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Discussion in 'Energy, Environment, and Policy' started by 182RG, May 16, 2016.
Forget Elon Musk's Batteries—Let's Fix the Grid With a Rock-Filled Train on a Hill
Couldn't you do something with a lift and go straight up, that way footprint on ground is minimised. Less space or real estate taken up.
Hopefully a physics-type will chime in. (I am not) My guess is there is some type of physics reason that the car generates (conserves?) more energy than a lift due to some obscure law of physics?
More likely they already had the land and train tracks. Plus you can use a lot more weight on an inclined track that is supported by the earth vs trying to build a tower strong enough to hold all that weight. You would spend a lot of money/energy building the tower which would dramatically increase the ROI.
No, the energy is just the weight times the height, the incline doesn't matter.
I wondered about that also, and my guess is that they want to use off the shelf train components. To do something like an elevator, you'd have to have a VERY strong set of cables to suspend it. With the train on a gentle incline, the friction of the wheels on the rails would be enough to keep it from slipping.
The video is worth watching, and helps explain why a tower / straight up lift isn't as effective. Part of the system they've built is that each car moves independently, with an intended steady state of a stack of cars somewhere in the middle of the track. Then you can have cars at the head of the stack go uphill when there is surplus power, with more and more cars going into motion to absorb more excess power.
And you can have cars going downhill. The key is many cars moving at different speeds to adjust to the power need / excess, and an independence that would be difficult in a tower (does each weight moving up and down have it's own independent set of cabling?
That is indeed slick. I wonder how much track and elevation gain you would need for the scale that makes this economical would be? I didn't see that addressed in the article or video.