you put what is basically a giant hump shunting yard?

 

Dave

[martyn11post]

I hope this is of interest.

 

https://interestingengineering.com/energy-storage-trains-work-power-gravity

 

It is a news item about a concept called 'rail energy storage'. Basically you use surplus renewable energy to push a train up a hill. When the sun goes in, wind stops blowing etc you let the train roll back downhill and harvest the energy.

 

 

Worth watching last week's BBC Click which has a report from the test track (first 7 mins): https://www.bbc.co.uk/iplayer/episode/b0b7x8gl/click-sustainable-states

[RJS1977]

I know all about inverters, we use 0.18kW to 100kW on  loads of motors, and they stick harmonics back into the grid. Didn't realise solar was quite that bad at it. Maybe we need to start converting homes to DC, afterall, apart from cooking and the kettle, what needs more than 24v ?

 

As for the gravity train, you could make it more efficient by running it uphill unloaded and bringing something back down. Downside, where do you put what is basically a giant hump shunting yard?

 

Dave

 

And you'd need a very long length of track for it to generate electricity for anything more than a couple of minutes. Might just about manage the 'Everybody makes a tea while the adverts are on' scenario but not much else.

[PatB]

Whilst I can see the advantages of not using water, I'm sceptical of the claims of low-cost infrastructure. As we know, reliable railway permanent way.is neither cheap nor particularly low impact.

[Pacific231G]

Amazing how many people comment on an article and the comments make it obvious that they haven't read it...

 

Andi

I have read it and I've done the maths.

The ffestiniog pumped storage scheme, which is far smaller than Dinorwig, stores around 2M tonnes of water with a height differential of around 300m (1000ft) Assuming that these trains could achieve the same ~80% cycle efficiency. you'd need over 3000 of the proposed 300 tonne trains operating over a similar height difference to store the same amount of energy.

I notice that with just 30 300 tonne trains the proposed system requires a 640m (2000 ft) height difference to generate 50MW (It doesn't say for how long but not very would seem to be the answer) so presumably you'd need to build it in the foothills of a mountain range like the Rockies.

Looking at photos of it, Llyn Stwlan, the upper lake of the ffestiniog scheme is fairly small, far smaller that the vast array of sidings and tracks that the proposed rail based system would require and if 2M tonnes of water in an artificial lake has geological implications I don't think a similar weight of trains would be any less so. It would certainly create plenty of work for track maintenance workers.

 

I did once see an interesting proposal to place your entire house on a sort of funicular and wind it up about fifty feet at night to store energy that could be converted into electricity for the next day.  Apparently, by the time youd boiled a kettle for your morning tea, shaved, checked your emails  and watched the TV news your house would be back at ground level having converted all that potential energy into electrical power.

Edited July 2, 2018 by Pacific231G

[DavidB-AU]

I had an unsolicited email from somebody a few years ago asking if I wanted to invest in this. Pumped hydro requires a lot less infrastructure and you lose a lot less from friction.

 

Cheers

David

[Reorte]

I had an unsolicited email from somebody a few years ago asking if I wanted to invest in this. Pumped hydro requires a lot less infrastructure and you lose a lot less from friction.

Plus in wet areas you get a bit extra free from the rain (in hot, dry ones evaporation might be an issue though).

 

This is a fun little idea but doesn't sound particularly useful, although I like the shades of gravity-powered tramways about it.

[Wild Boar Fell]

That's because 'renewable' energy of almost every source has to be put through and inverter in order to be compatible with the national grid, this results in a 'stepped' equivalent of AC and not true

sinusoidal

power from power stations. This combination of renewable and, I'll use the term 'proper' power produces harmonics within the system which start drastically increasing heat in components and/or increased power usage.

 

Here in the sunny southwest, there are strict controls on how much solar can be fed into the grid for this reason.

 

Regards

 

Matt

Another problem with such renewables (other than hydro & biomass, dare I saw traditional forms of generation) is the lack of inertia they provide to the grid. Nice hefty metal turbines feeding the grid are great at this, but if the source requires power electronics (wind,solar, bionic duckweed etc) you lose it.

 

I believe the Irish grid is suffering from over depedance on renewables, or so I have been informed.

 

 

Wild Boar Fell

[DCB]

Energy storage is the big issue for the mid 21st century.  Today Mid day, we have solar power delivering max output, wind virtually none, by midnight no renewable energy will be being created, only legacy renewables such as bio mass, coal, gas and oil will be available.  ( Coal = Legacy renewable in quasi Trump speak)  I did propose at a seminar about harnessing the power of the severn estuary with a barrage, that instead of feeding the national grid that we use the power to pump water up into the hills, flood the Stroud Valley with a dam at stonehouse and let the water down through turbines to match electrical demand while pumping water furiously uphill when the tide was coming in and out with no pumping at high and low water.  I was not taken seriously.

It would have been easy enough to re route the railway from Kemble to Cirencester and then down the old MSWJR route so apart from a few disgruntled folk in Stroud everybody wins

[ClikC]

Another problem with such renewables (other than hydro & biomass, dare I saw traditional forms of generation) is the lack of inertia they provide to the grid. Nice hefty metal turbines feeding the grid are great at this, but if the source requires power electronics (wind,solar, bionic duckweed etc) you lose it.

