5 ms·

Similar concept using trains: https://www.aresnorthamerica.com/grid-scale-energy-storage https://www.aresnorthamerica.com/grid-scale-energy-storage I wonder th

by FrojoS 8y ago

Similar concept using trains: https://www.aresnorthamerica.com/grid-scale-energy-storage https://www.aresnorthamerica.com/grid-scale-energy-storage I wonder though, the density of concrete is only about 2.5 higher than that of water. So, a concrete tower, comparable to a pumped-storage hydroelectricity plant would be gigantic. Seems infeasible to me.

Someone 8y ago
Build one inside Fort Knox :-) I also think it might be easier to do away with the crane and just put the weight on a huge moving platform. Where available, you could sink that into a disused mine shaft.
- roywiggins 8y ago
  This method uses rails and a hill: https://www.aresnorthamerica.com/about-ares-north-america https://www.aresnorthamerica.com/about-ares-north-america
st26 8y ago
Might come down to things like, how efficient are cranes & conveyors & so forth, vs water pumps & hydro generators. The nature of each material leads to different techniques which could have very different efficiencies.
- hinkley 8y ago
  Upfront costs can sink a project, but so can ongoing maintenance. Materials that don't foul as easily have a long term advantage. And when there's a drought people won't be too happy about all that fresh water you're taking to make electricity ('course, how much water does it take to make a cubic foot of concrete, cradle to grave?).
  - mmt 8y ago
    > how much water does it take to make a cubic foot of concrete The article does mention that they expect to use 1/6th the cement of construction concrete. This paper https://www.nature.com/articles/s41893-017-0009-5 https://www.nature.com/articles/s41893-017-0009-5 gives an idea: 2 Gt of water per 21.3 Gt of not-water. Assuming perfectly dry concrete (and none of the water converting to not-water mass, both of which I believe are counter-factual), that means a 2130 kg block of concrete would have needed 200 kg of water. Pumped hydro, assuming identical efficiency, would need all 2130 kg of water.
    - hinkley 8y ago
      2Gt of water was mixed into the concrete, but when you're calculating water footprint you need to look at how much water went into creating all of the ingredients. That can be pretty substantial. That article does go on to cover the water footprint, but what troubles me is that they switch units, and report it as 16.6km^3 of water. Which seems like they're trying to obfuscate the results (they have obfuscated them, whether that was intentional or not is another question). That's all the water for all the concrete. Which for a hydroelectric perspective, is about 5% of the volume of water behind Grand Coulee Dam, for all the concrete we currently make every year. So maybe concrete blocks make sense for power.
      - CydeWeys 8y ago
        Here's an idea: It's possible to make unreinforced concrete using seawater. Wonder if that would work here.
      - deleted 8y ago
        [deleted]
      - mmt 8y ago
        > 2Gt of water was mixed into the concrete, but when you're calculating water footprint you need to look at how much water went into creating all of the ingredients. True, though the paper makes a point, early on, that much of it is used in producing the aggregate, and the article makes a point of (potentially) using recycled/discarded aggregate, which would incur no additional water consumption. > report it as 16.6km^3 of water. Which seems like they're trying to obfuscate the results That's a remarkably harsh characterization, especially since that was parenthetical. The main reported amount was 16.6 × 10^9 m^3. With water having the convenient density of 1000kg/m^3 (1 ton/m^3) and 10^9 being equivalent to the SI G prefix (both facts which one reasonably expect a reader of a physical sciences journal to know casually), it seems hardly obfuscatory. I'd attribute, instead, a change of units to a desire to compare it to household use, later in that paragraph, which is more typically measured by volume. Although for commercial concrete block of 2130kg, that would, indeed, change the amount of water to be 1660kg from my original 200kg. However, I'm fairly confident that the ability to use 1/6th the cement combined with not needing any particular aggregate (even recycled) will bring the number for the article's application much closer to the smaller one than the larger one.
- mikec3010 8y ago
