Hi All, this question has been thrown around before but never fully answered so I'll put it very simply and cut out the ponderings: A 'gravity battery' could be created by using an energy source to slowly lift a large weight (using gearing or pulleys), then discharged by lowering the weight to run a generator when needed. Kind of like a giant grandfather clock. The effect would be the same as using a Tesla Power Wall but with cheap materials, no heavy metals, unlimited lifetime, and the ability to be infinitely reproduced inexpensively- making it economically viable. But what about physical viability: The gravity battery would not have to power the entire house at current U.S. electrical consumption rates (a previous debate in this forum - answer is it can't), just as the Power Wall is not designed to do this. The Power Wall is designed to assist by storing 10kWh of electricity, diffusing the power grid and helping to solve the biggest current problem with renewables - the fluctuation in production. I am not a physicist, so: Assuming a 5m drop length (about right for a house) what mass would a weight have to be to store 10kWh of electricity? More importantly, when you factor in likely energy losses and efficiency, could a gravity battery compete with a Power Wall as an economically viable power storage device?? Please approach this with an open mind. If we could somehow work our way through the practicalities just think of what this approach could mean for us, for developing nations, and for our energy future. I'm looking forward to some great minds and optimistic solutions here. Thanks.