 

I believe the Irish grid is suffering from over depedance on renewables, or so I have been informed.

 

 

Wild Boar Fell

 

Indeed, inertia directly effects supply frequency, so anything running synchronously with the grid (synchronous generators feeding too the grid, or Synchronous motors in use for correcting power factor) start to suffer. 

 

It's why Nuclear is the only viable short to medium term solution, but try telling that to normals.

 

Still once we've left the EU, we might be more reluctant to keep increasing our energy imports from France. Hell, might even have to start mining and burning coal again, like the Germans

 

Regards

 

Matt

Edited July 2, 2018 by ClikC

[scouser]

Just a few disgruntled folk in Stroud! Nice!!

[Pacific231G]

Another problem with such renewables (other than hydro & biomass, dare I saw traditional forms of generation) is the lack of inertia they provide to the grid. Nice hefty metal turbines feeding the grid are great at this, but if the source requires power electronics (wind,solar, bionic duckweed etc) you lose it.

I believe the Irish grid is suffering from over depedance on renewables, or so I have been informed.

Wild Boar Fell

This is surely no more than a technical problem requiring engineering solutions that will be found rather than a fundamental problem with non-mechanical generation. I doubt in any case if any single generator, however heavy, would provide much inertia compared with the totality of the grid (or the part of the grid it's contributing to) It used to be the case that you often got slight perturbations and momentary interruption in the power supply as generating plant was switched in or out of the grid; it's clearly now far more sophisticated than just lining up a synchroscope and banging in the breakers.

 

I'm also not sure why you think a wind turbine should be any less synchronised than any other type of mechanically driven three phase generator. If you look at most wind farms you'll see them all turning at exactly the same speed which suggests that they are synchronised with the grid.

Edited July 5, 2018 by Pacific231G

[tomparryharry]

This is surely no more than a technical problem requiring engineering solutions that will be found rather than a fundamental problem with non-mechanical generation. I doubt in any case if any single generator, however heavy, would provide much inertia compared with the totality of the grid (or the part of the grid it's contributing to) It used to be the case that you often got slight perturbations and momentary interruption in the power supply as plant was switched in or out of the grid; it's clearly now far more sophisticated than just lining up a synchroscope and banging in the breakers.

 

I'm also not sure why you think a wind turbine should be any less synchronised than any other type of mechanically driven three phase generator. If you look at most wind farms you'll see them all turning at exactly the same speed which suggests that they are synchronised with the grid.

Just remember that wind turbines do turn at different speeds. If over a certain degree change in direction, the blades are braked to turn into the wind. This often takes a few minutes. People look at a turbine and say "Ohh , no wind". There's plenty of wind, it's just blowing the wrong way at that particular time. You can take it from me, the company concerned spent a fortune putting up those turbines: They want every penny generated back. If you have the time, watch a stopped turbine. They will slowly turn into the most favourable orientation to resume generation. The greatest missed opportunity is stored water, We all know the tides run in & out. Running an excess of any generated power pumps the water back into the lagoon. It's simple really, just need to knock the blinkers off.

 

Cheers,

 

Ian.

[Wild Boar Fell]

This is surely no more than a technical problem requiring engineering solutions that will be found rather than a fundamental problem with non-mechanical generation. I doubt in any case if any single generator, however heavy, would provide much inertia compared with the totality of the grid (or the part of the grid it's contributing to) It used to be the case that you often got slight perturbations and momentary interruption in the power supply as plant was switched in or out of the grid; it's clearly now far more sophisticated than just lining up a synchroscope and banging in the breakers.

 

I'm also not sure why you think a wind turbine should be any less synchronised than any other type of mechanically driven three phase generator. If you look at most wind farms you'll see them all turning at exactly the same speed which suggests that they are synchronised with the grid.

If I remember I can go into a little more detail tomorrow. Yes there are ways being developed to add grid inertia back into a more renewables based grid, but it is indeed more infrastructure, equipment and more money needed to allow this. Correct a single generator will have little inertia compared to this system (if talking about national grids), but when you start taking a noticeable percentage of the total capacity away from the mechanical systems that's when things get more interesting.

 

Simple, you can either get synchronous or asynchronous wind turbines. But generally these still go through power electronics at some point before reaching the grid.

[jjb1970]

Solid state frequency control is used for wind turbines as it is much more flexible and cheaper than engineering a constant speed arrangement. Variable input, constant output mechanical drives can be made (I was very familiar with epicyclic drives) but since the cost of high power frequency controllers plummeted it is a lot easier to use them. They do introduce certain issues (I always thought increased partial discharge degradation of generators was being caused by unfiltered harmonics) but they will be managed. Electricity is like anything else, when you hit a technological discontinuity then it tends to be that you adapt to a technology rather than a technology being a simple drop in for what went before. Renewable energy is just one part of the discontinuity, just as important is the move towards distributed energy, micro grids and generation with energy storage and away from large centralised generation.