I want to build a green energy storage system. Where an engine lifts a big mass with the electric energy that is available at the moment, i.e solar/wind/grid. Then release the mass from about 30m - 50m to create an electric energy. Was thinking to use gear transmission to control the speed of the system energy discharge and electric voltage.
will appreciate an advice on the following:
1. How to I calculate the potential electric energy using the height and mass.
2. I also want to be able to calculate the time of discharge VS gear transmission VS mass VS height.
3. any recommendation of a design and parts type to purchase (turbine, dynamo, engines, gear transmission set etc.) will be appreciated.
A physical, rather than chemical, battery; what a cool idea Yonatan!
Welcome to Permies!
I'm no physicist/engineer, but your plan seems to be converting rotational kinetic energy into vertical potential energy, and vice-versa; in general, you're going to have a partial energy loss in transferring the energy between the two different systems(the friction of gears, activation energy, etc.) be sure to account for that in your design/calculations.
Also if your energy collection device(in my mind, wind) gearing does not disengage when the mass is triggered, you may have wind resistance during the fall(as the rotor spins backward), reducing your yield.
This sounds like an ideal application in a non-electrical system, similar to a ram-pump, where the wind would power a discrete task(grinding, pumping, lifting, etc), rather than charging a battery or producing electrical current.
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The simplest system for this that I am aware of is called a water battery. The basic design is two tanks with a change in elevation between them, there is a hydroelectric generator inline going from upper tank to lower tank. During times of excess energy production a small electric pump pumps water to the upper tank and it can then be released when energy is needed, turning the hydro generator as much as you'd like.
This could be a couple of 55-gallon barrels all the way up to several multi million gallon lakes
It's a great idea. Just make sure you appreciate the scale of things. Think about how much work an electric motor can do when lifting weight. The same weight can turn the motor and it will generate about as much energy as was used to do the lifting (minus some lost to heat and mechanical inefficiencies). Quoting myself shamelessly from another thread about a month ago:
A 1kW motor can winch a 1T mass up 10 m in just over 1.5 minutes (use a block and tackle, please). So you would need 40 tons of mass at a 10 m height to store 1 kWh of energy. A pretty frugal household (way better than mine) might use 10 kWh a day on average. So this means you would need 400 tons of mass lifted to 10 m to store that on a regular basis. Have a think about the sort of structure that you'd need to build to reliably lift and drop that amount of weight. That's where I bailed out.
Now, you might have a deep pit (think quarry) or cliff where you could rig something cheaply, in which case it would be incredibly cool. Or you might have a steep hill where you could build a cog railway and run wagons filled with dirt or rocks.
In a pumped hydro application, you need either a pretty big volume of water or a decent elevation gradient. Think on the scale of thousands of liters up on a hill. Again, there will be some losses from pump efficiency and friction. Like the deadweight scenario, it's totally doable but make sure you do the numbers to see what is required. If you've got the features on your site to make it work it's an awesome piece of appropriate tech.