The Gravity Harvester


Introduction: The Gravity Harvester

About: I am passionate about anything and everything engineering and physics. I am interested in much of chemistry and biology and I enjoy most art and craft + cooking and baking. I have completed my bachelor's in ...

This is a concept based on a idea I had on harvesting gravitational potential energy from rain or any elevated source of water.

The system works by having a pair of tubes that contain a cup each. When the cup is at the top of the tube, a valve opens allowing water to fill the cup. As water fills the cup, it gets heavier and starts to move down the tube. Once at the bottom of the tube a valve opens to drain the water, thus the cup is now lighter and can be pulled up by its partner cup that would be filled with water. The pair of cups moving up and down alternatively via a chain can now power a generator by meshing a sprocket to the chain.
An interesting feature of this design is that you can line up more pairs so you have a row of them and it would improve the output you can get.
Another possible configuration to "stack" the system is to have the pairs where one is upstream of the other thus requiring only one water channel

In this step the 2nd and 3rd pictures show the starting position of each cycle, half way through the cycle the condition is just mirrored where the left side cup is at the top and the right side cup is at the bottom

Here are the screenshots of the design in made in Solidworks
(I really wanted to put in an animation of it working and spent many hours/days getting it to work but my laptop just cant handle it and crashes too much to get any usable animation. but i will try and get one in later)

Please vote for me in the CAD contest if you like this concept, I hope to get some of the parts printed so I can actually test out the device as my access to tools and materials to fabricate this is very limited and quite insufficient.

As pointed out by Kiteman, frictional lose will be an issue, thus maybe the tube can be switched to a pair of guide rails since the tube is only there to guide the cup to the valve mechanisms. As for friction in the chain i guess we just need good lubrication

Step 1: The Cup

The cup is shaped to push the tube's valve open when its at the top of the tube to allow water to enter through its 2 openings.
When the cup reaches the bottom of the tube a plunger in the tube pushes the cup's valve open and drains the water

Step 2: Chain

I have also made the chain in Solidworks, pretty straightforward

Step 3: Final Word

I am really hoping to build a model of this design and I am looking for ways to build it even as I type this out. I hope to polish this design and maybe one day make it good enough to be commercialized and let every home be able to have their own mini hydroelectric station when it rains. I would also like to note this system is not only limited to rainwater, I see its potential to be used in many other places, anywhere a liquid has to travel downwards. This system might even be able to run on fine particles like sand, rice, flour, or even ball bearings. Lets reclaim that vast amount of energy of  Mass X Gravity X Height (mgh)

If anyone is interested in expanding on this idea or have questions please feel free to contact me.
Also I am still quite new to Solidworks, so any tips (exp:" you could have done ... instead of ... , that makes it faster and uses less system resources") would be extremely welcome

I hope you like my idea to help with the energy crisis. I would greatly appreciate any constructive feedback 



    • Water Contest

      Water Contest
    • Oil Contest

      Oil Contest
    • Creative Misuse Contest

      Creative Misuse Contest

    17 Discussions

    what about something like those autofilling and dumping buckets that you see at swimming pools as a play feature?

    The theory is that the water will fill the cup and run it down to the bottom ongoing the collection shaft. At this point the cup at top will activate the valve an fill with water as well. And repeat the cycle.

    2 thoughts, why not just replace the other cup with a weight? Then when the cup empties at the bottom the weight would reset the location of the cup.

    2 this seems to take up a lot more space than a few simple water wheels would. Especially if you are using this "chute collection" method.

    You could even use the same cups and chain for the conversion to the water wheel.

    3 replies

    To answer the first question, I want to try and use as much of the incoming water as I can, so this speeds it up. And If you use a counter weight consider these 3 weights
    A) weight = cup, the cup goes down well but might have trouble going back up since we want to turn a generator
    B) weight > cup, the cup goes back up well but will go down slower and face more trouble going down
    C)weight < cup, well i dont think its going back up
    By having both cups change their weight (light when down, heavy when up) we get the best results

    B) weight > cup, the cup goes back up well but will go down slower and face more trouble going down

    let me rephrase that,
    the cup has no problems going back up but more water is needed drive it down as opposed to having an empty cup on the other end

    water wheels and turbines might work better or they might not, I am proposing and alternative that might shine under certain constraints


    5 years ago

    what energy crisis? we have enough coal and natural gas to last us hundreds of years

    1 reply

    Haha maybe its not a crisis, but how wide does your scope of "us" go? and green energy is a thing now-a-days
    Anyway in many countries we get lots of rain and I feel its such a waste if it does nothing, many people collect rainwater for various uses, why not harvest the energy as you collect the water.

    The method I described would be more efficient and less complex. The more direct the more efficient. Wasting energy on cogs and valves etc. you could probably turn a CPU fan into a make shift turbine for testing both methods.

    1 reply

    This is a clever "small footprint" design, but there would be a lot of friction losses. You could, instead, use an automatic syphon to dump tanks of rainwater through a turbine, or, if you have space, build a see-saw affair, where the length of a lever is used to amplify the force of the weight of the cibtaiber of rain.

    3 replies

    I thought about the frictional losses too, but since the tube is only there to guide the cup, I think the bulk of the tube could be replaced by a pair of rails with bearings on the cup. Thanks for the ideas, i am not familiar with the see-saw affair, will look into it.
    The siphon would stop working when there is no water and require a manual "restart" when there is water right?

    Automatic syphons self-trigger when they fill to a certain level.

    Scroll down:

    Definitely interesting but it would be more efficient to trap the rain in like a bucket and have a little turbine at the bottom underneath a small hole. The water would rush out the hole at a fast rate and spin the turbine directly generating power. Let me know how you go

    1 reply

    That is a much more direct approach, simple and effective.
    But I was hoping to find a more efficient method, not sure if this is it as i can't test it or run simulations due to performance.

    Thanks for the feedback!

    Yup, the idea is to have it fixed to the gutter but i might have forgot to mention it

    Also it is probably better to attach this to a houses down pipe. That way you have a large surface area of rain to use. Rain on its own just out somewhere wouldn't do much