3 ms·

Flywheels would be a great solution here: http://en.wikipedia.org/wiki/Flywheel_energy_storage#Comparison_to_batteries http://en.wikipedia.org/wiki/Flywheel_ene

by pstuart 13y ago

Flywheels would be a great solution here: http://en.wikipedia.org/wiki/Flywheel_energy_storage#Comparison_to_batteries http://en.wikipedia.org/wiki/Flywheel_energy_storage#Compari... Someday they might be commercially viable....

masklinn 13y ago
Exactly what I was thinking about reading the article: you've got a huge, fixed energy storage system to set up, why not use a flywheel? That's pretty much a best-case situation for them even if you don't need the transient load ability of a flywheel.
- rwmj 13y ago
  Or even (it is a hotel) pump water to tanks on the roof, making a small pumped storage hydroelectric system. Would love someone to do the comparisons of cost and energy density of all 3 solutions.
  - masklinn 13y ago
    Pumped hydro scales awesomely and is relatively low maintenance, but it has a fairly low energy density, wikipedia quotes 272Wh for 1m^3 at 100m (~30 floors). That's 0.272Wh/kg. You either need tremendous amounts of water, significant height, or both. By comparison, your ultra-basic low-energy-density lead-acid battery pack is 30~40Wh/kg, 100 times the energy density, and a Li-ion is 130~200Wh/kg.
    - maxerickson 13y ago
      It's fun to throw out numbers for pumped storage. The Ludington pumped storage plant [1] is pretty big at 1.8 gigawatts. At full power, that's 33 million gallons per minute. The reservoir is 27 billion gallons of water (about 100 billion liters). [1] http://en.wikipedia.org/wiki/Ludington_Pumped_Storage_Power_Plant http://en.wikipedia.org/wiki/Ludington_Pumped_Storage_Power_...
  - sebnukem2 13y ago
    I looked at that in the past: storing energy in a massive ball going up and down a well. But you need tons of mass traveling a long distance. The energy density is just too low. To give you an idea: E(energy in Joules) = mgh(mass in kg x gravity in m/s2 x height in m). So one ton (1kkg) traveling 10m would store about 100J which is about 27Wh (1J = 1Ws), which is about nothing.

by pstuart 13y ago

masklinn 13y ago

Exactly what I was thinking about reading the article: you've got a huge, fixed energy storage system to set up, why not use a flywheel? That's pretty much a best-case situation for them even if you don't need the transient load ability of a flywheel.

rwmj 13y ago
Or even (it is a hotel) pump water to tanks on the roof, making a small pumped storage hydroelectric system. Would love someone to do the comparisons of cost and energy density of all 3 solutions.
- masklinn 13y ago
  Pumped hydro scales awesomely and is relatively low maintenance, but it has a fairly low energy density, wikipedia quotes 272Wh for 1m^3 at 100m (~30 floors). That's 0.272Wh/kg. You either need tremendous amounts of water, significant height, or both. By comparison, your ultra-basic low-energy-density lead-acid battery pack is 30~40Wh/kg, 100 times the energy density, and a Li-ion is 130~200Wh/kg.
  - maxerickson 13y ago
    It's fun to throw out numbers for pumped storage. The Ludington pumped storage plant [1] is pretty big at 1.8 gigawatts. At full power, that's 33 million gallons per minute. The reservoir is 27 billion gallons of water (about 100 billion liters). [1] http://en.wikipedia.org/wiki/Ludington_Pumped_Storage_Power_Plant http://en.wikipedia.org/wiki/Ludington_Pumped_Storage_Power_...
- sebnukem2 13y ago
  I looked at that in the past: storing energy in a massive ball going up and down a well. But you need tons of mass traveling a long distance. The energy density is just too low. To give you an idea: E(energy in Joules) = mgh(mass in kg x gravity in m/s2 x height in m). So one ton (1kkg) traveling 10m would store about 100J which is about 27Wh (1J = 1Ws), which is about nothing.