Build a sleek, modern (and adorable!) walking robot powered by salt water and magnesium — no batteries required! Discover how a metal-air electrochemical cell stores and discharges electrical energy using a simple saltwater solution. Explore the science of electricity, currents, and electric potential. An innovative pump mechanism provides a steady drip of salt water onto the magnesium plates and the robot walks for up to one hour on just one drop of salt water! The “fuel” bottle is easy to clean, refill, and reuse for hours of exploration. A full-color manual includes step-by-step assembly instructions and delves into how this green technology offers a truly safe, non-toxic, long-lasting, and renewable source of energy.