How Hundreds of 24-Ton Bricks Could Fix a Huge Renewable Energy Problem

Imagine a gigantic brick of highly compressed dirt -- as big as a pickup truck but, at 24 tons, about five times heavier. An elevator powered by solar panels or wind turbines hoists it over 300 feet up the side of a huge building, and a trolley stows it inside. But it's not alone. An automated system lifts and stores hundreds more bricks, like giant Pez candies, as the sun shines and the wind blows.

Now imagine the building's control system lowering those hundreds of bricks one by one, spinning electrical power generators in the process. They drop down every evening just as demand for power peaks but solar panel output fades away.

In effect, the brick-filled building is a giant battery that stores energy with gravity instead of chemistry...