That's a cute idea but it does not work, if you run the numbers. The formula for potential energy is mgh, where m = mass, g = gravitational acceleration (appro

That's a cute idea but it does not work, if you run the numbers. The formula for potential energy is mgh, where m = mass, g = gravitational acceleration (approx 10 m/s2) and h is the height. Let's say the vertical tunnel you want to build is 200 meters deep and 1m by 1m. Half of the shaft is rock, it's the thing you lift and lower. That's 100 m by 1m by 1m, which means 100 m3. You use lead, which has a density of about 11 tons/m3. Let's round to 1000 tons, or one million kg. Moving this column of lead from the lowest point to the highest requires the energy of mgh = 1 million times 10 times 100 = 1 billion Joules. Divide that by 3600 and you get about 280 kWh. For comparison the battery of a Tesla S has a capacity of 100 kWh.