  I wonder if you could compromise and use powdered concrete in a closed system? High powered fans could blow the fine powder upward in a silo so it would act like a liquid. Then large paddlewheels catching the powder could power a generator coming back down. I have no idea if powder going up a tube has less friction than blocks on a cable/pulley, however.
  - effie 8y ago
    That's not a good idea. You would have turbulent airflow with dust, most energy would get lost, resulting in low efficiency. Weights on cables pulled by electric motors is as efficient as it gets. Not to mention dust bucking up the gears and sockets.
- PeterisP 8y ago
  The efficiency is comparable, pumped hydro gets ~80% at large scale practice, while this is promised to be 85% and might turn out to be the same after all the implementation issues and wear&tear comes in. Which it should be - IMHO, despite the material, both systems get very similar techniques, at the core in both cases you have the loss of a motor+generator pair plus the friction of your mechanical system.
andbberger 8y ago
Previously discussed: https://news.ycombinator.com/item?id=11595195 https://news.ycombinator.com/item?id=11595195
monochromatic 8y ago
Pumped hydro has the downside that water evaporates too.
- your-nanny 8y ago
  and water is a rather precious resource in many localities.
mmt 8y ago
> So, a concrete tower, comparable to a pumped-storage hydroelectricity plant would be gigantic. There's nothing to suggest that each tower would need to be comparable. My reading of the article suggests the converse, that each installation is feasible at a fraction of the size of pumped hydro [1]. Although the article does mention land availability being an issue, to say the same for pumped hydro would be a gross understatement, since the latter requires not just land but a specific (vertical) shape of land in a continguous piece. [1] Article mentions "each 35 MWh system". I found it remarkably difficult to find the usable storage capacity of a PSH station.
- PeterisP 8y ago
  Well, https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Station https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Sta... lists a capacity of 44 GWh.
  - mmt 8y ago
    There's no citation for that, so it could be what WP calls "original research". It is, however, pretty likely the right OOM. That would put the storage capacity at around 1000x, and, if the estimates of the cranes' generating capacity elsewhere in the thread are correct, approximately proportional to that, as well.
eliaspro 8y ago
A local company [1] is taking a similar approach to the extreme and is developing a concept which involves cutting a 100-250m (328-820ft) diameter piston out of solid rock and then pumping water underneath to store up to 8GWh of energy. Sounds quite crazy at first but actually looks quite reasonable after looking at it a little closer [2]. [1] https://heindl-energy.com/ https://heindl-energy.com/ [2] https://heindl-energy.com/technical-concept/engineering-challenges/ https://heindl-energy.com/technical-concept/engineering-chal...
- ISL 8y ago
  How do they make the seal at the bottom of the piston?
  - ec109685 8y ago
    “The Gravity Storage is cut out of surrounding rocks. Because rocks nearly always have crevasses and fine cracks through which water can flow, it is necessary to completely seal the piston and the surrounding piston cylinder against the surrounding area. For this purpose, all freely exposed surfaces are sealed with a geomembrane and concrete.”
    - ISL 8y ago
      There still needs to be the equivalent of a series of O-rings between the piston and the cylinder bore to prevent the piston from sinking. I'd guess that it is the second-hardest technical problem, after the considerable challenge of isolating the piston.
      - gns24 8y ago
        The 'rolling membrane' that they are proposing is described here: https://heindl-energy.com/technical-concept/engineering-challenges/ https://heindl-energy.com/technical-concept/engineering-chal...
- bacon_waffle 8y ago
  That's amazing! Any idea how they will separate the bottom of the piston? I wonder how they will balance it too, so that it doesn't seize in the cylinder. It seems like (re)moving material would be straightforward enough, but figuring out what the current balance is, maybe not so much.
CydeWeys 8y ago
Concrete doesn't evaporate though, so there are some positives in its favor.
bacon_waffle 8y ago
It seems to me, that for smoothing generation from solar, the important metric is more like "max power over ~8 hours", rather than "total energy storage".

