35 ms·

A typical wind turbine is 80m high and and generates 1.5MW [1]. Gravitational storage in Joules is (mass in kg) * (height in m) * 9.8 (gravity). Divide by 3.6 m

A typical wind turbine is 80m high and and generates 1.5MW [1]. Gravitational storage in Joules is (mass in kg) * (height in m) * 9.8 (gravity). Divide by 3.6 million to convert to kWh. Suppose we raise a 30-ton weight (i.e. a big shipping container filled to capacity with rocks) all the way up that 80m turbine. We've stored 30,000 * 80 * 9.8 / 3600000 = 6.5 kWh of energy. That's 16 seconds worth of energy from the turbine spinning at full speed. [1] https://en.wikipedia.org/wiki/Wind_turbine#Design_and_construction https://en.wikipedia.org/wiki/Wind_turbine#Design_and_constr...

usrusr 10y ago
Impressive way to put the power generation capability into perspective. Also makes me wonder how a spring (instead of or in addition to those 30 tons) would scale to turbine tower size. Just don't think of the destruction when something breaks!
- beamatronic 10y ago
  Catastrophic energy release doesn't care if you're a spring, a flywheel, a lithium battery, or a chemical bomb - in fact all those things start to look pretty similar at high enough energy levels.
  - seanp2k2 10y ago
    But you must admit that an 80m (~262ft or ~24 stories) wind turbine blasting off like a giant pogo stick into the sky is by far the most comical. Maybe gravitational doesn't make sense, but compressed air might. Big compressor directly driven by the turbine (so as not to waste energy converting to electricity to turn an electric compressor motor) being used to compress normal air into large tanks inside the wind turbine tower which can later be used to spin another turbine-based generator using the same air. Not a physics major, but this seems feasible. Not sure of the potential energy storage, but I feel like the direct conversion of rotational energy to spin the pump has to be much more efficient than converting it to electricity first, then using that [many miles away] to compress air or drive a train up a mountain.
    - WiseWeasel 10y ago
      Bonus points if you can spin the wind turbine with the discharge of the compressed air, on the lag edge of the propellers.
    - usrusr 10y ago
      Dispatchable wind via compressed air storage seems to be quite a thing in the scientific community. Unfortunately, big subsidy schemes like the german one fail to acknowledge the importance of dispatchability, so they utterly disincentivize any development in that direction.
mrfusion 10y ago
What about lead or a heaver element instead of rocks?
- JonathonW 10y ago
  A 40' shipping container-sized box filled with lead would be roughly 90 metric tons, so multiply that number by three. Now you've got ~45 seconds worth of energy. (An actual shipping container would break before you hit this point; a standard 40' shipping container has a maximum gross weight of ~30 metric tons-- you're not likely to fill it to its volumetric capacity with rocks or lead.)
  - imaginenore 10y ago
    And lead is a lot more expensive than rocks.
    - theandrewbailey 10y ago
      And rocks tend to be not toxic and can be sourced from near anywhere.
dragontamer 10y ago
Good thing they're bringing SEVEN different 8600-ton trains up 4000 feet then. 5.5 Mile track * tan (8 degree slope) * 5280 feet per mile == ~4000 feet height. But yeah, gravity storage as part of the Turbine itself doesn't seem too useful.

usrusr 10y ago

Impressive way to put the power generation capability into perspective. Also makes me wonder how a spring (instead of or in addition to those 30 tons) would scale to turbine tower size. Just don't think of the destruction when something breaks!

beamatronic 10y ago
Catastrophic energy release doesn't care if you're a spring, a flywheel, a lithium battery, or a chemical bomb - in fact all those things start to look pretty similar at high enough energy levels.
- seanp2k2 10y ago
  But you must admit that an 80m (~262ft or ~24 stories) wind turbine blasting off like a giant pogo stick into the sky is by far the most comical. Maybe gravitational doesn't make sense, but compressed air might. Big compressor directly driven by the turbine (so as not to waste energy converting to electricity to turn an electric compressor motor) being used to compress normal air into large tanks inside the wind turbine tower which can later be used to spin another turbine-based generator using the same air. Not a physics major, but this seems feasible. Not sure of the potential energy storage, but I feel like the direct conversion of rotational energy to spin the pump has to be much more efficient than converting it to electricity first, then using that [many miles away] to compress air or drive a train up a mountain.
  - WiseWeasel 10y ago
    Bonus points if you can spin the wind turbine with the discharge of the compressed air, on the lag edge of the propellers.
  - usrusr 10y ago
    Dispatchable wind via compressed air storage seems to be quite a thing in the scientific community. Unfortunately, big subsidy schemes like the german one fail to acknowledge the importance of dispatchability, so they utterly disincentivize any development in that direction.

mrfusion 10y ago

What about lead or a heaver element instead of rocks?

JonathonW 10y ago
A 40' shipping container-sized box filled with lead would be roughly 90 metric tons, so multiply that number by three. Now you've got ~45 seconds worth of energy. (An actual shipping container would break before you hit this point; a standard 40' shipping container has a maximum gross weight of ~30 metric tons-- you're not likely to fill it to its volumetric capacity with rocks or lead.)
- imaginenore 10y ago
  And lead is a lot more expensive than rocks.
  - theandrewbailey 10y ago
    And rocks tend to be not toxic and can be sourced from near anywhere.

dragontamer 10y ago

Good thing they're bringing SEVEN different 8600-ton trains up 4000 feet then. 5.5 Mile track * tan (8 degree slope) * 5280 feet per mile == ~4000 feet height. But yeah, gravity storage as part of the Turbine itself doesn't seem too useful.