I mean, it’s not like concrete is scraping on the walls going up and down, it’s on a pulley system which would be efficient in terms of doing energy transfer. The article mentions round-trip efficiency above 80 percent, so I’m not sure pumping water could be much more efficient than that.
The main problem with gravitational storage is that it is incredibly weak compared to chemical, compressed air, or flywheel techniques (see the post on home energy storage options). For example, to get the amount of energy stored in a single AA battery, we would have to lift 100 kg (220 lb) 10 m (33 ft) to match it. To match the energy contained in a gallon of gasoline, we would have to lift 13 tons of water (3500 gallons) one kilometer high (3,280 feet). It is clear that the energy density of gravitational storage is severely disadvantaged.
It seems the problem is not necessarily one of conversion efficiency, but rather of scale. In order to store significant amounts of electrical energy using mechanical means, you need to move a lot of weight. Manufacturing the concrete blocks requires money and raw materials, and a pulley system robust enough to move them around wouldn’t be cheap either. The pumped storage hydroelectric systems which currently provide the vast majority of our grid energy storage partially circumvent this expense by taking advantage of natural bodies of water and advantageous topography.
That being said, it’s definitely a fascinating concept and one worth exploring. But there are well established difficulties that explain why this type of energy storage isn’t already widespread.
Or rather, it specifically might NOT make sense at scale. It might only make sense in middle scales, where there isn’t a topographic advantage to use, but the requirement is more than batteries can support.
Yes, I agree. I’m just making the point that there isn’t just a lower limit to the scale for a system like this, but an upper limit too, where you would have been better off just building a dam.
I mean, it’s not like concrete is scraping on the walls going up and down, it’s on a pulley system which would be efficient in terms of doing energy transfer. The article mentions round-trip efficiency above 80 percent, so I’m not sure pumping water could be much more efficient than that.
https://dothemath.ucsd.edu/2011/11/pump-up-the-storage/
It seems the problem is not necessarily one of conversion efficiency, but rather of scale. In order to store significant amounts of electrical energy using mechanical means, you need to move a lot of weight. Manufacturing the concrete blocks requires money and raw materials, and a pulley system robust enough to move them around wouldn’t be cheap either. The pumped storage hydroelectric systems which currently provide the vast majority of our grid energy storage partially circumvent this expense by taking advantage of natural bodies of water and advantageous topography.
That being said, it’s definitely a fascinating concept and one worth exploring. But there are well established difficulties that explain why this type of energy storage isn’t already widespread.
right, it only makes sense if you do it at large scale
Or rather, it specifically might NOT make sense at scale. It might only make sense in middle scales, where there isn’t a topographic advantage to use, but the requirement is more than batteries can support.
What I meant is that you need to build a unit of a certain size before it becomes efficient enough to be practical.
Yes, I agree. I’m just making the point that there isn’t just a lower limit to the scale for a system like this, but an upper limit too, where you would have been better off just building a dam.
Yeah for sure.