by FrojoS 8y ago

Someone 8y ago

Build one inside Fort Knox :-) I also think it might be easier to do away with the crane and just put the weight on a huge moving platform. Where available, you could sink that into a disused mine shaft.

roywiggins 8y ago
This method uses rails and a hill: https://www.aresnorthamerica.com/about-ares-north-america https://www.aresnorthamerica.com/about-ares-north-america

st26 8y ago

Might come down to things like, how efficient are cranes & conveyors & so forth, vs water pumps & hydro generators. The nature of each material leads to different techniques which could have very different efficiencies.

hinkley 8y ago
Upfront costs can sink a project, but so can ongoing maintenance. Materials that don't foul as easily have a long term advantage. And when there's a drought people won't be too happy about all that fresh water you're taking to make electricity ('course, how much water does it take to make a cubic foot of concrete, cradle to grave?).
- mmt 8y ago
  > how much water does it take to make a cubic foot of concrete The article does mention that they expect to use 1/6th the cement of construction concrete. This paper https://www.nature.com/articles/s41893-017-0009-5 https://www.nature.com/articles/s41893-017-0009-5 gives an idea: 2 Gt of water per 21.3 Gt of not-water. Assuming perfectly dry concrete (and none of the water converting to not-water mass, both of which I believe are counter-factual), that means a 2130 kg block of concrete would have needed 200 kg of water. Pumped hydro, assuming identical efficiency, would need all 2130 kg of water.
  - hinkley 8y ago
    2Gt of water was mixed into the concrete, but when you're calculating water footprint you need to look at how much water went into creating all of the ingredients. That can be pretty substantial. That article does go on to cover the water footprint, but what troubles me is that they switch units, and report it as 16.6km^3 of water. Which seems like they're trying to obfuscate the results (they have obfuscated them, whether that was intentional or not is another question). That's all the water for all the concrete. Which for a hydroelectric perspective, is about 5% of the volume of water behind Grand Coulee Dam, for all the concrete we currently make every year. So maybe concrete blocks make sense for power.
    - CydeWeys 8y ago
      Here's an idea: It's possible to make unreinforced concrete using seawater. Wonder if that would work here.
    - deleted 8y ago
      [deleted]
    - mmt 8y ago
      > 2Gt of water was mixed into the concrete, but when you're calculating water footprint you need to look at how much water went into creating all of the ingredients. True, though the paper makes a point, early on, that much of it is used in producing the aggregate, and the article makes a point of (potentially) using recycled/discarded aggregate, which would incur no additional water consumption. > report it as 16.6km^3 of water. Which seems like they're trying to obfuscate the results That's a remarkably harsh characterization, especially since that was parenthetical. The main reported amount was 16.6 × 10^9 m^3. With water having the convenient density of 1000kg/m^3 (1 ton/m^3) and 10^9 being equivalent to the SI G prefix (both facts which one reasonably expect a reader of a physical sciences journal to know casually), it seems hardly obfuscatory. I'd attribute, instead, a change of units to a desire to compare it to household use, later in that paragraph, which is more typically measured by volume. Although for commercial concrete block of 2130kg, that would, indeed, change the amount of water to be 1660kg from my original 200kg. However, I'm fairly confident that the ability to use 1/6th the cement combined with not needing any particular aggregate (even recycled) will bring the number for the article's application much closer to the smaller one than the larger one.
mikec3010 8y ago
I wonder if you could compromise and use powdered concrete in a closed system? High powered fans could blow the fine powder upward in a silo so it would act like a liquid. Then large paddlewheels catching the powder could power a generator coming back down. I have no idea if powder going up a tube has less friction than blocks on a cable/pulley, however.
- effie 8y ago
  That's not a good idea. You would have turbulent airflow with dust, most energy would get lost, resulting in low efficiency. Weights on cables pulled by electric motors is as efficient as it gets. Not to mention dust bucking up the gears and sockets.
PeterisP 8y ago
The efficiency is comparable, pumped hydro gets ~80% at large scale practice, while this is promised to be 85% and might turn out to be the same after all the implementation issues and wear&tear comes in. Which it should be - IMHO, despite the material, both systems get very similar techniques, at the core in both cases you have the loss of a motor+generator pair plus the friction of your mechanical system.

andbberger 8y ago

Previously discussed: https://news.ycombinator.com/item?id=11595195 https://news.ycombinator.com/item?id=11595195

monochromatic 8y ago

Pumped hydro has the downside that water evaporates too.

your-nanny 8y ago
and water is a rather precious resource in many localities.

mmt 8y ago

> So, a concrete tower, comparable to a pumped-storage hydroelectricity plant would be gigantic. There's nothing to suggest that each tower would need to be comparable. My reading of the article suggests the converse, that each installation is feasible at a fraction of the size of pumped hydro [1]. Although the article does mention land availability being an issue, to say the same for pumped hydro would be a gross understatement, since the latter requires not just land but a specific (vertical) shape of land in a continguous piece. [1] Article mentions "each 35 MWh system". I found it remarkably difficult to find the usable storage capacity of a PSH station.

PeterisP 8y ago
Well, https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Station https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Sta... lists a capacity of 44 GWh.
- mmt 8y ago
  There's no citation for that, so it could be what WP calls "original research". It is, however, pretty likely the right OOM. That would put the storage capacity at around 1000x, and, if the estimates of the cranes' generating capacity elsewhere in the thread are correct, approximately proportional to that, as well.

eliaspro 8y ago

A local company [1] is taking a similar approach to the extreme and is developing a concept which involves cutting a 100-250m (328-820ft) diameter piston out of solid rock and then pumping water underneath to store up to 8GWh of energy. Sounds quite crazy at first but actually looks quite reasonable after looking at it a little closer [2]. [1] https://heindl-energy.com/ https://heindl-energy.com/ [2] https://heindl-energy.com/technical-concept/engineering-challenges/ https://heindl-energy.com/technical-concept/engineering-chal...

ISL 8y ago
How do they make the seal at the bottom of the piston?
- ec109685 8y ago
  “The Gravity Storage is cut out of surrounding rocks. Because rocks nearly always have crevasses and fine cracks through which water can flow, it is necessary to completely seal the piston and the surrounding piston cylinder against the surrounding area. For this purpose, all freely exposed surfaces are sealed with a geomembrane and concrete.”
  - ISL 8y ago
    There still needs to be the equivalent of a series of O-rings between the piston and the cylinder bore to prevent the piston from sinking. I'd guess that it is the second-hardest technical problem, after the considerable challenge of isolating the piston.
    - gns24 8y ago
      The 'rolling membrane' that they are proposing is described here: https://heindl-energy.com/technical-concept/engineering-challenges/ https://heindl-energy.com/technical-concept/engineering-chal...
bacon_waffle 8y ago
That's amazing! Any idea how they will separate the bottom of the piston? I wonder how they will balance it too, so that it doesn't seize in the cylinder. It seems like (re)moving material would be straightforward enough, but figuring out what the current balance is, maybe not so much.

CydeWeys 8y ago

Concrete doesn't evaporate though, so there are some positives in its favor.

bacon_waffle 8y ago

It seems to me, that for smoothing generation from solar, the important metric is more like "max power over ~8 hours", rather than "total energy storage".