Hydroelectric Power

I would like to call this “hydropower” instead of hydroelectric, but that’s the common name that everyone uses. The thing is that we have been using some form of hydropower for a long time—the water wheel is much older than the invention of electricity. In terms of electrical energy, it’s not too complicated. In fact it’s mostly like the electrical energy from fossil fuels. However, instead of using steam to turn an electric turbine you use falling water, or, technically, moving water resulting from a change in height.

The key to all forms of hydropower is that water wants to move down closer to the center of the Earth. When 1 kilogram of water moves down 1 meter, the change in gravitational potential energy is about 10 joules (yes, it’s the opposite of lifting up a textbook). That might not seem like a lot of energy, but now imagine moving an entire lake lower by 1 meter. That’s a bunch of energy.

But would we run out of hydropower? What if we take all the water that is above sea level and move it down to sea level? Well, that would be the end of hydropower. But it won’t happen because of solar power. Yes, hydropower is a form of solar power. The Sun heats up water and causes evaporation. This means there is water vapor in the air which eventually comes back down to the surface of the Earth to fill up all those lakes and stuff. Hydropower is as renewable as solar (as long as the Sun keeps shining).