3 ms·

For fixed-site applications of sufficient land area and scale, it's difficult to beat pumped-storage hydroelectricity (PSH). The round-trip efficiency is around

For fixed-site applications of sufficient land area and scale, it's difficult to beat pumped-storage hydroelectricity (PSH). The round-trip efficiency is around or above 70%, the same or better than CAES. CAES is probably best used in applications similar to flywheel (FES), away from occupied areas.

doitLP 6y ago
Do you have any recommendations on how to learn more about this? My brother has a steep hill on his property and Ive been wondering about the feasibility of PSH. How high the tank should be, the equipment, the power output.
- timeinput 6y ago
  This isn't quite what you're after, but it's a pleasent read. https://ludens.cl/paradise/turbine/turbine.html https://ludens.cl/paradise/turbine/turbine.html there have been some discussions on here about it too. It at least gets you all the right words to start googling for turbine options which helped me to do some back of the envelope math. It's a steeper hill than seemed feasible to me.
  - ehnto 6y ago
    Thid has reminded me of this gentleman who has been using gravity fed old washing machines as turbines for electricity generation on his property for 16 years https://youtu.be/Xb6TIWub6KU https://youtu.be/Xb6TIWub6KU He doesn't need the pumped storage part of the equation due to a natural water flow, but it is part of the solution at least.
- creato 6y ago
  You could start by just calculating the potential energy of the volume of the tank you are considering, and the difference in elevation between the reservoirs (volume x 1 kg/L x gravity x elevation difference, plug in the units of your choice and let google figure it out). I suspect the amount of energy is far less than you are imagining... It takes a lot of water to generate a useful amount of energy. This video (https://www.youtube.com/watch?v=66YRCjkxIcg https://www.youtube.com/watch?v=66YRCjkxIcg) does an interesting demo and points out that a 5 gallon bucket on a ladder has the same potential energy as a watch battery.
deleted 6y ago
[deleted]
PaulDavisThe1st 6y ago
TFA already says that large scale CAES is probably a dead end and that small scale CAES is where we might/should focus our attention.
- notmadnomad 6y ago
  CAES also has awful energy density of ~100 kJ/m^3 or ~100 J/L. It's not worth it. Small CAES implies closer to people and more likely to experience heat and fires, more so than say 200 psi / 13 atm air compressors, and so inherently more dangerous than all existing residential and commercial products including water heaters with failed/blocked relief valves. Perhaps almost on-par with LPG tanks, which are not supposed to be stored inside building either but in a remote pit or shed. Large amounts of reactive lithium metal in NMC (0.90–2.43 MJ/L) "powerwall" reserve banks in or on a building also seems like a major fire risk. LiFePO4 (1.2 MJ/L) is safer due to much less lithium. By comparison with fuels: - Al thermite is ~18 MJ/L - Cu thermite is ~21 MJ/L - hydrogen is ~28 MJ/L @ 700 psi - gasoline is ~32 MJ/L - Jet A is ~35 MJ/L - diesel is ~36 MJ/L In the long-term, a reliable, reversible fuel cell combined with H2 tanks and H2 generation and distribution infrastructure seems like the best hybrid on- / off-grid way to go, at deployment cost though, but it could eliminate the increasingly-dangerous electrical grid and natural gas grid. Short-term, LiFePO4 looks better and better.
justasitsounds 6y ago
The world's first commercial liquid air battery project has been commissioned to be built in Trafford, Greater Manchester, UK - it's a very residential area: https://www.gov.uk/government/news/greater-manchester-to-house-to-worlds-largest-liquid-air-battery https://www.gov.uk/government/news/greater-manchester-to-hou.... This guy (https://www.youtube.com/watch?v=tMLu9Dtw9yI https://www.youtube.com/watch?v=tMLu9Dtw9yI) makes some good points about how cheap and scalable the technology is for medium-scale energy storage. It uses tried and tested, reliable and simple components for example

doitLP 6y ago

Do you have any recommendations on how to learn more about this? My brother has a steep hill on his property and Ive been wondering about the feasibility of PSH. How high the tank should be, the equipment, the power output.

timeinput 6y ago
This isn't quite what you're after, but it's a pleasent read. https://ludens.cl/paradise/turbine/turbine.html https://ludens.cl/paradise/turbine/turbine.html there have been some discussions on here about it too. It at least gets you all the right words to start googling for turbine options which helped me to do some back of the envelope math. It's a steeper hill than seemed feasible to me.
- ehnto 6y ago
  Thid has reminded me of this gentleman who has been using gravity fed old washing machines as turbines for electricity generation on his property for 16 years https://youtu.be/Xb6TIWub6KU https://youtu.be/Xb6TIWub6KU He doesn't need the pumped storage part of the equation due to a natural water flow, but it is part of the solution at least.
creato 6y ago
You could start by just calculating the potential energy of the volume of the tank you are considering, and the difference in elevation between the reservoirs (volume x 1 kg/L x gravity x elevation difference, plug in the units of your choice and let google figure it out). I suspect the amount of energy is far less than you are imagining... It takes a lot of water to generate a useful amount of energy. This video (https://www.youtube.com/watch?v=66YRCjkxIcg https://www.youtube.com/watch?v=66YRCjkxIcg) does an interesting demo and points out that a 5 gallon bucket on a ladder has the same potential energy as a watch battery.

deleted 6y ago

[deleted]

PaulDavisThe1st 6y ago

TFA already says that large scale CAES is probably a dead end and that small scale CAES is where we might/should focus our attention.

notmadnomad 6y ago
CAES also has awful energy density of ~100 kJ/m^3 or ~100 J/L. It's not worth it. Small CAES implies closer to people and more likely to experience heat and fires, more so than say 200 psi / 13 atm air compressors, and so inherently more dangerous than all existing residential and commercial products including water heaters with failed/blocked relief valves. Perhaps almost on-par with LPG tanks, which are not supposed to be stored inside building either but in a remote pit or shed. Large amounts of reactive lithium metal in NMC (0.90–2.43 MJ/L) "powerwall" reserve banks in or on a building also seems like a major fire risk. LiFePO4 (1.2 MJ/L) is safer due to much less lithium. By comparison with fuels: - Al thermite is ~18 MJ/L - Cu thermite is ~21 MJ/L - hydrogen is ~28 MJ/L @ 700 psi - gasoline is ~32 MJ/L - Jet A is ~35 MJ/L - diesel is ~36 MJ/L In the long-term, a reliable, reversible fuel cell combined with H2 tanks and H2 generation and distribution infrastructure seems like the best hybrid on- / off-grid way to go, at deployment cost though, but it could eliminate the increasingly-dangerous electrical grid and natural gas grid. Short-term, LiFePO4 looks better and better.

justasitsounds 6y ago

The world's first commercial liquid air battery project has been commissioned to be built in Trafford, Greater Manchester, UK - it's a very residential area: https://www.gov.uk/government/news/greater-manchester-to-house-to-worlds-largest-liquid-air-battery https://www.gov.uk/government/news/greater-manchester-to-hou.... This guy (https://www.youtube.com/watch?v=tMLu9Dtw9yI https://www.youtube.com/watch?v=tMLu9Dtw9yI) makes some good points about how cheap and scalable the technology is for medium-scale energy storage. It uses tried and tested, reliable and simple components for example